Re: DMP XR-20 - NO DC

["Bob La Londe" <onebikenut@xxxxxxxxx>]

"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.