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Old 1st August 2019, 02:16 PM   #21
barber02 is offline barber02
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Hey Perry,
Sorry for the delayed response. I had a thunderstorm come through yesterday so I shut my lab down early.

The diode connects to pin 7
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Old 1st August 2019, 03:14 PM   #22
barber02 is offline barber02
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Pin 8 and pin 5 are connected together via a 5 band resistor R227. Best I can discern is that it should a 12k ohm resistor 5 percent tolerance. In circuit it reads about 16k. I’m going to pull it and check it out of circuit.

Pin 8 connects to the high side FETs through a 7 ohm resistor R281 and then the trace continues on to a couple of at the gates of the high FETs (R237 and R235) at 27 ohms each on the last two high side FETs.

David
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Last edited by barber02; 1st August 2019 at 03:17 PM.
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Old 1st August 2019, 03:42 PM   #23
barber02 is offline barber02
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That resistor reads 83.2k ohm out of circuit.
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Old 1st August 2019, 04:53 PM   #24
Perry Babin is offline Perry Babin  United States
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Did that solve the problem (assuming that the 12k resistor was the one that was far out of tolerance)?

I've requested more information on this type of amp from another tech. There is little chance but I have nothing solid to work with.
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Old 1st August 2019, 05:45 PM   #25
barber02 is offline barber02
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No. Pin voltages are the same.
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Old 14th August 2019, 12:20 AM   #26
barber02 is offline barber02
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I pulled the J111 transistor that is identitfied as Q282 on the board and tested in my transistor tester and this is the result it gave me. Do you think this may be why my output section has no drive and is dead quite? I have positive and negative rail voltage but no drive.

I donít have any in stock so Iíll have to order some.
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Old 14th August 2019, 12:37 AM   #27
Perry Babin is offline Perry Babin  United States
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I don't know what the tester is telling you. Typically, a jfet will read low resistance between the drain and source with a meter and will read as a diode in one direction between the gate and the other terminals.
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Old 14th August 2019, 12:56 AM   #28
barber02 is offline barber02
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I know. I was a little confused as to the results myself.
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