atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Security, Alarms and Paging valcom blows fuses

my custoner has a v2000a page power supply and two 1030c horns. it uses a .5 amp fuse. it has been service a few years but has blown 2 fuses in a short period of time. any ideas. thanks dave

Well, a look at the specs for a 1030C shows 300 ma. per horn. Two horns = 600 ma. .5 A Fuse = 500 ma. Do you see what may be the problem?

Rcaman

Valcom uses self-amplified speakers so you need -24VDC power and tip/ring for the audio. Valcom has things rated in power units so you can easily plan the proper power supply for the speakers.

Looking at Valcom's documentation the V2000A provides 12 power units. A V1030C horn draws 5 power units. 2 horns draws 10 power units so you are within the rating of the V2000A as a power supply.

My guess would be you might have an intermittent short in the power pair. Perhaps a staple hit or a critter has chewed on it? Might be worth a look at the speakers to make sure the power leads are not shorting somehow.

Here in the tropics we have seen lizards get into things and short them out. Was pretty interesting to see an old school Definity PBX power supply fried because of a lizard. I have also seen these large ants that like to build nests within electronics with similar results. ~ Mike

thanks for the info. hope to take a close look next week. dave

Do those Power Units include any voltage drop in the speaker cable? With only 2 units left over you have very little Power headroom to spare if they don't.

I wondered about the 0.3A per speaker on a 0.5A until I dug further in the online PDFs and realized that the 0.5A fuse was on the 120V line and not the 24V speaker supply.

My money is with Meyery2k that there is a partial or intermittent short on the speaker power line.

OK. So, the information is this: The primary is protected by a .5 amp fuse and you have 2 units, each drawing .3 amps on the secondary side. According to the specs, you have plenty of power to supply those two speakers on the secondary side. If you are operating a .5 amp fuse on the primary, there would have to be an almost dead short on the secondary side to operate the fuse.

If you have a VOM, I would check the current draw on the speakers and then do a divide and conquer search on the speaker line to find out where the short is.

Rcaman

Let's take Rcaman thoughts a few step along.

According to Valcom the V-2000A Integrated Single Zone Page Control Unit power requirements are Input -115VAC @ 0.35 amps and it supplies -24VDC @ 600mA output for driving speaker amplifier assembles. Not sure where the 500mA fuse is located that you are talking about. If it's on the input side it would be rather small for that purpuse and you normally double the current draw to find the minimum fuse size, if it's on the output then it is definitely too small. Also an input power fuse is designed to protect the equipment from from catching fire and such and normally anything on the output won't cause an input fuse to blow. There is an old Electronic Technician says that goes 'If the input fuse is blown then the equipment is already fried'

The Valcom V1030C Paging Horn Amplifier Assembly draws 300mA @ -24VDC. The power wire run is limited to 125 ft for 24 awg wire and 200 ft for 22 AWG wire.

A Valcom Power Unit (VPU) is 50 Ma @ -24VDC, so each V1030C paging horn requires 6 VPU's. The V-2000A provides 12 VPU's and using two V1030C horns require 12 VPU's

Sounds like to me you are running the V-2000A at it maximum output and there is the question of how long and what size wiring you are using.

I am also curious about the location of the 500 mA fuse and if it is the correct fuse in the first place.

Any update on what the problem or solution was

A call to Valcom tech support would answer this question in about two seconds.

Just saying...

-Hal