Matrixambience said:
Anybody know here how easy it is to fix this? Is it for sure that pilot signal stength pot (19 khz). I love this boombox, and everything else works super on it. Anyone here have any ideas or want to fix it for me? Jeff
Jeff. Nobody can tell you
FOR SURE that it's one thing or another. But certain symptoms suggest certain failures and in your case, if your stereo capture is intermittent (sometimes it captures, sometimes it doesn't), then it's most likely the pilot signal adjustment, which adjusts the pilot signal frequency, not strength. You are adjusting for 19khz and normally done most accurately with a frequency counter. The simplified but less accurate method is to center R31 (on the M70) so that the stereo light illuminates at the 1/2 way point between the range of the pot where it lights. If you can never get the stereo led to light, then it could be the decoder itself has failed and the mpx decoder then will need replacement or diagnosis to determine if an adjacent component has failed.
Best thing is if you just attempt to adjust variable pot R31 yourself. That way you can save shipping costs back/forth. You have nothing to lose since it's not working right anyway. Just DO NOT ADJUST any of the other controls -- only pot R31. If you adjust the other trimpots, variable caps, transformer coils, etc.... you could throw the alignment off making it impossible to ever get it back, or require very expensive realignment service.
I am confident that I can fix this for you, if you like, but you'll not like the cost back/forth/repair. So if you can't fix it yourself, the brutal honest truth is that it's probably best for you $$ wise if you sell yours as-is, properly described, then use the proceeds to purchase another fully working one (from a trusted source, of course).
In the meantime, you should try the adjustment I prescribed above. You might be pleasantly surprised.
