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Hello all, I have a quick question regarding a Rowe R-3812a jukebox amplifier. One of the main output transistors is shot and I would like to replace them all (4 total). The problem is, I have searched online for replacement parts but I think these 4 outputs have an in house number on them, so no such luck. The numbers are as follows: 6819,6813,6814,6928. I know this is a push-pull setup so each is a compliment of the other, with respect to each side. Also, finding a schematic for this old dog is impossible. Does anyone have any insight on this?
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Those look like date codes. 6819 means the part was made in the 19th week of 1968, the next two in the 13th and 14th weeks, and then one that was maybe replaced at some time, 6928 from the 28th week of 1969.
WHat is the model of the jukebox? I have some old Rowe stuff. Did you contact Rowe? They could have archived materials, but i don't know that. Call them on the phone, it is harder to ignore than email.
is this stereo, with two transistors per channel, or is it mono with four? Or is this one channel from a stereo amp and the channel uses four? If this is late 1960s or 1970, I'd expect stereo, but never assume.
Push pull setups can be complimentary or quasi-complimentary. In complimentary we'd see an NPN and a PNP paired. IN Quasi, both would be NPN.
If you have three good ones left, check each with a diode test meter and see if all have the same polarity or if some are NPN and some PNP. If the three are the same - and likely NPN - then the amp is quasi.
In any case, most any power transistor will work. WHat voltage is the system? Either measure it or assume the main filter cap voltage. Maybe overkill, but good old MJ15024 and MJ15025 would probably work there.Education is what you're left with after you have forgotten what you have learned. -
1969 Rowe/AMI MM2 is the make and model of the jukebox. I will need to check the exact setup of the transistors. I have a load of the old standby 2n3055's with compliments sitting around. Would those work Enzo? Thanks!Comment
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well, sounds like the replacements are: 2n6284x2,2n6287x2. the amp is stereo. i will try these and let you know.thanks for your help!Comment
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