Unwell Phase Linear 700 series II

[laatsch55]

Sil-pads are the way to go now. Berquist..

 

[WOPL Sniffer]

I still have a bunch of new MJ21196 that were never used, I would only need the`95s.
The 2n6254s that were in there were mounted with a mica and some type of silicone pad with no thermal paste, should the new transistors be mounted the same way or with the more traditional mica/paste combination?

It had Mica AND the silcone pad???? Skip the mica/whale spooge

 

[Michael F]

Silicone pad it is then. Any particular specification? I see many choices are available.

 

[laatsch55]

Berqyist 400's

 

[grapplesaw]

Thanks for that grapplesaw. I have been unable to find any documentation pertaining to the comp version. Would you have a scan of those? I cant quite expand the image enough.

Ok
Will get them for you

 

[grapplesaw]

Thanks for that grapplesaw. I have been unable to find any documentation pertaining to the comp version. Would you have a scan of those? I cant quite expand the image enough.

Here are the schematics. Try downloading them to get clearer image

 

[MarkWComer]

The 2n6254s that were in there were mounted with a mica and some type of silicone pad with no thermal paste, should the new transistors be mounted the same way or with the more traditional mica/paste combination?

Most of us here use silpads alone, no grease, no mica.

 

[MarkWComer]

She's a beauty.

Yup!

 

[Michael F]

Here are the schematics. Try downloading them to get clearer image

Thanks for that .
A quick look and I see a few discrepancies, the schematic shows D107,D108. Those seem to be MIA but there are two 10R resistors instead. The IC in the control board is different from that in the diagram too.

 

[grapplesaw]

Thanks for that .
A quick look and I see a few discrepancies, the schematic shows D107,D108. Those seem to be MIA but there are two 10R resistors instead. The IC in the control board is different from that in the diagram too.

Yes those are delegated by factory. These are the fly back diodes. Much debate as to there requirement in full complimentary setup but Joe said they will not hurt so I add them. I don’t think Ed likes them put in. Your choice

 

[grapplesaw]

Thanks for that .
A quick look and I see a few discrepancies, the schematic shows D107,D108. Those seem to be MIA but there are two 10R resistors instead. The IC in the control board is different from that in the diagram too.

The ic should be lf351 and resistor r1 and r2 should be 7.5k 3 watt ( I use 5 watt or greater) with that opamp.

 

[Michael F]

The ic should be lf351 and resistor r1 and r2 should be 7.5k 3 watt ( I use 5 watt or greater) with that opamp.

Yes, that checks out.

 

[grapplesaw]

Yes, that checks out.

You got a hell of a good amp there. If you can do the rest of the WhiteOak upgrade you will have an amp to last for the next 50 plus years.

 

[Michael F]

OK, so aside from what was already mentioned, I checked all the back plane resistors and did some (in circuit) testing of diodes and transistors. A B-C short was found on Q204, both Q 105 and Q205 had cold solder contacts and Q 205 measures questionably. All diodes seem ok with the exception of D105 and D205.
These part numbers are taken from a Quasi diagram which might not necessarily coincide with the Comp model PL36 board which incidentally seems less populated.

This all brings me to a crossroads.
Seven years ago when I rebuilt my 700B I was fortunate enough to have a lot of technical papers on hand ie schematics, service manual and revisions, part numbers and pcb placements etc and only through the generous guidance of Lee, Joe, NavLinear and several other members to whom I`m eternally grateful, did I manage to accomplish that project.

The lack of documentation in this particular case has me raising more and more questions as I go along
Add to that the other variable of the unknown "servicing" that was performed previously raises more concern.
At this point, I know the back plane needs to be repopulated but I`m wondering if I should just replace the stock PL36 board with a WO unit, if one even exists for the Series II?
That is exactly what I did with the 700B, I dont recall the board model or revision but it worked out very nicely.
I would hate to jeopardize 24 brand new outputs by some mystery issue that resides upstream.
Your thoughts?

 

[wattsabundant]

Attached is the 700II manual. Read the troubleshooting section. Also note that R101, (7.5k, 2W) is known to drift and open up. If you're concerned about damaging a bunch of outputs, install the drivers and one output in each column.

 

[laatsch55]

The new generation G board is out now....and yes it will work in a Ser II...full comp or quasi, either one..

 

[grapplesaw]

Save yourself hours of head scratching to understand the pl36 board in the full complementary setup and buy a new WhiteOaks F or G Board Very easy install using Joe’s documents. Also get a watts abundant DCP board from Don.

 

[Michael F]

I think one of Joe`s boards is the safest and smartest option.
What`s the difference between the E5 and G1 versions of the board?

 

[laatsch55]

The G board is a true dual mono board. The channels share nothing...

 

[Gepetto]

Hi Michael
The release notes for each are attached which describe the features of each.
Joe