Perry,
Finally got a chance to pull the board and inspect the preamp board connections and the RCA connections. SOLID....at least as far as I can see. No cold or loose solder joints. Please see below pics.
I powered it up, off the board with all pots set to min and all measurements in pins 8, 12 and at the RCA jacks were the same as before, post fuse popping.
What i did notice after putting it back on the amp housing and securing everything, as soon as I put the remote wire to the B+ terminal the right channel only, had clear loud audio for a second. Then it died down to almost no sound. Also, no sound out of the left channel at all.
Not sure where to go from here.
Thanks for the patience and help
Finally got a chance to pull the board and inspect the preamp board connections and the RCA connections. SOLID....at least as far as I can see. No cold or loose solder joints. Please see below pics.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I powered it up, off the board with all pots set to min and all measurements in pins 8, 12 and at the RCA jacks were the same as before, post fuse popping.
What i did notice after putting it back on the amp housing and securing everything, as soon as I put the remote wire to the B+ terminal the right channel only, had clear loud audio for a second. Then it died down to almost no sound. Also, no sound out of the left channel at all.
Not sure where to go from here.
Thanks for the patience and help
Perry,
I'm sorry. I should have been a bit clearer on my previous post. What I meant was that after checking the solder joints of the preamp board and RCA jack, all which were solid and clean, none of the readings changed from the time the fuses starting popping and after I changed the shorted output transistors.
Please see below for current readings:
Pin#1= 15.09V DC
Pin#2 = -15.10V DC
Pin #8 = 15.8mV AC
Pin #12 = 14.3mV AC
Pin# 17 = 4.2mV AC
Pin # 18 = 4.5mV – 6mV AC (It alternates up and down through that range)
RCA Jacks = 4.5mV AC
I'm sorry. I should have been a bit clearer on my previous post. What I meant was that after checking the solder joints of the preamp board and RCA jack, all which were solid and clean, none of the readings changed from the time the fuses starting popping and after I changed the shorted output transistors.
Please see below for current readings:
Pin#1= 15.09V DC
Pin#2 = -15.10V DC
Pin #8 = 15.8mV AC
Pin #12 = 14.3mV AC
Pin# 17 = 4.2mV AC
Pin # 18 = 4.5mV – 6mV AC (It alternates up and down through that range)
RCA Jacks = 4.5mV AC
My apologies. I misunderstood. I thought I was measuring voltage without driving any audio signal. But your last comment makes total sense, now, to me. "You can't follow a signal through the amp if you don't drive a signal into it."
I’ll take the readings for Pins 8,12,17,18, and at RCA jacks while driving the test tone and will re-post.
Thanks
I’ll take the readings for Pins 8,12,17,18, and at RCA jacks while driving the test tone and will re-post.
Thanks
with and w/o audio measurements in AC voltage:
Speaker terminals
R Channel
+=3.5mV
- =starts at 3.5mV and goes all over the place
Left Channel
+=3.5mV
- =3.5mV
both audio driver boards
R Channel
+=3.5mV
- =starts at 3.5mV and goes all over the place
Left Channel
+=3.5mV
- =3.5mV
Getting static out of right channel speaker for the first time.
Speaker terminals
R Channel
+=3.5mV
- =starts at 3.5mV and goes all over the place
Left Channel
+=3.5mV
- =3.5mV
both audio driver boards
R Channel
+=3.5mV
- =starts at 3.5mV and goes all over the place
Left Channel
+=3.5mV
- =3.5mV
Getting static out of right channel speaker for the first time.
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