WIGGLING 'LITE' IN GUEST MODE

[davemoog]

I have a number of these old ARP 4012 modules. I have read that they were prone to failure? They seem OK. How did they usually fail? Anything to keep an eye out for when testing? High Frequency oscillation or what?

Thanks Dave

[Moog$FooL$]

hhmmm...

any chance there's a tempco glued over a trans. array??
common problem in some ARP synths.

other than that, i don't know?? someone's bound to come along & see this post though.

oh yeah, hello fellow Vancity - ite.

say hello in the Canadian eh thread if you've not yet.

[davemoog]

Well, glue barely describes it. ..they are completely potted in epoxy.

I was more looking for electrical/audio symptoms of how they fail.....i.e. distorted, unwanted hi-freq oscillation, no resonance....etc.. Internet references seem to suggest as "prone to instability failures" - really not sure what that means. The circuit is all discrete matched transistor pairs except using for a LM301 on the output. Schematic from Till.

[Moog$FooL$]

ah yes!! sorry.
i see they are those potted modules... my bad.

hhmmm... maybe try contacting the CMS guy, Phil Cirroco??