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i have an '02 orange AD140 HTC here. fizzy output sound, VERY quiet. tubes test OK. have tried other tubes.
using a probe, i find the signal is strong coming out of the preamp and into pin 5 of the power tubes, seems to be behaving normally. i'm using this schematic: http://elektrotanya.com/PREVIEWS/634..._amp.pdf_1.png
i try to get a signal to the probe off of pin 3 from the power tubes and i find that same fizzy sound that makes it to the speaker. i did a diode test from pin 3 to ground to see about D1 and D2, and it came back to me as a voltage drop of 1v. normal diode is supposed to test at around .5v.
D1 and D2 are in parallel to ground, but testing 2x known-good diodes in parallel doesn't read 1v. the meter still reads .5v.
the board is a pain to get out of the chassis, i'm hoping someone here has some input about what the problem might be. i'm wondering if something is going on w/ D1 or D2 or if my 1v reading is normal?
using a probe, i find the signal is strong coming out of the preamp and into pin 5 of the power tubes, seems to be behaving normally. i'm using this schematic: http://elektrotanya.com/PREVIEWS/634..._amp.pdf_1.png
i try to get a signal to the probe off of pin 3 from the power tubes and i find that same fizzy sound that makes it to the speaker. i did a diode test from pin 3 to ground to see about D1 and D2, and it came back to me as a voltage drop of 1v. normal diode is supposed to test at around .5v.
D1 and D2 are in parallel to ground, but testing 2x known-good diodes in parallel doesn't read 1v. the meter still reads .5v.
the board is a pain to get out of the chassis, i'm hoping someone here has some input about what the problem might be. i'm wondering if something is going on w/ D1 or D2 or if my 1v reading is normal?
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