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  • 3 weeks later...

Any suggestions on diagnosing problems with a Sub-10?

My receiver died like 2 years ago, and due to the pandemic and chip shortages, I couldn't replace it until last week.  I got everything hooked up, and was surprised to find the sub not working.  When I ran it through the new receiver's setup/calibration, the sub would make *some* noise when the system was testing that channel, but it was never enough for the setup mic to pick it up.  I picked up an R-100SW to test with, and it works just fine, so the problem is definitely the old sub, I just have no idea what the actual problem might be or whether or not it can be fixed (or if replacement parts are even available).

I don't *need* the Sub-10 anymore, but it seems like a waste to toss it if I can get it repaired and maybe return the R-100SW instead.

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Hello ngen33r, just wanted to thank you for putting all of this information on this site. I had picked up a non working Sub 10 a few years ago for $25 thinking I could possibly get it going again. I had no idea what a Bash amp was and there was little info online. My Bash boards all looked like new with no heat marks or obvious component failures. A while back I removed the conductive glue, replaced the Diac, the two switching mosfets and a 100v 470 uf cap that looked suspiciously damaged by the glue and still no joy. I happened to search online recently for any updates to troubleshoot the amp and luckily found this site and your posts. With your guidance I checked Q5 and the emitter to base was open. Ordered some 2N4401's as they are cheaper by the dozen. A bit delicate to replace the surface mount but was successful and for the first time I have an awesome sounding subwoofer. My wife is happier than I am because it is now out of the living room as an end table. Thanks !

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Hi ngen33r,

Thanks for the content that shared in this forum, it is extremely useful. I tried to use your guide to try to fix my friend's amp but due to lack of the tool that require (the desolder vacuum pump), I screw up multiple pad on the amp. To avoid further damage to the board, just curious will you be able to help us to sell the power supply to us ? If yes, I would like to enquiry about the price. 


Let me know how can I reach you to discuss further on this.

Edited by CuriousA
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Welcome, sorry but i can't help with finding your problem.
But if you wanted to keep it you could use a outbard or stand alone amp, no reason to ditch the sub. A regular amp could be hooked up and just put the bad amp back in it's place so the cabinet space stays the same. 

I found the issue. The crossover knob seems to have intermittent connection. If I press it down and up while turning, the signal is alive again.

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On 5/23/2020 at 3:31 AM, ngen33r said:

RPW-10 PLATE A506220506


FINALLY, something different. This failure was not one I have seen before. C31 appears to have prematurely evacuated and caused all sorts of issues. Z2 was toasted, Q5 evaporated and R51 failed. The BASH board was taken out as well with a blown diode, transistor and the IC. The IC's are a pain in the *** to replace because of the glue or epoxy used to try and hide the UC3842 chip. The board did have some damage to the copper plane under the cap, probably from the electrolyte. This is a fairly easy spot to repair. 


Best guess, Q5 failed and took out the bash board and caused Z2 to fail. R51 then failed from heat due to the current draw. When the bash board stops working the voltage on C31 goes over 100V, which it is only rated for and that would cause the leakage. Normal voltage is around 90V. This is why on later revisions this cap was upgraded to a 160V version. It is still OK to use a 100V cap here, as long as the amp is working properly. Go 160V if you want to play it safe.


As usual, glue removal and Q5 upgrade with a full recap.



Hi, I am a newbie but my sub started humming for a while (several minutes) upon powering up so I decided to crack it open, mostly to satisfy my own curiosity. It's a different model (old PSB Subsonic 5i) but it does have the big yellow thingy that can be seen at the top of the first pic of the quoted posting, the one with the text printed on top "indigo xxxx Rev. B xxx". In fact I think it may be the same part. On mine, however, it seems to have leaked a brown resin like goo all around and there's some browning on the underside of the circuit board, presumably as a result of the ooze. 

My questions are, 1) what is this component called? 2) Is the brownish ooze indeed from the failure of this component? 3) If so, can I simply buy this component and replace it myself or am I biting off more than I can chew as someone who just knows how to simply solder things on a board? 


Any guidance would be greatly appreciated. 

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  • 3 weeks later...
  • 2 weeks later...

Hey there this has been a super helpful thread.

I got a sub-10 to repair the original owner said it powers on but its quiet.


I opened it up and found the 470uf 100v cap was bulged

And q5 was toasty


I scraped all the glue




And all caps

Pdc board was good and fets appeared good. It was not blowing fuses. I get proper voltages 


I send a sine wave through and I check the signal path with my scope

And do not get a clean sign wave. I see noise without volume. Once I add volume I see the sine wave and the noise in the sine wave.

It has a like oscilating ripple in the signal

path that appears to be in the 16khz range. (Noise from a component in the board somewhere)

I cannot seem to find where in the circuit its being introduced.

The amp other wise seems to be operating properly


Is it possible that I have some op amp or amplifier fets that aren't bad but aren't good either.





Edited by Bman0202
Needed to add photo
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Hi this is a great forum. I have an RPW10 and have check the 5V and 28V tests according to Ngen (watched a lot of videos). Tests ok so I think power section is ok. I hear VERY feint music when I plug in a source. Do you think this might be a problem with the pre-amp or main amp section?


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This morning I decided to pull the 4 main output Mosfets 



Q14, and Q20


Irf9z14 Q13, and Q19



When diode checking source to drain of irf9z14 p-channel.

Anode is drain and cathode is source. I get 1.065v on one and 

1.105v on the other

I then switch on the Mosfet by applying voltage to gate I get continuity from source to drain. I then short the leads.

And check Source to drain in off state and I get 1.065 and 1.105 so they are bad

It should be .500-.600v yes?


Then I check irf914 n-channel.

Anode is source, cathode is drain.

Source to drain in off state its .575v and .580v

I switch on the fet and test and get continuity.

Then short it back to off state and I get the proper diode reading.


So I believe I found my problem.

To be q13 and q19


Q7 irf530  checks correctly at .529


I went ahead and ordered 

Q7, q13, q19, q14,q20

And ill replace them all

Then preform the bias test you outlined in your video.


Ill update after I complete those replacements


Edited by Bman0202
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6 hours ago, GrantCanada said:

Hi this is a great forum. I have an RPW10 and have check the 5V and 28V tests according to Ngen (watched a lot of videos). Tests ok so I think power section is ok. I hear VERY feint music when I plug in a source. Do you think this might be a problem with the pre-amp or main amp section?



I was unsuspecting on the amp section

But I found that when I pulled the fets and diode checked them


I found q13, and q19 to be faulty.

They arent shorted. But they were not reading correctly 


Ill find out for sure on Tuesday when I get my replacements.

Edited by Bman0202
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