[sdiy] Disassembling MKS-70 Power Supply

Bob Weigel sounddoctorin at imt.net
Mon Nov 3 21:38:52 CET 2008

Well...two JX8P's actually.  The JX10 has the same two JX8P boards in it 
but the MIDI is totally silly.  You can only do bulk dumps from a 
CARD!...for example.  The MKS70 has much better MIDI implementation.  -Bob

Csaba Zvekan wrote:

> Thanks, Bob.
> That's exactly what it was . It wasn't hard to get to the board  
> either. If you think they put two Roland JX-10s in a 3 HE Rack mount  
> unit. That's pretty cool :)
> So I put some flux on the regulator solder joints and added fresh  
> solder . I should have desoldered and removed  the old tin and 
> cleaned  pads. I was thinking of that later. Oh , well it works now 
> under  several hours of testing it seems fine.
> I have ordered some 6800uF and 4700uF that I want to replace them as  
> well. They took a lot of beating over the last 20 years, I assume.
> When I open up the unit again for that I will sure remove the old tin  
> and clean pads etc.
> Again thanks for the hint, it was very helpful.
> Csaba
> On Nov 3, 2008, at 7:13 AM, Bob Weigel wrote:
>> I don't recall off the top the circuit details but common problems  
>> are regulator solder joints on those.  If it shuts off after a few  
>> seconds that MIGHT be the problem..  On the other hand could be some  
>> leaking electrolytic or something.  But you have to pull a few  
>> things out as I recall to get that board out.  Get under there and  
>> verify the solder before you go to a lot of research time though and  
>> I'll bet you'll find the problem. If you have an esr meter it's nice  
>> to check the caps. -Bob
>> Csaba Zvekan wrote:
>>> Hi Group,
>>> My Roland MKS-70 (SUPER JX) 's power supply is failing . After two   
>>> seconds it shuts off. I am suspecting capacitors on the power  
>>> supply  board. Can anybody tell me an easy way to get to it. Before  
>>> I make  some stupid mistakes?
>>> It looks like I have to loosen the VOICE boards that are on  hinges 
>>> ,  right ?
>>> I googled the MKS series and they seem to be a bit flaky in age.
>>> Also maybe one of you knows already the problem. What's the deal  
>>> with  the sensing in the circuit ?
>>> Any help greatly appreciated
>>> Csaba
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