Re: DMP XR-20 - NO DC

["Bob La Londe" <none@xxxxxxxx>]

"Bob La Londe" <onebikenut@xxxxxxxxx> wrote in message
news:j2hl96$tev$1@xxxxxxxxxxxxxxxx
> "nick markowitz" <nmarkowitz@xxxxxxxxx> wrote in message
> news:c15f1da0-b149-436b-a324-4a3953926d4a@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> On Aug 17, 5:17 pm, Jim <alarmi...@xxxxxxx> wrote:
>>> On Aug 17, 4:18 pm, "Bob La Londe" <n...@xxxxxxxx> wrote:
>>>
>>> > I've got an XR-20 with no DC. Well its about 2.8 volts. Battery leads
>>> > and
>>> > Aux power both. I see no fuse on the board anywhere, so I am guessing
>>> > its
>>> > got circuit breakers. Any suggestions? What gets me is AUX and Battery
>>> > are
>>> > both low/dead. Most panels have separate fuses or circuit breakers for
>>> > 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. If 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 .... :-)
>>
>> 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
>
> I do have a good pull on the shelf.  I would just replace it with new, but
> I doubt DMP would sell to me anymore.  Alternatively I would just swap for
> a Napco P1632.  The system has a couple keypads though so that drives up
> equipment costs a little.

Ok, I am looking at my good pull right now.  No fuses I can find or fusible
links on the back like FBII either.  It doesn't appear to have a single
components bridge rectifier either.  Looks like they installed their own
diode ring as there are 4 of them on the board near a modestly large
capacitor.  There is also a small diode in that area.  No clue what that
would be for except maybe reverse protection.  I see a couple components
that "might" be circuit breakers.  Maybe I'll punch the numbers on it into
Google later and see what comes up.  Lots and lots of transistors, but only
one with a heat sink.  Maybe a voltage regulator?