Have you tested the fuse?

Yes.  Even changed the fuse for what that's worth.

Adjusting the forward/reverse LDR sensor sensitivity (for 620 mV) wouldn't zap the microprocessor.  It is more likely that a cable/wire came loose or some other board trace cracked.  Those LDR adjustment screws can be a pain. When a Beogram 800x project gets to this type of situation it is best to focus on the power supplies again. Verify that you have the supply voltages from the transformer to the PCB 1 destinations.  Check the voltages on the three largest PCB 1 capacitors for the respective pre-regulator voltages (+24 VDC, -24 VDC and +13 VDC ... or close to those). From there, assuming those voltages are good, check the output of the +5 VDC regulator and the +15 VDC regulator. If you have +5 VDC on PCB 1 then  it is a good guess that it is not making it to PCB 2 (where the microcomputer IC is). The twenty pin ribbon connector between PCB 1 and PCB 2 can often be a problem.  Especially if the pins in the PCB press-to-fit connector do not mate well. I happen to be finishing up a Beogram 8002 restoration now.  You can take a look here.  The posts are in reverse order (most recent first).  The power check post is here. That Beogram 8002 had a few of its own moments when connector pin issues were preventing proper operation after the electrical restoration work.  That is typical of a Beogram 800x turntable though. I would expect your Beogram 8002 to be okay...once you find the failed connection. -sonavor

Fantastic help!!  I'll also see about removing the keyboard and checking the traces. I haven't tried to remove the keyboard for fear of breaking something.

Be careful with the keypad.  I run into a lot of those where people have broken off the plastic tabs that hold the front plate with the keys tight against the keypad board. The keypad boards haven't been a problem area very often either. The LDR devices can sometimes fail and the lamp can burn out but they aren't usually a problem. Check the press-to-fit, small ribbon connector that goes from the keypad assembly to PCB 1. That is another problem area like the press-to-fit connector for PCB 1 to PCB 2. ...But start with tracing the Beogram 8002 power supply voltages first.

With your help I have made some progress.  I had power to the main capacitors but intermittent 5V to the PCB23 cap.  Someone had already done a recap but this capacitor was loose,  After replacement the unit fired up!... However, functions are not normal.  It does not recognize a record edge and thus travels all the way to the end and gets stuck. Manually backing the tonearm with the worm drive will release it and allows for <>, play and  stop functions but I cannot get a voltage at pin 4 or 6 of P5 at all. Seems encouraging at least. Probably stupid question... the short shielded black cable extending from PCB2 to a pin next R12 on PCB1 was broken.  The shield and internal wire derive separately from PCB2 but where would the shield go?  I attached only the internal wire... just don't know. Thank you for your help! John M

Obvious typo above: PCB2 not PCB23. Finally able to set close to 620 mV for <>.  Beyond that, live to fight another day.

Just the center wire of the shielded wire from PCB 2 connects to the single, terminal post on PCB 1. Your other problem with the position detection not working sounds like either the position sensors are not working or not reaching the microcomputer board on PCB 2. This post has some oscilloscope photos I captured of those signals for reference. Occasionally a sensor device fails but I always suspect the wire connections first on these turntables.

Just a quick update on the 8002 progress.  Your information was quite valuable.  To make a long  story short, I have seemingly appropriate voltage at all the checkpoints (R64 trimmer now maxed out) but still lack of complete function.  It appears to me (and that is a big "appears" that the problem is related to at least one (at the worm drive) and maybe a second (at the arm) photosensor.  Now waiting for parts. Thank you for your help! JM