Hi,I've got a 2950 with the 12z board and a bad driver final.Anybody have recommendations on what to replace it with?Go back to 2sc2166?Or replace driver and finals?Customer wants max watts(of course).
Thanks in advance.
Thanks in advance.
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2950 driver
- Thread starter flatlander89
- Start date
Yes, the 2sc2166 and 1969 are the driver and final(s) respectively. If your customer wants max output; that is probably what caused them to fail in the first place. Set them to stock specs, or they may fail again! That radio is rated @ 35w output - IIRC.
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Thanks for the input.I replaced the driver and finals with the original mitsu transistors from rf parts.Driver bias is within specs but bias for the finals is WAY off.I've checked bias diodes,caps that were low and resistors.Still pegging my meter out at 250mA.Any idea what I missed?
I wasn't aware of final bias adjustment pots on a 2950.I couldnt find em.Which ones are they?Sorry
You are right; was thinking of a DX model. Then it would have been VR 11 & 12. You can still check the bias current at the bias board and see if it too high on the finals. Should be around ~100 - 120mA.
Right on it Robb.Thanks a million by the way!The ammeter I was using turns out to be reading way too high.Now I've got 50 ma at the driver and around 95 at the finals.Might replace some caps an go from there.
That sounds about right; so long as it is close to 100mA; it should be fine for two finals. The mA of the driver is also correct. You will need to hunt for a different cause of failure before it happens again to the new finals.
Be sure to use some thermal paste. Make sure the heat sink on the back of the finals is flat against the case; sometimes they aren't. Doesn't hurt to put some compound between the heat sink and the case too.
Maybe he just drove the radio too hard.
Tell him it will cost him again if he keeps it up.
Be sure to use some thermal paste. Make sure the heat sink on the back of the finals is flat against the case; sometimes they aren't. Doesn't hurt to put some compound between the heat sink and the case too.
Maybe he just drove the radio too hard.
Tell him it will cost him again if he keeps it up.
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