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I repeat my question concerning Buffalo II and it’s AVCC module in particular. After successful assembling I used it for a few months having a good sound and no troubles and suddenly after an ordinary switching ON it stopped to function (with no external reason) - no sound. "Lock" LED on the Buffalo II board is ON, but LED D1 on the AVCC module doesn't light while D2 does. Voltages on the connectors and LEDs are shown on the picture attached. I need your opinion - what could happen with this module? Can I repair it replacing D1 LED or do I need to buy a new module? Thanks in advance. Nicolay Tupp attached the following image(s):  IMG_8280-1.JPG (173kb) downloaded 126 time(s).You cannot view/download attachments. Try to login or register.
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It may not be D1 that is the problem, but rather QP1 and/or QP2.
Measuring the voltage accross R4 and R5 would be helpful in diagnosis.
I would suggest replacement unless you have good rework gear.
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There is the input voltage (5,45) on both electrodes of both R4 and R5.
If there's a shunt stabilizer topology this maens a break of the output shunting transisitors.
Am I right?
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I need the voltage across the resistors - not to GND.
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Here are the voltages across resistors:
V(R4)=0V
V(R5)=0V
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Good day, Russ!
I've shown the voltage you asked.
What's your verdict?
Nicolay
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I believe you simply have a dead or shorted D1. :) I would try replacing it.
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Thank you, Russ! Could you give me a part specification on this D1 to find a replacement and the electrical scheme of the AVCC module? Thanks in advance. Nicolay Edited by user Wednesday, April 25, 2012 4:42:00 AM(UTC)
| Reason: Not specified
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Rank: Administration
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Really just about any green 1206 LED will work fine. You want a forward voltage ~1.8V. There is an orientation mark on the PCB. You should not need anything else. Edited by user Wednesday, April 25, 2012 4:43:13 AM(UTC)
| Reason: Not specified
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