updated power amp work list :
Replaced 14DEC2015:
R11, R12, R13, R14 (10 OHM)
C9, C10, C13, C14 (whatever)
In the mail I have received a number of components. A number of projection televisions gave their guts. In front of me, they are. And so, with newly fashioned tip I bear to deign them upon Devil, most dainty and malfunctioning.
*When replacing resistors, I increase the wattage of the component as far as the PCB will allow. This is because internet. Most of what I have used to replace compo are 1 watt metal film, across the board, for 1/4 - 1 watt resistors indicated in the schematic.
After consulting with the tech that raised me, we decided that upon reassembly I will :
1) test both valve groups individually, recording bias voltages
2) disconnect speaker load simulator and substitute with actual cabinet.
The latter is due to the schematic. It says that disconnected speaker jacks are shorted to ground to prevent 'excessive flyback voltages from damaging XF3.' So perhaps I have baddened a ground, overtensioned speaker jacks (my own theory), blown my load sim soak, or some other space wizardry.
I aim to test fire this evening. Which means ending this
-girls in space be wary-
R23, R24 replaced (220K)
BD 3 replaced (bridge diode)
R2 REPLACED (50K)
R4 REPLACED (100K)
C11 REPLACED
reboot...
... with speaker cable attached to speaker cabinet.
Bias reads 9V
WHOOP fuckin'
getting closer.
Attached to power soak, same reading. Not blown.
WHOOP FUCKIN'
Pull V4 (or power tube 1) - voltage reads 0.1V
pull V5 (or power tube 2) - voltage reads 6V
pull V6 (or power tube 3) - voltage reads 6V
Pull V7 (or power tube 4) - voltage reads 0.2V
power down
switch to 100W op mode, for literally no reason
enegage and the bias voltage is .45....
and I'm guessing this is becuase I have the trim pot turned all the way down
and it isn't drifting
and I turn it up to 0.6
and it isn't drifting
with old tubes.
what in the loving fuck
it's working
Which I suppose would point the dickfinger at me?
or the switch
Early start tomorrow, though, not necessarily on the amplifier; eventuality of testing tomorrow will be to wrangle new tubes in, bias, power down, bias, test run via emulation-minused balanced DI (-30) to 11R MIC in (PAD engaged.)
During this process, I plan on testing each of the preamp tubes I have lying around. To this end I will be using a lightly modified Marshall AVT20, which requires but one 12ax7 tube and a dummy plug.
<3
Replaced 14DEC2015:
R11, R12, R13, R14 (10 OHM)
C9, C10, C13, C14 (whatever)
In the mail I have received a number of components. A number of projection televisions gave their guts. In front of me, they are. And so, with newly fashioned tip I bear to deign them upon Devil, most dainty and malfunctioning.
*When replacing resistors, I increase the wattage of the component as far as the PCB will allow. This is because internet. Most of what I have used to replace compo are 1 watt metal film, across the board, for 1/4 - 1 watt resistors indicated in the schematic.
After consulting with the tech that raised me, we decided that upon reassembly I will :
1) test both valve groups individually, recording bias voltages
2) disconnect speaker load simulator and substitute with actual cabinet.
The latter is due to the schematic. It says that disconnected speaker jacks are shorted to ground to prevent 'excessive flyback voltages from damaging XF3.' So perhaps I have baddened a ground, overtensioned speaker jacks (my own theory), blown my load sim soak, or some other space wizardry.
I aim to test fire this evening. Which means ending this
-girls in space be wary-
R23, R24 replaced (220K)
BD 3 replaced (bridge diode)
R2 REPLACED (50K)
R4 REPLACED (100K)
C11 REPLACED
reboot...
... with speaker cable attached to speaker cabinet.
Bias reads 9V
WHOOP fuckin'getting closer.
Attached to power soak, same reading. Not blown.
WHOOP FUCKIN'
Pull V4 (or power tube 1) - voltage reads 0.1V
pull V5 (or power tube 2) - voltage reads 6V
pull V6 (or power tube 3) - voltage reads 6V
Pull V7 (or power tube 4) - voltage reads 0.2V
power down
switch to 100W op mode, for literally no reason
enegage and the bias voltage is .45....
and I'm guessing this is becuase I have the trim pot turned all the way down
and it isn't drifting
and I turn it up to 0.6
and it isn't drifting
with old tubes.
what in the loving fuck
it's working
Which I suppose would point the dickfinger at me?
or the switch
Early start tomorrow, though, not necessarily on the amplifier; eventuality of testing tomorrow will be to wrangle new tubes in, bias, power down, bias, test run via emulation-minused balanced DI (-30) to 11R MIC in (PAD engaged.)
During this process, I plan on testing each of the preamp tubes I have lying around. To this end I will be using a lightly modified Marshall AVT20, which requires but one 12ax7 tube and a dummy plug.
<3
why not just use a bias probe to set the bias? get a true reading of milliamps?
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