4230 problems

V

Vintagecasey

Active Member
I have a dumb question on the 4230 looking at it from the front is the amp board on the right side for the quad and the amp board on the left side for the regular stereo? My first question with this is I bought this thing knowing one channel wasn't working thinking it would probably be an easy fix. When I took the amp board on the left side (looking at it from the front) out there was actually a burn hole through the board. I looked for a replacement amp board but none available at this time. I've removed both the left and right amp boards and mark them right and left, to try to follow the traces on one side to the traces on the side that the board is burnt and can't really tell where they go. As a test, could I replace the left side and leave the right side completely disconnected to see if the stereo works or will that not work that way.. thanks
 
Register to hide this ad
Some time ago while helping another AK member I traced the 4 channels from the P700 boards to speaker outputs. I can't tell you which P700 is located on the L or R, but I can say that one P700 services the Main LF (Left Front) and Main LR (Left Rear) while the other P700 services the Main RF (Right Front) and Main RR (Right Rear).

See the attached schematic and colored lines.
 

Attachments

The reason I was thinking that the one on the left goes to the right front and left front is because they are each half is a mirror of the other half, while the board on the right uses lower voltage capacitors so I was thinking those would be for the backs? I'm not sure....
 
Well I recapped the unburned amp board, replaced a couple transistors, the four output transistors with MJE15032G. On a dim bulb it stays very dim, but still have no output to right left main remote front back... I don't see any test points to know what voltages I should have. Testing it with only one amp board in the other amp board I'm working on trying to make jumpers across the burnt areas. Can anyone help?
 
Vintagecasey said:
...but still have no output to right left main remote front back...
Click to expand...
One P700 board is for the LEFT FRONT and LEFT REAR. (as I showed in the schematic above)
The other P00 board is for the RIGHT FRONT and RIGHT REAR.
Main vs Remote is not affected by the P700 board, only the Main and Remote Speaker switch and Power Mode switch.
Put the Power Mode switch into 2-Channel to test. Connect your speakers to the Left or Right Front and Rear Main Speaker terminals.
If you have only one P700 board installed, you will only have sound on the LEFT FRONT and LEFT REAR or RIGHT FRONT and RIGHT REAR.

So, "right left main" means that you need to have both P700 boards installed
Also, "remote front back" you don't say whether it is L or R, but front and back are not a function of the amplifier but the switching.
 
Last edited:
OK, I would like to make sure that you have the other selections correct.
  • Monitor (source/tape)
  • Tape (1/2)
  • Dolby (FM Dolby/Play/OFF/Record 1/Record 2)
  • Selector (AM/FM/Phono/CD-4-Aux/Tape 1/Tape 2)
  • Mode (Mono/2 CH/Discrete/Vari-matrix/SQ Decoder)
  • Dimension
  • Bass
  • Treble
  • Volume
  • Hi Filter (Off/On)
  • Loudness (Off/On)
  • FM Muting (Off/On)
  • Spkr Main (Off/On)
  • Spkr Remote (Off/On)
  • Local/Remote (Local)
  • 2X/4X (2x)
Where did you connect your speakers to listen for audio?

Screenshot 2026-06-05 143905.jpg
 
Source
Tape 1
Dolby off
FM
2ch
Dimension center
Bass centerd
Treble centered
Volume 1/4
Main and remote pushed in
FM muting off
Loudness off
Hi filter off
Balance centered
400 tone off
Dolby all centered
Meter left
On FM signal meter moves to middle
FM tuning in the center
Also tried selector on AUX with phone playing music
Through RCA jacks
 
dankik said:
Some time ago while helping another AK member I traced the 4 channels from the P700 boards to speaker outputs. I can't tell you which P700 is located on the L or R, but I can say that one P700 services the Main LF (Left Front) and Main LR (Left Rear) while the other P700 services the Main RF (Right Front) and Main RR (Right Rear).

See the attached schematic and colored lines.
Click to expand...
Hey dankik, that was me that you were helping out (thanks again for the support!). The amp boards are on their respective sides when viewing from the front. Left on left, right on right. You can tell by the schematic to physical + voltage rail going to either the J721 or J722 posts on the boards. There is a confusing misprint also on the schematic for the right channel board showing two J721 posts. The lower post is actually the J722.

It would be good to see some pics of what you are dealing with on the burnt board.
 
I would definitely snip those collector leads on the outputs, as to not risk shorting out on the heat sink.

Yes, Jumpers look to be needed on a few spots. You can always check continuity on the traces to see where the problem spots are. I would say that you probably have a few fried components there on the board as well as some solder points that need reflow.

I would focus on getting the unburned board working first. Check all your diodes and transistors. You could have an open which may not show up on a dim bulb test.
 
Yeah just in case this fixed didn't work I wanted to leave those leads on there if I take them off and use them somewhere else...
 
Yeah the traces are still intact, but there's no board behind them to support them anymore. I was thinking of maybe getting some JB weld and flattening it out. Lots of work to do don't know if it's actually worth it or not, but I wanted to try to save it. It may be a little bit over my head though.
 
Anyone know why there is a resistor on the tuner board that is attached on one side and just goes to nowhere on the other side?1000002513.jpg
 
I've been looking for a picture of the p700 amp board in the net, can't find much... Anyone have a picture? I have my original pictures from before I started, but as I mentioned, this thing is really hacked up. No idea if they were in the right places when I started. These are what I have.

(Right side board looking at it from the front )
J715 Orange
j721 red
j713 white and purple
j707 black
j708 Black
j714 white and gray
j716 gray

(Left side looking at it from the front )
J715 Brown
J713 white and green
j707 black
j708 black
j714 white j716 blue
J722 red
J716 blue

Do they look right?
 
You must log in or register to reply here.
Back
Top Bottom