[sdiy] Disassembling MKS-70 Power Supply

mark verbos mverbos at earthlink.net
Tue Nov 4 01:18:46 CET 2008


My S-330 used to have this problem where it would not want to power  
up if it was cold. Once it was on, it stayed on forever. After years  
and years of this, I opened it up and found a hairline crack in a  
trace, so small I couldn't even see it. I spread some solder across  
it and everything was fine forever. Well, I sold it a couple years  
ago, but it was fine then still.

Mark




On Nov 3, 2008, at 4:23 PM, Dino Leone wrote:

> that's so interesting. Mine has the exact same problem. I found  
> that after it has turned off, it comes on again when I touch one of  
> the power transistors (even with an insulator). I need to check  
> those solder joints again.  Thanks for posting this!!
>
> Dino
>
>
>
> On Nov 3, 2008, at 6:38 AM, 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
>>>> _______________________________________________
>>>> Synth-diy mailing list
>>>> Synth-diy at dropmix.xs4all.nl
>>>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>>>>
>>>>
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at dropmix.xs4all.nl
>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy




More information about the Synth-diy mailing list