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Marantz 2500e.. needs a bit of elbow grease

It certainly won't hurt a thing to not replace the films as there's no reliability issues. Marantz units sound very fine to start with as designed with the components used.

I became convinced with replacing films in tone control circuits with polypropylenes or at least better films when PP caps weren't available when I tried it in a 2500 rebuild. I swept the distortion and phase response compared to the "OUT" position and the sweep traces layed on top of each other. Unfortunately I didn't do a sweep before the rebuild nand I've since returned the two channel audio analyzer to work and only have single channel ones at home.
 
rBuckner said:
It certainly won't hurt a thing to not replace the films as there's no reliability issues. Marantz units sound very fine to start with as designed with the components used.

I became convinced with replacing films in tone control circuits with polypropylenes or at least better films when PP caps weren't available when I tried it in a 2500 rebuild. I swept the distortion and phase response compared to the "OUT" position and the sweep traces layed on top of each other. Unfortunately I didn't do a sweep before the rebuild nand I've since returned the two channel audio analyzer to work and only have single channel ones at home.
Click to expand...


I am going to skip the films on everything except the tone control section.

I have the list of the caps completed, now I need to look at the relays and the power resistors. Any advice on the best source for the relays?

Oh.. What did you use for the bypass caps on the big cans?

And thanks to everyone for the comments and help!

As promised a few pictures.
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For the relays I have:
Omron MY2-DC48(S)
Tyco KUP-14D15-48

Bypass caps, I'm not sure exactly which part but it was 2.2uF and a film cap. I usually use 100V parts but I'd go up to the next voltage rating level than that. Here's a Mouser part to look at: 667-ECQ-E2225KB

Are you planning on restuffing the dual filter caps?
 
I did not find a polypropylene for .012 but I did use this/these from Mouser:

80-MMK5123K50J01L4

Not having all pp caps isn't going to mess anything up.
 
I just jumped right to post so this may have been suggested already. My system of cleaning this level of funk has never had a bad outcome and it is very straight forward.

1. A good blow out using a small shop-vac and medium sized needle nozzles.....use care.
2. At this point look for cap leakage or any type of spills etc....take pics and notes if needed.
3. QD Plastic Safe Electronics Cleaner to rinse and flood down from different directions and let dry well. (Fast for the open areas but extra time needed a bit for "trapped" fluid......stay away from tuner fins and any "slider adjustments" with it.)

Cleaning the face plate is always easy using Chrome Magic from HD and no matter how funky, a first and second quick clean leaves "perfect" and protected while minimizing/eliminating oxidation/acid spots in the anodized finish.
(Several other good ways used around here too but this works slick and fast for me.)
 
Update...

Well... The unit is back in one piece for the most part... Fired it up on the variac and it's alive :music:

It has a few problems.

1. The scope is not working. It worked before I stripped it down so it must be something I did to it. I am not sure where to begin on troubleshooting this. I guess I'll start with the power supply. I do not see the filament glowing.

2. I am getting some distortion and dropout in the left speaker. The problem seems to be in the volume pot. I cleaned it throughly while I had the unit apart so I may have a bad connection.

When it is working it really sounds nice...
 
Was hoping to hear some good news. I've been following as I'm a huge fan of the 2500. Glad to see your giving the unit a second life. I couldnt imaging having one stored in an attic.

I would clean/lube the pots and switches again. The units I've gotten this dusty always needed a second cleaning, sometimes a third.
 
You might have a dirty speaker relay (everything ELSE was dirty!). Try tapping it when the left channel cuts out and see if you get it back. Replacement relays are usually available at Mouser or Digikey for under $10 if you need one...
 
skibjr said:
You might have a dirty speaker relay (everything ELSE was dirty!). Try tapping it when the left channel cuts out and see if you get it back. Replacement relays are usually available at Mouser or Digikey for under $10 if you need one...
Click to expand...

The problem went away when I tightened down the pots to the frame under the face plate. I put in new relays during the recap.

There still seems to be a problem with the scope. The tube seems ok but it's not deflecting properly. I just get slanted line....
 
Ok... It looks like I have lost the vertical deflection, or most of it.

I checked the scope buffer amp board. I have signal in and out on both channels.

The signal heads into the Tape and Scope switch board. I noticed something strange... There are a couple of traces that have been cut. It looks like it was done for a reason so for the moment I am going to ignore it.

I can see left and right signals getting to the scope board. I am going to assume that something on the board is shot. The signals go to a pair of FET's and then to a set of PNP's. I am not really sure how this circuit should work. I need to study it a bit more or I could just shotgun it. I should probably check the power supply a bit better as well.

The parts list shows a 2SK30A for Q901-Q914 and a 2SC1756 for Q905-Q908

I found NTE parts that cross.. Anyone know of something else?
 
So you're getting a diagonal line in all modes? That would suggest you're getting both horizontal and vertical deflection Can you post a picture?

Generally, when I have scope trouble with a 4400 or a 2500/2600, it ends up being either an SK30, or a weak/dead resistor on the scope board - assuming the power supply is in order, of course. If you are indeed getting a diagonal line, I'd look more at the function switch board to ensure proper signal is getting to the deflection circuits.
 
A diagonal line can mean mono operation, does it sound like it's in stereo? Even so, is it changing in length, dancing to the audio so to speak?
 
skibjr said:
So you're getting a diagonal line in all modes? That would suggest you're getting both horizontal and vertical deflection Can you post a picture?

Generally, when I have scope trouble with a 4400 or a 2500/2600, it ends up being either an SK30, or a weak/dead resistor on the scope board - assuming the power supply is in order, of course. If you are indeed getting a diagonal line, I'd look more at the function switch board to ensure proper signal is getting to the deflection circuits.
Click to expand...


rBuckner said:
A diagonal line can mean mono operation, does it sound like it's in stereo? Even so, is it changing in length, dancing to the audio so to speak?
Click to expand...

More info.....

I did notice when the FM section switches over to stereo the scope has a full display but it's not right and I can't really adjust it properly.

I tried to follow the scope adjustment procedure:

1. Set the selector to the AUX position.

2. Set the scope level and volume controls to the FCCW position.

3. Depress the scope display on and audio push switches in.

4. Adjust the centering controls until the spot comes in the center of the small circle. (this works)

5. Adjust the Bright control (R002) on the rear panel until the brightness becomes dark a little (The brightness control works well and I can get a gain or reduction in output).

6. Adjust the focus control so that the spot becomes smaller and circular. (this works)

7. Turn the scope level control to the FCW.

8. Connect a 150mv, 1 kHz signal to the aux input right jack and adjust R928 (H.Gain) until the horizontal deflection is around 3 cm. (This sort of works.. To be fair I am not really using a good function generator for this. All I have is my iPhone running a function generator program. I set the frequency to 1KHZ then adjusted the volume while I measured it on a scope until I got 150mv p-p. I do get some horizontal deflection when I adjust R928.

9. Connect the same signal to the L jack and adjust R927 (V.Gain) until the vertical deflection is around 3 cm. (this seems to have no or very minimal effect)

I am going to repeat the tests when I get home from work and post a few pictures....
 
So it turns out that the procedure for setting the scope up is wrong. The pots called out are not correct for the H and V. Also it seems that a 150mv signal requires that the gain of the H and V circuits be cranked all the way up to get deflection. Once I gave the generator a bit more output I could then set the H and V gain to levels that worked.

Now I am on to another issue... Weak FM tuning. A couple days ago I had noticed that the tuning cap was dirty. It had green crap growing on the brass center posts where the grounding wiper contacts the shaft. So I cleaned it a few times following Dr *Audio's fine posting. Wash it out with a good, non residue cleaner, followed by a tiny drip of Fader lube.

I can only get one station in stereo so far. I will clean it a few more times..

(Side note... I was able to use one of the wife's bottles of eye drops to make a dispenser for the fader lube. Just pop the top, dump the liquid out, dry it out and then spray the fader lube into the eye drop bottle. The little straw fit right in the top of the bottle. She won't miss it :tears::tears:)

I took this picture by placing my phone pointing up to show the underside of the top of the tuning cap. Somehow I need to clean this out. I am seriously thinking about removing the tuning cap and cleaning it on the bench. Any suggestions ???


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It's nasty to get out, I've done it as I had weak FM too. It turns out the very first amp stage FET was blown. Then I had to get the board out as well, more fun! It's a dual gate FET and very rare these days. I got one from Consolidated I think it was. I'd leave it in unless I really had to get it out. Give the chemicals a day to work, maybe it will improve. Fingers are crossed!
 
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