Hallo JVC dude,

The failure is a strange background of a sort of "white noise" on one
channel only after, say, 30 sec. after power on. The sound is OK apart
from this noise.

Originally there was a faulty protective IC SVITA7317P which I
replaced.
I wonder if we are looking at the same schematics because I can't find
the references you mentioned for the transistor.

Is there a way to test the driver stages, after removing the final
power IC, so I can investigate the circuit? What should I put as a
load on pins 14 and 16?

Any other suggestions?

Thanks a lot for you help.


"JVC dude" wrote in message ...
Hi The manual won't give you any better help ~I'm afraid
the problems on this model usually are around the AN7062 and
Q501/2/3/4. its not often the main SVI fails (luckily)
the transistors above run very hot and will go leaky, there are also a
couple of 47 or 220 ohm resistors nearby which also burn out
What info do you have about the fault?
AW

Hi I was presuming the model I know as the SUV4X, a uk version , would
be the same. Perhaps it isn't.
Perhaps the refs are Q601/2/3/4 I haven't looked into my circuit yet.
As for the fault, a crackle/hiss is usually a noisy tr or IC. some can be
eliminated by swapping channel.
I wouldn't normally run it without the power IC, the 'computer drive' may
not operate correctly
AW

"er" wrote in message
om...
Hallo JVC dude,

The failure is a strange background of a sort of "white noise" on one
channel only after, say, 30 sec. after power on. The sound is OK apart
from this noise.

Originally there was a faulty protective IC SVITA7317P which I
replaced.
I wonder if we are looking at the same schematics because I can't find
the references you mentioned for the transistor.

Is there a way to test the driver stages, after removing the final
power IC, so I can investigate the circuit? What should I put as a
load on pins 14 and 16?

Any other suggestions?

Thanks a lot for you help.


"JVC dude" wrote in message
...
Hi The manual won't give you any better help ~I'm afraid
the problems on this model usually are around the AN7062 and
Q501/2/3/4. its not often the main SVI fails (luckily)
the transistors above run very hot and will go leaky, there are also a
couple of 47 or 220 ohm resistors nearby which also burn out
What info do you have about the fault?
AW

Hallo AW,

1) In my schematic diagram all the driver Qs are numbered as Q3xx for
both channels. Anyway, I think you are referring to the transistors on
the differential stages. Is that right?
The input stage is made with a differential amplifier realized with a
dual JFET
on one package ( 2SK109).

2) How can I realize in details this channel swapping you mentioned?
Can you explain?

3) In fact you are right. All the input circuitry is not working
properly without the final stage, so it is almost impossible to check
the circuit. Do you think what is needed are the transistors on the
input stage of the power IC to create the correct bias voltages ( and
currents)?

Thanks for your time.

Ciao

"JVC dude" wrote in message ...
Hi I was presuming the model I know as the SUV4X, a uk version , would
be the same. Perhaps it isn't.
Perhaps the refs are Q601/2/3/4 I haven't looked into my circuit yet.
As for the fault, a crackle/hiss is usually a noisy tr or IC. some can be
eliminated by swapping channel.
I wouldn't normally run it without the power IC, the 'computer drive' may
not operate correctly
AW

"er" wrote in message
om...
Hallo JVC dude,

The failure is a strange background of a sort of "white noise" on one
channel only after, say, 30 sec. after power on. The sound is OK apart
from this noise.

Originally there was a faulty protective IC SVITA7317P which I
replaced.
I wonder if we are looking at the same schematics because I can't find
the references you mentioned for the transistor.

Is there a way to test the driver stages, after removing the final
power IC, so I can investigate the circuit? What should I put as a
load on pins 14 and 16?

Any other suggestions?

Thanks a lot for you help.