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Marantz 4400 Quad Receiver

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Oliade677

Active Member
I fell victim to another beauty this afternoon. Picked up this beast for $250. She's in excellent cosmetic condition and mostly functional. The scope powers on but only emits an orange-ish hue. The lamps need to be replaced on the right half, it's missing one of the caps on a button, and the tuner control is loose and only responds effectively when moved at a high rate of speed. The tube for the scope lights up very dimly, though I am uncertain if it is the culprit for the scope issues. I'd like to do what I can to get her back to her original state, so any input is greatly appreciated. My Kenwood KR-9600 is definitely on the way out with this gem in my possession.





 
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Wow, just gorgeous. I have two 4300s and love them. The 4400 just takes it all that one step further. Good luck with the restoration process. I had a good recap done on one of my 4300s and it was well worth the effort and expense.
 
Yes, the unit is in amazing shape. There are initials (N.H.) and a number (P.O. XXXXXX) inscribed on the face, but it must have been done professionally as it looks very sleek. The initials are in cursive lettering, ha! The unit was likely purchased from the original owner, as the person I purchased it from had a pair of Altec Lansing Nineteen speakers. They were purchased from an estate sale. I really gotta get out to those estate sales...
 
Oliade677 said:
Yes, the unit is in amazing shape. There are initials (N.H.) and a number (P.O. XXXXXX) inscribed on the face, but it must have been done professionally as it looks very sleek. The initials are in cursive lettering, ha! The unit was likely purchased from the original owner, as the person I purchased it from had a pair of Altec Lansing Nineteen speakers. They were purchased from an estate sale. I really gotta get out to those estate sales...
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Sometimes estate sales really do pay off sometimes. If it a decent one there is at least some interesting stuff there even if it isn't audio.
 
Something is gone on the scope driver board. Power it off and see if a screen dot comes to the center. Before anything check the fuses in the unit.
 
So as it is powering off, see if the green dot appears? I'll try that soon as I get home. I had a mashed up Marantz Eighteen that did not output audio, but it did have a working scope oddly enough. Funny to see a nice receiver that is functional but does not have a working scope.
 
Had or have? Believe it or not the scope working is worth way more than the opt's. A few different things can go wrong in the driver circuit. The test is to see if a driver transistor has failed. Most people just see that the scope doesn't work but don't realize it could be a 10 cent transistor stopping it from working. There are usually 4 transistors responsible for providing voltage to the 4 sides if you will of the tube. If one transistor is fried then the ability to center the trace disappears. When you power off the unit, the voltage dissipates from the circuit and the trace will briefly center.
 
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Had, unfortunately. I sold it off, as it was far too big a project for myself. A prior owner had made at least a few adjustments that altered the unit from it's stock state. My experience in refurbing these units is nil. I know how to open them up, I can make out certain fuses and such, but that's about it. She was really rough, though. Pretty sure there was water damage on top of all the other issues.
 
No go with the scope. When it is in the off position, I can see a dim light in the upper left corner. When it is powered on, it has an orange-ish hue, which is strongest in that same corner. I listened to the radio and my turntable, no response. The dials on the back don't affect the scope whatsoever.
 
I repaired one of these a few months ago. One big caution: this amp has a very healthy B+ which stayed charged even after powerdown. OUCH! That hurt!

Check ALL voltages. The schematic was hard to follow at spots, I found a bad transistor in a voltage regulator circuit. IIRC that not only caused the scope to be off, but caused tuner issues as well.

Also, two of the boards are grounded to the chassis by their mounting screws, not by any other grounding wire. This amp had erratic grounding, you could actually hear the ground arcing intermittently. I pulled the center mounting strip off and cleaned the contact surfaces on the board.

After doing all that, the amp worked perfectly.
 
Right but if you power the unit off with the scope in the on position does a dot appear and fade out in the center. Seems as if your reply didn't match the test.
 
Oliade677 said:
No go with the scope. When it is in the off position, I can see a dim light in the upper left corner. When it is powered on, it has an orange-ish hue, which is strongest in that same corner. I listened to the radio and my turntable, no response. The dials on the back don't affect the scope whatsoever.
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The orange light you're describing is an incandescent bulb used for backlighting the graphic divisions on the scope's screen. You're looking for anything green.
 
You absolutely must rebuild the power supply board in the 4400 before attempting to repair anything else. The scope HV supply is run pretty hard in this unit.

nashvillebill said:
I repaired one of these a few months ago. One big caution: this amp has a very healthy B+ which stayed charged even after powerdown. OUCH! That hurt!
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Yeah, 570V. :D I'd bet that left a mark.

bktheking said:
Right but if you power the unit off with the scope in the on position does a dot appear and fade out in the center.
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The 4400 I restored didn't have the green dot fade off the display. Someone had tweaked the P900 pots far out of adjustment. Just a possibility if everything else checks out OK.
 
I recently sold my totally restored 4400 to buy a road bike. If your looking for a restoration i have a guy who did mine magnificently. He has restored probably over a 100 4400 that typically sell for $1,600-$2,000 on e-bay after being restored. There is no one better in the US for 4400 restorations if that is what you want. This unit is very complex.
 
bktheking said:
Right but if you power the unit off with the scope in the on position does a dot appear and fade out in the center. Seems as if your reply didn't match the test.
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Unfortunately, the scope does nothing when the unit is powered off and on. There is a very dim glow from one of the pin connectors internally, but that's it.

I removed the faceplate to inspect the scope tube, mostly out of curiosity. A portion of the scope looks like it might be damaged. The lower half of the tube is transparent, but there is one spot that appears oily. Is there something I can do to test it without a tube tester? Here are some pics:





I removed the bulbs that were blown in the light fixtures, but I am uncertain what I need to use to replace them. The only marking on the bulb is F8V.
 
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Scratch that, I found a site that has the 8v, 200ma bulbs. They are $.75 a piece, but you must buy 10. I only need four, but I guess more wouldn't hurt. I'd love to pick them up locally as I am pretty impatient with stuff like this, but I guess it can't be helped.

As far as the tube is concerned, I also found this info related to the tube. Can it be used to test the functionality?

**Pin 1: Heater
Pin2: G1
Pin 3: K
Pin 4: P1
Pin 5: X-
Pin 6: X+
Pin 7: G2
Pin 9: G1
Pin 11: P2
Pin 12: Y+
Pin 13: Y-
Pin 14: H

Connections to P900:

Pin # PCB #
1 J930
2 J932
3 J931
4 J934
5 J929
6 J928
7 J927
11 J927
12 J926
13 J925
14 J933
 
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Tube is fine, that is the "getter" flashing, if it were white you'd have an issue, since it's silver the tube is fine. The heater is working, that's what the glow is from. That unit has a fuse block and a few of the fuses feed the high voltage needed to drive the tube, check them, one might be blown- 99.9% sure the tube is good. Since you aren't getting the dot at power off, fuse would be my first suspect.
 
I'll inspect the fuses soon as I return from work today. Is the fuse located on the board beneath the scope, or is there a general area where they are all concentrated? I'll be off until after Christmas, so I have quite a bit of time to dedicate to fixing her up.
 
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