Advice Needed V-Box blew up :(

[Captain Jack]

Well, this is nice... Been sat watching TV just now, only to be greeted with a burning electric smell and smoke from the V-Box (green Alsat model V2000). Unplugged everything in panic and opened up the box.

Quick inspection revealed that two of the four rectifier diodes, D4 and D5, disintegrated and the ceramic capacitor C5 looking charred. The main 470uF electrolytic capacitor E5 is also bulging. The unit wasn't doing anything (i.e. driving the dish) at the time but was switched on. So, the immediate question is - what caused the thing to die in the first place?

Everything else on the board looks OK, but obviously I don't know if the unit survived the blown diodes.

Has anyone else had this issue? And are there any other components that I should replace along with the ones listed. Obviously, this left me with effectively a fixed dish. I do have another V-Box for the north/south jack, which I can use but that means reprogramming all the locations. Also, it hasn't left me with much confidence with regards to safety. Who knows what would have happened if I wasn't there at the time!

 

[Channel Hopper]

Mr alsat is currently at her majesty's pleasure, you could post it to him

 

[Captain Jack]

Indeed he is...

 

[aceb]

For crimes against spelling and the English language?

 

[Captain Jack]

OK, what's the best place to get the following components (other than eBay)?:

2x 10pF ceramic disc capacitor (orange disc with 104 written on it - no V value but I am guessing 50V)
8x RL205 MIC diodes
2x 470uF 50V (or higher) electrolytic capacitors

Maybe one someone has some lying around (@Vipersan?) as I don't want to by packs of 100 of each, since it would be a waste...

 

[hvdh]

104 capacitors are 100 nF, not 10 pF.
(104 means 10 with 4 extra zero's behind it, 100000 pF = 100 nF)

 

[Captain Jack]

Whoops! Indeed - thanks hvdh. How can I tell what voltage rating it is? Or should I just get the highest possible?

 

[hvdh]

I don't know, 100 nF also is a typical value for RF suppression at the AC mains side.
So check the PCB where they go to, or wait for someone to come up with a circuit diagram.

 

[Captain Jack]

Yep, it's on the AC side (after transformer of course), sitting between the two sets of rectifier diodes. I guess it's the capacitor that died, bringing death to diodes.

 

[william-1]

Well, this is nice... Been sat watching TV just now, only to be greeted with a burning electric smell and smoke from the V-Box (green Alsat model V2000). Unplugged everything in panic and opened up the box.

Quick inspection revealed that two of the four rectifier diodes, D4 and D5, disintegrated and the ceramic capacitor C5 looking charred. The main 470uF electrolytic capacitor E5 is also bulging. The unit wasn't doing anything (i.e. driving the dish) at the time but was switched on. So, the immediate question is - what caused the thing to die in the first place?

Everything else on the board looks OK, but obviously I don't know if the unit survived the blown diodes.

Has anyone else had this issue? And are there any other components that I should replace along with the ones listed. Obviously, this left me with effectively a fixed dish. I do have another V-Box for the north/south jack, which I can use but that means reprogramming all the locations. Also, it hasn't left me with much confidence with regards to safety. Who knows what would have happened if I wasn't there at the time!

That is why it is best to switch off the power when you are not there.

 

[2cvbloke]

Mr alsat is currently at her majesty's pleasure, you could post it to him

Didn't take 'em long to get him behind bars for a blown V-box...

 

[Waveguide]

First thing to do after replacing the components is to make sacrifices to
Odin (Óðinn, Wotan) or whatever housegod you have a contract with.
For a short while AC could have found it's way into the rest of the box.

All diodes are LED's or SED's for a short while if the power if sufficient.
(SED = smoke emitting diode)

 

[Lazarus]

Reversed polarity Tantalums are fun.

 

[Captain Jack]

I am going to nab my G-Box from my parents' place, while this one is in for repairs. It's noisy (transformer hummmmmmm) and it's not getting used much these days anyway...

 

[purplemarina]

Could you post a picture please, says more than words!;)
i got my spares from eb*y, you can buy small amounts conveniently (i know you pay a bit more) i went for branded parts =panasonic.

 

[Captain Jack]

Here you go

 

[Laser]

May sound extravagant. But I would replace the box completely. Just can't be too sure what actually caused the problem.
They sell them I believe on Satellite Superstore...?

 

[Captain Jack]

I know they are not expensive to buy new, but I'd rather repair it than throw out a potentially working box - perhaps to a better standard than originally made!

 

[Vipersan]

You may well get lucky with a repair ..BUT ..
Be aware the mains transformers run hot in these units ..even when in standby mode ..
AND they do fail ..
Ask Ged ..Digi247 for details ..
My advice fwiw ..
before attempting repair ..
Check the primary winding is not open circuit ..
When satisfied it is ok ..and the mains fuse in the plug has not also failed.
Use a multimeter in resistance mode for this ..with NO mains attached ie all unplugged.

Disconnect ALL 4 connections to the circuit board leaving the wires floating ..
connect a meter in the AC volt range to the secondaries in turn ...and apply mains ..
One winding ..most likely the 2 yellow wires should have abot 35v AC accros it ..
repeat this with the other winding ..(white) ..which should have around 12v AC accross it ..
If all is ok ...run the unit with the wires floating for about 30 minutes with mains AC connected ..
after 30 minutes disconnect the mains and finger check the transformer body ..
No more than faint warmth should be evident..
If all this checks ok ..proceed with the repair replacing all damaged components.
good luck
VS

 

[archive10]

May sound extravagant. But I would replace the box completely. Just can't be too sure what actually caused the problem.
They sell them I believe on Satellite Superstore...?

A SuperJack (aptly for Captain Jack, eh?) V-box II is EUR 39 at hm-sat-shop.de. Have one myself. Seems to work, although I would have expected a ramp up and down of power to actuator to provide smooth movement transitions...
(of course with HM sat, you may get something completely different than what you ordered...)