Guys, seems that I'm always asking for your help and giving little of my own, but here's another stupid question. I have a JL Audio 500/5 amp that came to me with a 6 amp idle current draw. It was easy to find the shorted outputs (Q102 & Q104)on the front right channel, and I replaced them with a matching pair. The high current draw is now gone and the rest of the amp works as it should however the MosFets must have damaged their drivers as the Left front output is clipped and low powered. I have no schematic but the driver appears to be Q101. The part is marked K131 and C3198. Can anyone identify this part? Any additional advice on this amp would be greatly appreciated as I am new to repairing class D amps. Thanks, Messerschmitt
Q101 is probably the bias compensation transistor, not a driver. All of the drivers are on the vertical driver board.
The c3198 is a KTC3198.
http://www.keccorp.com/data/databook/pdf/KTC/Eng/KTC3198.pdf
Are R140 and R141 within tolerance (±5%)?
Is the top, bottom or both clipped on the waveform?
The c3198 is a KTC3198.
http://www.keccorp.com/data/databook/pdf/KTC/Eng/KTC3198.pdf
Are R140 and R141 within tolerance (±5%)?
Is the top, bottom or both clipped on the waveform?
More about the 500/5
Well, this is just getting worse. I removed the KTC 3198 as mentioned in my last post. I brought it into my office to look for a cross reference and now it is gone. Probably in my wifes vaccuum cleaner. Does anyone know of a cross reference part or where I can get a replacement? I'll need to replace it before proceeding with my repair of the 500/5 and answer Perry's questions.
I have a water damaged 1000/1 that I could trade some parts from if needed.
Messerschmitt
Well, this is just getting worse. I removed the KTC 3198 as mentioned in my last post. I brought it into my office to look for a cross reference and now it is gone. Probably in my wifes vaccuum cleaner. Does anyone know of a cross reference part or where I can get a replacement? I'll need to replace it before proceeding with my repair of the 500/5 and answer Perry's questions.
I have a water damaged 1000/1 that I could trade some parts from if needed.
Messerschmitt
sorry for the slight off topic... just want to ask Perry something....
I'm having difficulty identifying a SOT89 SMD part... the markings are "BE" and then "RQ" below it. "BE" is identified as BCX55, there is no "RQ" in my database, but the BCX part is NPN and the part I need is PNP. any idea what it is or what is a good substitute?
it is part of a "half totempole" driver stage (the other half is the output transistor in the TL494) for the SMPS FETs (8pcs of 85N06).
I'm having difficulty identifying a SOT89 SMD part... the markings are "BE" and then "RQ" below it. "BE" is identified as BCX55, there is no "RQ" in my database, but the BCX part is NPN and the part I need is PNP. any idea what it is or what is a good substitute?
it is part of a "half totempole" driver stage (the other half is the output transistor in the TL494) for the SMPS FETs (8pcs of 85N06).
You'll probably have to find one the same size and try it. The LEDS in the circuit (when operating) have a forward voltage of ~1.8v. You need to use a replacement with approximately the same forward voltage. You may have to try several until you get one that has that forward voltage 'in the circuit'.
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