Burnt thing on my amp, what is it? *pics*

MikeHunt79

MikeHunt79

MikeHunt79

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One of the channels on my Gemini XPM-900 has stopped working recently, so i whipped the top off to find this: :eek:
imgp1126ck1.jpg


It's just behind the red cable in the middle at the top:
imgp1127fa9.jpg


Now, to me it looks like a toasted resistor, but I haven't seem that many burnt things, so maybe someone here would be able to tell?

Also, has anyone got any idea's what caused this and how to fix it? Also, whats the best way of cleaning the black crap off?
 
You have there what looks like a toasted resistor as you said, a toasted tantalum capacitor or 2 (the round orangey bits), and something which I can no longer recognise that looks to have gone bang ( that could be a resistor at a second glance).

The opamp (black thing with 8 legs marked IC2) looks a bit burnt too.

If you can't see the values given on any of these components and the other channel circuit layout isn't the same, I think you'll find it all but impossible to repair.
 
And even if you did manage to get all those parts replaced, it still may not work due to another underlying fault which could cause all those componants to go POP again. :(
 
Is that a nice big crack in the op-amp?, Its probably overheated and failed as well.

Unrepairable? Has the entire world become throwaway, its a "simple" solid state two channel amp. My Audiolab 8000P blew a couple of transistors and burned a couple of caps and resistors in the process and still only cost £40 to repair.

Here's the service manual, Armed with this, any competent electrical repair shop should be able to sort it. Just takes 1 person with a brain, a scope, and of course the parts :P.

http://www.geminidj.com/disc._prod_manuals/AMPS/XPM-600-900-1200/XPM-600-900-1200.pdf

Although thats not a very high res copy in the PDF, im sure gemini would supply an easier to read version if you requested it.
 
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Here's the service manual, Armed with this, any competent electrical repair shop should be able to sort it. Just takes 1 person with a brain, a scope, and of course the parts :P.
Click to expand...

there is no way of knowing how many components have been damaged from the short circuit. also the circuit board itself looks dead.

ive had caps blow on motherboards before, on further inspection 2/3 other caps at completly opposite side of the board are bulging.

not worth the hassle DIY repairing to be honest. if the manufacturer can fix it then great, if not then time to upgrade.
 
Crikey...sometimes you just have to admit defeat...I wouldnt be attempting to DIY that. Looks a bit dead. You could get a quote at a repair shop but whenever I tried that it never works out worthwile form just upgrading to a good condition used piece of equipment.
 
divuk83 said:
More like what was it than what is it. Not sure that will be an economical repair unless of course it's still under warranty?

There is a Gemini Dealer in Bristol, see if they will take a look at it for you but make sure to agree a price for checking it first.
http://www.geminidj.com/scripts/find3.php?country=UK&distance=5&zip=BS16

Dave
Click to expand...
Thanks for the info, I'll go pester then for a service manual, or a quote next time I'm around there...
Corasik said:
Is that a nice big crack in the op-amp?, Its probably overheated and failed as well.

Unrepairable? Has the entire world become throwaway, its a "simple" solid state two channel amp. My Audiolab 8000P blew a couple of transistors and burned a couple of caps and resistors in the process and still only cost £40 to repair.

Here's the service manual, Armed with this, any competent electrical repair shop should be able to sort it. Just takes 1 person with a brain, a scope, and of course the parts :P.

http://www.geminidj.com/disc._prod_manuals/AMPS/XPM-600-900-1200/XPM-600-900-1200.pdf

Although thats not a very high res copy in the PDF, im sure gemini would supply an easier to read version if you requested it.
Click to expand...
The opamp is fine, it's just got some black goo on thats also on the yellow cap to the left (in the 1st pic I posted). Here's a better pic with the burnt thing removed, i've wiped that black goo off. The opamp is a tl072cp:

imgp1133ii0.jpg


This must have got seriously hot. It's melted the tracks of the PCB! :eek:

Thanks for the PDF, as you say the schematic is a little low resolution, but it looks like a resistor is what went up. I've sent an e-mail to Gemini asking for a better quality version, but I'm not holding my breath...

I don't mind soldering it myself really, I know this thing has 80v rails so I'll be sure to discharge the caps before I do anything. I'll probably remove the PCB anyway as there's likely to be burnt bits of resistor under there.

I wouldn't throw it away, you are right when you say there is a throw away culture these days, when often it is better to repair than replace. Just the toroid alone would cost over £60 new!
neil_g said:
there is no way of knowing how many components have been damaged from the short circuit. also the circuit board itself looks dead.

ive had caps blow on motherboards before, on further inspection 2/3 other caps at completly opposite side of the board are bulging.

not worth the hassle DIY repairing to be honest. if the manufacturer can fix it then great, if not then time to upgrade.
Click to expand...
The PCB is probably only double layer, so it's a lot simpler than a motherboard... No SMD components either. I wouldn't try and fix a motherboard, but this is a lot less complex and therefore fixable!
 
neil_g said:
youre mad.

dont say i didnt warn you when you burn your house down reusing faulty electronics.
Click to expand...
This thing does have a fuse you know... but I keep a cup of tea on hand just incase. :p

Anyway, I was going to pull the PCB, but I found another burnt part... :eek:
imgp1137mz4.jpg


Hmm, one of the tank caps looks very burnt, they are 6800uF, and I only have some 10000uf ones which are the size of coke cans, they'll never fit. :(

Still, they should work ok for testing tho... :)
 
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