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2252B P.S. / Amp Board Access

c.coyle

c.coyle

Fighting the Dunning-Kruger effect.
What's the best way to get at the underside of the P700 power supply / amplifier board? Specifically, the end right above the filter caps. I'm thinking remove the filter caps, bridge rectifier bracket, and some switch arms. But, getting at the screws for the filter cap brackets looks like it will be a major challenge.

The other route would be to lift the board / heatsink up somehow, but it doesn't look like I would have a lot of wire slack. I don't want to disconnect wire wraps or unsolder posts.

There aren't any threads on this, so I must be overlooking something obvious.
 
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I absolutely hate that board. Usually do exactly what you said. Disconnect everything on the underside and work from there. Filter caps are a pain but will come out. A long, skinny screwdriver helps. And those speaker switch arms are an even bigger pain. I have a small ratcheting screwdriver that helps there and also need to wedge something to hold them in place as they are very flexible. Once one side is undone (front or back connection) you can swivel them out of the way.
 
Awwww shoot! I was hoping for a trick. I already stripped a screw and had to go to the Dremel.

I'm going to think of a more user-friendly way to secure those filter caps once I'm done. At least replacing the relay is a piece of cake.

One board for P.S., amplifier, and protection? Yuck.
 
I will 2nd that.Currently I have one on the bench and not too thrilled at the accessibility of "things".
Another reason I prefer the Non B versions.
 
I remove the Power Amp/PS board and the heat sink, then it's easier to get the filter caps out. Do the next tech a favor and put the screws for the filter clamps in the other way so they are easily accessible.

Tom
 
catrafter said:
I remove the Power Amp/PS board and the heat sink, then it's easier to get the filter caps out. Do the next tech a favor and put the screws for the filter clamps in the other way so they are easily accessible.

Tom
Click to expand...

So, do you un-solder and remove wire wrap posts?
 
Looked through some notes. Unscrew the board and heat sink from the chassis, remove the screws from the switch extenders and get them out of the way.
Flip the board with the heat sink attached up and away, keeping the connections intact. There may be some wire ties that need to be cut to gain some slack, don't remember, it's been a few years.

Tom
 
catrafter said:
Looked through some notes. Unscrew the board and heat sink from the chassis, remove the screws from the switch extenders and get them out of the way.
Flip the board with the heat sink attached up and away, keeping the connections intact. There may be some wire ties that need to be cut to gain some slack, don't remember, it's been a few years.

Tom
Click to expand...

Will do. You know Marantz.

Thanks, Tom.
 
Life is full of coincidences. I just finished recapping that board in my 2252b last night, and not more than ten minutes ago cranked up the variac to no drama. Happy since it's my first recap ever.

I struggled with the filter caps under the board also, and was in the process of stripping the screw head on the capacitor bracket. Then I had an idea. I put a flat head screwdriver under one of the large caps and the frame of the receiver, and gently shimmied each cap a little at a time. Since they are tied at the top, you have to alternate the "shimmy" to get progress. After a few minutes, they both popped out. It was easy to get the board out afterward. After removing the heat sinks, a tie or two, I was able to get the board to stand up vertically.
 
P.S.
The parts list for this board shows four 10uf (16v ?) capacitors. My P700 has four 22uf 16v capacitors at the output stages. Does yours have 22uf also?
 
Good idea on shimmying the caps out.

I just pulled the board and heatsink fairly far out, per Catrafter's suggestion. It's pretty tight. Not a lot of slack, and the bottom of the heatsink scrapes against the side of the chassis, but it barely clears and I can get it to about 45 degrees, which allowed me to get a screwdriver on the filter bracket screws. Working on the board shouldn't be too bad.

And Catrafter is right. The screw to tighten the filter cap bracket is on the inaccessible back side. Like the dark side of the moon! What were they thinking?

Thanks for all the help. AK is worth the cost of the subscription and then some.
 
windsor202 said:
P.S.
The parts list for this board shows four 10uf (16v ?) capacitors. My P700 has four 22uf 16v capacitors at the output stages. Does yours have 22uf also?
Click to expand...

Yes. C719 through C722 are 10uf on my parts list, 22uf on my schematic, and the original installed versions are 22uf/16v orange Chemicons.
 
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