Realistic Graphic Equalizer Power Transformer Identification

K

K. Hastings

Guest
Our Realistic 31-2020A home stereo graphic equalizer/spectrum analyser just
stoped this week - It's clear that the power transformer is dead (primary is
open).

Can somebody look up what the blue, black, red wires on the secondary should
have for ACV, and perhaps I can substitute something I already have.

Went to RS support, and they don't list this unit, or its parts list
anymore.

Part is labelled "10162731S A KS15DSND"

Thanks in advance
 
Did you check for an open thermal fuse that is part of the transformer?
Usually that is why transformers simply go open on the primaryas the thermal
fuse has been required for fire protection for some time in consumer goods.

At a minimum if it is the thermal fuse, you can TEMPORARILY jumper it to get
the secondary voltages you need to find a suitable replacement. DO NOT
leave it in the unit with this safety feature disabled.

David

K. Hastings <myfamilydotcom@hotmail.com> wrote in message
news:jJodb.16471$Ej.2362145@ursa-nb00s0.nbnet.nb.ca...
Our Realistic 31-2020A home stereo graphic equalizer/spectrum analyser
just
stoped this week - It's clear that the power transformer is dead (primary
is
open).

Can somebody look up what the blue, black, red wires on the secondary
should
have for ACV, and perhaps I can substitute something I already have.

Went to RS support, and they don't list this unit, or its parts list
anymore.

Part is labelled "10162731S A KS15DSND"

Thanks in advance
Click to expand...
 
Good point David - I presume that this component is somewhere under the
winding cover tape?


"David" <dkuhajda@locl.net.spam> wrote in message
news:3f7660a0@news.greennet.net...
Did you check for an open thermal fuse that is part of the transformer?
Usually that is why transformers simply go open on the primaryas the
thermal
fuse has been required for fire protection for some time in consumer
goods.

At a minimum if it is the thermal fuse, you can TEMPORARILY jumper it to
get
the secondary voltages you need to find a suitable replacement. DO NOT
leave it in the unit with this safety feature disabled.

David

K. Hastings <myfamilydotcom@hotmail.com> wrote in message
news:jJodb.16471$Ej.2362145@ursa-nb00s0.nbnet.nb.ca...
Our Realistic 31-2020A home stereo graphic equalizer/spectrum analyser
just
stoped this week - It's clear that the power transformer is dead
(primary
is
open).

Can somebody look up what the blue, black, red wires on the secondary
should
have for ACV, and perhaps I can substitute something I already have.

Went to RS support, and they don't list this unit, or its parts list
anymore.

Part is labelled "10162731S A KS15DSND"

Thanks in advance
Click to expand...
 
Usually there is three pins on the primary to which the thermal cutoff is
soldered on larger transformers, on smaller ones it is simply in series with
the primary. Sometimes you can feel a bulge under the tape where it is
located. Sometimes, they put it in the inside of the windings making it
impossible to jumper for testing however.

In that case you should see the diodes for the power supply and the filter
capacitors, the filter capacitor voltage rating will get you in the close
ballpark for input voltage. I typically use a close transformer on a variac
and input to the circuit to see at what minimum value proper operation is
achieved and from experience can guess within 1 volt of correct secondary
voltage rating. I am sure it uses voltage regulators on the input of some
kind, those require a minimum input voltage to regulate and that value
allows working backwards to the ac input to find out what value is needed.

David

K. Hastings <myfamilydotcom@hotmail.com> wrote in message
news:2uEdb.16797$Ej.2431469@ursa-nb00s0.nbnet.nb.ca...
Good point David - I presume that this component is somewhere under the
winding cover tape?


"David" <dkuhajda@locl.net.spam> wrote in message
news:3f7660a0@news.greennet.net...
Did you check for an open thermal fuse that is part of the transformer?
Usually that is why transformers simply go open on the primaryas the
thermal
fuse has been required for fire protection for some time in consumer
goods.

At a minimum if it is the thermal fuse, you can TEMPORARILY jumper it to
get
the secondary voltages you need to find a suitable replacement. DO NOT
leave it in the unit with this safety feature disabled.

David

K. Hastings <myfamilydotcom@hotmail.com> wrote in message
news:jJodb.16471$Ej.2362145@ursa-nb00s0.nbnet.nb.ca...
Our Realistic 31-2020A home stereo graphic equalizer/spectrum analyser
just
stoped this week - It's clear that the power transformer is dead
(primary
is
open).

Can somebody look up what the blue, black, red wires on the secondary
should
have for ACV, and perhaps I can substitute something I already have.

Went to RS support, and they don't list this unit, or its parts list
anymore.

Part is labelled "10162731S A KS15DSND"

Thanks in advance
Click to expand...
 
OK David - If I don't hear from someone with access to the schematics, I'll
haul the transformer and attempt to find & temporarily short out the thermal
unit, if it has one. Caps on down-side are 35 VDC ones and followed by
3-pin ICs that are labelled KD 880 Y8?L that I am thinking are the
regulators. Couldn't find their listings in my semiconductor reference
guide.



"David" <dkuhajda@locl.net.spam> wrote in message
news:3f774409@news.greennet.net...
Usually there is three pins on the primary to which the thermal cutoff is
soldered on larger transformers, on smaller ones it is simply in series
with
the primary. Sometimes you can feel a bulge under the tape where it is
located. Sometimes, they put it in the inside of the windings making it
impossible to jumper for testing however.

In that case you should see the diodes for the power supply and the filter
capacitors, the filter capacitor voltage rating will get you in the close
ballpark for input voltage. I typically use a close transformer on a
variac
and input to the circuit to see at what minimum value proper operation is
achieved and from experience can guess within 1 volt of correct secondary
voltage rating. I am sure it uses voltage regulators on the input of some
kind, those require a minimum input voltage to regulate and that value
allows working backwards to the ac input to find out what value is needed.

David

K. Hastings <myfamilydotcom@hotmail.com> wrote in message
news:2uEdb.16797$Ej.2431469@ursa-nb00s0.nbnet.nb.ca...
Good point David - I presume that this component is somewhere under the
winding cover tape?


"David" <dkuhajda@locl.net.spam> wrote in message
news:3f7660a0@news.greennet.net...
Did you check for an open thermal fuse that is part of the
transformer?
Usually that is why transformers simply go open on the primaryas the
thermal
fuse has been required for fire protection for some time in consumer
goods.

At a minimum if it is the thermal fuse, you can TEMPORARILY jumper it
to
get
the secondary voltages you need to find a suitable replacement. DO
NOT
leave it in the unit with this safety feature disabled.

David

K. Hastings <myfamilydotcom@hotmail.com> wrote in message
news:jJodb.16471$Ej.2362145@ursa-nb00s0.nbnet.nb.ca...
Our Realistic 31-2020A home stereo graphic equalizer/spectrum
analyser
just
stoped this week - It's clear that the power transformer is dead
(primary
is
open).

Can somebody look up what the blue, black, red wires on the
secondary
should
have for ACV, and perhaps I can substitute something I already have.

Went to RS support, and they don't list this unit, or its parts list
anymore.

Part is labelled "10162731S A KS15DSND"

Thanks in advance
Click to expand...
 
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