I recently got an MP-1 (rev B, 1.38 eprom) which is not working from a friend who pointed me in this direction for help.
The screen flashes on for about a second when I power on. LED's cycle on as well, but completely dissappear after about a second.
Wall voltage: 118v
1. C131 reads 11.9 volts with tubes in, with tubes out 13.2v.
2. Pins 11, 17, 24 and 25 of u29 reads 5.1v with tubes in or out.
3. Pin 16 of u29 reads 3.2v with tubes in or out.
4. Pin 6 of u29 reads 0.65v with tubes in or out
5. Pin 27 and 28 of the u30 reads 5.1v with or without tubes
6. VR4 reads 5.1v
I'm not sure how to test for pulses on pin 16 of u29. Its voltage is consistent with or without tubes.
I swapped out D38 and 39 with new ones.
Swapped out c136 for a new .047 cap.
No changes...
I'm starting to think it could possibly be the crystal? I have a new one on order(hope it's the right one, 12MHz). Should be here in a few days.
I'm wondering if these readings stand out as anything obvious? I don't own an oscilloscope.. but if need be, I could pick one up.
Thank you in advance for any help on this.