Mike's PL400 rebuild (or, Mark's WOPL III!)

MarkWComer

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#1
My first "outside job" came up- an AB-so-LOOT-ly PERFECT late-model PL400.
Original owner, purchased in 1975. Looks like it came out of the factory yesterday!

When the time comes to take her apart I'm gonna feel like I'm spray-painting Mona Lisa's face!

 

laatsch55

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#2
Those cherry's are not as rare as ya think. A lot of guys take care of their shit. I've seen and worked on a few that were museum quality..
 

bill7621

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#3
I have a very nice PL400. It's bone stock and I wouldn't say it's mint, but it's definately very nice. I'm the second owner. Like Lee said, they're out there.
 

MarkWComer

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#4
Those cherry's are not as rare as ya think. A lot of guys take care of their shit. I've seen and worked on a few that were museum quality..
This is the first I’ve ever seen one in this condition since the audio shop in Baltimore. Yeh, museum quality! They may be out there in the wild, but I’m used to seeing so many dumpster dives on ebay.

Dazzling...
 

Bradrock

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#6
How can you tell through that thick dirt & dust? C'mon Mark; get out your Hillary cloth & give it a wipe before taking glamour shots!

Just kidding.................

Do you have liability insurance for your new business?


Kidding again...................The videos should be fun on this one
 

laatsch55

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#8
How can you tell through that thick dirt & dust? C'mon Mark; get out your Hillary cloth & give it a wipe before taking glamour shots!

Just kidding.................

Do you have liability insurance for your new business?


Kidding again...................The videos should be fun on this one
Aw shit Brad...that's funny!!
 
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#9
Mine's an absolute dog. Like Philip Morris owned it, so much tar in- and outside. I've cleaned of most of it over time, but it never ceases to amaze me how much residue remains.
 

MarkWComer

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#12
Small problem:

I got to the point of putting the driver circuit into the chassis, FORGOT to discharge the PS caps, and while pulling off the electrical tape from the pad 11/12 wires I blew out the picofuses. Replaced them, but now during power up tests, voltages on pad 11/12 on the left channel are half the voltage of the right channel. What did I burn out? Other test points measure good.
 

MarkWComer

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#13
Small problem:

I got to the point of putting the driver circuit into the chassis, FORGOT to discharge the PS caps, and while pulling off the electrical tape from the pad 11/12 wires I blew out the picofuses. Replaced them, but now during power up tests, voltages on pad 11/12 on the left channel are half the voltage of the right channel. What did I burn out? Other test points measure good.
Hmmm... Measured again... Now it’s fine...
¿?¿?¿?¿?¿?
 

MarkWComer

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#14
As long as I’m here, I also have a model 1000 Autocorrelator that wants new input jacks. Looked on the Mouser site and I see about a dozen right-angle board mount jacks that all look the same. Has anyone else worked on these and know which ones I should order??
 

laatsch55

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Phase used a weird layout of those Jack's. The 2000 Pre's used em too. I bought a LARGE bag of them on ebay and the signal ground and hot were reversed.....
 

laatsch55

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#16
In other words Mark, be sure of the form or layout. The data sheet should show a detailed drawing with dimensions and specs. That should enable you to determine if they are suitable.
 

Gepetto

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#17
Hmmm... Measured again... Now it’s fine...
¿?¿?¿?¿?¿?
Good to hear because that path you discussed is just wire and a fuse. If you got half voltage, you invented something new Mark.

Did you accidentally short the 11 and 12 wires together to blow the picofuses? Or did something else occur?
 

MarkWComer

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#18
Good to hear because that path you discussed is just wire and a fuse. If you got half voltage, you invented something new Mark.

Did you accidentally short the 11 and 12 wires together to blow the picofuses? Or did something else occur?
Just doing the normally prescribed cycle of powerups and measurements. At the point where the driver board is to be inserted I pulled the electrical tape from the black and red wires, they sparked, and burned my fingers. Well, oops. Proceeded with the capacitor drain for the next powerup, finished connecting the driver board, and the next powerup showed no power being delivered to the board.

Checked the schematic to trace the issue, I saw what you said- wire and a fuse. DVM showed voltage at the in side of the fuses, but none at the out side. Easy diagnosis! The half-voltage is a mystery, maybe a dirty DVM probe?

Light board, DC protection next, then a day of burn-in. Pretty much done.

BTW: thanks for (accidentally?) adding the extra fuses to the little bags...
 

Gepetto

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#19
Just doing the normally prescribed cycle of powerups and measurements. At the point where the driver board is to be inserted I pulled the electrical tape from the black and red wires, they sparked, and burned my fingers. Well, oops. Proceeded with the capacitor drain for the next powerup, finished connecting the driver board, and the next powerup showed no power being delivered to the board.

Checked the schematic to trace the issue, I saw what you said- wire and a fuse. DVM showed voltage at the in side of the fuses, but none at the out side. Easy diagnosis! The half-voltage is a mystery, maybe a dirty DVM probe?

Light board, DC protection next, then a day of burn-in. Pretty much done.

BTW: thanks for (accidentally?) adding the extra fuses to the little bags...
On purpose Mark. Been to this rodeo before and it is more expeditious to put them in the kit than to deal with a request later on to send a replacement set.
 
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