That's reverse biased then if the base is 9 volts positive with respect to the emitter.
Not necessarily. It could be a fault elsewhere causing a reverse bias situation for that device.
Is the voltage OK on that zener diode. I don't recognise the number but you are going to need at least 12 volts or more there. Compare the voltage across the zener with the good channel as that is an unknown quantity at the moment.
If that is OK then it would help tremendously if you could list all the devices and their voltages. It would probably all make more sense then.
Make a list:
(All voltages measured from chassis ground)
Q401a
E =
B =
c =
Q402a
E =
B =
C =
Q403a
E =
B =
C =
Q404a
E =
B =
C =
Q405a
E =
B =
C =
Q406a
E =
B =
C =
Q407a
E =
B =
C =
Q408a
E =
B =
C =
Voltage on the zener =
(give reading for both good and bad channel for the zener)
Is the voltage OK on that zener diode. I don't recognise the number but you are going to need at least 12 volts or more there. Compare the voltage across the zener with the good channel as that is an unknown quantity at the moment.
If that is OK then it would help tremendously if you could list all the devices and their voltages. It would probably all make more sense then.
Make a list:
(All voltages measured from chassis ground)
Q401a
E =
B =
c =
Q402a
E =
B =
C =
Q403a
E =
B =
C =
Q404a
E =
B =
C =
Q405a
E =
B =
C =
Q406a
E =
B =
C =
Q407a
E =
B =
C =
Q408a
E =
B =
C =
Voltage on the zener =
(give reading for both good and bad channel for the zener)
The transistors are NTE equivalent transistors, I got them from a local electronics supply. I know NTE parts aren't that good, but it was all I could get.
thanks my man ....you ve made my day .... i almost fell of my chair and drop my coffee from LOL .....
NTE parts are worse than fakes, since you pay more and still get the same junk.
You'll need to get new transistors, preferably from Fairchild. FJA4210 and FJA4310 should be perfect as outputs. Get them from Mouser or Digikey. Most local shops only sell fakes (or NTE stuff), which won't do you any good.
You'll need to get new transistors, preferably from Fairchild. FJA4210 and FJA4310 should be perfect as outputs. Get them from Mouser or Digikey. Most local shops only sell fakes (or NTE stuff), which won't do you any good.
Last edited:
For driver transistors, use KSA1013 and KSC2383, also Fairchild parts.
And don't forget: FJA4210 and FJA4310 for output transistors.
These are all drop in replacements. Should cost you about $6 total for a full set (both channels), you (ironically) don't get NTE parts for those kinds of low prices.
And don't forget: FJA4210 and FJA4310 for output transistors.
These are all drop in replacements. Should cost you about $6 total for a full set (both channels), you (ironically) don't get NTE parts for those kinds of low prices.
Welcome really now what makes you think that these are drop in replacements ?
they seem to share a few things but no way these are drop in something will be required on the bias scheme and or compensation ...Highlighted in red
2SC2235 KSA1013
120V 160v
5V 6V
800ma 1A
900mw 900mw
120Mhz 50Mhz
30pf 35pf
2SD716 FJA4210
100V 200V
6A 10A
55-160hfe 50-180
5V 6V
10Mhz 30Mhz
150pf 400pf
No way drop in ....
they seem to share a few things but no way these are drop in something will be required on the bias scheme and or compensation ...Highlighted in red
2SC2235 KSA1013
120V 160v
5V 6V
800ma 1A
900mw 900mw
120Mhz 50Mhz
30pf 35pf
2SD716 FJA4210
100V 200V
6A 10A
55-160hfe 50-180
5V 6V
10Mhz 30Mhz
150pf 400pf
No way drop in ....
This looks promising
1/ Check that R405 feeding the zener is OK. It will be hot if its OK but check it.
2/ Diode D401 could be open circuit. You should have almost the same voltage on each end.
3/ The zener could be faulty. It looks to be a 19 volt device which is an odd value but its not very critical. An 18 or 20 volt part should be fine.
1/ Check that R405 feeding the zener is OK. It will be hot if its OK but check it.
2/ Diode D401 could be open circuit. You should have almost the same voltage on each end.
3/ The zener could be faulty. It looks to be a 19 volt device which is an odd value but its not very critical. An 18 or 20 volt part should be fine.
Thank You!
I removed R406, and it read about 3 M, so it failed open. I replaced it, adjusted the idle current and dc offset, it is working fine now. Thank you so much
This looks promising
1/ Check that R405 feeding the zener is OK. It will be hot if its OK but check it.
2/ Diode D401 could be open circuit. You should have almost the same voltage on each end.
3/ The zener could be faulty. It looks to be a 19 volt device which is an odd value but its not very critical. An 18 or 20 volt part should be fine.
I removed R406, and it read about 3 M, so it failed open. I replaced it, adjusted the idle current and dc offset, it is working fine now. Thank you so much
an old fashioned fault.Hello everyone !
I'm having some problems with a luxman l3 amplifier. The right channel started to "crack" strongly. I've bought all the electric capacitors and replaced only the ones from that channel. Now it's not cracking anymore but i get 90v on that channel. What should i check first ? I already checked capacitors polarity and soldering.
Thank you!
I'm having some problems with a luxman l3 amplifier. The right channel started to "crack" strongly. I've bought all the electric capacitors and replaced only the ones from that channel. Now it's not cracking anymore but i get 90v on that channel. What should i check first ? I already checked capacitors polarity and soldering.
Thank you!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.