[sdiy] Troubleshooting an ARP 2600

[Gavin Muir]

-- 
Hi all,

I'm doing some work on a friend's 2600 that he has loaned me, and I 
just wanted to run a few things by the list to see if anyone could 
give some guidance.

The synth is operating, however there are some circuits which are 
clearly dead. Firstly, the pulse converter on oscillator 3 is cooked 
(ie. no output). My suspicion here is that the op amp in the circuit 
is fried. Now, the service manual lists this as a strange part 
number; is this replaceable with a standard op-amp (I have heard many 
speak of replacing the 301s with LF411s)? If not, any ideas how these 
amps are selected and what may work here?

Second dead circuit is the S&H. I have been digging around the net, 
and have come up with a thread in which Joachim took part where again 
the problem was the op-amps, and the LF411 was a recommended 
replacement. Is this the best part for the job in the 2600? Is it 
worth going through and pre-emptively replacing the 301s with 411s?

Cheers and thanks,

Gavin Muir