Old 08-03-2020, 03:41 AM   #1
ramjet1962
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I bought some new cables to be able to connect my OEX-6sr output expander from my ASR-10 to my audio interface and then on to my speakers.
Hum and lots of it.
Disconnect all the cables and no hum. Connect all the cables and disconnect the mini MIDI cable to the ASR-10 and no hum. Both logical.
Connect the mini MIDI cable to the OEX and use one of the cables from my monitors which uses TRS plugs and 2 cores plus the ground, but the ground is only connected at one end. I believe that this is called 'ground lifted'?
The cables causing the issue are just TS plugs, so if I am not wrong, these cannot be ground lifted as they only have 1 core plus the ground shield.
So does that mean that I need to make my own cables with TRS plugs and 2 core plus ground shield wire?
I presume that nothing can be done with the mini MIDI cable prior to the OEX as any audio signal is only present after the DACs inside the OEX?

Have I got this right?
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Old 08-04-2020, 03:42 AM   #2
Allybye
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Suggestions but I am not familiar with the specific items!
Let's hope you are not shatter......same caveat!

Two main causes are likely.
1. A fault....we hope not. Make sure asr and osx are both powered off before connecting disconnecting the digital link cable!
2. Just a ground loop or two.

Hopefully the following will help to get I to to find out which, the problem and how to address it!

I cannot find a manual for the ASR10 or a spec but have located a user manual or the OSX-6sr which only gives limited info.

Your post is a little short of info so can you add:

Which audio interface you are using?
Which speakers are you using for monitoring? Powered? Using balanced inputs?

Can you confirm that what you call the midi cable is the digital cable linking the synth and expander?

When you connect your monitors directly to the OSX do you get any hum and if not how much gain is otherwise being provided by the interface inputs. Are you connecting to a mic input or a line level input?

When you connect your monitors directly to the OSX do you hear your osx/synth outputs on the aux connectors?

Further explanations:
Cables.
Do not alter the digital/midi cable!

One thing I am trying to find out is if the OSX output is balanced (monitoring question above) i.e using a trs socket (do you have the spec for it?). I expect the Aux outputs are at line level. Any idea? They may be but unbalanced.

If your interface interface has balanced inputs then there is a method to cope with it all even if OSX outputs are bal or unbal.

You cannot just lift the "ground"/screen on a TS (i.e. unbalanced) connection.
TRS cables that are balanced can have the screen 'lifted' at one end and still pass a signal. However some TRS connectors are for send/insert signal i.e. two way unbalanced signals and the ground should not be lifted -again reason for one of the above questions!

Last edited by Allybye; 08-04-2020 at 03:54 AM.
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Old 08-04-2020, 01:36 PM   #3
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This stuff is usually caused by poor power supplies in computers.
I just use an isolator directly before the Monitors.
http://orchid-electronics.co.uk/dual_isolator.htm

That guy is actually really cool if you are in the UK, pretty much unbeatable on price, and when I went round to see him (Hes down the road here) he was doing a DI repair under warranty, the DI was nearly thirty years old hahahaha.

But yeah, my set up is so much better since using an isolator.
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Old 08-05-2020, 12:50 AM   #4
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Hi Allybye,
I am going to try and let you know what I have found out from asking the guy that used to do all my repairs, but sadly has hung up his tools.
He has told me that the 6 outs on the OEX-6sr expander would all be mono TRS.

My interface is an ESI ESU1808 interface and all the inputs (according to the book) where I am plugging the cables into from the OEX are balanced.
Monitors are Mackie MR8s. Powered and had to use ground lifted cables to avoid the hum in them when I first connected them to the ESU. So when I have connected the cables from the OEX-6sr to the interface, I wondered if the interface was causing the issue? However, I have two cables from the outputs on the ESU to the ASR-10 (sampler) so that I can sample things into it via either my MAC or the other keyboards that I have. That signal is noiseless so that sort of rules out the ESU

I also have a microKORG and an ESQ-1 hooked up to the interface and neither of those has any issue with hum.

I tried last night with hooking up a speaker directly to the OEX using one of the ground lifted speaker cables and also one of the mono TS cables and then selected the correct OUT via the ASR-10 menu. I have more work to do here because even connected up this way with the correct AUX OUT selected, I get no sound from the monitor. Checked the keyboard volume and it wasn't that.

I'll do more on the weekend and write down everything so that I can try to hopefully work it out.
The Mackies are connected to two OUTS on the ESU that are a mix of all of the inputs into the interface.
I might try connecting the monitor cables to two other OUTs and see if that changes anything.

Hi Win,
I will have a look this isolator thing and see if that may be an answer.


Bloody frustrating.
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Old 08-05-2020, 01:49 AM   #5
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Isolating transformers could solve a problem of ground loops...but in the right places!

Will have a look at the interface spec.

You cannot go just plugging the wrong sort of cables into connections and expect them to work!

If the problem is ground loops then it is not any particular device that is at fault rather the connection of too many grounds/screens creating a loop with some differential voltages (ever so small) at points giving a current round the grounds.

Your system is more complicated than at first described! Could you draw out the devices and the connections (showing levels -particularly the input sensitivity in general such as mic, line, instrument etc.) and if they are balanced or unbal (TS will be unbalanced!).
It would be good to also show how things are powered (internally, external power supply, wallbox -as they seem to be known- i.e. plugtop switching, usb etc.) and if they are all getting mains from the same location i.e. socket.

Usb seem particularly problematic.
All that will enable better guidance on how to connect things.
No doubt 20 transformers at megadollars might solve it too!! but that would be overkill, expensive and require the correct types in all locations. A last resort! There are cheaper and easier solutions. Transformers have their downsides too!
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Old 08-05-2020, 02:21 AM   #6
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I've just thought of something else.

How am I getting hum through the monitors when they are both running ground-lifted cables?
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Old 08-05-2020, 05:16 AM   #7
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Originally Posted by ramjet1962 View Post
I've just thought of something else.

How am I getting hum through the monitors when they are both running ground-lifted cables?
That doesn't say much. Only that the hum probably comes from another point in the chain. Or maybe that you need a ground on the monitor cables?
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Old 08-05-2020, 07:59 AM   #8
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The um is being generated or picked up somewhere. That is what we are trying to find for you.
The monitors are just reproducing it.
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Old 08-05-2020, 01:58 PM   #9
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Based upon the info you post and what is available on the net for the devices ASR, OSX,ESU1808 and the Mackie's.

Your Mackie's are designed to allow balanced input. That's best.
Your 1808 is designed to use balanced outputs that is best and feeds the Mackie's (currently). Leave that working connection as is.

The 1808 has (according to manual) balanced and unbalanced inputs. Best to use the balanced inputs.

That was the easy bit

The ASR and OSX manuals online (all I have found) are, to be kind, rubbish as far as the specs go.
The ASR inputs have some spec but the outputs just say line level. No mention of bal or unbal! Some mention of ground loops and ground lifting. DO NOT lift any of the safety grounds!!! Do not follow what they show in the manual!

The OSX manual is nearly as bad, just no mention of output type of level
....both despite pro claims as far as I see!

This leads to my reasonable assumption they are all line level unbalanced outputs using TR jacks. So, should be fed into line level inputs.

That output type is not ideal from the point of view of hum and other noise rejection by the following balanced inputs. Also with the wrong connector types you can end up with no signal too (such as when you connect monitors to OSX.

Suggest the following.
Firstly disconnect the miniKorg and Esq on a temp basis from the interface and the two cables from the outputs on the ESU to the ASR-10 (sampler). They can just confuse.

Next to correctly interface the OSX to interface balanced rear inputs either:
a)
If you have to have the skills and bits use twin and screen connect (for interface ) a TRS to on end red to tip, blue to ring, screen to screen.
At the other end (for OSX) solder red to 270ohms resistor and the other end of resistor to jack tip, and solder another resistor (identical value 270ohms) to blue wire and the other end of the resistor to the jack screen. Do not connect the cable screen at this end -cut back and insulate.
This will give a cheap test connector to see if when connected between expander and interface you get signal and no hum.

or b)
A bit more expensive option
Buy one of the isolating transformers (as mentioned in an above post). It needs to use TS jack for the expander end (or a suitable very short adapted cable!) and a TRS one for the balanced interface end connected with a standard TRS balanced cable.

Try one or the other on a single channel a or b optional, you choice.

We can then progress from there, hopefully!

Note Beringer sell a useful 2 channel isolating transformer for about £40 UK so maybe about 80 AUD which might be more available for you.

If anything is not clear feel free to pm me.

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Old 08-08-2020, 12:25 AM   #10
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I will be getting into all of this trying to sort out based on your reply above.
Spent bit of time putting this together. Just hope it makes it onto the forum correctly.
I got a bad hum again once the OEX-6sr was connected.
Hopefully this will give everyone a better idea.
I will go through a bunch of steps as outlined by AllyBye and will let you know what I find out.

The microKORG and the ESQ-1 are now connected to the front inputs on the interface which are apparently optimised for unbalanced inputs. The ASR-10 and the OEX-6sr are all connected to the rear inputs which are optimised for balanced inputs.

I am not sure if an isolating transformer would work as I wasn't getting any hum before the OEX and the cables to the monitor are already 'ground lifted' which is what I presume the isolating transformer does?

Could I also ask, why 270 Ohm resistors?

Just been trawling through the Behringer website, but I can't seem to find the transformer that you are referencing?
Attached Files
File Type: pdf Studio Connections PDF.pdf (89.0 KB, 198 views)
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Old 08-08-2020, 03:09 AM   #11
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Do not confuse lifting screens/ground connections in cables with using a transformer. They have different actions!
Both are methods to remove ground loops.
A transformer uses the signal between source hot and cold connections be they from an unbalanced source (hot wire and ground [local to source]) or a balanced source (between the two balanced connections ignoring the third ground connection). The output feeds the destination loads input, again on two wires. Thus there is a signal connection source to destination but no ground connection being isolated by the transformer (called galvanic isolation).

The simple action of lifting a ground somewhere to try and cure a hum problem by
a) lifting (disconnecting the screen) on an unbalanced source signal (two wire, one hot and one ground) means that either the signal path uses another possibly circuitous routed ground from who knows where in an uncontrolled manner (with probably a poor and variable connection quality

b) disconnecting the ground connection (safety earth) to a device is unsafe potentially resulting in shock under a fault condition or at best damage to the equipment.

c) disconnecting a screen on an unbalanced source feeding a balanced input can have no effect whatsoever and will not make signal connection necessarily if the connections between the two are not properly configured.



Adding the resistors.
Balanced connections come in various forms. The simplest is purely when the impedance at the source of the two signal lines ( the hot and cold of the screened cable) to that local source ground are identical.
This allows the destination load input to differentially amplify the input signal. The true signal is different on both sides but 'picked up noise' is common. Thus the wanted signal is amplified and the unwanted hum/noise etc. is cancelled -in very simplistic terms!

We do not know the output impedance of the OEX but is likely very low. I have made a pure guess at under 50ohms so estimate (a more educated guess!) That 270 ohms (a common resistor value) would make the desired identical values mentioned above good enough for a test! (Cold connection 270ohms to ground, hot connection 270+ OEX output impedance ohms to ground).

The value could be a bit higher if more convenient but should be no more than a fifth or so of the input impedance of the interface to avoid signal loss. The 1808 line inputs (9 to 16) are 10k so up to 2k would be fine without a big signal loss. The mic inputs are 1.5k so 300 ohms would be max.

Keeping the resistor low keeps general noise low hence just advised 270! As you are using the bal line inputs picking the higher value (as above) would be a better test!


Phew! Did you get to the end or get lost in the Fex werds description!

Best when testing as per previous post to have Korg and output to synth from interface unplugged.
Note the outputs are not 'optimised' for balanced...they are balanced and really ought to feed into balanced inputs...but that should be for later!

As far as transformers are concerned I located several online sellers such as https://www.amazon.co.uk/s?k=hd400&ref=nb_sb_noss I assume a down under equivalent?

Last edited by Allybye; 08-08-2020 at 12:47 PM. Reason: link changed.
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Old 08-08-2020, 04:17 AM   #12
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Thanks for your reply.

I have a bit of mucking around to do tomorrow.
For some reason, every time I click on your Amazon link I get an error saying the Page No Longer Exists.
Doesn't matter though I went and found a link to an Aussie place that carries the HD400.
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Old 08-08-2020, 12:48 PM   #13
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Sorry, yes that link had a problem! I have updated it.
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Old 08-08-2020, 03:32 PM   #14
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Originally Posted by ramjet1962 View Post
Doesn't matter though I went and found a link to an Aussie place that carries the HD400.
Couple of places have them for $49.

If you're handy with a soldering iron these with mu-metal shielding aren't too bad: https://www.photonage.com.au/10k-10k...er-p-9439.html

(As I understand it, "Geelong" is the Aboriginal word for "Place of many bollards")
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Old 08-08-2020, 10:18 PM   #15
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Well I'm really confused now.
I have read that you will only see the AUX 1, 2, 3 OUTS if you have the card in your keyboard. I have and I get the AUX options. I have removed every cable going into the ASR-10 and connected my headphones to the AUX3 out on the OEX. Loaded an instrument, changed the output to AUX3. Nothing.
I also got the OEX-6 when I got the keyboard, so to eliminate that I may have a dud OEX-6sr, I hooked up the OEX-6. Still nothing.
Then plugged my headphones into the Right OUT on the ASR and loaded an instrument up and changed the OUT again while playing the keyboard. When the OUT becomes any of the AUX OUTs, no sound which is exactly what should happen.
My headphones have a TRS plug so I would expect that I should get something when I select an AUX output when connected to either of the expanders?
I would also point out that there is no hum.
What I am confused about is that I cannot get any sound out of the outputs on either the OEX-6 or the OEX-6sr that I have.
If I have done everything correctly in the ASR to select the AUX out (I did follow the manual to the letter), that makes me think that the output expander card in the ASR is shot or the cable that I have is no good. It is brand new. It is 8 pin mini DIN and it is a standard cable.
Garth from Chickensys confirmed with me that his expander cable was standard. There is someone on the internet trying to sell cables and claims that they are not standard. i.e. same pin one end to the same pin on the other end.
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Old 08-08-2020, 11:33 PM   #16
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In answer to your questions AllyBye,

1) I cannot find anything on the outputs from the OEX-6sr. I believe them to be line level unbalanced outputs.
2) I isolated everything from the interface and worked straight to my headphones. As I said earlier, nothing at all.
3) I have never connected anything while anything has been turned on. Not to say that the previous owner didn't though.

I have just connected the ASR main outs and the AUX1 pair from the OEX to the interface and the speakers. Hum as I would expect. Loaded an instrument and nothing but hum.

I am not sure what to try now.
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Old 08-09-2020, 08:31 AM   #17
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Well you are confusing me too especially with your apparently random connections!
You cannot just connect a balanced input (TRS or XLR)input via the same type of cable connections with a TRS on the other end to an unbalanced output (like ASR or OEX) and expect it to work at least not properly unless the correct wires are connected correctly!

It does however surprise that your headphones did not let you hear any output. If they are stereo ones they will use a TRS with tip one channel, ring the other and screen the common for both. Plugging into your ASR or OEX outputs would expect just the tip channel to connect and get a one side headphone.
Unless there is insufficient drive coming out of the outputs of there is a fault. Best leave the headphones (or speakers) monitoring your interface and first prove you hear interface output with any signal. Leave them there so you know something is certainly working.

Do you have ANY configuration where the interface input can hear any ASR or OEX output (note if you have lots of loud hum you may have turned down the gain and just not hear any signal under the hum!!)?

Did you try adding the resistors as I suggested or getting a transformer. There are some very cheap of the latter on Amazon etc. Maybe not up to scratch for high quality but very adequate for a test!
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Old 08-09-2020, 12:00 PM   #18
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Ah!

Apologies I had missed the attachment that you had put in a post! That does help a bit!

Considering the blue audio leads from the OSX and the ASR into your interface.
I had understood that those were all TRS leads atboth ends ....
But I now see from your key they are all TS leads!

Feeding those leads (with the unbalanced signals) into your interface balanced TRS inputs makes your interface act as if it too were unbalanced plus connects the screens as well.

What you need at the interface is TRS connectors and cable....and then the resistors or transformer at the other ends as per one of my previous posts. In your case you need a transformer on each output so that becomes quite expensive. Suggest disconnecting all but one to try out the suggestion and then take it from there.

Will try and send you a diagram of that helps.
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Old 08-09-2020, 01:12 PM   #19
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Quote:
Originally Posted by Allybye View Post
Well you are confusing me too especially with your apparently random connections!
You cannot just connect a balanced input (TRS or XLR)input via the same type of cable connections with a TRS on the other end to an unbalanced output (like ASR or OEX) and expect it to work at least not properly unless the correct wires are connected correctly!

It does however surprise that your headphones did not let you hear any output. If they are stereo ones they will use a TRS with tip one channel, ring the other and screen the common for both. Plugging into your ASR or OEX outputs would expect just the tip channel to connect and get a one side headphone.
Unless there is insufficient drive coming out of the outputs of there is a fault. Best leave the headphones (or speakers) monitoring your interface and first prove you hear interface output with any signal. Leave them there so you know something is certainly working.

Do you have ANY configuration where the interface input can hear any ASR or OEX output (note if you have lots of loud hum you may have turned down the gain and just not hear any signal under the hum!!)?

Did you try adding the resistors as I suggested or getting a transformer. There are some very cheap of the latter on Amazon etc. Maybe not up to scratch for high quality but very adequate for a test!
Hi AllyBye,
The configuration that I attached previously worked fine if you remove all of the OEX-6sr connections to the interface. No hum and everything is recordable etc.
That is where I am back to at the moment.
Sorry if my explanations did not accurately depict what I was doing. I used the headphones yesterday so that I had access to TRS connector which I could connect to the OEX-6sr. No ouput has me quite confused though?
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Old 08-09-2020, 01:47 PM   #20
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It really is not surprising with all those interconnects that there is hum. It is very difficult to determine which connection(s) of ground(s) causes it. That is one reason that studio setups use balanced connections all over and the odd transformer to connect in unbalanced sources where necessary.sometimesjust pulling/adding one connection can have a big effect on hum but is is terrible to keep under control.

Still cannot understand why you get no signal via headset or indeed no obvious signal from OSX to interface.

Still suggest my earlier cable resister mod or getting a cheap transformer for test. Too many unknowns at the moment.

When you say that is where you are back at the moment Osx dissed from interface but Asr connected? (and osx still connected to the ASR?) do you get clean signals?

If so or (as the outputs from both seem to be similar in type and level) it points towards the expander having a problem. Difficult to diagnose remotely so can you find an electronics engineer to have a look?

If there is no hum with all connected as per diagram but the digital cable twixt synth and expander not connected that might just point to it causing the hum loop or a power supply issue in the expander. Really needs more tests and diagnosis locally.

Just another note on connectors. 'Generally' only plug in TRS plugs into TRS sockets; and TR plugs into TR sockets. Some other configurations can work but not really as intended. Unless you know what you are doing or are lucky best avoided!


Till you can do more of the suggested logical testing I am running out of new ideas!
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Old 08-11-2020, 03:14 AM   #21
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I've PM'd you ramjet.
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Old 08-30-2020, 12:49 AM   #22
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Well, I have made up a balanced TRS lead and a test lead as Allybye suggested in a) above. Tested with a multimeter and everything tests as it should.
Everything else is disconnected, other than the speakers (powered). If I plug the test lead into one of the MAIN OUTS and into a balanced input on the interface, I get sound on BUS 1, 2 & 3 as I should. If I change the output to AUX 1, 2 or 3, I generally get no sound. I say generally as sometimes striking a key does sound which it shouldn't do.
If I connect the resistor end of the test lead into the Oex-6SR. Nothing. It doesn't make any difference whether I select R or L outs, none of the AUX outs sound.

I also took the bottom off the ASR to check that the Output Expander board was all connected. Guess what? Flat cable was not seated home all the way on the board. Removed, checked and reseated. That should do it.
Nope. Didn't make an ounce of difference.

So it is a brand new 8 pin mini Din lead. I am going to test it with a multimeter to make sure that it is all ok.
If it is, I am officially stumped.

Well I just checked the lead. I am now officially stumped as to why the Oex-6SR does not output sound.
However, I am going to sideline it and go back to the setup that I had. The ASR, the ESQ and the liitle Korg could all play to the interface with unbalanced leads. Whether through the balanced inputs or the unbalanced inputs. I will revert back to that and I am out of pocket for the extra leads that I bought.
I have no idea whether testing the expansion board for the output expander inside the synth is even possible? If it is, it would not be by me.
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Old 11-08-2020, 01:25 AM   #23
ramjet1962
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Well I have finally had a bit of time to muck around with things and log the connections I have been making.
An unusual thing, which was not happening before, is that I was getting the electronic smell that you got when something is getting really hot? Then the main 2A fuse went and that was the end of things. Now rummaging through my boxes as I am pretty sure that I have some of these fuses. And no I don't. So off to Jaycar tomorrow.
The odd thing is that I can only recall getting the smell since mucking around with the expander.
With all of the connections that I have made, I have also still not been able to get sound from the AUX1,2, or 3 busses. I think I will simply put both my OEX-6 and OEX-6sr on the market and free up some space and not worry anymore about what I could have gained from it.
I am trawling through the ASR10 service manual now to see what sort of checks I can do.
A question for anyone that can try and answer it.
Would the continuing hum be the source of the main line in transformer overheating and blowing the fuse? This board does have a power supply takeoff which goes to the board that looks after the OEX so I am wondering if that could be a possibility?
The service manual has some voltage checks to follow so I will try and do those after I get a new fuse.
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Old 01-04-2021, 04:36 AM   #24
ramjet1962
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Hi everyone. I have not been able to get on much with working from home etc.
I have kept trying to make connections that made sense and have noted quite a few down using the cables that allybye suggested to me. I appear to get hum in just about every setup, if memory serves me.
Something I noticed while I was doing this, is that electrical smell that you get before everything goes pear-shaped on you.
Well sure enough, blew the fuse on the main in. I have replaced it, but then dove through the Service Manual to see what I could find.
So working my way through it, I get to voltage checks. Simple line voltage checks with unit turned off. All ok. Almost the same again with unit turned on. All ok.
Then there is a paragraph in the manual telling you how to check the 7 voltage regulators on the Analog Board. I am not getting the correct voltages on 6 of the 7. It actually got worse the longer I tested. I am not sure if that is things heating up or what I believe to be the issue. I had trouble suspecting that 6 of 7 solid state Texas Inst VR's had all gone bad. So then the manual asks you to check the supply voltages from the power board. Seems a bit of reverse thinking but whatever. Anyway, the power board supplies all test ok except for the supplies to the Analog Board.
Now here is where this gets a wee bit interesting.
I have got lots of hum. I have had trouble with no signal via the Aux busses to the OEX. When the OEX is connected was when the keyboard blew the fuse. I had no reoccurrence of any of that electrical waft when I was testing today.
The Analog Board looks after the following:
Main L & R out. Phones output. Line In L & R. Internal DACs. Power & signal via the 8 pin Mini Din cable to the OEX. Basically, everything that has not made sense.
I am wondering if this has been the culprit all along? It had to be working correctly at some stage as there are sticky notes throughout the manual from the previous owner about connections etc.
IO have actually disconnected the cable from the power board that goes directly to the Analog Board and still do not get correct voltages at the power board.
Now I just have to find either another board or an electrical type of fix-it-up person that I can trust to have a look. I suspect the transformer that sits on this board. None of the Caps look like they are bulging and nothing else sticks out as strikingly obvious. The transformer on this board is one of those glazed ones and that is the smell that I was getting. Much like a hand drill when they overheat.
I'll keep you posted.
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Old 01-04-2021, 07:33 AM   #25
mozart999uk
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Quote:
Originally Posted by Win Conway View Post
This stuff is usually caused by poor power supplies in computers.
I just use an isolator directly before the Monitors.
http://orchid-electronics.co.uk/dual_isolator.htm

That guy is actually really cool if you are in the UK, pretty much unbeatable on price, and when I went round to see him (Hes down the road here) he was doing a DI repair under warranty, the DI was nearly thirty years old hahahaha.

But yeah, my set up is so much better since using an isolator.
Thanks for this. He's not far from me either! What a great set of solution oriented products!
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Old 01-09-2021, 04:45 AM   #26
ramjet1962
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Well here's the next bit of news.
I asked someone on the internet that has an ASR-10 keyboard and a connected OEX-6sr.
After asking him, he confirmed that the cable was standard. ie. pin 1 to pin 1, pin 2 to pin 2 etc.
It appears that this is not the case.
The correct cable is wired differently. The fellow from Thesoniq said this to me today when I rang him.
So now I am going to purchase another cable and get that over from the US to me here in Australia. The postage is twice the price of the cable itself.
I hope that connecting this cable has not caused me other issues in the ASR-10.
I am getting some odd voltages in the power supply board as I said before this.

Stay tuned for the next enthralling update. Sigh.........................
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Old 01-17-2021, 01:43 AM   #27
ramjet1962
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Well after looking at the cables from Syntaur and adding postage, the price got insane for just a cable.
I am going to buy the bit I need from a store tomorrow and I'm going to make one.
I was able to get a drawing finally of the pin assignments on each end so that is safely saved on my computer now.
Once I have done that, I am going to cut the standard one that I have, rejoin it correctly and heat shrink all the individual joins and then heat shrink that area. Bit of work but there you go.
Hopefully that will fix things.
My next concern is what is going on with the power supply board and what might be causing incorrect voltages.
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Old 02-16-2021, 02:53 AM   #28
ramjet1962
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Well I simply cut off one end, soldered the wires onto the pins of the new plug. All checked and ok. Will now have a bit of a look at the power supply board and see if I can see anything obvious that may help with why the voltages seem to be all messed up.
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Old 06-12-2021, 01:29 AM   #29
ramjet1962
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Hi again.
I finally got my ASR back after repairs. I have also modified my 8 pin Mini Din cable so that it is configured correctly.
I will do some connection tests tomorrow and record everything that I do to see how I go.
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Old 06-14-2021, 11:48 PM   #30
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Hopefully progress. Good luck
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Old 07-10-2021, 04:31 AM   #31
ramjet1962
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Well I obviously have not had a chance as yet to do any testing. Life got in the way for a bit and then the surgery to repair my torn right bicep has left me unable to do anything with that arm so clambering around on the floor under the table to connect cables etc to test has not been possible. I am basically not allowed to lift anything more than a cup of coffee with my right arm.
Hopefully, going to get to it tomorrow. I have made up a spreadsheet that I will follow that shows what will be connected and what I get from the speakers.
Some of the setups are obvious that they will not cause anything, but are there for completeness.
Something that was suggested to me by a fried was to power the ASR-10 from a different power circuit in the house. Everything is plugged into the same power outlet so I will also try that once I run into a situation that causes a hum.
I am also going to make an effort to ensure that every audio cable crosses any power cable at 90 degrees as well.
I'll keep in touch.
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Old 07-11-2021, 01:07 AM   #32
ramjet1962
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Well I have good news and even better news.
I began working through my spreadsheet of connections tests and everything was going along fine.
At the point I thought I would have issues, I did.

I then got an extra issue on top off the hum which was a lot of crackling static.
It would change if I fiddled with the audio lead or the mini din lead from the Output Expander to the ASR 10.
I had this crackling with several tests. For some reason, when I had picked up the Output Expander to wiggle the leads, the hum and static disappeared. That change coincided with me lightly squeezing the top and bottom of the Output Expander together. Ok, different problem and result. If I went through the process of changing the output to the connected audio lead from the Output Expander, I got the instrument sound as I should.

Out came the screw driver and off came the cover of the Output Expander. I first looked to see if there was some sort of ground between the PCB and the case that contacted when I squeezed the case. Nope.
Ok. What else could change? Static when moving the leads. Ok. Connections. Bingo.

The hum and the keyboard issue that I had awhile back was caused by an incorrectly wired mini din lead. I got the keyboard fixed and I corrected the wiring in the lead.
The hum this time was caused by the replacement plug that I had soldered onto the lead being too big for the hole in the case of the Output Expander. Took the PCB out and out with a rat tile file and opened the hole out so that the plug casing could fit through. Put the PCB back in and test. All ok.

Went back to my keyboards and connected things up. Working exactly as it should and no noise whatsoever.

So, all it was this time was the pins in the lead not making full contact with the connections in the plug.

I suppose that going through all the tests helped me with problem solving and going through the process.
I am stoked that I have it working now.
From the tests that I have done, I am fairly sure that I don't need ground lifted TRS leads between my audio interface and my monitors. This has me stumped a bit as when I first connected things, I ended up with hum through to the monitors. At that time the Output Expander was not connected as I did not have a lead.
Why the hum is no longer there, I am not sure.
Oh well, never look a gift horse in the mouth.
Thanks to everyone who offered advice and assistance.
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Old 07-12-2021, 06:14 PM   #33
ramjet1962
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I had a bit more of a think about things and I think that there was an issue with the transformer that finally failed from when I first got the keyboard.
The ASR was the keyboard that forced me to get ground lifted cables. It worked, but hummed when connected.
Hooking it up with the wrong cable to the Output Expander blew that transformer up.
Now that it is fixed and I have the correctly wired cable between the ASR and the Output Expander, I have used balanced cables between my audio interface and my Mackie monitors and there is nothing but sound coming out that is meant to come out.
So I'll modify my ground lifted cables to be balanced cables again, turn the test lead the Allybye had me make into a balanced cable as well and everything will be good.
Every other audio cable that I am using is unbalanced.
I was really close to selling the Output Expander due to frustration, so happy that I did not give up.

Serendiptous to be truthful.
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