Post by mb9513 on Aug 9, 2018 20:13:34 GMT
Hi all. am working on a 426 with a 40218 amp this is the 1st generation of the solid state amps. as it had lost one channel I noticed that the 2 auto bulbs that protect the output transistors for that channel were burned out. when I briefly plugged it in with replacement bulbs. they lit up brightly. so I replaced the output transistors on that channel assuming they were shorted.
with another set of transistors bulbs did not glow. so I thought good to go. well, I thought I heard sound out of the bad channel but after working all the other sound related problems with rock ola's, volume pot, sound distribution controls, etc. I came back around to no sound again. the replacement bubs were burned out again. I have replaced them once again and do not get light from them when plugging in. so I hope they did there job to protect the output transistors. but now I am not sure where to proceed. my service manual does not have the amp schematic. the closest one I found on line is for a 40276 amp that is supposed to be for this juke. it is not a good copy so I cannot read any voltages. Oh and I did adjust the bias voltage when I swapped the outputs. thanks Mark
