Hmm... yes they are a bit on the bright side. And it will run hot, that's normal. 50 mv across 0.22 ohm is 220ma. That is current per transistor, and each transistor sees 50 volts across it giving 11 watts dissipation. Eight transistors per channel, 88 watts quiescent dissipation per channel. Hot !
Should I be concerned about the output transistors failing? I understand they're designed to run hot, but they're over 35 years old. 🙂 I know others have installed new output transistors in these amps. Would that be a waste of money? I also wonder if it would change the sound of the amp...
I don't think there is any reason for concern and you wouldn't alter the sound either by changing them. I wouldn't just change them for the sake of it.
On the kardon 16 question... little mishap... I had replaced power caps on hk 16 and working beautifully, until i shorted one of the top transistors to the chasis when putting it back together. smoke and hum now from right channel. Any idea what damage I did and what to test for/ start changing out?? Basics first please.
If I pull transistors what should they read?
Thanks, and I DO understand that working cold on the amp was what I should have done, no power, caps powered out etc. 🙂 and 🙁
If I pull transistors what should they read?
Thanks, and I DO understand that working cold on the amp was what I should have done, no power, caps powered out etc. 🙂 and 🙁
Sorry to hear about the mishap... easily done but hugely annoying.
Basics... you need to be able to at least test semiconductors although usually any failed devices will read almost short circuit.
What transistor did you short and what components are obviously damaged/smoking.
Basics... you need to be able to at least test semiconductors although usually any failed devices will read almost short circuit.
What transistor did you short and what components are obviously damaged/smoking.
Thanks for the reply Mooly. I damaged the one transistor alone, thankfully. I pulled and tested them all then stole one from the other channel, defused the other channel, and fired it up and it tested fine. Found a replacement(s) on the bay (my original was a RCA 0404a) and replaced with spec part RCA 1B04 (and bought a few extras for future, RCA 1B04, RCA 1B05-is alternate spec part number in tech manual)
Re-tested both channels and works very well. If that trans can't be found the MJ15024 seems to be the go to replacement with good results from what i have read. cheers and enjoy the music!
Re-tested both channels and works very well. If that trans can't be found the MJ15024 seems to be the go to replacement with good results from what i have read. cheers and enjoy the music!
hello, the problem is always the potentiometers vr1 and vr2
is necessary to change
the pots are carbon...over time and temperature lose their value
i have two amp harman kardon 16 and 16a
is necessary to change
the pots are carbon...over time and temperature lose their value
i have two amp harman kardon 16 and 16a