BASH Subwoofer Amp No Sound, Power Ok (Atlantic Technology 642eSB)

[nobbnobb1]

Hello,

I have a really nice Atlantic Technology 642eSB subwoofer that I would love to get working. The problem is that the power appears ok (LED light is on), but there is no sound. I don't believe it to be the audio input board or anything wrong with the power as when in standby mode (LED = red), I can play a source and the LED turns green suggesting the input is being detected ok.

The amplifier is a common BASH design, my interpretation of the layout based on Picture #1:
- Top most hanging board is the audio input section. Note I accidentally broke the crossover potentiometer, but operating this on bypass mode for now so should be ok.
- Middle board appears to be some daughter board for the final amplification of the speaker outputs. I'm guessing there's something wrong here.
- Bottom board is the BASH power circuitry.

I have inspected all the boards and have not found any typical anomalies like burnt components or cracked solder. There is yellow glue, some of which is turning brown, but it's only mostly on mechanical areas where stuff isn't going to short together so I don't think that's an issue. I have also tested the transistors (MOSFETS) on both the BASH and final audio output board and have not found any issues.

The BASH amplifier is labelled as an Indigo 600109, of which I found a schematic online here (see pages 7, 8, 9):


I'm out of ideas now. Can someone suggest other things I could try?

Thanks!

[tibimakai]

Re: BASH Subwoofer Amp No Sound, Power Ok (Atlantic Technology 642eSB)

Power supply output has ~8V?
Once I have fixed a Klipsch R-110SW, that looked like everything was working, but did not have sound. The issue was the speaker. The "wires" to the coil were open. I have purchased new ones, replaced them and it worked. I still have a pop, when signal is applied though.

[nobbnobb1]

Re: BASH Subwoofer Amp No Sound, Power Ok (Atlantic Technology 642eSB)

I tested the speaker with a small battery, it's fine.

I had spare capacitors laying around from an Energy subwoofer that I re-capped of which surprisingly has the same values as this one (BASH amps all seem to be similar). So I swapped out the caps here and viola, I think it's working again! Strangely none of the caps looked problematic, no bulges. But I discovered the 1000uF @ 100V cap, which appears to be on the power supply output side, may be bad. Tested ~5 ohms which is kind of weird. Maybe not a full short but partially?

Disappointingly I also damaged the crossover knob when taking this apart. It's got a B503 stamp on it. Can I replace it with any generic 6 pin 50K unit? Picture attached.

[tibimakai]

Re: BASH Subwoofer Amp No Sound, Power Ok (Atlantic Technology 642eSB)

I would remove that glue, between the transformer and that vertical board. That is causing a short over time, as it starts getting brown.
Here is a Youtuber, who repairs these Bash amps: https://www.youtube.com/channel/UCOM...7lbGj1hLzUkmwQ
Most likely you can.

[nobbnobb1]

Re: BASH Subwoofer Amp No Sound, Power Ok (Atlantic Technology 642eSB)

Thanks I'll have a look.

I removed most of the yellow glue in conductive parts. They also used this white glue in some areas, like between that transformer and metal heatsink. This glue doesn't seem to have the same breakdown problem.