Bulk Capacitor Replacement Procedure for the PL 700B

Phase Linear Phanatic · Jun 12, 2013

By the way. Nice schematic. Sadly, I understand what it all does now? And i was hoping just to be a dumb guy and drop in and play. Look what happened? A full 700b schematic? My fault! ha ha! Sorta looks like the one in the back of my PL manual now? Lol. (only more transparent).

Gepetto · Jun 12, 2013

Phase Linear Phanatic said:

I would LOVE to have an oscilloscope, but I can't afford a descent multimeter at the moment. I got fed up with replacing soldering irons, i broke down and bought a soldering station. Over a hundred in the hole for that this week. So yeah, nice machines like THAT are on hold. Lee......these resistors in the photo that is being blocked by my new shielded grey wire, are of the same banding as that of those 220k ohm resistors you had me remove. Now see in the pic Joe just provided where he says thats how it SHOULD look, he HAS the two 220k ohm resistors coming in from the RCA's and soldered to the RCA bar. So are they or aren't they supposed to be there?? Before i go cutting that black/white/ green wire from the switch, that goes over to the nearest triple bar on the back wall..... I will try to upload clear and more pics. Every time i try to get a close up shot, the dumb camera fuzzes out the foreground and when i move back, vise-versa so i never get a whole clear pic of the damned thing? Grrrr.... As for that WOAPL schematic I showed, I downloaded it directly from the WOA website where it says "click here on installation procedures". I guess if that is currently incorrect, maybe consider an update? If you sent me proper documentation in email, stupid windows live mail would not open excel. I do not have the program. It even cut off my adobe attachments list and I couldn't pan over to see past 7 attachments? And i know you said there were nine? So it's been a frustrating week. And to boot i just got home from work, its midnight and i have to go to bed and wake up and go back to work! Stupid job keeps getting in the way of my WOAPL project!

Point is; i believe those ARE two 220k ohm resistors there on that switch. And as you see I cut the solid wire above and below that. Leaving that banded wire going to the back wall. I will cut that also if that is an issue for ground. This means i SHOULD also remove those resistors at the switch? And move them to the RCA bar like in your pic Joe? And after that, i will remove white from 5R and go to 5L with it (just to be right) and then solder it to star ground. Am i making any sense? Or just a blabbering fool? By the way, excellent, detailed answer to my question Joe. I guess a picture really is worth a thousand words? Lol! I will try to take more pics soon.

I hope you didn't bother Ed too much Lee? This should clear things up a bit. Until I can get back to the amp...... Cannot provide more. Will try in the morning.

Hi Dave
If you want the best performance out of your PL700s, then you should attempt the wiring that I showed in the photos. I recently did that for a friend in FL (a complete rewire) and the amp was like a black hole afterwards from a noise perspective. If you are in there, you might as well get all that substandard original PL wiring made right.

BTW, I have many more photos of different areas of the PL700 amp if you have any interest.

laatsch55 · Jun 12, 2013

Ed and I have an interesting relationship, If it's a phone call it's a 2 hour minimum with many lasting 3. This was an e-mail, sometimes he jumps on em and sometimes he doesn't. A lot of things happening in Ed's life right now....

laatsch55 · Jun 12, 2013

Dave, we were talking about the odd colored emitter resistors....

Phase Linear Phanatic · Jun 12, 2013

laatsch55 said:

Emitter resistors? Oh. I thought you were talking about the second picture with the normal/direct coupled switch that was being blocked by my wire? Apologies. Well, the resistors "look" standard PL issue? They way they are shaped and all? Maybe I have a lemon amp or something?? I am seriously considering have someone send me a cabbage case here............. seems there is still all sorts of fun stuff to fix and figure AND measure..........since I lack the proper bench tools. :-(

I mean....... I have three of these amps. Its not like I need a loaner or anything, but still.......this was my nicest one. Being WOAPL and all. Takers? Takers?......... Then you can make a thread about "Dave's 700B" LOL! What takes several chats, would take one of you guys an hour to fix on my amp. Soooooooooo what's your time worth? :toothy8:

jbeckva · Jun 12, 2013

Phase Linear Phanatic said:

For me? Just parts... I have a 700 and a 400 here, rebuilt, and I'm working on another 400 that as of yet I haven't figured out what to do with (but I DO almost have a "plan" there, to be revealed in due time... hehee). All because I enjoy the hell out of a rebuild. I take my time and spread it out over a few weeks, just so I don't get to the end of it.

(hmm.. reminds me... guess tonight I'll run the AC n DC wires for the DCP. Last night was the TO3 replacing phase... :toothy10:

)

laatsch55 · Jun 12, 2013

Here is Ed's answer---=----
Lee,

Yeah I just saw Phase Linear Phanatics pictures and instantly recognized the modifications that were performed by Mila Nestorovic while he worked at Phase Linear. (See attached photo). Mila was a friend of A.P. Van Meters. They both worked together at McIntosh in the early 1960's. A.P. helped get him the job at Phase Linear. Mila had several speaker patents that Bob Carver intended to use at Phase Linear but the details couldn't be worked out. From what Dean tells me Mila's mods were only used for a month or two on some 700B's and Phase Linear eventually returned to their original design. Apparently the mods must not have been reliable enough

Gepetto · Jun 12, 2013

Well it looks like Dave has a much bigger task on his hands now to undo Mila's work. Else the assymetry of signal output will limit the full capability of this amp.

laatsch55 · Jun 12, 2013

Indeed. When the service department got one of these in, they immediately converted them back. They would blow up eventually, they ran a lot hotter than normal.

laatsch55 · Jun 12, 2013

Joe, Dean had just left Ed's place when Ed called. Dean was somewhat surprised that Ed did not have the Mila schematic. Dean was going to remedy that and wqe shou;ld have our copy soon after. Joe, did you see R38, 39?? Or are they MIA??

laatsch55 · Jun 12, 2013

Daver, if at all possible, I would like to get my hands on that old board....

Gepetto · Jun 12, 2013

laatsch55 said:

They seem to be there Lee but they are tucked into unconventional places. You can see them somewhat piggybacked across the lowest set of emitter resistors if you look carefully. Certainly a PIA to set the bias with them located in that position when you do not have the benefit of the WOA board to bring those test points to you.

Gepetto · Jun 12, 2013

Dave is going to get a lot of practice with his new solder station

With this modification in front of you Dave, you will be putting 50,000 miles on that new Weller of yours

laatsch55 · Jun 12, 2013

Yep...., Joe, what do you have in mind when the 410's run out.....,

Gepetto · Jun 13, 2013

laatsch55 said:

Are we coming to that point Lee?

I have not seen a single bad one yet so have not had need to replace them unless you get an amp that has had the swap done prior to arrival.

Gepetto · Jun 13, 2013

laatsch55 said:

For the PL400, full complementary

laatsch55 · Jun 13, 2013

I have 18 left Joe....

Phase Linear Phanatic · Jun 13, 2013

laatsch55 said:

Oh that's just fantastic! I have an amp that will blow up on me? Greeeeeeeat. But I have a phase linear branded fan that blows across the heat sinks on this amp so I shud be ok? Jerry, its seems now I should have traded that Rotel for your time. Lol! My other two PL 700b's don't have this? At least i don't think they do? Lee, I DO have the old boards, they have a transistor leg broken off from bending the board down I think, but three leg transistors are probably a dime a dozen. Are you looking for rare parts off of it? I have a 700B here (early model), that I WOA light boarded. That's it. Even all driver transistors are phase linear stock. They say phase linear on them. (See my photo album in my profile. Some old 7040 board is in that amp. I thought it was PL20 or PL36? Never heard of a 7040? But that pic is in my album too. Thats the amp I would like to sell. And now with a perfectly working meter board, its great. Take a look see? Lee......if you want the board from THIS amp......send me a cabbage case and we'll do a trade? ;-)

fix my issue and its yours free. I am getting asked by work to pull 70hrs a week now. I am afraid my PL fixing time is drawing to a close. After all...if we are going to reverse and rework an engineers design on my amp, then I lack the skill. Or time. As soon as i get a chance, i will take a pic of the inside of all three amps. All three have different driver boards in them and different component configurations. Jeeze....phase linear sure was NOT consistent............

Phase Linear Phanatic · Jun 13, 2013

Gepetto said:

Joe, funny you mention that. The day I bought it, I simultaneously purchased a dozen spare tips! I just "assumed" this was going to happen. It's this weird gray cloud over my head.... :-/

laatsch55 · Jun 13, 2013

For me it's that yearning for experience that does me in...

throw in a couple pair of rack handles and we are closer to working a deal...

Bulk Capacitor Replacement Procedure for the PL 700B

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