[sdiy] Disassembling MKS-70 Power Supply

Csaba Zvekan czvekan at gmail.com
Mon Nov 3 15:38:23 CET 2008


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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