I AM AN IDIOT!!!
I just changed the 2W resistors of my L25D's for higher rated ones, and after putting the modules back into the chassis I noticed one of them wasn't turning on. I was checking if the power cables where connected sturdy when suddenly BOOM!! SPARKS!!!
Obviously I forgot to switch off and unplug the amp. I must have shorted the power and 0v terminal. I am happy to announce that I still have 2 eyebrows though.
Can anyone tell me what to do now? I see no damaged components, but I expect the IC's might not have survived. How do I check them?
Is it doable to change the SMD IRS2092 on the bottom of the board by hand?
I'm really not looking forward to having to buy a new set of 2 amp modules.
PLEASE HELP
I just changed the 2W resistors of my L25D's for higher rated ones, and after putting the modules back into the chassis I noticed one of them wasn't turning on. I was checking if the power cables where connected sturdy when suddenly BOOM!! SPARKS!!!
Obviously I forgot to switch off and unplug the amp. I must have shorted the power and 0v terminal. I am happy to announce that I still have 2 eyebrows though.
Can anyone tell me what to do now? I see no damaged components, but I expect the IC's might not have survived. How do I check them?
Is it doable to change the SMD IRS2092 on the bottom of the board by hand?
I'm really not looking forward to having to buy a new set of 2 amp modules.
PLEASE HELP
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Bad luck - I've done similar myself in the past. Magic smoke escapes, nothing works any more.
Do you know whether it's the amp module or the power supply that's failed? If you shorted the supply, then it may be that which has failed, rather than (or as well as) the amps. If it's a SMPS, I've had no luck fixing one that I blew up. If it's a linear supply, check fuses, transformer and rectifiers and make sure you've got the right +/- voltages.
If you're sure it's the amp, you should check the mosfets and transistors on the heatsink, plus any of the zener diodes. You may well have to replace the IRS2092 IC as well - I've done this before and it's not too difficult if you have reasonable solder skills. If you have a hot air rework station it's probably even easier. Not too expensive just to replace all potentially damaged semiconductors anyway if in doubt. I bought about 5 sets of IRS2092, plus the mosfets and transistors for 'future proofing' against my own stupidity, but of course haven't had to use them since.
Anywar, for the IRS2092, I used a solder sucker and wick to remove any excess solder, then very carefully desoldered and lifted the pins on one side of the IC by running the iron over them to melt them all while gently levering the IC with a thin pick. Then the same on the other side, being careful not to overheat the board, or the copper tracks might lift.
I then soldered a tiny bit of solder onto each pin pad, then when cool, a bit of flux paste to help stop the IC moving around too much. I positioned the IC onto the pads with tweezers and soldered one corner pin by just touching the iron on the pin (helps to have a fine-tipped iron), holding the IC in place with the tweezers. Then I realigned the IC carefully if it had moved, and soldered the opposite corner pin.
After that, it was pretty easy just to touch the iron briefly on each pin enough to melt the flux and solder already on the pads, being extra careful not to let the solder run and join two pads together. If this happens, just use the solder sucker to remove the excess solder and try again. Finally I checked everything under a magnifying glass to make sure that it was all as it should be. And it worked again when I put it all back together, which was very gratifying.
Anyway, good luck,hope you can get it working again.
Cheers, Jon.
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Thanks so much man, I was honestly prepared for replies telling me to toss the board and order new ones.
My experience with soldering smd components is limited, but I'm happy to hear it's possible to replace the IRS2092.
The power supply and the other board survived miraculously.
I have a couple of cheap ebay IRS2092 boards laying around, the ones with the green heatsink and fan. I can could use the chip from one of those, but I'm not sure if there is a large variance of quality or possible fakes in IRS2092.
SMPS voltage still measures normal. I have a fuse in the AC input socket at the back of the chassis. It's 10A I believe but it hasnt blown. I'm definetly replacing that for a lower value. My metal tweezers show significant damage from the impact
If the mosfets / transistors have blown, they'll usually show as short circuit on the multimeter. Blown diodes may be shorted or open circuit. Don't know how you could test the IRS2092, but assume it's dead. You could try replacing the IRS2092 from your other boards, and the other semiconductors assuming they are the same as your L20D's. Or just buy new components - they're not too pricey.
BTW, don't feel too bad - the most idiotic thing (of many) I've done was to accidentally reverse the +/- supply connections on one of my seven boards - that spectacularly blew up the amp and the PSU - sparks and smoke and small bits flying here and there. Luckily they all missed me. But an expensive mistake and not something I'll do again!
for fast checking for you, i dont think irs2092 damage, also i dont think mosfet damage, for safety reason to fast checking, pull out power mosfet from the board, then put board back to power supply ( check not shock it again), you need frequency meter, after power on, then check on each gate to mosfet if you can see any frequency running there, it must be more than 200khz, check bost side, hi and low, if there is frequency appear then everything was allright and you can safe put the mosfet back and power it on again, (use fuse each rail power supply).
Never use screw connectors to connect a HV DC bus its just irresponsible, the designer should have done better work here.
They are terribly exposed indeed. I also don't like that the signal output shares the same terminal block.
Generally speaking, components that may be damaged.
IRFI4020, IRS2092S。
5V6 , 15V.
2SD669
SF14
That adds up. It should not be expensive.
If you ask the seller. I can supply you with these components.
But maybe the postage will be more expensive than the components.
Thanks for the offer, but I've already ordered the IRS2092s chip and the transistors from various sellers on ebay. They should arrive any day now. I've also replaced the zener diodes just in case.
Is it possible that instead of SF14 on my boards 1N4004 is used? I have not seen SF14.
Hi I have 2 L-20D vers4 completed pcb's that I want to know if some one can help me with both don't work, Its been a while since I tried them so I cant remember what happened now but I have been checking the soldering joints and wondering if I need the surface mount capacitors on 2 places on the track side of the PCB?
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SF14 must be used. D669 must be used
1N4004 cannot be used.
If TIP31C is used. You need to reverse it. And insulation needs to be installed.
And install a separate radiator. I don't recommend it.
After a long experiment, I found out. The chip capacitance of 0.1uF is not reliable.
It is easy to damage. Short circuit to power supply.
So. Do not install SMT 0.1uF 1206 capacitor.