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Luxman L3 38VDC On Speaker Output?
Luxman L3 38VDC On Speaker Output?
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Old 24th September 2016, 08:22 PM   #21
Mooly is offline Mooly  United Kingdom
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Luxman L3 38VDC On Speaker Output?
Quote:
Originally Posted by klh2000 View Post
The 9 volts is base positive on a PNP transistor.

I have used all modern equivalent parts.
That's reverse biased then if the base is 9 volts positive with respect to the emitter.
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Old 24th September 2016, 09:24 PM   #22
klh2000 is offline klh2000  United States
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Quote:
Originally Posted by Mooly View Post
That's reverse biased then if the base is 9 volts positive with respect to the emitter.
So could that mean that the transistor is bad? It is brand new.
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Old 25th September 2016, 07:49 AM   #23
Welcome is offline Welcome  France
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Where did you buy it? What transistors did you use?
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Old 25th September 2016, 03:05 PM   #24
Mooly is offline Mooly  United Kingdom
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Luxman L3 38VDC On Speaker Output?
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)
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Old 25th September 2016, 03:06 PM   #25
klh2000 is offline klh2000  United States
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Quote:
Originally Posted by Welcome View Post
Where did you buy it? What transistors did you use?

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.
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Old 26th September 2016, 09:50 AM   #26
east electronics is offline east electronics  Greece
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Quote:
Originally Posted by klh2000 View Post
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 .....
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Old 26th September 2016, 04:46 PM   #27
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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.
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Last edited by Welcome; 26th September 2016 at 04:50 PM.
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Old 26th September 2016, 05:31 PM   #28
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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.
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Old 26th September 2016, 09:53 PM   #29
east electronics is offline east electronics  Greece
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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 ....
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Old 27th September 2016, 02:55 AM   #30
klh2000 is offline klh2000  United States
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Quote:
Originally Posted by Mooly View Post
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)
I am away this week, but I will let you know as soon as possible.
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