A new project to tinker with...PL P3600

e30m3mon

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#1
A while back, a friend was clearing out some old electronics and invited me over to take whatever I liked. Some crusty old cassette decks and other ‘70s crappy stuff....and a PL3600! According to the rear panel, this was the Jensen era stuff. Not nearly as well appointed as the prior generation stuff, but hey...it did say “Phase Linear” on it. I made a list of electrolytics back then and finally incorporated them into a Mouser shopping cart. Changed out the mouse chewed power cord while the covers were off. I noticed the two “ribbon cables” were a significant design “enhancement” over other generations, as was the enhanced turntable EQ section. MC and MM inputs with selectable capacitance loading was very cool.

So I noticed the larger ribbon cable had delaminated and since I wasn’t sure of the wire integrity, I unsoldered all 29 (x2 ends) of that cable and tried sourcing some modern-day alternative. Found what actually worked in an Arduino wire kit I had...complete with male 2.5mm spaced connectors on each end. Soldered those in place of the old ribbons, Nichicon electrolytics swapped in, replaced the op-amps with same numbers since I already had them and powered it on. Sounds great!
My buddy had a note taped to it that the right channel crapped out, which is why he dumped it ... might have been that faulty ribbon cable.

Has anybody else worked on one of these? not a commonly found box on ebay. I searched the forums but found only comments regarding the phono preamp section.

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George S.

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#2
Nice work, especially on the ribbon cables. Those come up occasionally on Craigslist along with the matching tuner and amp. Should be a nice preamp and definitely worth saving. I like that remote mounted pushrod operated power switch. I have a Akai integrated amp with similar power switch, I like the feel of those pushrod switches. That's a very clean example. Nice!
 

e30m3mon

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Elegant solution to the cable problem..
Not sure I would call it “elegant”, but certainly colorful (!) and hopefully the wire will have better long-term integrity. Interestingly, it seems some alternating wires have no connection to circuitry on either end, bur seem to attach to “dead end” circuit board traces. Possibly some attempt to provide an “isolation plane” between signal planes?

@George S. Thread has inspired me to re-open the 2000 II that I re-capped last year. Lots of good tips in his work that I would like to adapt and I would like to share some op-amp insight that I learned and implemented along the way. This P3600 will be swapped in where I have been using the 2000 and then ultimately get it back together with the WOPL 400 II I sure wish White Oak Audio had upgrade kits for the 2000!!
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mlucitt

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#7
sure wish White Oak Audio had upgrade kits for the 2000!!
WOA began with the idea (among others) to fix a fatal flaw (flame linear, blaze linear) in the Control Board circuit; and of course expanded their awesome product line, but always along the lines of "trying to make it better."
The PL2000 has no such fatal flaw, just some obsolete and lesser quality components. Most of us part-changers can fix these issues by reading George's excellent thread (which I have asked him to reduce to a concise document, ahem!) and log some time on the Mouser website. The result is a much improved or even audiophile-level preamplifier that will serve us well into the future.
 
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Gepetto

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#8
WOA began with the idea (among others) to fix a fatal flaw (flame linear, blaze linear) in the Control Board circuit; and of course expanded their awesome product line, but always along the lines of "trying to make it better."
The PL2000 has no such fatal flaw, just some obsolete and lesser quality components. Most of us part-changers can fix these issues by reading George's excellent thread (which I have asked him to reduce to a concise document, ahem!) and log some time on the Mouser website. The result is a much improved or even audiophile-level preamplifier that will serve us well into the future.
While fixing the grounding flaw that exists in the 2000s and the balance pot flaw in the 2000 Series 2
 

George S.

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WOA began with the idea (among others) to fix a fatal flaw (flame linear, blaze linear) in the Control Board circuit; and of course expanded their awesome product line, but always along the lines of "trying to make it better."
The PL2000 has no such fatal flaw, just some obsolete and lesser quality components. Most of us part-changers can fix these issues by reading George's excellent thread (which I have asked him to reduce to a concise document, ahem!) and log some time on the Mouser website. The result is a much improved or even audiophile-level preamplifier that will serve us well into the future.
I just think I'm not qualified or able to answer technical questions that would result from such a document or thread. You guys did all the heavy lifting on figuring out what works. I don't want to take credit for it. Shoot, choosing capacitors confuses the hell out me.
So how about this. I need to get another PL2000 for my computer room system to drive the amp in the photo that my father built for me in the early 70s. I'll document that build.
 

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MarkWComer

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#10
HA HA! SCSI ribbon cables from a computer? I used to have that stuff by the mile! Can't strip the ends, you need to crimp the connectors to the ends.
 

e30m3mon

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HA HA! SCSI ribbon cables from a computer? I used to have that stuff by the mile! Can't strip the ends, you need to crimp the connectors to the ends.
Believe me, @MarkWComer , I had spent too many years troubleshooting those damn finicky crimped ribbon cables and building new cables, that I was not going down that path again! Actually, these cables have pre-made ends in either gender, and the females would be un-pluggable if needed with header pins coming out of the PC board. I like soldered ends and the reliability of a flowed joint on both ends, so I chose the male pinned cables. Just peel off the number of conductors and plug away. Solder seals the deal. Pitch is 2.54mm which matches the hole spacing on the board.
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e30m3mon

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#12
I just think I'm not qualified or able to answer technical questions that would result from such a document or thread. You guys did all the heavy lifting on figuring out what works. I don't want to take credit for it. Shoot, choosing capacitors confuses the hell out me.
So how about this. I need to get another PL2000 for my computer room system to drive the amp in the photo that my father built for me in the early 70s. I'll document that build.
From what I’ve seen George, you got a far better grasp on this stuff than you give yourself credit for. I scratch my head when I read many posts out here, but you get it done. So go for it!
 
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