Hi all, Looking for some help to repair my soundstream rubicon 405 amp.
I use the amp on my room, connected to my computer. 12v from a server psu with 1farad capp for extra smoothing. Overal worked great and sounded awesome for 1year+. Until my computer got a grouding/psu problem.... Causing 120vac (max 8mah when shorted) between "ground" of my pc and the ground of my amp. After this the amp stopped working.
long story short, the amp got 120vac(max 8mah) on the input(s).
It looks like the amp powers up normally, ~2A @12v when idle (normal as i remember). But doesn't output any sound. No dc on any in and output. rail voltage to the sub and speaker output seems OK.
All help is appreciated. I have some basic amp repairing knowledge (repaired a few output problems before) and own a basic scope. i don't own the schematic of the amp.
https://imgpile.com/images/7yGrJN.jpg
Duncyy
I use the amp on my room, connected to my computer. 12v from a server psu with 1farad capp for extra smoothing. Overal worked great and sounded awesome for 1year+. Until my computer got a grouding/psu problem.... Causing 120vac (max 8mah when shorted) between "ground" of my pc and the ground of my amp. After this the amp stopped working.
long story short, the amp got 120vac(max 8mah) on the input(s).
It looks like the amp powers up normally, ~2A @12v when idle (normal as i remember). But doesn't output any sound. No dc on any in and output. rail voltage to the sub and speaker output seems OK.
All help is appreciated. I have some basic amp repairing knowledge (repaired a few output problems before) and own a basic scope. i don't own the schematic of the amp.
https://imgpile.com/images/7yGrJN.jpg
Duncyy
Thank you for the schematic. Helps a lot. i added the picture of the pcb
After some measuring it looks like the inputs work, but there is no -17.4v rail. flowing the schematic q149(tip107) and q148(MPS8599) are responsible for this. They get the -33v, but only deliver -2v and are warm.
The MPS8599 measures short between emitter and base. I have a few mpsa56 laying around. I found online they are a suitable replacement so i will give that a try
.The PE connection inside of the power supply died somehow.
update: so now i have -4v instead of -2v. its a improvement lol.
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yes the signal to the ch5 driver board is clean. The output on ch5 plays on max gain softly and extremely distorted. There is no hearable sound output with lower gain. The switches have no negative or improving effect on the output (except from changing the signal(lowpass etc)).
do you know if all the "PA_D13.SCH" driver boards are the same for all channels?
if so, i can compare some signals.
update: i compared the signals on the driver board of ch5 to the other ones and the +33v rail seemed missing. At further inspection the solder joints to the driver board looked a little crusty. Some flux and a quick reflow later and ch5 is up and running again!
will do some extensive testing of the amp later this week.
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