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Soundlab G097F advice please.

My neighbour has a Soudlab G097F amplifier that no longer functions.

The symptoms are that everything seems to power up ok but the "protect"
indicator lamp remains lit resulting in no output, whereas normaly it
would only light up for a couple of seconds at power on before hearing a
click and extinguishing, then fuction as normal.

Could anyone suggest where I might start fault finding?

Thanks.
 
A

Arfa Daily

Jan 1, 1970
0
My neighbour has a Soudlab G097F amplifier that no longer functions.

The symptoms are that everything seems to power up ok but the "protect"
indicator lamp remains lit resulting in no output, whereas normaly it
would only light up for a couple of seconds at power on before hearing a
click and extinguishing, then fuction as normal.

Could anyone suggest where I might start fault finding?

Thanks.

First two places to look are for an external short across the output - ie a
faulty speaker or wiring whisker, or someone having driven a nail through
the speaker wire, and then look inside for an open fuse. If either supply
rail is missing, it will stay in protect. However, any sign of a fuse being
blown violently - blackened glass or metal beads - would indicate more
serious trouble in the output stages. No signs of distress at all, could
indicate a problem with the fault detect / relay drive circuit itself, or
even possibly something as simple as a bad joint. What is your level of
experience at working on this type of equipment, and what test equipment do
you have ?

Arfa
 
Arfa Daily said...
First two places to look are for an external short across the output - ie a
faulty speaker or wiring whisker, or someone having driven a nail through
the speaker wire, and then look inside for an open fuse. If either supply
rail is missing, it will stay in protect. However, any sign of a fuse being
blown violently - blackened glass or metal beads - would indicate more
serious trouble in the output stages. No signs of distress at all, could
indicate a problem with the fault detect / relay drive circuit itself, or
even possibly something as simple as a bad joint. What is your level of
experience at working on this type of equipment, and what test equipment do
you have ?

Arfa

Thanks for your reply Arfa.

I am an electrician by trade, but I have a basic knowledge of
electronics although I only have a half decent multi-meter to hand.

The fault persists with the speakers disconnected which themselves show
no evidence of shorting,both the two glass fuses on the circuit board
are fine and ther is no visual signs of overheating that I can see.

The cooling fan comes on immediately at power on, but my neighbour
insists this has been so since purchase.

One thing I have found, is the sensor on the heat-sink is closed circuit
in the amp's present state (cold) - should this be the case?

(Sensor at bottom left corner of image 5 at
http://picasaweb.google.co.uk/fayd2gray/G097F)
 
A

Arfa Daily

Jan 1, 1970
0
NOTE: disconnected from board when tested.

I would say that the thermoswitch reading closed, is correct. There are both
open and closed types, but closed types in this application are by far the
most common. I have looked at the images, and C210 leapt out at me (
heatsink away from you, left side of board, just in front of centre
connector ). This cap looked as if it had a domed top. I have looked at this
from all the angles that I can, with the photos zoomed up, and it definitely
looks as though it is. If it is domed, then that would be the very next
thing that I would try with a replacement. I don't know how much actual
electronics knowledge that you have, but faulty electrolytic caps are very
very common, and a domed top is usually a red-flag giveaway. If it is, and
you decide to have a go and replace it, note that these caps are polarised,
so must be fitted the correct way round ( sorry if I'm treating you too dumb
here ). The board may be marked with a "+" symbol, but more likely from what
I can see, a bar at the "-" terminal. This corresponds to a stripe, usually
marked "-" on the cap body itself.

Arfa
 
A

Arfa Daily

Jan 1, 1970
0
Arfa Daily said:
I would say that the thermoswitch reading closed, is correct. There are
both open and closed types, but closed types in this application are by
far the most common. I have looked at the images, and C210 leapt out at me
( heatsink away from you, left side of board, just in front of centre
connector ). This cap looked as if it had a domed top. I have looked at
this from all the angles that I can, with the photos zoomed up, and it
definitely looks as though it is. If it is domed, then that would be the
very next thing that I would try with a replacement. I don't know how much
actual electronics knowledge that you have, but faulty electrolytic caps
are very very common, and a domed top is usually a red-flag giveaway. If
it is, and you decide to have a go and replace it, note that these caps
are polarised, so must be fitted the correct way round ( sorry if I'm
treating you too dumb here ). The board may be marked with a "+" symbol,
but more likely from what I can see, a bar at the "-" terminal. This
corresponds to a stripe, usually marked "-" on the cap body itself.

Arfa
Where yoo gon?

Did you get any success with it ?

Arfa
 
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