I wasnt sure, starting to confuse myself. The other pads are labled IN1, IN2, and so on, and it is labled "OUT," but looking at it seemed like it would work as "IN" wired as described. signal in, to volume pot, then to board, right?temp only until tomorrow PM. Iron heating up. This way I will know whether or not everything else is working as it should before the disassembly and re assembly. I would hate to do those changes and then have to trouble shoot.
Russellc
Russellc
As a point of clarification, I have a stand alone mounted volume pot, with wires going to the pads the Alps was to fit on, operated with an extension to front panel.
Russellc
Russellc
Maybe I better wait and hook it up proper. All the other RCAs are wired to I-select, using this out as an in might be problematic with the other parts of I-Select wired up.
No joy there. I must have miswired something, but I sure am not finding it. Continuity from pot pads on I-select to pot, everything seems OK, all leds on pre board lit up, light bars on PS, rails measure good. I installed two RCA jacks in a thick piece of fiber board, ran a right and left to them and ran their grounds to the center ground pad. Phone as signal source, audioquest dragonfly cable to these inputs.
I assume since it lights up and measures correctly the pre board in functioning. Same with PS. volume pot is a stepped ebay job, I've used a bunch of them and have it wired as I usually do, and even when miswired something usually comes through, but nothing.
I cant imagine it will work with I-select wired up I dont think that is the problem. The pads for the Alps pot buzz when touched to the matching pads on the "out" pad, and from the alps pot pad to the volume pot so wire not broken.
RCA outs to amp are wired to the line and G pads, volume pot wired to the IN and G pads. Start again tomorrow. At a loss, I will stare at it some more later, but not seeing it.
Russellc
I assume since it lights up and measures correctly the pre board in functioning. Same with PS. volume pot is a stepped ebay job, I've used a bunch of them and have it wired as I usually do, and even when miswired something usually comes through, but nothing.
I cant imagine it will work with I-select wired up I dont think that is the problem. The pads for the Alps pot buzz when touched to the matching pads on the "out" pad, and from the alps pot pad to the volume pot so wire not broken.
RCA outs to amp are wired to the line and G pads, volume pot wired to the IN and G pads. Start again tomorrow. At a loss, I will stare at it some more later, but not seeing it.
Russellc
I decided to measure the A/C signal using phone as source. Picked up varying A/C, went to 0 if I hit pause. Like the pic of the volume pot pad's wiring, I got the A/C signal to the red ones where it comes in, but not on the blue ones and I can see why. Just to be certain of what is hooked to what It looks like Moving the R and L lines to the center pads would get signal to pot,
Hooking up a set from the center (light red) R and L gives signal to pot, I can trace it to the outputs on the pot and to the input on the preamp board.
This seems all together wrong, but if it passes signal to the amp, I will disassemble to lift PS board and hookI-Select up properly and clean up the wiring.
Hooking up a set from the center (light red) R and L gives signal to pot, I can trace it to the outputs on the pot and to the input on the preamp board.
This seems all together wrong, but if it passes signal to the amp, I will disassemble to lift PS board and hookI-Select up properly and clean up the wiring.
turned everything on, started play, I can faintly hear over speaker if turned almost full. I am figuring it is some hook up errors. Is it possible that this preamp board would measure properly at all points and not work? starting to suspect volume pot but whats the chances both channels are bad. At least some very very faint signal is getting through. Are there any other voltage points to check?
I hate to do it but I may try by passing the volume pot and adjust volume on laptop or phone, just to hear this thing function.
On a positive note at least it isnt a hum festival....not yet anyway.
Russellc
I hate to do it but I may try by passing the volume pot and adjust volume on laptop or phone, just to hear this thing function.
On a positive note at least it isnt a hum festival....not yet anyway.
Russellc
Disassosiate from the board, wire it alone to make sure. As we watch a volume pot from its back: Left leg is input, middle leg is output, right leg is ground.
Well, just posted but it vanished. More trouble. Decided to check voltages and R10 is still mid .90s as before. Rails about 17.4 ish. Offset measured at 40 mV so began cranking down. Continued to lower until it occurred to me I had turned this pot way more that could be possible and stopped. voltage continued to lower without any twisting of pot, so I tried to see if it would turn up, but it continued drifting down to 0, then through the minus numbers and so on. Other channel doing same thing. Likely Mosfets and AD823 dead?
Russellc
Russellc
Bias seems still good so the Mosfets must be ok. Stop experimenting with the input circuitry, maybe some DC offset is fed in. Wire everything up by the book first, including IN-Select DC power line from DCSTB. After that repeat the offset procedure. Out goes the op-amp, trim down, put it back again. If output DC mV remains very low, proceed to audio test.
Properly wired now. Led on I-select lights up and I can hear the relays click. Offset continues to drift steadily still. Before AD823 installed I dont recall it roaming like this, it was just high, I turned it close to 0 and it hung around there. it moved a bit, but not just steady going through the numbers, all the way up, then to minus numbers all the way the other way. does not pause at all. Once AD823 was installed it seemed to sit around 1 mV.
Makes me think maybe more than the AD823 is dead, or maybe its dead corpse still plugged in is the problem. Should I power down, remove the AD823 and power up? If it acts like before I guess the AD823 is killed? I did an awful lot of turning for nothing, maybe pots need turned a BUNCH of times? I doubt it.
Russellc
Makes me think maybe more than the AD823 is dead, or maybe its dead corpse still plugged in is the problem. Should I power down, remove the AD823 and power up? If it acts like before I guess the AD823 is killed? I did an awful lot of turning for nothing, maybe pots need turned a BUNCH of times? I doubt it.
Russellc
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I turned pots until they clicked, then 12 turns back. No difference on offset, just slow up and then down.
Russellc
Russellc
There's no reason to speculate failed components as for now. If DC offset mV is steady with the AD823 in place and if there will be audio all is well. If not, we will talk debug & servicing.
It is not steady. It constantly climbs up, then back to 0, minus numbers, over and over. Turning the pots has no effect.
Say when you measure offset, it is 246 mV. Then 245, 244, 243, all the way to 0, then -1, -2, -3 all the way. Pots have no effect.
Russellc
Russellc