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-   -   Fried T-Amp? (http://www.diyaudio.com/forums/class-d/84659-fried-t-amp.html)

Bingobing 13th August 2006 07:19 PM

Fried T-Amp?
 
Hi,

A silly mistake!! I was trying to hook up a SLA battery to a SI T-Amp when I smoked the PCB because of reversed polarity. I am not sure if the Tripath chip is fried. How can I test whether the chip survived?
Thanks!

KC

Buckapound 14th August 2006 04:06 PM

I did the same thing.

Maybe I was lucky, because all it did to mine was fry the positive power supply trace from the 12v+ in connection over to the switch wire pad on the other end of the board. I simply used a wire to replace the burned trace--not too hard to find--and it was probably a blessing in disguise to have the thin circuit board trace replaced by a real wire.

Can't guartantee this will be the same with yours--but have a look on the bottom of the board. Try adding the wire and see if the unit doesn't fire right up

--Buckapound

Bingobing 14th August 2006 05:24 PM

Yes, indeed there was a broken and lifted trace (on the underside of the PCB) leading to the switch wire pad.
I will try to bridge this with a wire during the weekend and post the result.

Thank you for sharing.

Cheers, KC.

Davet 14th August 2006 05:30 PM

Maybe not Fried
 
I thought I had done the same last week. I had a Power Supply which had the plug reversed. It had been some time since I had last used the PS with a gerry rigged tip. I plugged in the unit and I smelled something burning. I unplugged it and did it again, before it dawned on me the polarity was reversed.

I disconected the PS, and on the following day I connected mt AA batteries. The T-Amp worked just fine. I had read that the chip and the PCB had diodes to limit damage based on reversed polarity. I have sinced modified the PS such that the tip is wired correctly.

So give it a try! It may just work.

Pano 16th August 2006 04:31 AM

Re: Maybe not Fried
 
Quote:

Originally posted by Davet
I had read that the chip and the PCB had diodes to limit damage based on reversed polarity.
Hmmm..... Not that I know of. I'll have another look. Would be a nice feature.

pekar 16th August 2006 08:05 PM

Buckapound, you just saved my T-Amp! I just fried it yesterday (reverse polarity) and was going to give up on it. Your post prompted me to investigate, and I was able to bypass the trace and revive my amp.
Thank you!

entropy0 17th August 2006 09:42 PM

I also fried my first T-Amp after reversing polarity on the AC adapter. I figured it was a lost cause, that the chip was fried, but this thread gives me hope! However, I have no burnt traces or visible signs of damage I can find. Assuming the 12+v in is the center pin, is it possible to identify where on the board to connect this point to? I don't know where the switch pad is, or which point on it connects to the 12+v in.

If we are talking about the volume/power connector (which has 7 pins), and looking at the underside of the board, pin 1 is nearest to the red LED, which pin would make the connection to 12v+ in?



Quote:

Originally posted by Buckapound
I did the same thing.

Maybe I was lucky, because all it did to mine was fry the positive power supply trace from the 12v+ in connection over to the switch wire pad on the other end of the board. I simply used a wire to replace the burned trace--not too hard to find--and it was probably a blessing in disguise to have the thin circuit board trace replaced by a real wire.

Can't guartantee this will be the same with yours--but have a look on the bottom of the board. Try adding the wire and see if the unit doesn't fire right up

--Buckapound


Buckapound 18th August 2006 12:52 PM

Entropy0, if you haven't already, get out the magnifying glass and check the possibly destroyed trace carefully, as it only takes a small break to, well, make a break.

The trace that burned out on mine is the long thin one that (looking at the underside) goes from the large blob of solder that connects the + pin of the power plug and snakes all the way to the opposite corner of the board to the switch pads. Looking at the top of the board, in the row of pads that connects to the ribbon cable that goes to the pot/switch, you want that replacement wire to go to the second pad from the left (+), although the printing is shifted about half a hole to the right in order to find space for the lettering.

The starting point for the replacement wire is from the +12v pad (the second one behind the power plug).

--Buckapound

BWRX 18th August 2006 01:21 PM

That's kind of funny actually. Tripath unknowingly created a PCB trace fuse by having a long and thin power trace on a 1/2oz copper board! If you made these mistakes with any other amp that has a better PCB the chip would definitely fry instead of the trace.

bingomore 19th August 2006 07:33 AM

2 Attachment(s)
Thanks a lot, Buckapound !!

I reconnected the broken trace and the T-Amp works. BWRX is right, the trace acted like a fuse.

Attached pic of the broken trace on the reversed side of the PCB. It's the U-shaped trace around the Tripath chip.

Cheers!


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