Help please with my poorly Stasis 2

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#321
go back and test just FE board

test entire span of voltage between D+ and D- you can get fiddling with trimpot for biasing; red probe on D+, black probe on D-

also test span of voltages between D+ and GND, fiddling with DC Offset trimpot; red probe on D+, black probe on GND

write here what you got ......... and then we will know is it functional

after that we need to determine proper layout of OS connections - is everything in place (due to fingerpoking in past) and (hopefully) once again to confirm that all semis are functional

only then, with clear arrangement, is sane to go further

dang, I did tell (in other thread) that I'm not going to build damn thing, and again here I am ....... own hostage :rofl:
 
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#322
Zen Mod said:
go back and test just FE board

test entire span of voltage between D+ and D- you can get fiddling with trimpot for biasing; red probe on D+, black probe on D-

also test span of voltages between D+ and GND, fiddling with DC Offset trimpot; red probe on D+, black probe on GND

write here what you got ......... and then we will know is it functional

after that we need to determine proper layout of OS connections - is everything in place (due to fingerpoking in past) and (hopefully) once again to confirm that all semis are functional

only then, with clear arrangement, is sane to go further

dang, I did tell (in other thread) that I'm not going to build damn thing, and again here I am ....... own hostage :rofl:
Click to expand...
Thanks Zen , I’ll do those recommendations shortly
 
#323
Blk Dynamite said:
Are you certain Q6 and Q7 are in correctly? Like you i was up late working on mine. One channel biased up but the other channel wouldnt. I went to sleep, relooked at everything in the morning and retraced the fault to one of those transistors being backwards. Also another goof up i did was breaking a lead to the thermostat when i was finally mounting it. I couldn’t get any bias
Click to expand...
Hi , thanks for your input. How do tell which way around to place the a1220a ? I have it with the writing facing up . I had my suspicions about the thermostat, if I bridge its contacts briefly will that tell if it’s an issue or not ?
 
#324
Blk Dynamite said:
Are you certain Q6 and Q7 are in correctly? Like you i was up late working on mine. One channel biased up but the other channel wouldnt. I went to sleep, relooked at everything in the morning and retraced the fault to one of those transistors being backwards. Also another goof up i did was breaking a lead to the thermostat when i was finally mounting it. I couldn’t get any bias
Click to expand...
I have both Q6 and Q7 with the writing facing up ( towards me ) then they are around the right way ie: Q7 emitter on the left ( or E ) and Q6 emitter one the left
IMG_5627.png
 
#325
Zen Mod said:
IMG_5631.jpeg
IMG_5632.jpeg
IMG_5633.jpeg
go back and test just FE board

test entire span of voltage between D+ and D- you can get fiddling with trimpot for biasing; red probe on D+, black probe on D-

also test span of voltages between D+ and GND, fiddling with DC Offset trimpot; red probe on D+, black probe on GND

write here what you got ......... and then we will know is it functional

after that we need to determine proper layout of OS connections - is everything in place (due to fingerpoking in past) and (hopefully) once again to confirm that all semis are functional

only then, with clear arrangement, is sane to go further

dang, I did tell (in other thread) that I'm not going to build damn thing, and again here I am ....... own hostage :rofl:
Click to expand...
D+ and D- = 1.905 ( variable upon turning P2 pot )

D+ and ground the voltage is all over the place without touching the pot
 
#327
post #324 - Q6 and Q7 are ok, but I would have preferred KSC3503 / KSA1381 for those positions, but that won't keep this from working

post #325 - we need a range from D+ to D-, for example you would say "hey Zen Mod, the minimum voltage I can obtain by turning the pot is XXX volts, the maximum voltage I can obtain is XXX volts..."
 
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#329
Zen Mod said:
go back and test just FE board

test entire span of voltage between D+ and D- you can get fiddling with trimpot for biasing; red probe on D+, black probe on D-

also test span of voltages between D+ and GND, fiddling with DC Offset trimpot; red probe on D+, black probe on GND

write here what you got ......... and then we will know is it functional

after that we need to determine proper layout of OS connections - is everything in place (due to fingerpoking in past) and (hopefully) once again to confirm that all semis are functional

only then, with clear arrangement, is sane to go further

dang, I did tell (in other thread) that I'm not going to build damn thing, and again here I am ....... own hostage :rofl:
Click to expand...
Hi Zen Mod 😉
D+ and D- the voltage varies when turning the P2 pot from Min 1.899 to Max 4.143

IMG_5634.jpeg
 
#332
Zen Mod said:
go back and test just FE board

test entire span of voltage between D+ and D- you can get fiddling with trimpot for biasing; red probe on D+, black probe on D-

also test span of voltages between D+ and GND, fiddling with DC Offset trimpot; red probe on D+, black probe on GND

write here what you got ......... and then we will know is it functional

after that we need to determine proper layout of OS connections - is everything in place (due to fingerpoking in past) and (hopefully) once again to confirm that all semis are functional

only then, with clear arrangement, is sane to go further

dang, I did tell (in other thread) that I'm not going to build damn thing, and again here I am ....... own hostage :rofl:
Click to expand...
Just tried to note the voltages at D+ and GND
05.35
-3.167
-2.586
-0.819
0.786
255.3
Like I said it’s all over the place and changing too rapidly to record and p2 has no effect.
 
#333
Maybe a failure on the output stage is pulling that (D+) down. The front end should be tested in isolation (not connected to the OS) when we are spinning P1 and P2 all over the place. Only power and ground connections. And we always short the input to ground (the RCA) when setting up a new amp to get all these DC parameters and idling currents where they need to be. Once that is finally acheived, we can remove the short and then feed it our AC music signal (or test tone, whatever). But back to the issue... I would be curious to see what the voltage range (lowest=, highest=) is with red probe on +V (+73V), and black probe on Base (B) of Q7 when you spin P1 end to end. If it's ~.3 to ~1.5 I think this FE checks out..
 
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#334
TheFinisher said:
D+ and D- the voltage varies when turning the P2 pot from Min 1.899 to Max 4.143
Click to expand...

say preliminary that's good

I need to check what's minimum appropriate voltage; maximum isn't critical

TheFinisher said:
Just tried to note the voltages at D+ and GND
05.35
-3.167
-2.586
-0.819
0.786
255.3
Like I said it’s all over the place and changing too rapidly to record and p2 has no effect.
Click to expand...

just to be sure - inputs shorted to GND, no OS connected to FE?
 
#335
I would be curious to see what the voltage range (lowest=, highest=) is with red probe on +V (+73V), and black probe on Base (B) of Q7 when you spin P1 end to end. If it's ~.3 to ~1.5 I think this FE checks out..


At powering on it was -000.2mv
Then 1.299v
Then 1.307 which it stopped at and is the maximum on P1
Minimum is 0.494

High = 1.307v
Low = 0.494
 
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