Cambridge amp A5, blown transformer
 

After 2 years of fine operation my cambridge A5 amplifier suddenly
stopped working two days ago. Having an understanding of electrics I
tested the transformer and discovered that there is no continuity in
the primary winding. Since it was quite cheap originally it seems not
worth spending a lot of money on it, meaning I could stick an other
transformer in it if it is cheap and if it is likely to be the only
thing wrong with it. Since the primary winding is burnt out it seems
likely that no other components are damaged. Am I right with that
presumption? There is no specifications written on the transformer.
Does anyone know which kind I need and where to get it? Every
suggestions are welcome.

Cambridge amp A5, blown transformer
 

"short_and_ugly" wrote in message
ups.com...
After 2 years of fine operation my cambridge A5 amplifier suddenly
stopped working two days ago. Having an understanding of electrics I
tested the transformer and discovered that there is no continuity in
the primary winding. Since it was quite cheap originally it seems not
worth spending a lot of money on it, meaning I could stick an other
transformer in it if it is cheap and if it is likely to be the only
thing wrong with it. Since the primary winding is burnt out it seems
likely that no other components are damaged. Am I right with that
presumption? There is no specifications written on the transformer.
Does anyone know which kind I need and where to get it? Every
suggestions are welcome.


It's quite common on all makes of amp for the tx primary to go open, but
it's not the winding that burns out usually. There is very often a thermal
fuse link buried in the windings at the time the tx is made, and these often
go open for no apparent reason. Occasionally, depending on the way that the
tx is constructed, these fuses can be withdrawn, and replaced, but more
often than not, a failed fuse junks the tx. Have a careful look, and see if
you can see a pair of insulated wires disappearing into the windings, with
one of the wires connected to one of the primary terminals. If you can, try
reading across them on ohms. Chances are you will get an open. You can of
course bridge this fuse, but it is a designated safety component, and if you
do, on your own head be it ...

Arfa

Cambridge amp A5, blown transformer
 

In article ,
Arfa Daily wrote:
You can of course bridge this fuse, but it is a designated safety
component, and if you do, on your own head be it ...

You can buy replacement thermal fuses. Maplin, etc.

--
*Why is "abbreviated" such a long word?

Dave Plowman London SW
To e-mail, change noise into sound.

Cambridge amp A5, blown transformer
 

"Dave Plowman (News)" wrote in message
...
In article ,
Arfa Daily wrote:
You can of course bridge this fuse, but it is a designated safety
component, and if you do, on your own head be it ...

You can buy replacement thermal fuses. Maplin, etc.

--
*Why is "abbreviated" such a long word?

Dave Plowman London SW
To e-mail, change noise into sound.

Yes indeed, you can get replacement thermal fuses,but as I said in my reply,
in most cases, it's not possible to remove the original from where it's
buried in the windings. There's no point in trying to fit a replacement
elsewhere on the transformer, as it just won't ever get hot enough to fail
under fault conditions until the tx catches fire !

So, as a " home use only " bodge, if you really want the thing working
again, and are prepared to rush at it with a fire extinguisher if things go
wrong, the original can be shorted either by bridging the tags it's
connected to, if that's the type of tx construction, or cutting back some of
the insulation on the device's legs as they disappear into the windings, and
carefully soldering a wire bridge across, if it's not a tagged type.

I have seen amps in for repair where a previous shop has soldered a wire
ended fuse across an open thermal fuse. I guess that this is better than
just a short, but is by no stretch of the imagination, a valid substitute
for a designated safety component thermal fuse, and I certainly would not
let any such ' repair ' out of my shop and back into a customer's house.

Arfa