PowerMax Vbox X Transformer?

[Lone Gunman]

Had a Vbox X power transformer go up in smoke yesterday for no apparent reason on my SAMI system? Doesn't look like anything on the board inside is smoked and the smell is from the transformer itself so was wondering if it can be replaced to try to save this one instead of buying a new one since they're somewhat hard to find any more?

Problem is though there is nothing on this one to identify what the voltage output is and it's a dual output transformer with one set of wires powering the electronics on the board and the other two (which are much larger) probably supplying the 36v to the dish mover motor.

While I've got another one of those that I could "possibly" check myself, I'm not sure exactly how to go about doing that and don't want to risk smoking that one too.

So does anyone have one of these in their system and have the knowledge to find out what those two voltages are so I can see about getting a new power transformer to fix this thing? If we can do this then others may be able to do the same in the future.

Thanks

 

[Lone Gunman]

66 lookers so far and no help? Hummm

I've got a digital multi-meter but not real proficient in it's use. Can someone explain to me how to check this voltage?

 

[primestar31]

66 lookers so far and no help? Hummm

I'd doubt too many people ever opened up their v-box, and measured the voltages. My best guess would be: 110 volts on the primary side, and 36 (or maybe only 24 nowadays) volts on the secondary (motor) side. Those are standard transformers readily available.

 

[Magic Static]

I pulled the cover off of one and plugged it in and measured voltages on the blue and yellow wires pins 1 ~ 4. It didn't tell me much. Both blue wires 8v DC and both yellow 0v with the unit on or off. I would probably need to take the load off(take it apart) to find the voltages. I see no markings on the transformer in my unit.

 

[FaT Air]

Motor volts is probably going to be 24, as that's the legal limit. Measuring secondaries. Set to AC volts, Scale above 20 volts. Place leads on secondary terminals. apply power, read meter*. I'm going to guess, one secondary is in the 12v range. Rectified, filtered and regulated to feed the electronics. The other 24-28v for the motor(~24 after rectification)
*If readings are below 20, set meter to next lower scale, for a more accurate reading.
Note: a lot of these transformers have a thermal fuse buried in the windings**. But as you experienced, they are junk in some instances. I remember a post of a GBox actually catching fire and scorching the shelf it was on. (Luckly caught in time and no further damage)
**replacement may not include it.
If a transformer with the necessary 2 secondarys cannot be located. Use 2 transformers. You could 'outboard' one or the other, or both. Use a small inline fuse.
How about some pictures?
Magic- transformers don't produce, or work, with DC. Only AC.

 

[Magic Static]

I did check for AC voltages first and found less than 3v on pin 3, nothing on the other pins. Hope you find what smoked it or you could do it again. Could be I didn't find a good ground when checking

 

[Magic Static]

OK a more concentrated effort for you
Yellow wires 37v Blue wires 17v

 

[Lone Gunman]

OK here's a pic of mine. I'm surprised that the secondary voltage for the board is that high? That stuff is usually either 5 or 12 volts in computers. At least now I've got an idea of what to look for.

THANKS GUYS!!

 

[Magic Static]

Your meter only uses the battery for Ohms testing (resistance) You are fine checking voltages. Set the meter to AC voltage and hook the leads to one set of wires from the transformer. Polarity doesn't matter when checking AC

 

[gpflepsen]

Put the meter on ~AC. The battery is for checking resistance (ohmmeter mode). The voltmeter input should have a high enough impedance that nothing will be harmed. Just don't short across anything with the same probe when checking.

 

[gpflepsen]

I guess I should have said polarity on AC doesn't matter.

 

[Anole]

Couple of ideas to ponder

1. It would be interesting to see what you read on a 12v transformer, and one rated 24v, without load.
Could you repurpose one from an old analog receiver?

2. Something likely blew up the transformer.
I'd check to see what that might be before installing another.
- shorted rectifier?
- blown electrolytic capacitor?
- welded (stuck) relay contacts?

edit:
i remember a similar thread some time ago.
probably worth checking the ideas there, too.
.

 

[Lone Gunman]

1. It would be interesting to see what you read on a 12v transformer, and one rated 24v, without load.
Could you repurpose one from an old analog receiver?

2. Something likely blew up the transformer.
I'd check to see what that might be before installing another.
- shorted rectifier?
- blown electrolytic capacitor?
- welded (stuck) relay contacts?

Yeah I was wondering that same thing! I did check the actuator with a 12 volt battery this afternoon and it does run in both directions. I was wondering if it was locked up and might have caused the failure.

When this happened we had just had a storm go through but prior to the storm I had disconnected the coax at the box from the LNBF and also turned the power strip off that supplies all the system power. The smoke got out when I turned it back on after the storm went through.

Any way to fuse that transformer to keep a welded contact from horking up another one, IF that's what the problem is that is.

Thanks

PS, any suggestions for a transformer (or two) for this. Doesn't matter whether it will fit inside or not as this one would be in the shop so I could "rig" it if necessary. Just want to see if it can be fixed.

 

[Anole]

The box should have a fuse in the incoming power line.
First thought might be for a 1 amp slo-blo, but that's up for discussion.

 

[Magic Static]

I found two at DigiKey. One is $7 PCB mount and I don't think it's big enough and the other is $44
http://www.digikey.com/product-detail/en/266K35/266K35-ND/2358036

 

[Lone Gunman]

The box should have a fuse in the incoming power line.
First thought might be for a 1 amp slo-blo, but that's up for discussion.

Hummm, was thinking that I saw where these things are rated at 3.5 amps? They are 5 watts just sitting there and 70 watts max under load. NO FUSE on this one that I can see.

 

[waylew]

Might be a fusible link in the Xformer,when it blows, throw it out.

 

[FaT Air]

I think you're right, there's no (line) fuse. Only the, apparently crappy, thermal fuse within the original transformer.

 

[Anole]

I made a mistake suggesting a guy measure some voltages in his receiver, recently.
He didn't know what he was doing and had the damned meter on CURRENT!
Needless to say, he did even more damage.

So, I will absolutely NOT say the following:
- once the transformer is removed, you can peel back some of the protective paper
- as long as you don't break any of the windings, you might find the thermal fuse
- short the fuse, and press the paper back into place
- install a fuse holder on one of the transformer primary lines
- I'm leaning toward using a slo-blo fuse around 1.25 or 1.5 amps
- the thermal fuse may be too deep inside the transformer, but no loss for looking.

C A U T I O N - the above idea could kill you, or create a dangerous hazard.

I know what I'm doing; if you don't, then maybe this is where you salvage a transformer from that analog receiver you've been holding onto all these years, and throw the rest of it away!

 

[Cham]

I've fixed a few transformers that way...

"I know what I'm doing; if you don't, then maybe this is where you salvage a transformer from that analog receiver you've been holding onto all these years, and throw the rest of it away!"

Yes an old analog receiver with the motor drive circuit would likely have a better quality transformer than the original. It might even have a better rectifier separate from the circuit board. Might not fit into the V-Box X though... a separate box for the power supply wouldn't be a bad thing...

Just one question... since I do not have one of these diseqc dish mover controllers... are they ULC/CSA approved? If so they should have the appropriate fuses and circuit protection.. at least one would think so. Transformers catching fire is not a good thing!