Fender trem roach in Ampeg?

[LarBal]

Gemini I, circuit G12, just trying to get the trem going. Shotgunned all the caps, and new tube. Overall amp volume changes when turning intensity pot, but no trem . From what I understand, that means the LDR device is bad.
Customer isn't too concerned about the trem, he said if easy fix , do it, if not, forget about it.
I have a Fender roach here, but I'm a bit confused on how to orient it. Will it even work ? https://ampeg.com/data/6/0a0005091ab...plication/pdf/

[Helmholtz]

First you need to identify the LDR leads using an Ohmmeter.
The other 2 leads belong to the neon and should measure open.

[LarBal]

Thanks, so when I took it apart from it's shrink wrap (it clearly was spliced in at some point in this amp's life) this is what I had. The top 2 black leads went to ground and voltage, and the bottom 2 went to the pot (X and Y on scheme). This is clearly not correct as you can see there is continuity between the 2 legs on the left. I will say that when IO took it apart, the bottom left leg was not soldered to the LDR lead, which made even less sense, but now I realize soldering it back to the spot it was certainly shorting to at least intermittently inside the shrink wrap, doesn't make sense either. The neon does pulse though, I got that out of it, and changes with the knobs

[g1]

The Fender part won't work right as a replacement, the LDR side is too different. ( https://music-electronics-forum.com/...736#post179736 )
If your leads were just twisted around and shorting, you may be able to re-assemble and use.
Otherwise, fliptops sells the TM-1 opto but they are expensive ($45 now).

[g1]

It sounds like this is something someone made and they didn't understand the schematic. The original parts were plastic encapsulated (not heatshrink). Have a look on fliptops for a picture.
From the schematic I get the impression the dotted line in the module is a shield, and not connected to the LDR side. Maybe someone else will comment on this if I am wrong.

[dmeek]

I had to make one of these just yesterday for a GS-12R. I had to use a metal can LDR. I don't know the part number but it worked. I can confirm the Fender type LDRs don't work, I tried a few of them.
The original LDR has a case lead which is grounded. Doesn't seem to be necessary.

[Justin Thomas]

I think I've got the module I pulled out of a GU-12 years ago which I'm prettysure is the same. It worked when my friend blew up the OT. Message me if you're interested; I'll send it out free of charge if you wanna try it. I'm never going to use it.

Jusrin