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marantz 4400 Power board p800

hello there.
i have an updated on my project.
i have replaced all e-caps to include filter caps. i have cleaned all v-resistor and switches. new housing for dial lights and new led bulbs for dial plate. i kept regular bulbs for indicator lights. new v-resistor on power amp boards. once i put everything back together i went and i did the power amp alignment for 0 vdc and 12 mv. it went smooth. no problems. i fired it up to see where i am sound wise before i go with fm/am Dolby and all other adjustments.

Here is the issue.
i get sound at low level. both speakers same low level. it seemed to me at first that the power amp section is dead and the signal just passes without amplification. well i applied signal straight to power amps from different pre-amp and both channels work as they should, loud and strong. that take cars the power amp issue at this point.
well then i started messing with volume control and i noticed that it does not change the volume at all... if it does it is at very slight level.
bass, treble a and mid controls work as well. all filter push switches work but the loudness switch has no effect on the volume of the sound.
it makes me believe that for some reason the pre-amp is not amplifying the signal at all.

Before i started recapping and cleaning the volume control worked.
In addition i replaced the power switch as well. i got the e-switch KutzlerTrans suggested. thx for that.

i removed the volume control and checked it for proper OHM reading and it seems to worked just fine.
That leaves me with the question, what is the problem.


Any ideas where is the problem?

i will upload some pics later with the progress.
 
catrafter said:
Local/Remote switch on the rear panel in Remote or not making good contact, no +35V from the power supply or a broken wire feeding +35VDC to one of the many boards that use it.

Tom
Click to expand...
Yeah, your were correct, the remote switch was the issue. it did not went all the way to the "Local " position, a bit of cleaning and it works, i spend many hours trying to figure it out and it took you 2 sec ... I have to learn a lot....

Anyhow, volume control works and both channels work.

Next issue i have now is that right channel is not affected by bass, treble and mid controls. it does not have any bass at all. filters seem to work, as well as loudness switch.
I figure i ask before i spend another half of the day trying to get it fixed, maybe a hint from some of you will safe me some of my time.
Thank you again.
 
Your remote switch problem was an easy one, it has happened to me so many times it is the first thing I check!
I am looking into your much less frequent tone problem, give me a little while to see if I can come up with some more ideas.
Please try testing with the rear panel Power Mode switch in 4X (power off before switching!), speakers on both front and rear Main, selector in AUX/CD4, Mode in Discrete and a source into all four (front left, front right, rear left , rear right) aux inputs.
This makes each of the four channels through the whole receiver independent of each other which makes troubleshooting easier.

Tom
 
ok i did like you sad and here are the results:
BL no sound at all
BR OK
FL OK
FR no treble/bass/mid.
i tried main and remote speakers, same results.

and i thought i was close to get it done.....
p.s
the build-in scope shows signal for each channel like it should.
 
On the positive side, You are closer to getting it done than you were a month ago, and you have a Top Shelf guy helping you.

Tom is the cream of the crop! Or best said, He got my vote for member of the year, last year.:thumbsup:
 
KutzlerTrans said:
On the positive side, You are closer to getting it done than you were a month ago, and you have a Top Shelf guy helping you.

Tom is the cream of the crop! Or best said, He got my vote for member of the year, last year.:thumbsup:
Click to expand...

i which i had 10% of the knowledge he has on the subject. i would have that thing done by now..
But,,, yes, im lucky to get the help. as you can see i definitely need it :idea:
 
If you had worked on as many Marantz quads as I have you would have the same knowledge, If you think I don't get stumped and spend hours chasing things around you are wrong.:)
The signals to the scope are tapped off after the buffer amp, before the preamp and any volume, balance or tone controls.
My first guess is bad solder connections between the PF/PD boards. This is where the small 'daughter' board connects to the board that attaches to the tone controls.
These are always a problem, it is a poor design with little mechanical rigidity, fortunately, I think you can get to them without doing anything more than turning the unit upside down and removing the bottom cover.
It might be a good idea to keep it set up as four independent channels until we get it fixed. The no Left Rear and no tone control of the Right Front may not be related, I am still looking...

Tom
This block diagram might help, it is from the owner's manual.
 

Attachments

updated:

Thank you for the block diagram.
I stared with trying to figure out the dead channel.
Well i used my tube vintage signal tracker :rockon: and i was able to find a bad transistor HE14. I had a signal at the base but not at the emitter. I removed it from the PCB ,check it with the transistor checker and sure enough its bad.
Now i have to find a replacement for 2SC1345D or E TRANSISTOR. I see one on ebay ror $7, not cheap.
Any suggestion what should i use other than the ebay one.
 
yeah after a few minutes of thinking.. I figured, if i get a different one i would have to get all four (one for each channel) to mach them up... i went with the ebay.
Now i wait for it to come.


here are a few pic of my project:

before


after


after recap




 
Last edited:
Bad transistor HE14 R&R. BL channel came back to life. Now all i have is the treble/mid bass controls not working. I noticed that FR channel is weaker all together. I will have to investigate some more. I notices that all signals coming out of preamp are the same strength, so the problem is right after that section somewhere.
I did check the PF/PD boards connections. re-flow the solder. it seems to be ok.
 
catrafter said:
[..]
My first guess is bad solder connections between the PF/PD boards. [...]
Click to expand...

After checking and rechecking.. tracing signals, voltages at every transistor form source to output and finding nothing really, finally what i did find was a voltage difference at preamp out connectors between left and right channel. I went back to PF/PD boards and as i was measuring the voltages i saw a voltage drop. I thought maybe i moveed my connections, well i tested it for a while. I even re-flew the solder.. Well i still had some abnormal voltage readings. i decided to remove solder completely, and as i was sucking solder away, a small aluminum tap came right off. I decided to go with a jumper wire to fix it. and once i was done doing so, i checked my voltages and i was right on.

next came speakers test.
Clean and load audio from both channels. bass/treble and mids work for left and right channel. (rear channels worked fine before)

going back to the quote, thank you again Tom. You were right on form the start.

My fix: don' t judge me lo :)



 
Anyone who can fix a 4400 get's my congrats- i've repaired 3 of them, still to this day I hate working on them.
 
Thank you. I could have done it without your assistance.

now im looking at AM/FM align procedure and im lost..
i have a Fm gen. But how am i supposed to get 3 to 5uV output. I can set db output on my FG but this micro volts business seems confusing to me.
Any idea ho to go about this. i look at forums and maybe somebody has posted something about this already.
 
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