Jerry's "Gonna Rebuild me PLWO 1000" thread

[laatsch55]

Gonna move the AC mains "in" location?

 

[jbeckva]

Gonna move the AC mains "in" location?

Whatcha mean?

 

[jbeckva]

Crap crap crap... Looks like I am going to need to get some 150 ohm resistors. I just measured 'em.. anywhere between 140 and 283 ohms! Wow.. the 140 I can probably live with, but 283??

(placing order with der-mouser place... )

Hmmm.. so these 150 ohm resistors (the one's across the driver Q's on the bottom)... I can get away with them being 1/2 watters, right? .5 voltage drop.. 3.33mA.... 1.66mW.. (did I get that right?.. I think so... )

Rat shack's down the street and I think they have 'em...

 

[Gepetto]

Yes, these are low power resistors. Phase used 1/2W or larger for everything. 1/2W is overkill for this location

 

[jbeckva]

Uh oh.. I need the fabled "lead stretcher".. the emitter resistor leads for the top tranny down to the tie point aren't long enough..

Hmmmm.. no fears, Lee... "I have a plan... "...

 

[laatsch55]

Because of the new sockets??

 

[laatsch55]

Gonna move the AC mains "in" location?

Whatcha mean?

After your amp I have been moving the power cord and fuseholder to the transformer side.

 

[jbeckva]

Because of the new sockets??

Probably - The square ones have the emitter connection post offset "just enough" to where the lead can reach, but these have the connection posts directly in line with the TO3 pins themselves.

To solve it, I just piggy backed onto the lead from the next one down, on the common side. (pics later.. gotta start on the other "half" for the right channel... )

 

[jbeckva]

Dang... mofo.. somofabee!!!

Had a slipped disk of the mica kind. Gotta redo the positive rail buss since it happened to be the last dang tranny that was shorted to the chassis.. grrrrrr..

Hmmmm.. maybe there is a lesson in here, eh? Perhaps I should mount the transistors with the unconnected sockets FIRST, and just hope that I can solder fast enough for any heat to not affect 'em. Been a PITA keeping them in their holes, lined up and whatnot..

 

[jbeckva]

ps. Any of ya's ever feel like this guy when you're working on one of these?? "No more mister nice guy" heheh..

(If ya aint seen "Shocker", you won't get it... so go see it... )

 

[laatsch55]

Can't you just throw a small washer under the Allen head and snug em up??

 

[jbeckva]

Can't you just throw a small washer under the Allen head and snug em up??

Suuurre.. If I had one heheh (aint got none)

 

[laatsch55]

Not a real good screw and bolt collection eh??

 

[laatsch55]

Got some 6-32 phillips paneads??

 

[speakerman1]

I may. How long? I have washers also what size?

Larry

 

[jbeckva]

I'm just thinking that the trannies should be premounted with the sockets. Aside from being able to test for proper alignment before parallel paths are introduced, I've had a couple of instances to where a lil bit of solder actually went down and clogged the pins.

Hmmmmm... It'll get there eventually.

Hmmm(2) - has anyone thought about making a pcb backplane instead of sockets? (Just thinking out loud now... ). Guaranteed "good" connections there.. no doubt.. Maybe not tho - it would be a real bitch if there was a failure.. serious burns and lifted traces eh?

 

[laatsch55]

Unless you had bulletproof traces. Seems a lot of inductance could happen in a plane arrangement.

 

[Gepetto]

Crown DC-300 uses a PCB plane on the heatsinked devices, all devices soldered in to the PCB. Bulletproof reliability in that amp. I have thought about doing that for the PL400 too. It is a major replacement undertaking so not sure of the market acceptance.

 

[laatsch55]

So the exposed traces would indu ct no more than the exposed bus bars??

 

[Gepetto]

Can achieve even better results with the proper ground plane return associated with the signal or voltage plane. It can be worked out. The biggest challenge quite frankly is mechanical. Not sure that Phase Linear adhered to exactly the same layout in every amp vintage.