CurtPalme.com Home Theater Forum

[macgyver655]

Well that is great to hear. Now you can enjoy it.

[jgrice53]

Hi mac, yes it is working but there is a problem with the right front channel. The volume output is very low and the sound is distorted. Do you have any ideas?

[macgyver655]

Must be 1 or more bad parts still in there. Set your DMM to DC voltage and test all the speaker terminals and see if the RF has any DC. Not likely but check there first.

[jgrice53]

volume min. or does it matter? speaker connected or not? i have never done this test before.

[macgyver655]

Speakers disconnected, volume doesn't matter. The only thing that needs to be sure is that the speaker relays are latching on but since you have sound coming out then they are latching. That is why this test does not always work. If the relay is not closing then you cannot test for DC at the speaker connectors.

[jgrice53]

So even if the sound is good at the left front channel, I still should test it? As well as the center and rear channels?

[macgyver655]

Sure. It only takes a few seconds. I always check for DC on all channels after a repair. And idle current should also be checked and adjusted if needed. But it needs to be running properly first for that.

[jgrice53]

R channel .033v
L channel .028v
C channel .038v
R surround .035v
L surround .033v
B L channel .000v
B R channel .000v
Sub .000v

[macgyver655]

I hope you already tried a different speaker on the problem output?

Those numbers look ok for now. The FR amp appears to be balanced but unknown if running. So problem could still be in amp section or could be in preamp section. The best approach is to verify which section the problem is in instead of hunting blindly. So in looking at the schematics I believe this to be the best approach.

On the amp board, locate the harness connected to CP401. This harness goes to the audio board. You need to swap 2 wires and see if the problem stays or moves. If you can get the wires out of the connector with the releases that would be good but if not you will have to cut.

On CP401 you need to swap pins 1 and 9. This is for FR and FL. I have attached a pic for guidance. After the swap, connect speakers to FR and FL and see if the low volume and noise is still where it was or moved.

[jgrice53]

hi mac, is there another way to troubleshoot the r.channel besides switching pins 1 and 9 on CP401? i really do not want to cut the wires and i really don't think i could ever get them out of the connector. I have checked with headphones and the output and sound is good on channels A & B, so I would say the pre-amp is okay right? Maybe i missed one of the output transistors on the amp board? if you say that swapping pins 1 & 9 is the best way, i will go ahead and do it.

[macgyver655]

Are you good at looking at schematics or even ok at it?

[jgrice53]

ok i would say

[jgrice53]

i can read as far as symbols go and tracing out the parts, but what does what i have problems with.

[jgrice53]

for instance i can find a diode or transistor and test them but i don't how one will will affect the other

[jgrice53]

in the above schematic of the channels coming off of CP401, I can see the right and left are the same circuit so with out your help i would just try to compare the voltages and values of each component in the left and right channels and knowing that there is a problem in the right channel, i would look for any test point and then value that is different than the left channel.

[macgyver655]

Ok, then you should be fine with this. In the image below you will see CN1 which is all 5 channels coming into this board. Now these lines are final lines which means they have gone through preamp and final amp stages and now are just being directed to where they need to go. So if you look at your problem speaker line (FR) where it comes into CN1 you can then follow it to relay 2. But you will see where it also splits off to speaker B terminal and relay 1.
So if relay 2 is activated then your A channel speakers will play. If relay 1 is activated the head phones will play. And if B channel is selected then speakers B will play.

But regardless what is selected, it still comes from the same, final speaker line.

SO........ if your headphone RF plays fine but the speaker RF does not, then it would be either the speaker, or relay 2, or a problem on the line from the relay 2 to the speaker A terminal.

If your unit has B channel speaker you could test that output and see if it is distorted. BUT, it will have to also turn off the A channel relay. Because if the is a problem on the line from the relay to the terminal and the A relay is on then the same problem will exist on the B channel also.

Hopefully you got all that, lol.

[jgrice53]

RIGHT speaker channel A & B have the same problem. i know it is not the speaker because i am using 1 speaker and changing it from one channel to the other channel

[jgrice53]

Only 1 speaker connected to the speaker A r.channel and selector on channel A only there is low volume. turn off receiver and move connection to speaker B
r. channel and selector on speaker B only there is still low volume.

[macgyver655]

And on headphone the RF sound fine and the same as the LF?

[jgrice53]

yes headphone and LF good sound.