110-50 RD AMP 1N4751A Zenier Diode keeps failing

MidCenturyAudio

Iv'e gone through 2 1N4751A diodes (D9) on the 1650-rd schematic). The amp will play and sound great for about 3 hours and then nothing. Is there a better replacement for this or should I look for a problem somewhere else?

Full Name
Lars Verholt
Music Man Equipment
HD-130 head, 210X cab, 210RH cab, RD-50 110 combo, Sixty-Five 112 combo, RP65-112

Member for

11 years 2 months

lmv Fri, 10/23/2015 - 19:35

I'd say - considering the 1N4751A has lasted over 30 years (as opposed to 3 hours) in so many amps, look for the problem elsewhere. Check the components surrounding the zener. Does zener survive with no tubes in the amp?

Cheers,
Lars Verholt