Outputs were badly blown on this guy, mostly at the mute circuitry.
Wondering if anyone can help ID these 4 parts.
IR soic8 part labeled p202 4dat_ f7341. Thinking ir7341pbfct, I already purchased replacements..
Large diodes labeled ON u4d ra23. Thinking mura1203tg.
Slightly smaller diodes labeled wj z8, not sure yet.
5pin small trans/fets labeled k2. No idea.
Dmm is my tool at this point.. Just finding shorted and low z parts by comparing. Found plenty.. few zorched traces as well.
Once I feel everything compares out channel to channel with dmm, I'll think about reinstalling mezz pcbs and go from there.
Thanks!
Wondering if anyone can help ID these 4 parts.
IR soic8 part labeled p202 4dat_ f7341. Thinking ir7341pbfct, I already purchased replacements..
Large diodes labeled ON u4d ra23. Thinking mura1203tg.
Slightly smaller diodes labeled wj z8, not sure yet.
5pin small trans/fets labeled k2. No idea.
Dmm is my tool at this point.. Just finding shorted and low z parts by comparing. Found plenty.. few zorched traces as well.
Once I feel everything compares out channel to channel with dmm, I'll think about reinstalling mezz pcbs and go from there.
Thanks!
Attachments
Page 27. Look familiar?
https://www.infineon.com/dgdl/iraudamp4a.pdf?fileId=5546d462533600a40153569abbd52bf3
Notice that the 5-pin device is numbered differently than normal.
https://media.digikey.com/pdf/Data Sheets/Panasonic Semiconductors ICs PDFs/XN01215.pdf
https://www.infineon.com/dgdl/iraudamp4a.pdf?fileId=5546d462533600a40153569abbd52bf3
Notice that the 5-pin device is numbered differently than normal.
https://media.digikey.com/pdf/Data Sheets/Panasonic Semiconductors ICs PDFs/XN01215.pdf
Ordered those and the 15v zeners, some are measuring open, so they went too... BZT52C15S-7-F Diodes Incorporated | Discrete Semiconductor Products | DigiKey.
With your reference design, figured out how to backohm output devices. Sure enough.. theres a shorted one. DirectFet isn't as bad as it seems, done it before with air pencil.
Adding up quick, this one...
With your reference design, figured out how to backohm output devices. Sure enough.. theres a shorted one. DirectFet isn't as bad as it seems, done it before with air pencil.
Adding up quick, this one...
The 2.2k at the output of the most damaged channel (ch5) measured 2.4k. Replaced it too. Doubt it was coincidence but seems odd..
Amp really took a beating, +B or -B (not sure which yet) nets were blown open in a couple spots to the diode clamps on the outputs too. Just going to change everything I think might be borderline on output side.
Hope i can fire it up with the mezzanine boards out when the time comes, will help with debugging.. Think i'm at the point where nothing measures odd between channels so once i get parts installed I'll think about my options. Pulling the mezz pcb's again would be awful so hope to get it right.
Odd to me ch3 was blown badly too and the output devices seem ok.. Per the seller, the shop that installed new speakers for him screwed up and the wiring was touching ground on that channel (i assume ch5)..
Anyway, figure i'll leave a trail of my progress for people that read this in the future. Still waiting on most of the parts.
Amp really took a beating, +B or -B (not sure which yet) nets were blown open in a couple spots to the diode clamps on the outputs too. Just going to change everything I think might be borderline on output side.
Hope i can fire it up with the mezzanine boards out when the time comes, will help with debugging.. Think i'm at the point where nothing measures odd between channels so once i get parts installed I'll think about my options. Pulling the mezz pcb's again would be awful so hope to get it right.
Odd to me ch3 was blown badly too and the output devices seem ok.. Per the seller, the shop that installed new speakers for him screwed up and the wiring was touching ground on that channel (i assume ch5)..
Anyway, figure i'll leave a trail of my progress for people that read this in the future. Still waiting on most of the parts.
Also found both 1ohm snubber resistors blown open at outputs on ch5/6 mezz pcb.
Kind of leery of popping those boards back in and powering things up without shooting the irs20957 driver IC's first.. Nothing available locally, guess i could try to get them from Newark (stock in UK).
Backohming the 20957 Ic's from vdd to all pins (and that kind of thing) doesnt give me anything fishy, so might be ok.. but from what i read, usually if the outputs short on these then the driver goes bad too.
I ordered the wrong 15v zeners.. 200mw instead of 500 (smaller package), put them in while i did testing with mezz pcb's off. I have the correct ones on order. I'll have them installed in a few days then make a decision.. Really don't want to try to get a mezzanine pcb out again if things go wrong!
Fwiw, I've put power on the main board with mezz pcb's off. Rails are good etc, thinking all is well there, hopefully on other boards too.
Kind of leery of popping those boards back in and powering things up without shooting the irs20957 driver IC's first.. Nothing available locally, guess i could try to get them from Newark (stock in UK).
Backohming the 20957 Ic's from vdd to all pins (and that kind of thing) doesnt give me anything fishy, so might be ok.. but from what i read, usually if the outputs short on these then the driver goes bad too.
I ordered the wrong 15v zeners.. 200mw instead of 500 (smaller package), put them in while i did testing with mezz pcb's off. I have the correct ones on order. I'll have them installed in a few days then make a decision.. Really don't want to try to get a mezzanine pcb out again if things go wrong!
Fwiw, I've put power on the main board with mezz pcb's off. Rails are good etc, thinking all is well there, hopefully on other boards too.
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Sigh.. i shorted another fet on ch5.
Took the mezz pcb off again and found its a different one than before. Amp has similar scheme to the Iraudamp4, only with 4 total fets on each channel. Only isolation with gate resistors. Oddly enough this fet is shorted drain to source.. about 95ohms. Corresponds to pin9 to 13 on irs part. The first time i had a shorted fet (as recieved) it was one of the two on the B+ side (think gate to source). This time have a blown one on the B- side..
Going to wait for digikey or mouser to get parts and order good irs20957 parts and new fets.
Not finding a reason for it to have blown though.. other than maybe a POS irs chip i installed from ebay, wasn't esd sealed etc...
Took the mezz pcb off again and found its a different one than before. Amp has similar scheme to the Iraudamp4, only with 4 total fets on each channel. Only isolation with gate resistors. Oddly enough this fet is shorted drain to source.. about 95ohms. Corresponds to pin9 to 13 on irs part. The first time i had a shorted fet (as recieved) it was one of the two on the B+ side (think gate to source). This time have a blown one on the B- side..
Going to wait for digikey or mouser to get parts and order good irs20957 parts and new fets.
Not finding a reason for it to have blown though.. other than maybe a POS irs chip i installed from ebay, wasn't esd sealed etc...
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