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2385 reconnect PS00 to P400 pin question

Well I was waiting to see if you guys made it to 1000 posts, and today is the day.
I am surprised how many issues there are.
To help @dankik out since he is just a swell guy to hang in here this long, man you deserve the AK member of the year award in my books. Also help Pete too :-)
Marantz always had the knack to draw circuits as confusing as possible, to the point you have your head spining in circles.
The power amp is something Bryston did in some designs, has a differential input stage (IPS) with collector loads. They take each phase and create a push pull voltage amplifier gain stage. They have an emitter follower on each phase, after the ips. They have a transistor (bjt) in the middle of the push-pull VAS that acts as the bias voltage spreader ( Vbe multiplier: pot & thermal bias temperature sensor, bjt mounted on the output heatsink). This is followed by a two stage class a-b push pull emitter follower. They have I-V current limiters on the positive and negative cycles, sensing is done across the output stage emitter resistors. The I-V bjts turn on during over load current and shunt the drive current from the pre-driver bases. Worse than clipping, called the tweeter eater circuit. If you use replacement 250w output transistors, id disable that circuit.
As for Pete, these are trouble shot using a DMM in diode test mode. Check each bjt junction, using the six-way test. Test diodes in both polarities. Test resistors in both directions, note that when testing in circuit, the DMM test current can flow in parallel circuits, effectively reducing what you measure. Ecaps should Show shorts initially, rise in readings as they charge up. Compare what you read against the schematics ( to try to make sense of what you are measuring) and compare the good channel to the bad channel, both should match using this nodal comparison method.
Standard bjt components to use servicing such an amp are, ksa992,ksc1845,ksa1381,ksc3503, mje15032g,mje15033g,mj21193,mj21194.
Good luck.
 
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dankik said:
Since that amp design is more complicated than I can comprehend, unless someone else chimes-in I would check the EBC transistor voltages and see if anything looks amiss. Maybe a bad resi
Click to expand...

rcs16 said:
Well I was waiting to see if you guys made it to 1000 posts, and today is the day.
I am surprised how many issues there are.
To help @dankik out since he is just a swell guy to hang in here this long, man you deserve the AK member of the year award in my books. Also help Pete too :-)
Marantz always had the knack to draw circuits as confusing as possible, to the point you have your head spining in circles.
The power amp is something Bryston did in some designs, has a differential input stage (IPS) with collector loads. They take each phase and create a push pull voltage amplifier gain stage. They have an emitter follower on each phase, after the ips. They have a transistor (bjt) in the middle of the push-pull VAS that acts as the bias voltage spreader ( Vbe multiplier: pot & thermal bias temperature sensor, bjt mounted on the output heatsink). This is followed by a two stage class a-b push pull emitter follower. They have I-V current limiters on the positive and negative cycles, sensing is done across the output stage emitter resistors. The I-V bjts turn on during over load current and shunt the drive current from the pre-driver bases. Worse than clipping, called the tweeter eater circuit. If you use replacement 250w output transistors, id disable that circuit.
As for Pete, these are trouble shot using a DMM in diode test mode. Check each bjt junction, using the six-way test. Test diodes in both polarities. Test resistors in both directions, note that when testing in circuit, the DMM test current can flow in parallel circuits, effectively reducing what you measure. Ecaps should Show shorts initially, rise in readings as they charge up. Compare what you read against the schematics ( to try to make sense of what you are measuring) and compare the good channel to the bad channel, both should match using this nodal comparison method.
Standard bjt components to use servicing such an amp are, ksa992,ksc1845,ksa1381,ksc3503, mje15032g,mje15033g,mj21193,mj21194.
Good luck.
Click to expand...
Ive already compared all of the left channel resistors with matching right channel resistors. I know in circuit they will be off but I find they all match, so they may be fine.
I was thinking of comparing each transistor voltage with matching to see if there is a major issue.
Do you feel I should do the diode mode test instead? Thanks for helping here and yes Dankik should get a metal for his insight and time
 
dankik said:
This is a quick test to see if a diode junction is shorted/open. It should be quick to check first.
Click to expand...
I tested all of the Diodes both boards the same
I tested all of the transistors on Diode test . tested Base and collector on each . found both channels very close. Not sure if thats good enough or if i have to do 6 way test on each transistor, Or if i should just check all voltages.
 
After testing the P700 left amp this is what seems amiss, I tested resistors both way and the numbers i list were quite different left to right then right to left
R705 R713 R715 R727 R803 R831
I compared transistors doing 6 way test and found these to be far off from right amp
Q713 Q715 Q717 Q718 Q721
Any idea what i should replace these with, resistors i will go by parts list
 
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sendust said:
I compared transistors doing 6 way test and found these to be far off from right amp
Q713 Q715 Q717 Q718 Q721
Click to expand...
Did you really mean something else besides Q718 (or did you mean the other channel was bad)?
sendust said:
I tested resistors both way and the numbers i list were quite different left to right then right to left
Click to expand...
It would be helpful if you listed the resistances measured both ways.
 
dankik said:
Did you really mean something else besides Q718 (or did you mean the other channel was bad)?

It would be helpful if you listed the resistances measured both ways.
Click to expand...
Im listing the resistors with first number left to right, second number right to left
R705=50k, 43k R727= .825M , 30K R803= 53k, 71k R831= 7.6k , 5.0 k
All other resistors showed virtually the same number both ways.
 
sendust said:
All other resistors showed virtually the same number both ways.
Click to expand...
That's OK, but did they compare close to what is on the schematic?
sendust said:
R705=50k, 43k R727= .825M, 30K R803= 53k, 71k R831= 7.6k , 5.0 k
Click to expand...
I would lift one end of these two (or all 4 resistors if you want) and recheck resistance.
sendust said:
I compared transistors doing 6 way test and found these to be far off from right amp
Q713 Q715 Q717 Q718 Q721
Click to expand...
Click to expand...
What were the values you measured? It doesn't help if you don't list what you measured.
 
Q721= red BC=0 BE=.246 EC=.641 black BC=.601 BE=.246 EC=0
Q720= red BC=.271 BE=.271 EC=0 black BC= .271 BE=.271 EC= 0
Q719 = red BC=.615 BE= .272 EC= 0 Black BC= 0 BE=.273 EC= .657
Q722= red BC=0 BE=.247 EC= .249 black BC=.604 BE= .247 EC=0
Q717= red BC=.192 BE=.239 EC=.239 black BC=.193 BE= .238 EC=.683
Q718= red BC=.537 BE=.401 EC=.893 black BC=.700 BE=.400 EC=.784
Q715= red BC=.665 BE=.679 EC=.632 black BC=0 BE=.593 EC=.594
Q714= red BC=1.76 BE=.583 EC=.732 black BC=.630 BE=.651 EC=1.60
Q713= red BC=1.50 BE=.580 EC=.728 black BC=.580 BE=.580 EC=.728
Q716= red BC=.667 BE=.679 EC=1.4 Black BC=.591 BE=.591 EC=.704.
 
Just to confirm when I tested transistors I made sure from l was always testing left and right channel the same way. The base was marked clearly at each transistor
 
sendust said:
Q721= red BC=0 BE=.246 EC=.641 black BC=.601 BE=.246 EC=0
Click to expand...
What does red and black mean here? I assume it is the color of the DMM lead.
What you should be doing when measuring a transistor junction is:
  • measuring base to emitter junction,
  • red to base, black to emitter, read voltage
  • black to base, red to emitter, read voltage
I don't know how to interpret your measurements above.
Were these in-circuit measurements?

If you used your Fluke 115, then it should not read 0, but OL for a reverse bias diode (transistor junction). Otherwise it may mean it's shorted.
1788673473659.png

1788670952926.png
Are you sure about the measurements. It looks like the odd number parts voltages look better than the even numbers?
Thanks.
 
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dankik said:
What does red and black mean here? I assume it is the color of the DMM lead.
What you should be doing when measuring a transistor junction is:
  • measuring base to emitter junction,
  • red to base, black to emitter, read voltage
  • black to base, red to emitter, read voltage
I don't know how to interpret your measurements above.
Were these in-circuit measurements?

If you used your Fluke 115, then it should not read 0, but OL for a reverse bias diode (transistor junction). Otherwise it may mean it's shorted.
View attachment 3831250

View attachment 3831243
Are you sure about the measurements. It looks like the odd number parts voltages look better than the even numbers?
Thanks.
Click to expand...
How testing was done and how to read results
On each transistor this was the order , Red lead on Base, black on Emitter. then Red on base, Black on collector .then Red on emitter Black on collector then i reverse
Black on base, Red on Emitter. then Black on base, Red on collector. then Black on emitter Red on collector. Then i would test what i believed was the matching transistor from the other side, this is why i listed them to confirm i have the correct transistor. Most of the transistors from side to side where reversed, i made sure i was always testing each transistor in the same manor. Base, Emitter and Collector was marked on board so easy to follow.
As for the 0, it meant OL . you wouldnt know this but if i had 0 voltage i would have marked it 0 vl . my bad.
If you would like them tested differently i will gladly do it. All other transistors matched or almost matched their counterparts, these were the only ones different.
 
sendust said:
On each transistor this was the order,
Red lead on Base, black on Emitter. then
Red on base, Black on collector. then
Red on emitter Black on collector then i reverse
Black on base, Red on Emitter. then
Black on base, Red on collector. then
Black on emitter Red on collector
Click to expand...
Q721= red BC=0 BE=.246 EC=.641 black BC=.601 BE=.246 EC=0
Your description of the order of test does not match your measurements??
Please clarify the order of testing. Your first line in your response says "this was the order", but if you look at post #1012 it is in a different order. Just want to make sure you noted the leads correctly.
Thank you for clarifying the 0 vs OL. I was concerned that it was a short.

The odd number parts which should be the bad channel seem to look better than the even channel??

Please confirm one or the other.
Thanks.
 
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dankik said:
Q721= red BC=0 BE=.246 EC=.641 black BC=.601 BE=.246 EC=0
Your description of the order of test does not match your measurements??
Please clarify the order of testing. Your first line in your response says "this was the order", but if you look at post #1012 it is in a different order. Just want to make sure you noted the leads correctly.
Thank you for clarifying the 0 vs OL. I was concerned that it was a short.

Please confirm one or the other.
Thanks.
Click to expand...
Base collector, then Base Emitter, then Emitter collector then reverse leads and measure the same. these are the measurements you see. in my post 1012
 
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The reason I ask is that measurement order on your list of measurements does not match the description you just provided.
For example:
You said ... this was the order...Red lead on Base, black on Emitter​
But your list of values show... Q721= red BC=0 BE=.246 EC=.641 black BC=.601 BE=.246 EC=0 (red on base, black on collector?) or should this be BE?​
Understand what I am saying? Is this description incorrect "As I described is exactly how I tested." or is your measured list incorrect, or did you write it out of order?​
Just trying to make sure I get the right values before I dig into it.
 
dankik said:
The reason I ask is that measurement order on your list of measurements does not match the description you just provided.
For example:
You said ... this was the order...Red lead on Base, black on Emitter​
But your list of values show... Q721= red BC=0 BE=.246 EC=.641 black BC=.601 BE=.246 EC=0 (red on base, black on collector?) or should this be BE?​
Understand what I am saying? Is this description incorrect "As I described is exactly how I tested." or is your measured list incorrect, or did you write it out of order?​
Just trying to make sure I get the right values before I dig into it.
Click to expand...
It must be something I'm not making clear
The numbers on 1012 came this way.
Red lead on base, black on collector
Red on base ,black on emitter
Red on collector,black on emitter
Black on base red on collector
Black on base red on emitter
Black on collector red on emitter
 
Thank you for clarifying that, it's just that you then stated on post #1015 that is a different order, testing the base to emitter first, NOT base to collector. If you didn't make this statement, I would understand but this is different than the order of your measurements.
And, yes you are not clear because you have two different measurement orders stated.
For now, I will assume that the table is correct and your description below is incorrect. OK?

"How testing was done and how to read results
On each transistor this was the order , Red lead on Base, black on Emitter. then Red on base, Black on collector .then Red on emitter Black on collector then i reverse
Black on base, Red on Emitter. then Black on base, Red on collector. then Black on emitter Red on collector."
 
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