Vbox7 zapped (@#$% lightning!)

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FTA4PA

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Nov 13, 2013
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We had some bad storms come through our area last night and our Vbox7 got zapped by lightning. You could feel it in the air - even had a battery operated electronic music box start playing all by itself. I always disconnect everything when storms are approaching but this one snuck up on me. I managed to unplug the receiver and disconnect the coax to it and unplug the Vbox7 before I didn't feel safe touching the wires anymore. :flameAfter the storms passed I hooked the receiver back up and the Vbox7 was dead - no indicators on the display at all, not even the decimal that is always lit when it's plugged in. I took the top off today to have a look. There is no visible damage and no burnt smell. I checked the fuse (ok) and the transformer (ok). The board in these does not look that complicated and there's no surface mount devices. I do have a spare in the basement but I'd really like to fix this one if I can. Maybe it's not even possible as I haven't checked to see if parts are availble. Any ideas where to start or is it a lost cause? Thanks! :)
 
Getting a programmed MCU is the first problem. If you can find a source for that, if that is even fried.

Start by checking the to see if you are getting AC out of the transformer. Some of those have a fuse wrapped inside the transformer.
If that is good, then replace the diodes in the power supply section of the board and get power back to the chips.

Here is a link to the Micro controller in the vbox 7. Note: I would not just fire off and order this as it will be blank.
Just use it for reference to research.
http://www.ebay.com/itm/like/361226799889?lpid=82&chn=ps&ul_noapp=true
 
Getting a programmed MCU is the first problem. If you can find a source for that, if that is even fried.

Start by checking the to see if you are getting AC out of the transformer. Some of those have a fuse wrapped inside the transformer.
If that is good, then replace the diodes in the power supply section of the board and get power back to the chips.

Here is a link to the Micro controller in the vbox 7. Note: I would not just fire off and order this as it will be blank.
Just use it for reference to research.
http://www.ebay.com/itm/like/361226799889?lpid=82&chn=ps&ul_noapp=true
Thanks for the quick reply! The transformer (and fuse) were already tested and are ok. :) I will test/replace power supply diodes then go from there checking other components. Two of the four chips used on this board are readily available.
  • ULN2003A (Available from Mouser @ .50 cents each)
  • LM339N (Available from Mouser @ .50 cents each)
Another chip (an EEPROM) is available from China:
  • 24C02AN (Available via AliExpress @ $2.67 for lot of 20)
That leaves the Holtek chip. This board has a HT48R066, not the HT48R50A-1 in your ebay link (but perhaps yours can be substituted?). The HT48R066 appears to be available in single quantity from several sellers on Alibaba but, available or not, if it comes down to this one it's unlikely I would go to the trouble of trying to obtain and program one. Wish me luck that it's one of the other parts! :D
 
The LM339N is used for DiSEqC detection.
The EEPROM is for storing your favorite bird, and the Transistor array is used for driving the relays.
 
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Here is a LARGE (detailed) pic of the board, and a smaller one for those with lower bandwidth (both thumbnailed). I see four MOV's on there. Wonder if they took the hit to save the rest of the components? :)

2809x3614: Vbox7 Board - 2809x3614.JPG 622x800: Vbox7 Board - 622x800.JPG
 
Very good possibility.
So you are getting AC voltage out of the transformer?
 
Yep there are two voltages, one around 36V for driving the actuator and the other is usually 12.6V that is knocked down to 5V for the circuit with a 7805.
 
Since you say that the decimal is not lit, I would suspect that you are missing one of the DC voltages from the power supply, the 12.6V and 5V mentioned by K4EST above.
 
Yep there are two voltages, one around 36V for driving the actuator and the other is usually 12.6V that is knocked down to 5V for the circuit with a 7805.
Just checked again and got 36.8 VAC on the black wires and 15.5 VAC on the red.
 
I was asking about the AC to make sure he had actually measured it instead of checking the fuse. Some of those units put a thermal fuse in the transformer.

Are you getting any DC voltages FTA4PA?
 
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That's a late model VBox7. It does not have a thermal fuse in the transformer. This has a fastblow 2a fuse on the board. But be sure to check the fuse with your meter. The earlier models had a thermal fuse and no fastblow fuse :( The early models had a different firmware as well.
 
I was asking about the AC to make sure he had actually measured it instead of checking the fuse. Some of those units put a thermal fuse in the transformer.

Are you getting any DC voltages FTA4PA?
Yes, but not what they should be - output of the LM7812CV is 2.26VDC and output of the LM7805CV is 1.34VDC :(
 
That's a late model VBox7. It does not have a thermal fuse in the transformer. This has a fastblow 2a fuse on the board. But be sure to check the fuse with your meter. The earlier models had a thermal fuse and no fastblow fuse :( The early models had a different firmware as well.
Yep, it was pulled and checked with meter. ;)
 
What are the input voltages on those regulators?
 
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The LM7805 should be outputting 5VDC, or very close to it, not 13V. The input to it could be 12-13V, make sure you're measuring on the right pin. One pin is ground too, of course, which may show a volt or so, depending on where you're putting your negative meter lead.


Lm7805-pinout-diagram.gif.png


If the output is truly 13V on the 7805, it's shorted and bad, replace it. The LM7812CV should have the same pinout, input on that one could be 15V, output should be right around 12V.
 
The LM7805 should be outputting 5VDC, or very close to it, not 13V. The input to it could be 12-13V, make sure you're measuring on the right pin. One pin is ground too, of course, which may show a volt or so, depending on where you're putting your negative meter lead.


Lm7805-pinout-diagram.gif.png


If the output is truly 13V, it's shorted and bad.
Measured on underside of board right at regulator pins. The LM7805's only outputting 1.34V not 13V (http://www.satelliteguys.us/xen/posts/3914616/) but neither one is good. :D
 
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