2275 Re-cap journey & a few questions

2

2dFx

Two Dimensional Effects!
2275 Re-cap journey...DONE!!!

Howdy AK, just thought I'd show you the progress of the re-cap I'm doing with a trashpicked 2275. Fires up, but there's a 60Hz hum in the output as well as poor FM reception quality.

Started with the power supply board. All caps removed here, some were definitely burst. What is this stuff on the PCB? Some sort of epoxy?:

DSC00383.jpg

Old caps out:

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A close up of the bigger ones with the gunk on the PCB. I cleaned that gunk off before I proceeded:

DSC00385.jpgDSC00386.jpg

All done! Silmic II's were the replacement of choice for this one. Phono board needs some help and the P700 power amps are all original, will go after those ones later.

Question: for the 35V adjustment, should I be doing this in-circuit with the output stages connected? I currently have the L&R power amps disconnected as I'm evaluating a re-cap procedure on those. Thanks!
 

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The "goo" is glue.

Its used to hold the caps in place, I think for assembly line soldering and also for stability during shipping so the caps don't get worked loose in transist.

May people think that what "leaking" caps do. :nono:

Leaking usually refers to DC leakage.
But a cap can "vent" and that blows gunk out of the cap. That's much more rare.

I mention these things to help educate folks.
 
Oh, the 35V should be done with everything connected.
Need a load to get an accurate reading.
 
Newly refurb'd P800 board re-installed:

DSCF0023.jpg

WOW!!! :music::music: What a difference from when I picked this thing out of the dump. The FM reception is GREATLY improved...before every station, weak or strong, would come through almost with an intermittent clip. Now every FM station received comes in as it should.

The 60Hz hum I was experiencing on speaker output is still there, but it is less pronounced.

DSCF0026.jpg

Replaced all the dead lights in the front face too. Beautiful!
 
Fun, great and lucky find for sure! Looks like you are well on your way to getting back working great :D

What do the face and knobs look like?
 
2dFx said:
Newly refurb'd P800 board re-installed:

View attachment 399592

WOW!!! :music::music: What a difference from when I picked this thing out of the dump. The FM reception is GREATLY improved...before every station, weak or strong, would come through almost with an intermittent clip. Now every FM station received comes in as it should.

The 60Hz hum I was experiencing on speaker output is still there, but it is less pronounced.

View attachment 399593

Replaced all the dead lights in the front face too. Beautiful!
Click to expand...
Nice....Keep on going...Replace All the Old Caps...
 
little-al said:
Fun, great and lucky find for sure! Looks like you are well on your way to getting back working great :D

What do the face and knobs look like?
Click to expand...

They're all intact but dirty. I'll clean her up real nice when all the repairs have been completed.

VintagePlus said:
Lookin great! Amazing that someone would put that in the trash. Glad you rescued it!
Click to expand...

I guess the previous owner decided that after the front panel had burned out and the FM reception went south that he didn't want to fix it/cost too much from a professional shop. Shame really...cosmetically the unit is in great shape!
 
Starting on the phono amp board...something of interest caught my eye...
DSC00396.jpg

What are these caps? Metal film? And should I replace them or just stick with replacing the electrolytics? Beyond that, I might have found a bug in the service manual. Those caps, C409 and C410 are marked '5600J' and the smaller ones C411 and C412 are marked '1600J'. Here is the service manual parts list for the board:
p400.png

...now wait...are they in micro or picofarads? One of them has to be incorrect...the service manual as you can see lists the 5600's in microfarads and the 1600's in picofarads.

Finally, in regards to the P700 power amp boards I also highlighted some of the other caps that I believe are films...worth replacing?
DSC00397.jpg
 
The caps on the phono board are polystyrene film types, picofarads sizes and 5% tolerance ("J" designation). These are used for the RIAA equalization, no need to replace. Also, no need to replace the polyester films on the power amp boards.
 
On the phono board you may want to replace those small blue tantalum caps C401/C402? use a film there. You also have an axial cap at C413 and may want to use: the leads on a radial may also work.

http://www.digikey.com/product-detail/en/MAL213831101E3/4238PHCT-ND/263351

Measure to make sure it will fit.

If H405 and H406 are 2SC458 you may want to replace with KSC1845, And H409 can be replaced with 2 1N4448 in a series.
 
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Leestereo said:
The caps on the phono board are polystyrene film types, picofarads sizes and 5% tolerance ("J" designation). These are used for the RIAA equalization, no need to replace. Also, no need to replace the polyester films on the power amp boards.
Click to expand...

Interesting, so the service manual has an error then. Thanks for the tip!

patfont said:
On the phono board you may want to replace those small blue tantalum caps C401/C402? use a film there. You also have an axial cap at C413 and may want to use: the leads on a radial may also work.

http://www.digikey.com/product-detail/en/MAL213831101E3/4238PHCT-ND/263351

Measure to make sure it will fit.

If H405 and H406 are 2SC458 you may want to replace with KSC1845, And H409 can be replaced with 2 1N4448 in a series.
Click to expand...

I'm going to throw a radial Silmic in that spot, I can make it fit.

The transistors are indeed 2SC458's, yeah I'll order a bunch and get a match on forward current gain. In your rebuild thread you stated 400...any reason for that value? It can't be overdriven too much I assume?
 
2dFx said:
Interesting, so the service manual has an error then. Thanks for the tip!



I'm going to throw a radial Silmic in that spot, I can make it fit.

The transistors are indeed 2SC458's, yeah I'll order a bunch and get a match on forward current gain. In your rebuild thread you stated 400...any reason for that value? It can't be overdriven too much I assume?
Click to expand...

It does not need to be 400 but you usually look for the highest value you can get a match on, for phono I was happy to get an exact match.
 
Took out the tone board today:
DSC00398.jpg

I shot the EQ pots with a shot of my tuner clean n' lube and they were still quite stiff...not to my liking. Removed them from the board and gave them a good shot with the lube, now they turn as they should:
DSC00399.jpgDSC00402.jpg

Also took the opportunity to take the indicator face off the unit and replace the vellum paper. The picture is too bright...the yellowing is actually much darker in real life:
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You can see it's actually not that bad from holding it up in the light, but I figure I might as well replace it anyway to restore it to 'true blue'. Might as well do it while I've got it disassembled, right?
 
Thanks for all the great information and "pitchers".

Just found one of these in good shape and working. An unrestored unmolested unit that has been in service pretty much since the day it was sold. Bought it from a younger guy that needed some money for his car so we both won.

Adjusted the idle voltage, offset etc. and was surprised that none of these values were very far off. Thinking about recapping her before winter is over. So I am watching your journey as you do yours.

Are you going to replace the main power caps as well?
 
Fairlane said:
Thanks for all the great information and "pitchers".

Just found one of these in good shape and working. An unrestored unmolested unit that has been in service pretty much since the day it was sold. Bought it from a younger guy that needed some money for his car so we both won.

Adjusted the idle voltage, offset etc. and was surprised that none of these values were very far off. Thinking about recapping her before winter is over. So I am watching your journey as you do yours.

Are you going to replace the main power caps as well?
Click to expand...

Currently on order from Digikey!
 
Main filter caps finally came in today. Took the old 1966 Panasonic ECE ones out:
DSC00403.jpg

Chemi-Con replacements - 75V 18mF:
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Side-by-side shot - the height fits perfectly as you will see later:
DSC00405.jpg

Blue beauties in the blue beauty - just clears inside room:
DSC00406.jpg

Perfect diameter too, no modification necessary, except on the underside which I will do later:

DSC00407.jpg
 
Nice work. Is the increase in size from 13000 to 18000 OK. Also where did you source the caps if you do not mind me asking.

I have been listening to my new 2275 more recently and just love it. Seeing your post has inspired me to do the same thing.

How does it sound now that you have replaced the main caps, any difference?
 
Thats the same filter cap that I use in the 2275. Nice increase and still within range spec'd by factory. Never caused any problems for me...
 
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