Krell KSA-250

[WOPL Sniffer]

Started putzing with the Krell. Some of the Emitter resistors were overheated, and some of the factory soldering is in need of some help. The planes on the boards are fairly large and require some heat from the soldering iron. I think some spots may need 2 irons to get good flow. I just ordered some parts to start doing some work on the amp.

 

[WOPL Sniffer]

Started installing the emitter resistors. There is a shit-load of them

 

[laatsch55]

What does it use for outputs?

 

[BlazeES]

Big caps make me ...

 

[WOPL Sniffer]

What does it use for outputs?

It's getting MJ21195's/96's

 

[WOPL Sniffer]

Remember, this is just the Left Channel

14 NPN's
14 PNP's

Same for the right side.

 

[mr_rye89]

Ooof! Maybe they shoulda stood those resistors off on that relay board.....

 

[WOPL Sniffer]

Ooof! Maybe they shoulda stood those resistors off on that relay board.....

Yeah, they get moved to the back side of the board

 

[mlucitt]

Ooof! Maybe they shoulda stood those resistors off on that relay board.....

It looks to me that the heat came from the relay coils...
In any case the radial capacitors near the relays look baked too. I wonder if Krell spec'd 125 deg temps for those caps?

 

[WOPL Sniffer]

It looks to me that the heat came from the relay coils...

Nope. Those 700 Ohm resistors run at about 400 degrees.

 

[mlucitt]

Nope. Those 700 Ohm resistors run at about 400 degrees.

Well then, the Krell is both an amplifier and a small room heater. Trying to imagine the wattage and the amperage involved.
At 400 degrees, those relay flyback diodes are completely useless, leaking voltage beginning at 175 degrees C, or 260 degrees F.
May want to lift them off the board as well.

 

[WOPL Sniffer]

Wait till I'm done. I know what to do with it.

 

[Michael F]

You know that an amplifier has a serious torque specification when buss bars are used to mate the output terminals.
Nice amp.

 

[FredR]

Please keep the updates coming. Really interesting project.

 

[WOPL Sniffer]

So I sent Krell a request for the schematics for this KSA-250. The COO kindly pointed out that there was a sticker on the amp that said "No User Servicable Parts Inside" an I should take my amp to an AUTHORIZED" service shop and they would "Sort" my amp out. Fuck Krell. What a bunch of pompus twats.

 

[Gepetto]

So I sent Krell a request for the schematics for this KSA-250. The COO kindly pointed out that there was a sticker on the amp that said "No User Servicable Parts Inside" an I should take my amp to an AUTHORIZED" service shop and they would "Sort" my amp out. Fuck Krell. What a bunch of pompus twats.

I am sure you are 'shocked' by their response Perry...

 

[WOPL Sniffer]

I am sure you are 'shocked' by their response Perry...

Indeed Joe I am..... WELL. not really..... HUH?

 

[krellmk]

Personally, I would stay with the original power transistors

 

[WOPL Sniffer]

Personally, I would stay with the original power transistors

Junk compared to the 95's and 96's

 

[stetter]

Perry, You been lifting weights to get ready to lift that on the bench?