Help - Tremolo Opticoupler Needed

[loumur]

Hi. I need help in finding a suitable replacement to my tremolo opticoupler in a 1969 Guild amp. The original failed neon/LDR is a Clariex Photomod CLM4120A. I found a Fender Vibrolux opticoupler from Antique Electronics for under ten bucks. Could I just use this as a replacement without adverse effects. Thanks

[Robert M. Martinelli]

Hi,
did you mean Clairex?

try this link, they claim they have the "original thing" in stock.

Clairex In-Stock Parts Catalog Page 1

Hope this helps

Best regards

Bob

[loumur]

Yes, that's it. Great find, I did a google search with various keywords and didn't find this vendor. I really appreciate your help!

Thanks

-Lou

[loumur]

Robert - FYI on 4StarElectronics

I just contacted 4star, they quoted me $40USD for the optocoupler. That's not the bad part. I found out that they (along with other obsolete electronic parts dealers I subsequently found) have a minimum order qty (4star is $100 per line item).

When I compare the purchase of an OEM part to using the Fender Vibroverb part as a possible substitute for $10USD, it's hard to justify spending $120 (w/o shipping). Maybe it's worth the experiment. I guess the other option is to use a Perkin Elmer Vactrol, but it's LED driven, and I'd have to modify the circuit to drive the LED, versus the ~100V neon bulb.

[Robert M. Martinelli]

Hi,
I'm sorry to hear that, I find their policy to the least questionable, but let this sleeping dog lie.....

If memory serves me well, the "old type" vactrols Fender used back in the old days were made by ( quite obviously ) an LDR and a neon lamp, just like the original Clairex, so chances are the one you found will work.

It's also possible that it won't work exactly as the old one did, though, and some circuit tweaking might become necessary; should this be the case, it would be useful to find both LDRs' datasheets to help you in modding the amp.

Hope this helps

Best regards

Bob

[loumur]

That's what I'm now thinking. I'd have to determine the properties of the replacement LDR in order to match characteristics as best I can. The amp is from 1969, and I'm trying to restore it. It's in such great shape that I really don't have much to do. Again, appreciate your help Bob.

Lou