Sv: Re: [sdiy] Sv: ARP Pro Soloist strangeness continues! SOLVED!!!

[Daniel Araya]

Per told me to check op Z24 (a LM301) and there it was!
I swapped it out for a TL071 and removed the compensation capacitor.

Many thanks to those of you that has helped me!

/Daniel

>>> Per Broberg <info at pbit.se> 08-06-03 22:23 >>>
Ah - you've got the same answer here...

/Skaune-Phaer


Igor_D skrev:
> Hi, Daniel.
> Imho, problem in opamp. It working as follower. Check voltage on pin # 3.
> Or replace OA.
> Igor.
>
>   
>> -----Original Message-----
>> From: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-
>> bounces at dropmix.xs4all.nl] On Behalf Of Daniel Araya
>> Sent: Tuesday, June 03, 2008 5:07 PM
>> To: synth-diy at dropmix.xs4all.nl
>> Subject: [sdiy] Sv: ARP Pro Soloist strangeness continues!
>>
>> A few month ago I asked opinions about a Pro Soloist that had the notes in
>> the octaves *reversed" when you played.
>> I got a few replies and looked at the obvious...like connectors in the
>> wrong way, shorts, bad sockets but no luck!
>>
>> I decided to have another look at it yesterday and the keyboard encoder
>> works fine according to the truth table in the manual but the D/A still
>> outputs the highest voltage (+9V) at the lowest key and vice versa! The
>> notes are somewhat out of tune  and the two highest keys have almost the
>> same voltage out so that suggests something wrong with the D/A resistor
>> network.
>> The signals on the first six resistors all seem ok but I'm unsure what the
>> NAND-gates further down do. I'll try to swap them out tonight and see if
>> that changes anything.
>>
>> D/A schematic
>> http://farm4.static.flickr.com/3068/2547452021_09c5baab28_o.jpg
>>
>> D/A circuit description (not that good)
>> http://farm3.static.flickr.com/2169/2547472603_53f9343f86_b.jpg
>>
>> full schematics:
>> http://www.poconothermionics.com/arp.html
>>
>>
>> Any help or theories are greatly appreciated!
>>
>> /Daniel
>>
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-- 
/Per Broberg

http://www.pbit.se

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