Ed's fault PL400

[Billboard]

Saw a face book post that Ed "liked", saw it in my feed. Had to purchase it. The amp was the 8 fin 400 listed in Derry NH for $200.

Amp is mint looking, listed as non functioning. Will get it on the bench soon.

Doesn't look like a screw has ever been removed from the case.

 

[laatsch55]

Saw that too, good pickup...

 

[WOPL Sniffer]

Great price

 

[Billboard]

Nice guy, he had another 400 SII in his system. i already own a "spare" 400, didn't need a second spare 400, but couldn't pass on this one. I guess that's how we gather a heard of amps.

 

[WOPL Sniffer]

Spare??? Never heard of such a thing......

 

[WOPL Sniffer]

Spare??? Never heard of such a thing......

That's like calling the clothes in your dresser/closet spare.....

 

[Billboard]

Cleaned off the bench, fired it up with a dim bulb tester. Short to the outputs, meters pinned and 50 VDC on the speaker out connectors.

took the transistor covers off, pulled the top three rows, left the drivers in. The output transmitters were all PL909, two were shorted. They were all mounted using silicon pads. Someone has been in here before. The drivers are SJ2741 mounted using wafers and white thermal paste.

next I will check the bios on the control board.

Capacitors seem to be glued in.. haven’t got too far with them.

 

[WOPL Sniffer]

Nice clean amp too.

 

[George S.]

Those caps were often "glued" to the cradle with double sided sticky tape at the factory.

 

[Gepetto]

Those caps were often "glued" to the cradle with double sided sticky tape at the factory.

Yup, the bean counters suggested that after they found out it was a dollar less than the clamp plate...

 

[wattsabundant]

What's amazing is the caps are nearly 50 years old and it appears the tape is still holding them in place. Obviously this amp never saw road duty.

 

[Billboard]

I ordered replacement output transistors from Joe. When it is repaired I will then order a DC protect relay and new power supply Caps. May drop Joe a message and add the caps to the transistor order.

 

[Gepetto]

I ordered replacement output transistors from Joe. When it is repaired I will then order a DC protect relay and new power supply Caps. May drop Joe a message and add the caps to the transistor order.

If you are Bill, recommend you speak fast as the box is sealed and ready to ship tomorrow...

 

[Billboard]

If it’s not an issue, go ahead and add the caps, send invoice and I will pay now.

thanks Joe!

if things are posted up and weighed, separate order is fine.

 

[Billboard]

Finally got to powering up the PL400.
Replaced blown fuse, I powered it up via a DBT with all of the output transistors removed. All seemed well, so I installed a single row of new outputs. DC offset next to 0 (less than 10mv). Bios high (.5v) but would adj down. Sent 1000hz tone through the amp, looked pretty clean. I then installed the rest of the outputs, adjusted the bios to .35V, sent the 1000hz tone all looked good even with an 8ohm load.
Hooked up some speakers and played music at a low volume for a while (it’s late, half the house is sleeping).
Must say this amp is as clean on the inside as it was on the outside.

what’s next is install power supply capacitors, and a DC protect board, possibly a meter light board from Joe. Then I am going to call this one done.

 

[WOPL Sniffer]

Save the BIOS for the computer..... We use BIAS for amps.....

 

[Billboard]

I saw that later, bias/bios, the amp sounds great!

 

[WOPL Sniffer]

I saw that later, bias/bios, the amp sounds great!

And THAT's what counts......

 

[wattsabundant]

I noticed that the bottom cover is in place while testing. That's a disaster in the making. A paper towel is a poor insulator. Also the leads on the back of the board should be trimmed. Another disaster when the board is installed and pressing against the wire bundle.

 

[Billboard]

Regarding the papaer towel, if you know the rules, you can break the rules. I was very cautious with the board. Also the paper towel was doubled up, lol.