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Marantz 4400 Weirdo-scope!

R

Roosch

Member
Hello dear marantz fellows! My nicely working 4400 has a slightly defective scope...

I've been trying to fix the unkwon issue lately, because i think part of the 4400's soul lies in the scope itself:yes: Hence, for proper liveliness i need to fix it.

I have been reading a bit about defective scopes, where people suggest a switch of scope circuit-board transistors, which i replaced without effect. The trimmers work in the sense that they succesfully adjust the signal.

Now, to the problem.

I have only a moving vertical line on the scope in 2 channel mode. Whereas in vari matrix the signal moves only in three ways but not in all four....

If anyone has any suggestions on what can be done please let me know...

all the best and may our marantzes live 4-ever!
 
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The problem is not on your scope board. IIRC, there is a 'diode matrix' circuit board that splits the channel information into the "X" - shaped scope display. There's probably a dried-out electrolytic cap on that board blocking the scope input for that channel. I can give you a bit more detail once I dig out my 4400 service manual...
 
Roosch said:
Now, to the problem.

I have only a moving vertical line on the scope in 2 channel mode. Whereas in vari matrix the signal moves only in three ways but not in all four....
Click to expand...

Hi,

I have had exactly the same issue with my 4400. The scope (if in audio mode) receives the information from the pre-amplifier.
The problem with mine was, that one channel on the PE01 board (buffer and pre-amplifier assembly) was broken. One of those VD1212 diodes failed and took some other stuff with it...

If you check this Quadroreceiver, it has always to be in the 50Wx4 position. (Never ever turn this switch at the back, when the receiver is on. Always shut if off before and wait a minute or two....)

Then check, if all 4 channels are working. Easily checked with headphones. I guess they are not. Look if you find any burned areas on the PE01 board. It is underneath the chassis, you will see it, if you remove the bottom plate.
Probably one channel of your preamp is defective.

Maybe it is the same with your 4400. I dont know, as I am no electrician at all. But it might help or it might not.

Good luck!
 
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Agree with or the wiring from the Diode matrix.

jk

skibjr said:
The problem is not on your scope board. IIRC, there is a 'diode matrix' circuit board that splits the channel information into the "X" - shaped scope display. There's probably a dried-out electrolytic cap on that board blocking the scope input for that channel. I can give you a bit more detail once I dig out my 4400 service manual...
Click to expand...
 
Boy o boy o boy!!!:banana:
I fixed the scope and it looks great!!! Im very happy to see it dance around so beautifully to the wonderfully warm and lovely tunes!:banana:

Very good my fellow marantz frriends! thank you so much for the advice!

I did a check on the Tone and matrix board, and yes, i thought i saw a few weirdo trannies in there. I replaced these four sk30's with some spare ones i bought to replace the scope board trannies.

without a doubt the marantz 4400 oscilloscope is among the top three greatest inventions of the 21st century:tresbon:, right after lazers and cold fusion.


Now to my last potential marantz project for awhile:

I was wondering if anyone knows any good and suitable replacement Main caps for the 4400. I am a bit uncomfortable having heard that if they fail a lot of other things often will fry as well... Hence i thought it would be a good idea to swap them.
It seems, however, quite difficult to find replacements online.

If any one knows of good replacements please let me know.

All the best! and merry xmas!
 
Perhaps these are good? Does anyone know?

If so i will buy them, but they look a bit old, although it says factory surplus.

peace and love and marantz
 
Hi Roosch!

VERY nice that you fixed the scope - I can really follow your joy about this.

Regarding the Power supply caps I'd definately leave them alone - As long as you do not have an audibly hum in your speakers and if they look ok - no bulges or other bad signs of electrolytics going south. They do go bad - but my experience is, that small caps of that kind dry out easier than the biggies.. especially if they are located close to "hot" areas in the amp.

best regards
Freddy
 
Yes thanks again Wilfred and freddy for helping me out getting this babe back to life! Great work Wilfred and nice transport Freddy!

Merry xmas!!:music:
 
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