Phonoland

From a mechanical standpoint, I have everything going on the Rockola 440 mentioned in this thread:
viewtopic.php?f=3&t=4252

As mentioned in the subject line, this Model 440 has a 44790-A amplifier. I'm having a hard time finding information about it. I do have a manual and schematics.

My remaining problem is that the left channel of the amplifier outputs nothing, not even any hum when unmuted. I measure no voltage from the left output of the amplifier itself, so the problem is not with the speaker distribution. What I've done so far:
-Tested and swapped the output transistors, no help, the left side still doesn't work and the right side does
-Checked continuity for the left drive transformer, it appears fine and measures the same as the right
-Tested continuity for the dual lamp Barretters, they are fine
-Tested and compared whatever transistors I could, all appear fine
-Visual inspection of all components, nothing looks bad, no evidence of magic smoke

I don't know a ton about amplifiers so any hints or pointers are appreciated. Thanks!

Stangbat,
I thought I had posted a reply--but i see it's not there--
If you have not located the problem yet, I suggest that you might just try swapping the input leads, to see if the problem is ahead of the amp--
BTW--IMHO, it is not wise to "Swap output Transistors", in any amp -- Ron Rich

Thanks, Ron, I'll try that. I'm back to messing with this. So far in addition to what I did above, I've verified that the muting relay is working fine and the contacts are good. So I don't think the problem is there.

Ron, maybe I should get some clarification. I had already switched the input at the stylus, and the left channel still didn't work. So I've ruled out the stylus/cartridge as a potential problem.

I don't see any issues with the left preamp from a visual standpoint. I guess at this point I'm not sure if the problem is with the preamp or later. What do you suggest I switch at this point?

Did you switch the out put wires (going to the speakers) ? Could be a dead short in the speaker line---
Ron Rich

Ron Rich wrote:Did you switch the out put wires (going to the speakers) ? Could be a dead short in the speaker line---
Ron Rich

I haven't physically switched the output wires, but I did check continuity of the wiring. I'll double check. I also measured voltage directly at the amplifier's output and get nothing on the left channel.

Well, if all's well outside the amp---that leaves a bad component inside the amp--most likely a coupling cap,or resistor, since you have "checked the transistors"--
Ron Rich

I should post the resolution to this problem. It was embarrassingly easy. As most of you know, the speakers are wired in series, not parallel. One broken wire leading to the first speaker, no sound for anything else.

Thanks for posting this "embarrassment"--we have ALL "been there"--but not many will admit it !!
Ron Rich