marantzfan's 4400 - All Out Restoration!

[Jailtime]

A picture might be worth a thousand words here. In the first picture, you can see the test points for where signal leaves the PF01 tone control. The blue ones are high (correct signal), yellow ones low. The red wires tie to the 1uF caps on PD01, the white wires to the 3.3uF caps.

The next picture shows the 1KHz signal as low. Other picture is 1KHz high, ignore the messed up trace, shaky hand with the camera. Quite a difference there.

I wish that PD01 wasn't such a bitch to separate from PF01, those solder pads look like hell. :sigh:

 

[bktheking]

J007 is a ground rail, maybe it's a broken trace you can't see. Did you check to see if the ground rail is good on both sides?

 

[Jailtime]

Looks like the bad channels were caused by a bad ground. I checked all the ground points that are screwed to the chassis, and tightened them. Recapped the PE01 preamp board too, still need to replace those little varistors. Got good sound on all four channels now in Vari-Matrix mode.

Sounds pretty good, now I just have to get the tone control board back in without breaking anything.

 

[jstang]

I forgot what a pain in a rump that was.....

 

[EchoWars]

Looks like the bad channels were caused by a bad ground. I checked all the ground points that are screwed to the chassis, and tightened them.

And that was the fix?

 

[Jailtime]

And that was the fix?

:yes: Looks that way. I recapped the PE01 preamp board at the same time, but it had good signal output before the recap.

The loose ground point was the one for all the preamp section boards, screwed in near the tape monitor switch.

 

[69sixpackbee]

That effin' sucks!
I run into that a lot when troubleshooting the industrial gear I work on. This is very common on especially the robotics I have to work with that comes from our sister divisions. Seems common when these are bounced about on a plane coming overseas.
Good work!


Sent from my iPhone using Tapatalk

 

[EchoWars]

:yes: Looks that way. I recapped the PE01 preamp board at the same time, but it had good signal output before the recap.

The loose ground point was the one for all the preamp section boards, screwed in near the tape monitor switch.

Well, I'm celebrating with a Guinness for ya buddy. :thmbsp:

 

[Jailtime]

Well, I'm celebrating with a Guinness for ya buddy. :thmbsp:

It's really nice to hear this thing again after all the problems it's been giving me.

Finished up the PH01 filter amp and PM01 phase converter today. Running in bridge mode with my DQ-10s now, this 4400 is really strong bridged. It's dead silent at idle, pretty impressive considering all the circuitry in this thing.

VariMatrix board, Dolby unit, and meter driver board to go. LED install, faceplate polish, and power output/listening tests will finish this 4400 up. :yes:

 

[ChrisMarantz]

Glad to see that you figured it out. You must have been sooooooo happy when it finally played correctly

 

[EchoWars]

I know the feeling...the first impulse is to buy a keg and throw a party.

 

[1978_DREAMER]

Did some one say keg and party in the same sentence?????? That sounds like a good time!!! Ya know Kyle, I can't think of very many projects that I've been exposed to that didn't have at least one ground or connection type problem. Good work tracking that one down!:thmbsp:

 

[Jailtime]

I know the feeling...the first impulse is to buy a keg and throw a party.

I'll do that when I finish it up for good. Been a bit over two months now. I bet Anthony would like to wring my neck.

 

[marantzfan]

I'll do that when I finish it up for good. Been a bit over two months now. I bet Anthony would like to wring my neck.

Funny. I figured it was you wanted to wring my neck after all this.

 

[Overundr1]

Like fine wine ----

 

[Jailtime]

Here's PM01 phase converter and PH01 filter amp. Just 5 caps for each board. Both boards offer easy access to the foil side, just undo that wire clamp to free PM01.

 

[jstang]

Good on you.....you ditched the tantalums.....

I might re-re-cap one of my 4400s.... when I did them Silmics were not in vogue yet. Might do some of the easier boards.

I also re-enforced the power and output wiring with some 18 gauge solid core wire. That helped a lot more than you might think....especial for the 5$ cost.....

jk

 

[Jailtime]

Latest progress on the 4400. Vari-Matrix board rebuilt, first picture shows access. Pretty easy to get to the foil side of the board. Yes, I did remember to clip those cap leads. Next up is finished Vari-Matrix, those Silmic II caps are a tight fit in a few areas.

One side of the Dolby unit finished up. 20 caps per side.

 

[ChrisMarantz]

Wow, they really packed a lot onto those boards. How many caps do you think you will have replaced when your done? Looks like you might be approaching 200 pieces

 

[Jailtime]

Wow, they really packed a lot onto those boards. How many caps do you think you will have replaced when your done? Looks like you might be approaching 200 pieces

I could count all the caps in my garbage box to find out. Here's about 75% of the mess from the Dolby unit.

It's damn close to 200 caps, I know that much.