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ARCHIVED FORUM -- April 2007 to March 2012
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This is the first Archived Forum which was active between 17th April 2007 and 1st March February 2012

 

Latest post 10-21-2008 8:42 PM by Phil Hunt. 0 replies.
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  • 10-21-2008 8:42 PM

    4002: no 45spd after recapping/lamp replacement

    "A week has passed-I just got a DIN adapter and several bulbs to try as the "33" bulb is burned out. Properly connected to my system both cartridges play fine-excellent!  And  after a little lubing, the arm sevo system is much quieter. All functions seem good. However, if I try putting any new bulb across the 33 circuit, the machine shifts to 45 and lights that/good bulb. And if I try to put the new/test bulb in parallel w/45 bulb  (a good way to see if they are of matched intensity/wattage I'd think), the machine shifts down to 33 again, energizing the dead 33 lamp circuit w/22.3v. This is of course exactly what Mehahem described and repaired in his "4002 problems/solutions" at the top of this forum. So now I have what seems to be a well functioning, quite presentable 4002 with a great and a not so great cartridge (4000 missing guard, and mmc20CL new or near new) that doesn't illuminate the 33 lamp and will not until several components are replaced...and while it's apart I should replace "all electrolytic and tanatalum capacitors as follows..." because-well just because"

    Martin was a prince and supplied a cap-kit in exchange for pis of the US board. All supplied caps replaced, and both speed indicator bulbs were replaced with 75ohm bulbs, the closest to the one good 61ohm bulb I had. So now, 45 only works as long as you hold down the key. D6, C4&5 are OK (Yachadm replaced them as part of his fix). Prior to recapping, loading the empty 33 lamp circuit would flip the TT to 45; that problem is now gone and 33 illuminates. In the svc manual (diagnostic tree): 8-2: #6 45rpm function: does neg integrator appear accross 1C3?     voltage stays @.3v even when pressing 45.

    Does negative pulse appear @1TR2?:   .77v run/.01press 45.

    Does pulse train appear @C of 1TR23?:   +.14VDC always/no AC

    Checking TR3 & 4, R6&7: TR3 is closed w/.76v @base; when 45 is pressed TR3 base goes 0, but TR4 base stays @.01v/doesn't turn on and flip. I'm not great at this. What am I missing?

    On another note-I'm not digging this TT like I do the 8002-not my cup of tea. Once I get it working right, I'd love it to find a good home.

     

     

     

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