Where to get original IRS20956S? I cant find datasheet in IR homepage. Is it really custom made?
It likely is custom made. I think the datasheet for the AUXS20956S will be the same (same number, with an automotive prefix). I've seen literature that listed the aux version but no datasheet. If you contact tech support at IR, they may be able to find the datasheet.
Had 2 amplifiers with DC offset. One amp -21vdc on the + speaker out and the other with -51VDC on the + speaker out. Both amplifiers victim of same fate I presume. Replaced all 4 IRF3205 power FETs and both IRFB4321 mosfets. Still had the offset. I replace that IC with IRS20957S (datasheet from IRF says uses the 7 instead of the IRS20955S). DC offset is gone in both amps. Idle is stable at ~.9 amp. Drive signal on the IRF3205's look good on scope. But no audio either amp. Nothing gets hot all voltages look ok per service manual and the mosfets voltages look good compared the working amp I have. I bought 6 of these amps CHEAP. Any idea what else to check? Checked voltages on the 4560 Op amps and they look good.
It appears that pins 3, 4 and 5 are different, You may be able to make it wirk by lifting them from the board and hardwiring the pins to the correct circuits (preferably at a point away from the IC to increase clearance between terminals and pads).
I guess I must have missed that. I think pin 4 is NC it appears to be only a pad on the PCB. I don't have data sheet in front of me but what is it 3 and 5 reversed? I'll try when I get home if so
I jumped pin 3 on IC to PCB pin 5. Pin 4 on IC to pin 3 on the PCB. That produces ~50 VDC offset and a pretty hot IC in a few seconds.. Pin 12 worries me too looking at the datasheet. Sent a inquiry to Utsource says available? Thoughts Perry?
Power it up for short periods (just enough to check one or two pins to prevent overheating) and compare the voltage in your amp to those in the manual.
I was worried also about pin 12. irs29057s should work?
Perry, i sent you SM.
Perry, i sent you SM.
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I can confirm that it did not work in my amp. See above post. I desoldered the side of the IC with 1-8. Lifted 3,4,5 way up. Pushed IC back to board and resoldered it. The jumped IC 3 to PCB 5 and IC 4 to PCB 3 (see previous post I think that's right not in front of amp right now) it smokes the IC in a second or two. I think pin 12 is some kind of control timer or something. It's definitely not the same IC. I sent inquiry to UTSOURCE in China. They got back to me and said they will quote me. They show 16000 in warehouse. I'll order 20 or so if reasonable. If it works I'll send you one. Thanks for the SM 🙂
Confirm that the package size is usable. From what I found, the package from utsource is an SOP-16, not an SOIC-16.
You are correct sir. They sent me back pricing for them at $3.50 for 20 pieces. Sop is 3.5mm wider. Man this amp is really starting to suck. Why do that with a cheap priced amp? I can get the ICs but that really be a mess trying get that to work. You have any suggestions? If it's the only way I can fix this amp I'll do it like we used to do PlayStations. Lol
I think you have to decide why you're repairing it. If it's to learn, you have to realize that education isn't always free. You could try several things (as you already have) and never repair it. The simplest thing (won't learn anything but should give you a working amp) would be to buy the original IC from PacParts or whatever distributor can supply it. If someone asked me to repair one of these, I'd suggest buying another amp.
I'm doing it to learn about them. I have hit another rut lately can't fix anything. Lol. I'll try the SOP version. See what happens. I just fix them and mount them on the wall anyway. But so far I won't allow myself to mount a non working amp. This thing stinks of bad design. Maybe that's why I got some many and eBay is full of them. I paid about $10
Per amp in the lot I bought.
Per amp in the lot I bought.
Just got a reply back. Was told SOP-16 3.9mm was all the supplier had. You have any luck getting data sheet?
You can still come out ahead if you can repair them and have less than $30 in each one.
Have you determined if there could be something else (supply voltage too high or something beyond the IC shorted...) in the amp causing the ICs to overheat when jumped like it would appear that they need to be to function?
No datasheet.
Have you determined if there could be something else (supply voltage too high or something beyond the IC shorted...) in the amp causing the ICs to overheat when jumped like it would appear that they need to be to function?
No datasheet.
True. Only real way to tell is to order one IC from PP. I don't see anything else abnormal in this amp. Drive looks good on the IRF3205. Everything measures out. But I've been wrong before I guess I could throw a known correct part at one to see if it's ok. Pin 12 on IRS20957 says no connection but on the PCB it's suppose to be CT. What designation is CT and it has ~-51VDC on that pin. I bet that's why the 20957 smoked.
CT is often a timing capacitor but that's generally written as Ct.
Remove the IC and post the DC Voltage on all pads for the IC.
Remove the IC and post the DC Voltage on all pads for the IC.
FWIW: since I smoked the IC (IRS20957SPBF) in a nice smokey blaze of glory NO telling what else that took out in this amp... Heres what I read via my Fluke 12
1: 14.95
2: 0
3: 0
4: 0
5: -52.5
6: 0
7: -57.1
8: -57.1
9: -57.1
10: -45
11: 45
12: 0
13: -2.091
14: -.473
15: 26.75
16: 2.316
1: 14.95
2: 0
3: 0
4: 0
5: -52.5
6: 0
7: -57.1
8: -57.1
9: -57.1
10: -45
11: 45
12: 0
13: -2.091
14: -.473
15: 26.75
16: 2.316
Response from IR
Hi, Mike,
I can't find any related document about it. But from the part number, I guess it is a part which doesn't in mass production. Most probably, it was obsolete after samples due to some reason.
sorry for any inconvenience.
Hi, Mike,
I can't find any related document about it. But from the part number, I guess it is a part which doesn't in mass production. Most probably, it was obsolete after samples due to some reason.
sorry for any inconvenience.
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