Phase Linear D-500 DC Protect (and other questions)

[laatsch55]

BTW, Joe and I just finisned a "build off" on his new backplane boards for the 700B's. I'll link the threads. Peruse those builds to see how one of these critters can look on the inside. Joe is a very meticulous feller, his might look a wee bit better than mine, but mine will still be quieter....and I say that with a bit of braggadoccio, as the final analyzer measurements have not been taken yet....



http://forums.phxaudiotape.com/showthread.php/4747-What-We-ve-All-Been-Waiting-For-700-BP-boards!!!!!!!!!

http://forums.phxaudiotape.com/show...se-Linear-700B-Going-Fully-Comp!!!!!!!/page37

I started both threads but he featured his in the first one. When reviewing his keep in mind he's very, very good at what he does....

 

[laatsch55]

Are your outputs MJ15024's and MJ15025's?

 

[jshupe]

How are your tech skills? You feel comfortable inside that monster?

I dabble in this stuff, but have an expert on hand to make sure I don't do anything stupid.

 

[laatsch55]

Excellent..me too...

 

[jshupe]

Are your outputs MJ15024's and MJ15025's?

Motorola TP9054 and RCA 66546.

I was also told that both of these amps were built/modified by an engineer named Leroy Weber in the early 80's. I have no idea what was changed, but they were supposedly configured for increased output over stock.

According to http://home.earthlink.net/~dimlay/sitebuildercontent/sitebuilderfiles/outputs.pdf, the TP9054 is the MJ15024. The 66546 is the same as the RCA 410. On both amps, the 9054 and the 66546 positioning is the same, so I doubt they were haphazardly mismatched during repairs.

I did find something concerning when looking over these: the power fuse on one of the amps has been removed and is internally fused rather than the replaceable fuse on the outside. If anybody has the main fuse assembly, I'd be interested!

I grabbed the serial numbers for fun: 1158 and 2548.

 

[laatsch55]

The 66546 are RCA-410's, the TP9054's are rebadged Mj15024's. So you have a quasi-complementary D-500. The fuseholder is a standerd AGX available from any electronics supplier.. I see no reason a WO board won't work, but like I said we'll se what Joe comes up with.
The 410's are drivers and the 9054's are outputs. Do they work?

 

[jshupe]

I'm still not home, but I pulled the covers off while these were sitting in the trunk of my car to take some better photos of the boards. I found that one amp has been repaired and/or modified in the past. See photos:

 

[laatsch55]

Well, the board does not mount the same, so there may be some problems there.

 

[jshupe]

I made it home today and was able to power up both amps on a Variac. I didn't test any audio input or output, but noted the following:

Amp1: Hi-Freq lit up, Power button does not work (but amp defaults to on)
Amp2: Hi-Temp lit up, Impedence button does not work

Amp1 & 2: smoke coming from right side of driver board!









I'm going to work on recapping everything before continuing testing.

 

[jshupe]

Schematic from the original owner's manual (attached)

View attachment BRWB8763F64D3E9_000264.pdf

 

[laatsch55]

Have you identified the component from whence the smoke escaped??

 

[jshupe]

Have you identified the component from whence the smoke escaped??

R101, I think.

 

[Skratch]

I made it home today and was able to power up both amps on a Variac. I didn't test any audio input or output, but noted the following:

Amp1: Hi-Freq lit up, Power button does not work (but amp defaults to on)
Amp2: Hi-Temp lit up, Impedence button does not work

Amp1 & 2: smoke coming from right side of driver board!

View attachment 12575
View attachment 12578
View attachment 12579
View attachment 12580
View attachment 12581
View attachment 12582
View attachment 12584

I'm going to work on recapping everything before continuing testing.

It looks like someone worked on these before, I thinks it is time for them to see a doctor? The drivers are in the wrong position

 

[laatsch55]

7.5K 5 watt?

 

[laatsch55]

It looks like someone worked on these before, I thinks it is time for them to see a doctor? The drivers are in the wrong position

These are nothing like the 400's or 700's Mark. I believe they're in the correct position..

 

[jshupe]

7.5K 5 watt?

3K. I'm about to remove the D101 and test it.

Here is another photo I forgot to take earlier; the output and driver transistors:

 

[Skratch]

These are nothing like the 400's or 700's Mark. I believe they're in the correct position..

Never too old to learn

 

[laatsch55]

Amen Mark. Got a service manual comin myself so I appear I will know what I am talking about..

 

[laatsch55]

1 driver and 8 outputs......that sound familiar Mark?

 

[laatsch55]

From where that resistor is located it's part of the low voltage supply. Check EVERY semiconductor on that board. For that to smoke you probably have a predriver smoked, one of the MM4003's or 40327. Check the 40412v's also..