In article gTN4b.20519$Go4.19208@lakeread01 writes:

My Behringer T-1953, Microphone Pre-Amp suddenly stopped working. I
replaced the ceramic fuse with an equivalent clear fuse (1 Amp, 250V like
the specs required), but the unit still does not work.

Do I definitely need a ceramic fuse or will the clear ones work?

Many ceramic fuses are slow-blowing, which take a higher than rated
current for a short period of time. You need to determine the type of
fuse and replace it with a similar one. It may indicate the type of
fuse on the panel near the fuseholder, or in the manual.

But is the problem really that the fuse has blown? Occasionally a fuse
will blow from natural causes, but most of the time if it blows once,
a replacement will blow also. Fuses are meant to protect the wires
that go to them so that they don't overheat when something goes wrong
that makes the device draw excess current. If the fuse blows, it's
drawing too much current and will continue to do so (and not work
right) untill you fix what's wrong.



--
I'm really Mike Rivers - )

Thanks, this is *very* helpful. The actual fuse is T 1A H, which is
explained below. I'll run the continuity check on the ceramic fuse. I did
not observe any damage visually, but will check with the multimeter.

The suggestion about the internal transformer is a good one. The unit just
quit and was not overloaded at the time. I'll check that and let you know.

Thanks.

john



"Pooh Bear" wrote in message
...

Mike Rivers wrote:

In article gTN4b.20519$Go4.19208@lakeread01 writes:

My Behringer T-1953, Microphone Pre-Amp suddenly stopped working. I
replaced the ceramic fuse with an equivalent clear fuse (1 Amp, 250V
like
the specs required), but the unit still does not work.

Hmmm - you don't say if the original fuse was actually blown !

If you have a multimeter, check the original fuse. If it conducts - then
that
wasn't the fault.
If it *was* blown and it blew the replacement too - see analysis below.

Do I definitely need a ceramic fuse or will the clear ones work?

Many ceramic fuses are slow-blowing, which take a higher than rated
current for a short period of time. You need to determine the type of
fuse and replace it with a similar one. It may indicate the type of
fuse on the panel near the fuseholder, or in the manual.

Errr - actually it ain't that simple. Fuses to the IEC spec, which will
certainly be used by Behringer ( being European ) have specific marking
regarding their fusing characteristics.

An example fuse marking goes typically like this F 1A L. Look on the metal
cap
on the end of the fuse. It'll also say 250V too.

F denotes the fusing speed F= fast T=time delay ( slo-blo in US speak )
FF (
rare ) = ultra fast, sometimes used to protect sensitive semiconductor
devices.
In theory there's an M ( medium ) although I've never seen one.

1A = 1 Amp ( or whatever current the number says ) - the design current.
IEC
and US fuses rate the carrying current differently - that's why we say -
"replace with same type and rating" !

L = Low breaking current - invariably a glass fuse. H = high breaking
current (
often ceramic but may also be glass with sand fill ). A ceramic body will
almost never fracture under a fault condition- whereas glass types may do.
The
breaking current rating indicated on the fuse cap is only a recent
addition to
the spec. The required breaking rating is something that needs to be
determined
by the designer of the product - see above -" replace.......


But is the problem really that the fuse has blown? Occasionally a fuse
will blow from natural causes, but most of the time if it blows once,
a replacement will blow also. Fuses are meant to protect the wires
that go to them so that they don't overheat when something goes wrong
that makes the device draw excess current. If the fuse blows, it's
drawing too much current and will continue to do so (and not work
right) untill you fix what's wrong.

Yes indeed. Don't know the product as such - but if the fuse has blown,
most
likely sounds like the power transformer has failed shorted. 2nd guess-
rectifier(s) after the transformer have gone short circuit.

Oh - if the fuse hasn't failed - the transformer may have failed open
circuit.
Did it run hot ? Many small transformers have internal thermal fuses that
don't
reset. You can also check this with a multimeter to see if there is
circuit
continuity between the live and neutral on the a.c. input. Expect a 'good'
transformer to have a primary ( input ) DC resistance of ohms to a few
tens of
ohms. If it's kilohms or more it's 'dead'.


Graham