SH101 Strange Noise bleed

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ndrik
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SH101 Strange Noise bleed

Post by ndrik » Wed Mar 15, 2017 12:24 pm

My beloved pristine blue SH-101 is starting to show one strange sign of fatigue. After much googling, I simply cannot figure out what is wrong with it.

The current issue that I have is that whenever the GATE is opened, some strange digitalish and random noise comes out. This is totally independent of any VCO slider, FILTER (although it does get filtered a bit) or ENV settings. It’s like there is some strange bleed somewhere.
The clip below is how it sounds like.



This noise appeared all of a sudden, and does rise when the synth is started AND a key (or the GATE is open). It does react a little to the filter, but not much as you will hear in the clip. I believe it is not related to the PSU, as the noise is also there when running the synth on batteries.

This situation is somehow preventing me of playing with it, which is a shame… I'm hoping someone can help me out here?

Tech guys in Switzerland are crazy expensive, so I want to be able to debug the issue as much as possible before resorting to going to one.

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Re: SH101 Strange Noise bleed

Post by Solderman » Wed Mar 15, 2017 3:19 pm

I had a similar problem during modding and it turned out to be a disconnected common(ground) wire from the main board to the metal base of the keyboard. Might still want to take it to a tech if you don't know anything about servicing and repair.
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Re: SH101 Strange Noise bleed

Post by ndrik » Wed Mar 15, 2017 3:26 pm

Hi @Solderman,

Thanks for your response. I'm indeed not so experienced with repairs, but my neighbourg happens to be pretty good with electronics, so i'm hoping to ask him for help regarding soldering material etc.

Would you recommend doing this mod to fix my issue then? https://tubbutec.de/blog/sh-101-noise-reduction-mod/

I would love to take it to a tech, but 120€ just for an estimate of how much the repair might cost is a bit steep for me at the moment.

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Re: SH101 Strange Noise bleed

Post by jxalex » Wed Mar 15, 2017 3:40 pm

You do not know how much time it will take.
THe thing is that tech can spend quite much time (can be entire day or several days) to pinpoint the problem but it can be also 10 minutes and it is the time which costs.

The classical case with the repair bill:

1 resistor 1.2k 0.125W - 0.1 USD
putting in a right place - 200 USD
--------------------------------------
total - 200.1 USD

Which is totally unfair for a customer to point (well, hey it did not took so many details to repair the thing!). You can get that one resistor too separately for a 0.1 USD, but its no use if You do not know what exactly to do with that or where to put it. ;)

Various things can make this trouble. But if it is worse than faulty contact then it goes beyond the skills to just solder
properly. THere is certainly need for a oscilloscope. Just multimeter is not enough.


Open the synth and knock around the circuit boards and connectors lightly with a rubber hammer or a pencil. Is it on some particular area worsening?
How is it when the synth has been powered on for a hour? Better, worse?
Do it again.
Some solder joints bad due to heat expansion/bending, contacts loose can be found with this method. Somehow. :)

In worse case there is uncoupled DC in a signal path (due to bad capacitor or some problematic element).
All beyond that needs oscilloscope, or atleast some probe to check the signals and testpoints. And of course plenty of time and patience.
Last edited by jxalex on Wed Mar 15, 2017 3:54 pm, edited 3 times in total.

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Re: SH101 Strange Noise bleed

Post by ndrik » Wed Mar 15, 2017 3:49 pm

I'll check about the loose contacts and solder joints as you suggest. I'll post my findings ASAP.

The synths behaviour isn't worsening with time powered. However before i truly noticed this behaviour it was something that would worsen over time, until it was there from boot.

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Re: SH101 Strange Noise bleed

Post by jxalex » Wed Mar 15, 2017 3:56 pm

well it is then the classical repair bill you get I guess.
(see my previous post).
Also there is NO WAY to say how easy or how hard it is, to NO ONE. NOt even for a tech .

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Re: SH101 Strange Noise bleed

Post by jxalex » Wed Mar 15, 2017 4:20 pm

One thought more.

IF you neighbour is wideminded for equipment, ideas and experimenting daily, and loves the challenge (i.e. does hardware "hacking") plus also has all the needed equipment (oscilloscope, multimeter, re-soldering station and if needed SMD-rework station) then You are better off with Your neighbour and it is really better that You remember him after that in order to still keep the good relations. ;) ( At least that he will get the fee what the tech in Switzerland would have got instead. 100 EUR for a whole day work plus free beer (and/or chocolates) is totally ok. )
Certainly you need his help soon again with next equipment.

However if both of You just have only one difference -- that Your neighbour has a soldering iron and has used it sometimes -- then You are better off to send it to the tech if You cannot locate the fault Yourself. Just tinkering inside it without any knowledge nor measurement instruments will do more damage than repair.


Please note ASAP again how is the synth and what fault it was. ;)

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Re: SH101 Strange Noise bleed

Post by ndrik » Wed Mar 15, 2017 4:34 pm

thanks for the insight.

I'm expecting to pay a price for repairs, heck, I've been an architectural consultant in parametric design. I know how much an hour of work should cost. But the pricing I had was 120€ before knowing anything and then 120€ per hour of work. So a whole day here is more like 800€ than 200-300€.
I'm also aware it's impossible to estimate the amount of work needed. I had a superJX in the shop for 3 years, and 2 techs until i got it fixed in Luxemburg. This experience makes it so i don't really want to go down that road again and need a good tech straight away.

Anyways, I'm back at the 101 :)

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Re: SH101 Strange Noise bleed

Post by ndrik » Wed Mar 15, 2017 5:09 pm

So after much wiggling, I can't say any particular part impacts on the noise.

It is affected by the filter to some extent, but still comes through above the filtered signal (with all the OSC volumes down). Moving the boards a bit seem to have diminished it, but as the volume is random, it's hard to tell really. It's very hearable above a filtered sound, so the synth is still unusable as it is. Thank you all for your help and your time. I'm curious to figure out what the issue is really.

As I understand this could be suggesting it is a faulty part, but it's up to the skills of the tech to find it fast enough.
Any other hints are very much appreciated while I look for a technician. I reckon it might even be cheaper for me to travel to Berlin or Paris to have it fixed...

edit:

recorded a few more seconds while playing with the filter and the oscs.


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Re: SH101 Strange Noise bleed

Post by jxalex » Wed Mar 15, 2017 9:20 pm

Good that You understand. I hope we can give tips and hints here but it is You who touch that thing.
ndrik wrote:. But the pricing I had was 120€ before knowing anything and then 120€ per hour of work. So a whole day here is more like 800€ than 200-300€.
I'm also aware it's impossible to estimate the amount of work needed. I had a superJX in the shop for 3 years, and 2 techs until i got it fixed in Luxemburg. This experience makes it so i don't really want to go down that road again and need a good tech straight away.

Anyways, I'm back at the 101 :)
I am aware of these situations. BUt 3 years!!!
What that SuperJX did in the shop?! What was the fault with it anyway? Just out of curiosity. It seems that they were not interested.

well, then almost any synth costs less than the repairs when it comes to vintage synth racks... this kind of situations make me mad too and (So, the warranty replacement is the cheapest way, but heh, what if it is discontinued, or vintage already) ;-) ANd then comes the situation where I get a need for custom, modified equipment.

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Re: SH101 Strange Noise bleed

Post by ndrik » Wed Mar 15, 2017 9:27 pm

The JX had a faulty power supply, and one capacitor that was dead on the MIDI board, which prevented any MIDI of going out....

I indeed suppose they weren't interested.
I feel you when you talk about replacements and al. I'd rather not go that way if I can. I could easily fly with the synth and get it fixed somewhere else in Europe for cheaper (flight and hotel included). My issue with technicians, is that there aren't that many here and they are not that good either...

I've bene suggested on GS that it could be the VCA ic that's broken. My guess is that it is broken somewhere along the VCA, as all the rest seems to work perfectly fine. Gonna check with the neighbour how he feels about helping out and how confident he is about his skills :)

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Re: SH101 Strange Noise bleed

Post by jxalex » Wed Mar 15, 2017 9:35 pm

These 120 EUR/hour are really prices which show that there are seven other middlemans grabbing the money between the tech and customer, and so You make the other seven middlemans rich instead.

Faulty power supply... phew...! Thats a piece of cake actually to do even by-the-book.
OK, visit Your neighbour.

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Re: SH101 Strange Noise bleed

Post by Mooger5 » Thu Mar 23, 2017 1:10 pm

Mess with the power switch a bit and see if the noise changes. If yes, then clean the contacts. I think I recall having disassembled mine to clean it thoroughly (too many years ago).
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Re: SH101 Strange Noise bleed

Post by ndrik » Thu Mar 23, 2017 3:42 pm

@Mooger5:

I tried the wiggling, but that has no influence on the noise. I've been suggested on Reddit it's either the VCA IC - the BA662 - that's dying, or sliders dirty / going bad. As per this thread:

I'm going to the tech tomorrow, so will post my findings after that :)

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Re: SH101 Strange Noise bleed

Post by Mooger5 » Thu Mar 23, 2017 6:26 pm

The second audio example sounds like the Juno voice chips when they go bad, even after the acetone treatment. Reworking the solder joints usually fixes it. May not be the case here, but it resembles a lot.

So the noise appears only when the gate is opened?
A bad VCA means there should be a clean signal at the BA662 input, pin 3, without pressing a key, provided source mixer and cutoff faders are up.
If the noise happens when either ENV or GATE is selected, it could be TR28 gone bad.

Careful when desoldering components for testing or replacing. Pads lift off that type of substrate really easy.

Good luck.
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