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2385 reconnect PS00 to P400 pin question

It could also be a hairline crack or a cold solder joint on a trace on one of the boards. Going to be hard to track down. Try to isolate it to a single board by wiggling each board separately.
 
dankik said:
It could also be a hairline crack or a cold solder joint on a trace on one of the boards. Going to be hard to track down. Try to isolate it to a single board by wiggling each board separately.
Click to expand...
I think i found it, just want your thought on this, if you look at the photo , you can see the nine pin connector solder joints, if you start from the left and go to the fourth pin, when you follow the trace it goes to a ground at the bottom., i have no continuity from 4 to ground. I was thinking of just jumping a wire from 4 to ground. petePXL_20260609_162426831.jpg
 
You have not continuity because that trace from "pin 4" (actually JE05 pin 6) does not connect to anything.
Take a look at the board layout and schematic.
The trace from the connector, 4th from the left, is "6". If you trace it down to the bottom of the board it just stops.
Compare the layout to the schematic, connector JE05 in 6. It shows that it is not connected to anything.
Screenshot 2026-06-09 095820.jpgScreenshot 2026-06-09 095718.jpg
 
Thanks, i will still need to find out why i have no right channel? I exposed the boards and all components on the right side, i tried with the rubber of a pencil to touch all connections, no luck, when i touch the green, right channel wire i get a louder hum but no sound. Ill keep looking, something is broken.
 
re tested volume pot ,both channels the exact same values, could the issue be on the board or is there a wire in the area of the volume pot that can affect left channel? , put all back together now even if i wiggle the pot no right channel. May need to get someone with scope to find issue.
 
Is it worth my time to remove relay to test?
 

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If you remove it, you might as well replace it. I think this is the correct replacement relay. Please check the pin spacing dimensions. Corroded relay contacts could be causing an intermittent channel audio?

EDIT: Not sure what the voltage is? -77V?
Looks like 48V from PL description.
Screenshot 2026-06-09 161026.jpg
Screenshot 2026-06-09 160820.jpg

Screenshot 2026-06-09 155801.jpg
 
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Did we previously determine if the problem Left channel is in the Preamp or Main Amp? If not, take a short stereo RCA cable and cross connect the L Preout to R Main In and R Preout to L Main In and see if the bad channel switches sides. If it stays on the L then it is a problem with the Main amps, if it switches, then it is a problem with the Preamp.
 
dankik said:
Did we previously determine if the problem Left channel is in the Preamp or Main Amp? If not, take a short stereo RCA cable and cross connect the L Preout to R Main In and R Preout to L Main In and see if the bad channel switches sides. If it stays on the L then it is a problem with the Main amps, if it switches, then it is a problem with the Preamp.
Click to expand...
will do. pete will the test work if the receiver is connected internally pre and main?
 
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This is Dan... Yes, when you push in the RCA cable into the Preout and Main In, it will disengage the automatic jumpers.
 
dankik said:
This is Dan... Yes, when you push in the RCA cable into the Preout and Main In, it will disengage the automatic jumpers.
Click to expand...
Sorry i was ending the reply with my name, then thought about the internal connection. pete
 
I connected as per your instructions, before attaching the RCA cables, right side no sound, after connecting RCAs now left side no sound. I guess that means pre amp. Does that give me an area to check?
 
Im not sure what this tells us, i connected my 2275 to my 2385, pre out from 2275 to main in 2385, powered up 2275 then 2385, volume on 2385 50%, set 2275 to am, i get both channels no issue.
 
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OK, let's summarize. Here is the first test where we swap channels and the dead channel moves from R to L side seeming to indicate that the Main Amp is OK and that the problem is in the Preamp somewhere.

Screenshot 2026-06-10 075913.jpg

Now your latest test, using your 2275 as a Preamp and BOTH channels work OK. This still shows that the 2385 Main Amp is OK.
Screenshot 2026-06-10 080102.jpg

Now try the opposite. Connect the PreOut of the 2385 to the Main In of the 2270. I think you will see that the 2385 has a bad R channel?
Screenshot 2026-06-10 080551.jpg
It makes sense so far...
 
dankik said:
OK, let's summarize. Here is the first test where we swap channels and the dead channel moves from R to L side seeming to indicate that the Main Amp is OK and that the problem is in the Preamp somewhere.

View attachment 3780167

Now your latest test, using your 2275 as a Preamp and BOTH channels work OK. This still shows that the 2385 Main Amp is OK.
View attachment 3780169

Now try the opposite. Connect the PreOut of the 2385 to the Main In of the 2270. I think you will see that the 2385 has a bad R channel?
View attachment 3780170
It makes sense so far...
Click to expand...
Yes right channel still out but there is a hum on the right that is not affected by increasing volume Does the issue need to be in the volume pot, or board its attached to, or boards in that area because i used to be able to get the right back by lifting the rod on the volume stem, since checking board and replacing no it does not affect right.
 
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Here is a block diagram from the SM.
  • We know that the Main Amp is good (green)
  • I presume that the AM/FM and Phono inputs are good (green)
  • I don't think that we tested the Tape inputs? (yellow)
  • So the problem seems to be in either the PE00 Pre & Tone Amp or PT00 Filter Amp (red)
  • Also, just outside of the Pre & Tone Amp is the Balance control?
  • We need to devise a test to isolate the board that has an issue

Screenshot 2026-06-10 083820.jpg
 
There is a mode control that selects Stereo, Reverse, and L+R. I presume that you have had it in Stereo during the above tests.
Does anything change if you put it in REVERSE or L+R? Right channel still bad in all cases?

Screenshot 2026-06-10 085000.jpg
 
dankik said:
Here is a block diagram from the SM.
  • We know that the Main Amp is good (green)
  • I presume that the AM/FM and Phono inputs are good (green)
  • I don't think that we tested the Tape inputs? (yellow)
  • So the problem seems to be in either the PE00 Pre & Tone Amp or PT00 Filter Amp (red)
  • Also, just outside of the Pre & Tone Amp is the Balance control?
  • We need to devise a test to isolate the board that has an issue

View attachment 3780180
Click to expand...
I saw an earlier thread on testing the voltages on the PE00 board , not sure how to get access to pins while board is attached but i will look into it.
 
dankik said:
There is a mode control that selects Stereo, Reverse, and L+R. I presume that you have had it in Stereo during the above tests.
Does anything change if you put it in REVERSE or L+R? Right channel still bad in all cases?

View attachment 3780184
Click to expand...
Yes all testing in stereo, also no sound when balance full right on any of the settings.
 
If you put the mode control to:
  1. L, do you get sound in both channels?
  2. R, do you get no sound in both channels?
  3. Or does it not matter still no sound in R channel?
  4. Do you have the Tone Mode selected to OUT? If yes, that should bypass the tone controls and eliminate them from the problem.
Screenshot 2026-06-10 100053.jpg__Screenshot 2026-06-10 103417.jpg
 
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