[sdiy] broken chorus on mks-30

[Bob Weigel]

PS I have NOS chips also in the US.  At the time I was figuring what I 
should charge it looked like a lot of valitility in the market and I 
wasn't sure what to charge.  I think after time I have enough stock and 
they move slow enough to put $20.00 on them.  The 3101 I had 6.50 on and 
I can't recall how I arrived at that price at all. 

Anyway the less seen part of my page is under the 'parts' link with 
'semiconductor' link from the main sounddoctorin.com/synthtec/synth.htm 
page.  I also recently got a large quantity OF POLYSIX RAM!!  Will make 
quantity deals on those for anyone who wants to build expanders for a 
ps6 etc. Some yamaha's use those chips too I noticed.. can't recall 
which device it was. -Bob

Jason Proctor wrote:

> i found the jx-3p schems easy enough and then cross-referenced the 
> chorus chips with bob's site - the BBD chips are mn3009 and mn3101. 
> senso has these for E18 and E3 respectively.
>
> ISTR reports of other Roland synths needing replacement BBDs a while 
> back? a 5 minute search didn't bring anything obvious up.
>
> either way, parting out a mostly working instrument angers the synth 
> gods, so don't do that.
>
>
>> I pulled my mks-30 out of the closet and found that it is no longer
>> working %100. The synth works perfectly until I turn the chorus on.
>> With chorus engaged the output is distorted and I hear a loud hum.
>>
>> I can find schematics for every part of the mks-30 except for the
>> power board that has the chorus circuit on it.
>>
>> Has anyone experienced a simmilar problem and know how to fix this?
>> Maybe they have a scan of the schematic?
>>
>> In exploring the synth which has 6 perfectly working 80017A chips I am
>> wondering if this synth is worth more as parts then as a working
>> synth? For example the the 80017A chips sell for $60 each x 6 = 360USD
>>  while the average mks-30 only sells for about $275.
>>
>> cheers,
>> Danjel
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