DChristie's PL 2000

George S.

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#86
Me too Bill!!! Thanks..
Only thing that stands out to me is I still think the LED transistor, if it is a TIS97 is in backwards or somehow not compatible with the original GES97 in this specific application. I searched some for the pinouts and can find nothing on the net. Other than Grapplesaws post that the pinouts are reversed, I can find no specifics. Maybe he can comment. Wanted to sit down and look at the schematic to see how the TIS and GES 97s are implented but have no time.
 

George S.

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#87
Oh, and in one post Joe says the GES97 is being used there as a zenor diode being as only two of the 3 legs are used. I don't know enough how to figure out what diode to sub there, so I used a GES97 as originally installed.
 

George S.

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#88
Got a couple free minutes and looked at some other photos of other members PCBs. Some of them have that "LED driver" facing forward. Now I'm confused. And further confused because the schematic shows Q1 GES97, Q2 TIS97. On mine, it came reversed Q1 TIS97, Q2 GES97. Weird, those look like the pinouts are reversed. I give up for now. When I get time I'm going to look at all the 2000 service manuals to try to figure this out.
 

George S.

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#89
Probably on Monday I'm going to pull those two transistors, multimeter the pin out, note it on a note card I'm going to leave inside the case, and make sure they are installed correctly per the schematic. Enough of this confusion. Per the schematic they do look like they have different pin outs don't they?
 

laatsch55

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#90
Yes. Some may have different spinouts in the same series. I have a B and K 510 transistor tester that gives the pinout and that's pretty handy.
I have matches the trannys with the schematic and they are in correct.
 

Gepetto

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#91
After being on awhile minus 15 and plus 25..

A wild ass guess Lee because I am not there with you to help you debug. The PL2000 uses the chassis for ground continuity purposes. Don't ask me why they did this and did not run the wire on the board instead, but they did. In order to have ground continuity is is imperative to have the leftmost and rightmost chassis screw that goes into those small L brackets make good contact with the chassis and with the PCB trace on the bottom side. Otherwise you will have an open center tap connection to the PSU and will get uneven secondary DC voltages on the circuit side of the preamp, where all the action is.

I would recommend putting a jumper between the 2 ground traces (they run across the back of the board near the rear chassis wall, you will see that they do not join. Then I would insulate the leftmost screw from the chassis, the one near that large chassis ground screw on the back of the chassis. Then ensure that the rightmost screw nearest the AC line connection is in great contact with the chassis and ground trace.

Clear?? If not squawk back.

IMG_4014[1].JPG
 
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George S.

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#95
I think Joe solved it. Especially if you had that shield out along with the two screws when you were testing voltages. Brilliant!
 

laatsch55

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We now have balanced voltages, although a tad high, with no IC"s mounted, +20.56, -20.67

Why were the resistors added Joe?
 
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