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  1. Michael F

    Unwell Phase Linear 700 series II

    OK, so aside from what was already mentioned, I checked all the back plane resistors and did some (in circuit) testing of diodes and transistors. A B-C short was found on Q204, both Q 105 and Q205 had cold solder contacts and Q 205 measures questionably. All diodes seem ok with the exception of...
  2. Michael F

    Unwell Phase Linear 700 series II

    Yes, that checks out.
  3. Michael F

    Unwell Phase Linear 700 series II

    Thanks for that :). A quick look and I see a few discrepancies, the schematic shows D107,D108. Those seem to be MIA but there are two 10R resistors instead. The IC in the control board is different from that in the diagram too.
  4. Michael F

    Unwell Phase Linear 700 series II

    Silicone pad it is then. Any particular specification? I see many choices are available.
  5. Michael F

    Unwell Phase Linear 700 series II

    Thanks for that grapplesaw. I have been unable to find any documentation pertaining to the comp version. Would you have a scan of those? I cant quite expand the image enough.
  6. Michael F

    Unwell Phase Linear 700 series II

    I still have a bunch of new MJ21196 that were never used, I would only need the`95s. The 2n6254s that were in there were mounted with a mica and some type of silicone pad with no thermal paste, should the new transistors be mounted the same way or with the more traditional mica/paste combination?
  7. Michael F

    Unwell Phase Linear 700 series II

    Here ya go
  8. Michael F

    Unwell Phase Linear 700 series II

    Back plane view.
  9. Michael F

    Unwell Phase Linear 700 series II

    Good catch.
  10. Michael F

    Unwell Phase Linear 700 series II

    OMG, this is a fully complimentary amp???How could you tell? FFS, No wonder it doesnt work! Wrong NPN output transistors, all the way around. No point in testing, I`ll just toss them. I downloaded a service manual and schematic from HiFi Engine but it`s quasi version. Can someone point me in the...
  11. Michael F

    Unwell Phase Linear 700 series II

    Hi All, It`s been a while since I posted, hope you`ve been keeping well. I`m liking the sites new look. I`ve been Phase Linear-less for a few years now but I`m back :). I just a acquired a model 700 which looks like it was manufactured yesterday, near mint condition but it`s very sick. The...
  12. Michael F

    BGW 210 power amp

    Update It turns out this amp is a later, fully comp version virtually identical to the model 410 who`s schematic is available :) I tested all the semiconductors and resistors including the emitter resistors and everything checked out fine. Because this was done in-circuit, there were a couple...
  13. Michael F

    BGW 210 power amp

    Please keep in mind the schematic is that of a model 250. The output sections appear to be similar but things are different upstream, notably 3 pre drive TO-225 MJE transistors compared to 5 TO-5 found on the model 210. You say the MJE340 is the negative predriver, would that make the MJE350...
  14. Michael F

    BGW 210 power amp

    This amp is a rare bird. My understanding is that it`s a home version of the model 250E, no balanced input options, banana speaker terminals, lighter gauge front panel. It has a bigger sibling, a model 410 which is likely a scaled down 750B. Take a look at the screen shot of a model 250 D and E
  15. Michael F

    BGW 210 power amp

    Lee, you are likely looking at a very early model (I`d say pre `77) 250 where a crowbar circuit was used, all models used a big ass relay from that point on.
  16. Michael F

    BGW 210 power amp

    The power supply seems fine because the right channel performs properly.
  17. Michael F

    BGW 210 power amp

    Voltage at opamp comes in at 19.67. Can you tell which are the negative predrivers from the photo?
  18. Michael F

    BGW 210 power amp

    No Lee, I havent checked anything yet as I dont know where to start.
  19. Michael F

    BGW 210 power amp

    Hi Lee, The outputs are Motorola MJ15015 and MJ15016, input is LM318 opamp.
  20. Michael F

    BGW 210 power amp

    HI all, hopefully some one here can shed some light on a power amp that doesnt seem to like a load placed on it :( With no load connected to the output, it will swing 36 vac with a clean waveform but as soon as you connect a load, the protection relay kicks in. Backing down the input...
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