Re: DMP XR-20 - NO DC

[nick markowitz <nmarkowitz@xxxxxxxxx>]

On Aug 17, 5:17=A0pm, Jim <alarmi...@xxxxxxx> wrote:
> On Aug 17, 4:18=A0pm, "Bob La Londe" <n...@xxxxxxxx> wrote:
>
> > I've got an XR-20 with no DC. =A0Well its about 2.8 volts. =A0Battery l=
eads and
> > Aux power both. =A0I see no fuse on the board anywhere, so I am guessin=
g its
> > got circuit breakers. =A0Any suggestions? =A0What gets me is AUX and Ba=
ttery are
> > both low/dead. =A0Most panels have separate fuses or circuit breakers f=
or the
> > battery and Aux circuits.
>
> I don't know what you've already tried so here's what first comes to
> mind.
>
> Bad rectifier? or the battery leads were reversed? ( I don't know how/
> if they have breaker for reversed leads) If the transformer got a
> blast etc............. might have taken out the rectifier. =A0If there's
> no breaker .... settable or self resetting ....... are there any
> permanent fuses on the board or on the back of the board?
>
> If you can find the rectifier, measure the DC output. It's going to be
> unregulated so if you have an analog meter, it'll allow you to better
> guess at the average output. If it is the rectifier you can usually
> replace it pretty easily or substitute four healthy diodes. Alarm
> mfg's pretty much use compressed mud for components. Don't know how
> much you get into circuitry but sometimes the rectifier is good but
> the regulation components are bad. Capacitor or Zener diode ( if they
> still use them anymore). If you can find the regulation components,
> measure on the other side of them to see if you get better DC. If it's
> all good up to that point then ....
>
> If there are breakers and you get a good DC reading after the
> rectifier it could be a bad breaker. You'd have to follow the DC out
> from the rectifier to each of the breakers. Not too easy to do. A
> partial voltage reading could be indication of a bad (not resetting)
> breaker. But since more than one voltage output is bad, it doesn't
> seem like they'd use one breaker for all of them.
>
> Did you check the back of the board for a burned conductor?
>
> If you have another working board, you can use it to get comparison
> voltage readings to determine where it differs.
>
> Or ..... you could just throw it in the garbage and buy another
> board .... =A0:-)

Dont forget to power cycle the board some of the newer PTC thermals
have to have power turned off before they reset.  have this problem
with vista 32fb etc bell loop when it shorts you have to power panel
all way dawn and back up and it resets