marantzfan's 4400 - All Out Restoration!

[Jailtime]

Well, I finished up the solder slinging part of the restoration tonight. Dolby unit finished, and installed the LEDs. Didn't even cut the tuner string with my solder iron.

I installed a new sheet of mylar in place of the old vellum paper. Also waxed the faceplate and did a little cleanup. The LEDs look fantastic, I couldn't capture how deep the color is in the pictures. It's perfect.

Only thing left is testing of all functions and scope repair. Did a little digging on the scope board tonight, looks like the HV is present on the board, so the HV section of the transformer/power supply is good. But there's no light in the scope tube, I should be able to see the heater. I'm thinking the tube is bad. :sigh: Scope expert opinions welcomed.

 

[joel27]

Those leds look sweet!

 

[bktheking]

Measure pin 1 and 14 at the tube socket, be safe of course. What are you getting? Alternative- measure j910 and j914 on the driver board. Also check all diodes on p800, seems there is high voltage on that board that as well as fuses feeding that board.

 

[ChrisMarantz]

Didn't even cut the tuner string with my solder iron.

This must not be your first rodeo.

 

[Jailtime]

This must not be your first rodeo.

I haven't cut one myself, but I've read of lots of folks here on AK doing it. That's about the only thing I haven't learned the hard way.

 

[Jailtime]

Measure pin 1 and 14 at the tube socket, be safe of course. What are you getting? Alternative- measure j910 and j914 on the driver board. Also check all diodes on p800, seems there is high voltage on that board that as well as fuses feeding that board.

Got nothing on pin 1, -571VDC on pin 14. My schematic shows J917 as the pin for socket pin 1.

EDIT: Found bad fuse FP02, on HV line from transformer to PS board.

 

[Jailtime]

Here's where were at on the scope now - Heater filaments light, the fuse FP02 was bad. Looks like the HV from P800 power supply is good to J909 and 913. I still don't have a spot though, I'd figure the problem is isolated to P900 scope amp now.

And here's a glamour shot of the 4400 in glorious FM stereo.

 

[marantzfan]

Almost there. I can taste it.

 

[bktheking]

Leave the unit on for 2 minutes , shut it off and observe the scope. If the dot swings center its either a blown transistor or fet, it should do this now if all the voltages are hitting the tube. Measuring the transistors with the receiver on, move the horizontal and vertical controls and observe the voltage swing. If one of the transistors is blown it will stay pinned at its highest voltage. Then measure the fet that corresponds to the transistor in question. If voltage varies at the fet then the transistor is blown. Its my experience that you can remove a questionable transistor and the scope will come to close center without it, just to test of course.
The spare fets you pulled also work on this board but you know that .
Looks fab kyle, 95 percent there.

 

[69sixpackbee]

Hopefully you don't need a new tube. Those are unobtanium. I tried numerous sources.....nada.

Looks great!

How did you get the LED's to diffuse so well without a hotspot? I've read a tutorial from "that guy who got banned" and it shows him taking a Dremel disc to the front of the LED to diffuse the light.
Thanx,
Bud

 

[bktheking]

Got nothing on pin 1, -571VDC on pin 14. My schematic shows J917 as the pin for socket pin 1.

EDIT: Found bad fuse FP02, on HV line from transformer to PS board.

Yup J917 and 910, read it wrong. J915 also needs high voltage.Pin 7,9,11,12 are your x/y adjustments, tube disconnected they should show a swing with the pots.

 

[marantzfan]

Hopefully you don't need a new tube. Those are unobtanium. I tried numerous sources.....nada.

Looks great!

How did you get the LED's to diffuse so well without a hotspot? I've read a tutorial from "that guy who got banned" and it shows him taking a Dremel disc to the front of the LED to diffuse the light.
Thanx,
Bud

I will find a new tube if need be. Come hell or high water, there will be a working scope at the end of this epic saga. Guaranteed. :yes:

 

[bktheking]

Probable that it doesn't need one

 

[Jailtime]

Thanks for the scope tutorial, Brad. Should come in handy in the future.

Scope works now. It was that fuse, and the pots on P900 were way out of adjustment, so I couldn't locate the spot with the centering controls on the back panel. A little tweaking brought the spot into view, and I almost freaked out. I did the calibration in the service manual, and the scope works great in all modes now.

How did you get the LED's to diffuse so well without a hotspot? I've read a tutorial from "that guy who got banned" and it shows him taking a Dremel disc to the front of the LED to diffuse the light.
Thanx,
Bud

The LEDs are dull on the front, and I also used a piece of mylar to replace the old vellum. The mylar is awesome.

4400 is in testing now, that's my way of saying that I'm holding it hostage to listen and enjoy. Check out the scope shots below, first three are FM stereo, last is Vari-Matrix in a quiet moment.

 

[joel27]

Holy crap, that is awesome looking with the scope.

 

[downhiller20]

What are the details on the mylar?

 

[Jailtime]

What are the details on the mylar?

I dunno, I got a big sheet from a friend. It's thin, it stays flat when you unroll it, and it's translucent white. Works great for this application, and I have enough to do around 20 more Marantz receivers.

 

[bktheking]

Man, just a fuse, that's not fair! Lol

Looks awesome! Something tells me those pots were played with prior to it getting to you. If it was just the fuse, a replacement should have brought it back to viewing range.

Congrats!

 

[pioneervato]

Thanks for the scope tutorial, Brad. Should come in handy in the future.

Scope works now. It was that fuse, and the pots on P900 were way out of adjustment, so I couldn't locate the spot with the centering controls on the back panel. A little tweaking brought the spot into view, and I almost freaked out. I did the calibration in the service manual, and the scope works great in all modes now.



The LEDs are dull on the front, and I also used a piece of mylar to replace the old vellum. The mylar is awesome.

4400 is in testing now, that's my way of saying that I'm holding it hostage to listen and enjoy. Check out the scope shots below, first three are FM stereo, last is Vari-Matrix in a quiet moment.

So Kyle, since I'm gonna be sending you some money for the restoration of the Marantz does that mean it comes to my house first for "additional testing" before it eventually gets to Anthony? :scratch2:

 

[Jailtime]

Something tells me those pots were played with prior to it getting to you. If it was just the fuse, a replacement should have brought it back to viewing range.

They were adjusted prior to me getting the unit. Anthony did it.

I really should have followed the KISS principle on this one. Check the easy stuff first. Oh well, I wouldn't have learned anything about the scope circuit if I didn't dig around in there first.

So Kyle, since I'm gonna be sending you some money for the restoration of the Marantz does that mean it comes to my house first for "additional testing" before it eventually gets to Anthony? :scratch2:

Yes, yes it does. I support a rigorous testing process.