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  1. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    Joe thank you for the clarification. New resistors and diodes on order.
  2. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    I think I'm going to rebuild the back wall. A couple of questions. What I have differs slightly from the schematic included with the narrative wiring instructions. Resistors R36&37 are 150 ohm, on the schematic, but I have 100 ohm. Assuming I rebuild it should I get the 150's? **...
  3. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    Joe, Thank you for the help with this. Alan
  4. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    While I'm at it would it be of benefit to replace the .22 emitter resistors and the 10 and 150 resistors? What wattage would they be? Is a metal oxide the right part?
  5. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    The strap, if you will, for my transistors doesn't completely enclose the Q6. Is that something anyone would have a couple of? Once I remove the heatshrink etc I don't think the bracket I have will hold a TO92 part.
  6. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    Here's a close up of the bias transistors
  7. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    The bias transistor IS encapsulated in heatshrink and what looks like silicon. Is there a suggested replacement if it breaks while I'm reconfiguring it?
  8. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    :hello1::hello1::hello1::hello1: Cheap Chinese Tester to the rescue! Rewired the bias transistor per the results of the CCT and the 400 powered up properly. As soon as I started to increase the variac, the B+ increased as well! The relay kicked in at about 110VAC. Once at 120VAC the offset...
  9. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    I thought I'd check the bias resistors since I thought the connection might be compromised. I only have a cheapie Chinese testor but it does tell me which lead is what. Good news is the Bias Xistors are still have a good connection. Bad news is based on the testor my colors do not match the...
  10. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    Went through BOM item by item and found no parts mis-placement. I thought I found something but it turns out it was nothing. R53 Actual=Brown Grey Violet Brown Brown (1.87K Ohm Correct per description) vs BOM said Brown Grey Black Brown (1.8K Ohm) R35L R35R R37L R37R Actual = Red Red Black...
  11. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    A couple of questions / concerns about possible cause of this overcurrent situation. *would loosing connections with one of the back wall thermal transistors be a source? When fiddling with the heatsinks there was a lot of stress put on those connections. At least once I lost my hold on the...
  12. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    When you say base drives do you mean disconnect 3L&R and 9L&R? Can I assume that the WOA board is causing the problem somehow? I think I'm going to have to go through the build with a fine tooth comb. One thing that did happen when I was soldering it, I installed Q3, 4,5L backwards. I noticed...
  13. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    With B+/- disconnected at the cap the power supply is OK. DBT acts as it should. Can I disconnect the WOA board only from the B+/- leaving the SJ2741's connected? Will it cause them issues with their base floating?
  14. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    7 M ohm from collector to chassis on all 4 SJ2741
  15. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    I'll check but only SJ2741's installed.
  16. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    What happens if I disconnect the B+/- from the WOA board? Does it hurt anything such as the SJ2741 pre-drivers? I'm curious if the DBT will behave with it disconnected. I'm not finding any smoking guns regarding misplaced components on the WOA board.
  17. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    Both B+/- fuses OK
  18. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    Keep in mind that after installing the DCP and new bulk caps it was working albeit with a high offset on the left (edit) .
  19. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    None. When I turn on the DBT I get a brief voltage but with in a second goes to 0. After switching off the DBT voltage is shown quickly dissapating to 0.
  20. punchback

    My New Early Model PL400 w/ 4 Fin Heat Sink

    +/-15 is about 6 volts. No DC on the outputs as measured on the left channel input of the DCP board.
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