WTB PL400 meter bezel and a couple of FPL909's

girbob75

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Feb 8, 2023
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10
#1
Hello all,
I'm new to the Phase Linear but recently acquired a series 1 400 in need of repair. It's missing the right meter bezel and a single transistor was shorted in one channel. I need to tear through it more but these are the obvious things I have found. Any help finding these parts would be much appreciated.
Thank you
 

wattsabundant

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#5
....and if you're not going to upgrade the driver board, replace the 4 x TO92 transistors (Q1-4) As they have become failure prone in their old age. This assumes you have the PL14 board. Driver transistors at the bottom of each stack need to be retained to avoid oscillations. Attached is the 400 manual with valuable information in the service bulletins on the TO92's. Any troubleshooting should not commence until the manual is read cover to cover. I've probably read it 400 times.
 

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girbob75

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Feb 8, 2023
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#6
Insterad of runniong old outputs, perhaps you should consider replacing all outputs?? With MJ 21196's?
I hear you and agree. My ultimate goal is to go full comp with 21196's. I haven't heard the amp yet. I kinda want to get a baseline on sound before alteration. Blown fuses was the first thing I looked for. Found one then went straight to looking for shorts. One of the Fairchild PL909 was shorted. The others in the channel were not.
 

girbob75

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#7
....and if you're not going to upgrade the driver board, replace the 4 x TO92 transistors (Q1-4) As they have become failure prone in their old age. This assumes you have the PL14 board. Driver transistors at the bottom of each stack need to be retained to avoid oscillations. Attached is the 400 manual with valuable information in the service bulletins on the TO92's. Any troubleshooting should not commence until the manual is read cover to cover. I've probably read it 400 times.
Wattsabundant... Just purchased an output relay board on ebay earlier. I felt it was a must have for this amp. Driver transistors are the RCA 410's correct? Is there any modern replacements for these when replacing all the transistors? I'll have to check the driver board.
 

girbob75

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#8
....and if you're not going to upgrade the driver board, replace the 4 x TO92 transistors (Q1-4) As they have become failure prone in their old age. This assumes you have the PL14 board. Driver transistors at the bottom of each stack need to be retained to avoid oscillations. Attached is the 400 manual with valuable information in the service bulletins on the TO92's. Any troubleshooting should not commence until the manual is read cover to cover. I've probably read it 400 times.
Thanks for the note on the TO92's and the Manual. I do plan to upgrade the driver board eventually.
 

wattsabundant

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#10
Wattsabundant... Just purchased an output relay board on ebay earlier. I felt it was a must have for this amp. Driver transistors are the RCA 410's correct? Is there any modern replacements for these when replacing all the transistors? I'll have to check the driver board.
The service manual lists acceptable devices for the RCA 410 drivers all of which are likely hard to find. They don't fail very often. When knuckleheads wrap foil around the fuses all bets are off.

When the amp is updated with Joe's full comp backplane and driver boards, the driver transistors are the same as the outputs. Prior to doing the full blown upgrade, an ambitious person could convert a stock quazi comp amp to full comp. I've done it. It's not for the technically challenged person.
 

girbob75

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Feb 8, 2023
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#11
The service manual lists acceptable devices for the RCA 410 drivers all of which are likely hard to find. They don't fail very often. When knuckleheads wrap foil around the fuses all bets are off.

When the amp is updated with Joe's full comp backplane and driver boards, the driver transistors are the same as the outputs. Prior to doing the full blown upgrade, an ambitious person could convert a stock quazi comp amp to full comp. I've done it. It's not for the technically challenged person.
I did see that in the service manual and figured as much on the replacements. I have read about the oscillation issues with these. No foil on mine and fuses are the right ones for the job. It's actually a really clean unit except for the missing bezel. Thanks for the advice. 20230212_183743.jpg
 

AngrySailor

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#18
Replace the fuse once. If it blows again stop. Every time after that replacing the fuse does at least $100 more damge each time.
I blew a fuse in Linda (400/1) and replaced it. Was too lazy to bring the dim bulb over and nuked a pile of stuff I shouldn’t have...
 

J!m

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#20
Yeah, Canadian gun laws do not make sense.

You have frickin polar bears! They rip steel fire doors off of concrete buildings looking for food that isn’t in there. Got the low down from a girl I dated years ago who worked for MNR.
 
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