[Heathkit] HX-10 Maurader

[Constantine Thomas]

Hi, there is a better way to check a transformer that might have one shorted
turn that will not show on an ohmmeter.
You need a square wave and a scope, most scopes have a square wave for
calibration, and that is enough for this test.
The test is very simple, just watch the square wave of your scope with one
of the windings in series. (from square wave to transformer, other side of
the winding to the input of the scope)
If you see a SQUARE wave you have a shorted turn and that is enough to blow
the fuse.
If the transformer is good you must see a WEDGE in the beginning of each
horizontal part of the square wave. It is a ringing that takes place in a
good transformer but is killed even if there is one turn shorted.
Good luck

WA1WLA

----- Original Message ----- 
From: "Sandy and Kees Talen" <windy10605@juno.com>
To: <Heathkit@mailman.qth.net>
Sent: Sunday, March 03, 2002 9:35 PM
Subject: Re: [Heathkit] HX-10 Maurader


> Hi Jim,
> 
> Start by making some resistance measurements (all wires 
> removed) .....filament winding should be a low reading and 
> should measure equally either side of the center tap if it has 
> one, HV should measure the same from each side to the 
> center tap if you have one, AC input should be low like the 
> filaments (some transformers have two windings ...paralleled
> for 110VAV and series for 230VAC), measure between 
> windings (filament to HV, etc) and from the windings to the 
> case (none should be connected to the case). 
> 
> Can't hurt to take it apart if the transformer is toast anyway. 
> I have been able to fix some. If the transformer is held together
> with bolts, remove them and see if there is anything obvious 
> relative to a short inside.  
> 
> I don't know exactly what a Maurader runs but a good 200W
> power supply will have approximately the following readings:
> 
> 110V  AC  1-2 ohms 
> HV  12-15 ohms
> LV   ranging from 5 ohms to 8 ohms depending on tap voltages
> Fil   less than 1 ohm either side of the center tap. 
> 
> 
> 73s  Kees K5BCQ
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