Bill's PL-400 journey

[Goggle1824]

Hey guys, I'm finally posting outside of my Introduction because I have (FINALLY!) acquired my very first Phase Linear amp and am excited to get going with her.

Picked her up off "the bay" for just over $200 delivered. She's non-working but isn't in TOO bad of shape. She looks like she may have been ridden a little hard and put away wet but from my very limited knowledge she doesn't SEEM to be too bad...

Anyway, it's my pleasure to formally introduce ya'll to "Deb" (Sorry about the fuzziness of that frontal shot!)

 

[Goggle1824]

Control Board Pics

Here are some shots of her control board (version 14-B).

I'm pretty much noob when it comes to working inside of amps, though I HAVE been reading through tons of these other PL400 rebuild threads for the better part of a month.

I've downloaded, printed and bound the service & owners manuals (via the Watts Abundant website) so I THINK I'm identifying these positions correctly (fingers crossed).


So, what I SEE that looks like it will need replacement (at least to start) is a cracked resistor (R16) furthest top right of the board and about 4 smoked/swelled ones (both R24 & R25) in what I ASSUME is in each channel, those sets are just below the center of the board along the row inline with the Q8 & Q9 caps.

Do you guys see anything else I need to add to a Mouser order list?

 

[nadude98]

I wouldn't even mess with restoring the existing boards.. WOPL it! My two sense... pun intended.

 

[Goggle1824]

Outputs & Drivers

Ive got a whole mishmash of drivers and outputs here, all with a decent amount of the white thermal compound squished out and sort of all over (pictures to follow)



For future reference someone please correct me if this is wrong: the PL-400 has 12 OUTPUT TRANSISTORS and 4 DRIVER TRANSISTORS all located on/in the heatsink fins on the rear of the chassis.

Of those 16, 4 columns of 4, the bottom transistor in each column is the DRIVER, the other 3 in each column are the OUTPUTS and are "essentially" acting as a bigger transistor.

The Left and Right channel each have 2 drivers and 6 outputs, right? 1 driver and 3 outputs for both the negative and positive lines or "rails"? Hopefully I have this somewhat correct



What Deb is currently 'dressed with' is:

Facing the front of the amp:

Right most column (furthest away from the transformer)
Top:
F PL909
F PL909
M C4000
RCA 410 (driver)

Right side inner column:
Top:
F PL909 (black Sharpie X on this one)
M C4000
F PL909
RCA 410 (driver) (black Sharpie X on this one)

Left side inner column:
Top:
F PL909
NEC 2SD555
NEC 2SD555
NEC 2SD555 (driver) ??? Should this one be here as a driver???

Left column (nearest the Transformer):
Top:
F PL909
F PL909
F PL909
RCA 410 (driver)

 

[oblivion321]

Glad to see you made it Bill ! I've been waiting to see your rebuild happen since we spoke over at AK. This is definitely the place to be to learn what you need to know and get expert opinions and answers. I'm sure you've read my thread (which isn't over yet) and hope that maybe some of my failures and fortunes might help you along. Since I'm a novice with more guts than brains most of the time, My best advice to you is to ask many ?'s, order your DC from Don and whatever else you can from Joe. This place is like a cult. They'll tell you whatever it is you need to know to turn you into a believer... I'm gonna crack open a beer and see what happens here.

 

[laatsch55]

Here are some shots of her control board (version 14-B).

I'm pretty much noob when it comes to working inside of amps, though I HAVE been reading through tons of these other PL400 rebuild threads for the better part of a month.

I've downloaded, printed and bound the service & owners manuals (via the Watts Abundant website) so I THINK I'm identifying these positions correctly (fingers crossed).


So, what I SEE that looks like it will need replacement (at least to start) is a cracked resistor (R16) furthest top right of the board and about 4 smoked/swelled ones (both R24 & R25) in what I ASSUME is in each channel, those sets are just below the center of the board along the row inline with the Q8 & Q9 caps.

Do you guys see anything else I need to add to a Mouser order list?

Did you build a dim bulb tester first??

 

[laatsch55]

I've had a 2SD555 cause oscillations as a driver ..never seen an MC4000.....

 

[oblivion321]

Did you build a dim bulb tester first??

Do it. It's saved my ass right from the beginning.

 

[laatsch55]

We're the fuses intact??

 

[Goggle1824]

We're the fuses intact??[/]

The middle supply fuse was blown, the others were/are good and are the correct rating per the sticker on the heat sink.

The wire in the blown fuse was broken and curled up but no black or charring on the glass.

Yeah, I haven't found anything on the MC4000 outputs, so I'm thinking I should stick with what is recommended here and will likely be replaced regardless of how they test.

I have a decent DMM, now with mini-grabbers! And a Hakko 936 soldering station.

Yes, check, dim bulb tester is constructed and ready.

Thanks to one of the member's here excellent and enjoyably entertaining YouTube instructions, MarkWComer, whose videos really helped convince me to take this on myself!

They aren't brief, but, they are informative and entertaining (for me at least, usually pretty late night viewing after my little ones and my wife are tucked-in and asleep).

I do need to order Don's protectors, I'm thinking I have a couple of things to replace on this board before I try to hook-up to any speakers.

 

[laatsch55]

Finally got a look at your pics. The top right resistor is toast. Can you identify it from the layout in the manual? Have you reviewed the transsistor testing thread from AK?

When in doubt....measure it.....

 

[Goggle1824]

The broken "R16" resistor looks to be a 1/2 watt, 3.3k, metal film, axial.

I've reviewed the testing thread on AK but will go back and refresh myself since I have the physical items in front of me now.

 

[laatsch55]

Good idea.....

 

[Goggle1824]

Daaah!!! Not finding it in my bookmarks, though I'm 99% sure I bookmarked it...

 

[laatsch55]

I asked markthefixer to import that thread when he gets some time...

 

[NavLinear]

http://audiokarma.org/forums/index.php?threads/bipolar-junction-transistor-testing-basics.43186/

 

[Goggle1824]

Thanks Nav the Italian is fantastic! And the link is much appreciated as well