MKS-80 transformer

The Roland Super-Jupiter (MKS-80) analogue synthesizer
catfish
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MKS-80 transformer

Postby catfish » Mon Oct 27, 2008 3:07 am

I'm looking to replace the transformer in my MKS80. Does anyone know a good source for a new one and what the specs are?

Thanks!
-B
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sjones
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Postby sjones » Tue Oct 28, 2008 1:50 am

Just out of curiosity, why do you need to replace it?

catfish
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Postby catfish » Tue Oct 28, 2008 2:11 am

It makes this awful buzzing sound (out of the back of the box, not the audio signal). It starts small and gains intensity until it's really loud and the synth stops working.

Before it stops working the audio signal acts like it has a really slow LFO on it, with each trigger being a bit different sonically from the last.

It's one of my favs, so it's a real bummer, no one seems to know were to find one. I've attached a picture of the culprit.
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sjones
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Postby sjones » Wed Oct 29, 2008 7:08 am

Have you replaced any capacitors yet? You might just need to do that.

catfish
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Postby catfish » Thu Oct 30, 2008 4:58 am

I replaced all the caps awhile ago. ALL OF THEM!

Most people I've talked to said that's generally the problem with old synths (it fixed my prophet 600), but alas, the MKS is still jacked.
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Postby Synthfool » Sat Nov 01, 2008 5:33 am

Most people I've talked to said that's generally the problem with old synths (it fixed my prophet 600), but alas, the MKS is still jacked.


No slam, but I repair synths for a living and don't recall having to replace a power transformer in any synth in well over 5 years.
It's not a "general" thing. It's quite a rarity really.
Misdiagnosed synths problems are pretty common though.

I would suggest actually testing the transformer before considering its replacement.
It's quite easy to test using a dual trace scope.
Your symptoms could also be a bad rectifier, transistor or power regulator.

Also since you say all the caps were replaced previously, I'm hoping the tech knew that one cap goes in backwards normally on one rev of SupJup - the silkscreen is wrong.

Best of luck,
Kevin

catfish
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Postby catfish » Mon Nov 03, 2008 6:37 am

Hi Kevin,

I agree with the oddness of a transformer going out, that's why I went for the caps first. The transformer's increasing buzz is what makes me think it's causing the trouble. I know they'll buzz if not well secured, but with this one the buzzing gets louder over time and that's when it stops making sound.

If I can't figure this one out I'm going to need a good Roland tech. What do you charge for a diagnostic?

Thanks,
B
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Postby Synthfool » Tue Nov 04, 2008 10:21 pm

I probably would have replaced the caps anyways myself, so it's a good thing you eliminated them upfront as the problem. :)


As for estimates, I don't provide that sort of thing any longer.
I might get into an instrument, then find other problems.
The instruments are larger variables then they were when new.
All instruments I see nowadays are vintage and all need a certain level of service.
So when one asks how much something will cost, I have no exact amount.
Most MKS80s serviced here have run $300 or less, if that provides any idea.

But the way I approach repairs is to offer the owner that if I can't repair it, they don't pay.
They still have to pay shipping and any parts installed, but I won't charge for failed attempts usually.

My costs are actually fairly low when compared to a service center.
I have much lower overhead than them.
But the flip side of the coin is that I have no shortage of clients, so if someone says they're going to pay and doesn't, lies, has an unreasonable attitude or whatever, they probably won't get in the door again.

noidear
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Postby noidear » Thu Nov 13, 2008 10:37 am

I dont mean to hijack this thread but while on the subject of power supplies for the MKS-80, is it possible to swap out the supply for an MKS-80 that is 110 Volt for one that is 220 V. I am in UK and have a 110 Volt MKS-80, rev 5 if that helps, and have been running it via a step up..or is it down...transformer without problems, but have often wondered if it was possible to get the supply changed and if so is it worth considering?

Thanks for any advice.

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Postby Synthfool » Fri Nov 14, 2008 3:06 am

You'd need a new transformer inside the instrument and obtaining one would probably be difficult.

It's easiest overall to do just what you're doing now with the external transformer.

So it is possible- the only thing different between these units are the transformer and fuses.
But it's still time and expense to basically get what you already have.

noidear
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Postby noidear » Fri Nov 14, 2008 10:55 am

Thanks for the advice Kevin.

Its good to know that it can be done, but I guess I'll just leave it at least for the time being, as it does work fine as is. I have a big sticker on the back of the MKS-80 near the power socket just to remind me that it is 110 Volts only, for when I am re racking things :)

Like you said, its all extra expense, so I can put that towards some other gear I have in mind....EMS VCS3 perhaps :)

Thanks again and I appreciate the advice.

All the best


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