SAE 2401 Rebuild

[hamrules]

Got one of these to work on.

 

[hamrules]

Have some bolts in it just to hold together for now.
Put a new switch in as the one in it had seen better days.
The upper right corner is bent, will work on that later.
Unfortunately the handles are MIA so not sure there. Finding some would be a miracle so either use a bolt with some head that looks good or I could install handles from a 2400(L) with minimal effort. Not sure. Oops, they use two different length spacers.
Anyone have a couple extra spacers they don’t know what to do with.

 

[hamrules]

Here it is, a pile-o-pieces right now.

 

[hamrules]

I want to replace the main caps but I’m not sure my soldering iron is good enough. We will see.
I have enough MJ21195/96’s to replace the Toshibas so we’ll go that route.
Did I say I hate thermal paste, argh.

 

[RVT1K]

I want to replace the main caps but I’m not sure my soldering iron is good enough. We will see.
I have enough MJ21195/96’s to replace the Toshibas so we’ll go that route.
Did I say I hate thermal paste, argh.

I have, on many an occasion, resorted to using two irons when one didn't have enough punch.

 

[ivandezande]

I was halfway designing a new main cap PCB to fit a bunch of smaller ones. The wide flat ones sure are strange.
Good luck!

 

[hamrules]

Got one of these filter caps out, did I say it’s glued too. Oh man. I have to try something else to de-solder this was ridicules.

 

[hamrules]

One of the overheat thermostats was no good.

Everything cleaned and tape residue removed. Just have the output finned heatsinks yet. Yes I hate thermal paste, did I say that already. Ha ha

 

[hamrules]

Bottom side of output board. This is where the bias adjustment pot is located. You can see where there is a piece of, what looks like wire, connecting two terminals. The actual circuit board has no connection there but the board layout drawings for the 2401 show there is a connection.

 

[hamrules]

Here’s a shot of the circuit from the schematic. It shows a resistor (120 ohm) that should connect those points and not just a “wire”.

I’ve checked schematics and even the P500/A1001 shows the 120ohm resistor. Unfortunately what I don’t have yet is an actual pic of an A501 to see if that resistor is on the board.

 

[hamrules]

Found a pic. R60 is the 120ohm resistor. Obviously they made an update. Will add that in.

 

[hamrules]

Got the caps off. Trace side a little dinged but not bad. Probably hit it with conformal coating, only cause I have a spray can here.
Did I say they were glued on also, yes I did, what a pain.
And for the testing news. Two caps tested great, one a little high on ESR and the last one was was high UF wise and high ESR. All in all not bad but I think these amps could fair better with them replaced. Problem being it’s a total pain, probably need a new circuit board for something readily available.
Waiting on new parts now, hopefully by weekend.

 

[drumbum]

View attachment 3785818
CR38 is incorrect on board, should be opposite like CR31.

While you are in there....lol....Do you see a way to add a pot to dim the leds on the power meters and maintain full function?

TIA

 

[hamrules]

I do not understand why that would be something to want to do?

 

[drumbum]

I do not understand why that would be something to want to do?

When I went through my 2300, I replaced all the leds when some were found bad and the replacements are WAY too bright.

 

[hamrules]

Relay board ready to go.

 

[hamrules]

New caps installed. Worked out fairly well. About 2-3mm space between transformer and capacitor.
Used 15,000uf @ 100volt —> 63MM length & 50MM dia

 

[hamrules]

All assembled and fits correctly. Plenty of room with the longer 63MM caps. Some wiring work left then I can move ahead.
Edit: Wiring done on back end now.

 

[hamrules]

This was the pattern I made to mark out the new holes to drill.

 

[hamrules]

Had some time today so I put the green LED’s in. Now it’s like the P250 display. Yes I’m sure some people won’t like that but I do anyway.