DMS Vbox 7 Transformer? (1 Viewer)

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KE4EST

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One set should have 36-38V.
The other set will be 15-18V.
 
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Lone Gunman

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An old WSI Vbox X transformer has 38v a/c on the yellow pair of wires and 18v a/c on the blue pair. I tried checking the old Vbox 7 transformer but only one pair has voltage on them since I last smoke tested it and they only show 16v a/c.

I've got one in the works from KE4EST that should be here early next week so I'll compare that one with this Vbox X one to see what is what.

Last week I couldn't even spell lektroniks tekniton and now I are one! :facepalm
 
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Magic Static

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Always said when I was a kid I wanted to be an electrical engineer. Well you need proper schooling for that and with my GED I became a mechanic. But that always interested me. Now with a little prodding from KE4EST I'm working with micro controllers, building electrical circuits and learning C++. That's almost like an engineer right? ;)
 

Lone Gunman

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RE: Mechanic? Nothing wrong with being a mechanic and I also started my working career with only a GED. I happened to get into an Apprenticeship Program with Babcock & Wilcox and made a very good living as an Industrial Maintenance Machinist during my working life. It was good enough that I RETIRED in 2006 at 60 years old living in a new house that we moved in to in June of 2000 THAT I DIDN'T OWE A DIME ON THE DAY WE MOVED IN IT!

Electronics? I was never interested in it too much other than what I needed to know. With Race Car electronics they have to make it pretty simple for the Gear Heads so I guess that's why I never got into the "nuts and bolts" of that field.

What's odd though is I did run a commercial computer repair business for about 6 years working that job on my off days from my regular mechanics job, which was only 3 days a week. Don't have any idea how many computers I built over that time but it was quite a few starting during the Windows XP OS years. Still do some of that now for the other old folks in the neighborhood just to keep somewhat up to date, which is also why I got involved in the Windows 10 Insider program at the start of Beta testing. That computer experience sure did help a lot when I put a data logging system on that dragster I had.

I guess that's enough history for now, hey!
 

Lone Gunman

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Well, bad news. It is something on that board that's shorted out because this new transformer I got in the mail today started heating up as soon as I plugged it in and turned it on?? Within 30 seconds I couldn't keep my finger on the primary coil even without the actuator moving. That transformer's voltage readings are still good though so the thermal fuse didn't blow. When it's plugged in without the board connector connected it doesn't heat up at all??

So I guess this Vbox is toast. :deadhorse2
 

Trust

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I'm pretty shure the rectifier for the 36 V has a short .
Or the contacts of one of the motor relays are burned together .
Can you show a picture of the circuitboard ?
 

migold

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Lone; You definitely have an over load on the transformer. It is best to find the over load before running the transformer hot any more. A picture of the circuit board may show a faulty component, sometimes a bad component shows signs of over heating. Visual inspection may help, or if you feel adventurous, touching the components may reveal an overheating part. Good Luck.
 

KE4EST

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Just saw this. Sorry to hear you have other problems and the transformer I sent you is still good.
Agree with others, There is a 99.99% chance that 1 or more of the rectifier diodes on the 36V line are shorted.
Those will be the 4 diodes marked in red in the photo.
There are part number: 1N4008
IMG_20160807_130323236.jpg
 

Lone Gunman

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RE: Pics, Trust, if you're wanting to see if there's any burnt marks on anything.............there isn't, neither on the top or the bottom. Mine looks exactly like the pic that KE4EST posted.

I might be able to solder those in since they are fairly large compared to some of the other stuff.

Also, the diodes on this board are 1N5408 and are only rated at 3A? The ones on the Motek controller are 1N5402 and 3A also and the ones in this old Vbox X are 1N5404, which are also 3A?

I found a pack of 10 replacements on fleabay for $2.59 shipped, but, I was wondering if I'd be better off moving up to a higher amp rating? Seems that 3A is a bit low isn't it?
 

KE4EST

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It wouldn't hurt, but that transformer is so small it is probably only rated itself at 2-3 amps.
 

KE4EST

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Also you are correct. The ones in the pic are 5408 NOT 4008. Should have known better, as the 40 series is usually rated at an amp or less.
 

Lone Gunman

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Well, I just ordered that 10 pack of diodes from fleabay. I guess I'll get them by the end of this week.

Oh, and I checked those diodes with my meter (it has a diode check setting) and it does look like one of them is bad as it shows the same reading on the meter (000) even when I swap ends with the leads. The other 3 don't do that. They only show a reading (608/640) with the positive lead opposite the end with the white ring on top.

Yup, I'm REALLY in uncharted territory now! :eek
 
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. Raine

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Replace all four diodes, not just the one that checks bad. When stuff takes a hit like that, diodes can take a beating.

Also, I don't know if anyone has mentioned this, diodes go in circuit only one way, so pay attention to the original orientation. Usually there's a line or some mark to go by. You can do it!
 

migold

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The 1N540* series of diodes are all 3 Amp, the last digit indicates the voltage rating. If you want a 5 Amp rating, any of the FR504, FR505, FR506, FR507 would do, but would be somewhat larger physically. I think that they would mount in that area, with some care...
 

Lone Gunman

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The 1N540* series of diodes are all 3 Amp, the last digit indicates the voltage rating. If you want a 5 Amp rating, any of the FR504, FR505, FR506, FR507 would do, but would be somewhat larger physically. I think that they would mount in that area, with some care...

Ebay search doesn't bring back much of anything on those FR numbers? Google didn't do much better either as far as a supplier goes. Digikey didn't list them at all. May check locally today to see what I can find.

Interestingly enough, that Motek Vbox II controller I just bought recently has the 1N5402 Diodes which are 200v 3A and it has a 5A fuse on the main board?? This Vbox 7 I'm working on has the 1N5408 which is a 1000V 3A but it only had a 2A fuse on the board?? Not sure I understand all that because that fuse "seems" to be feeding that 38v to these diodes?

I think I'm getting a headache! :deadhorse2
 

KE4EST

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Look at the diodes in this unit:
They are RL205's. Data sheet attached.
gbox_normal.jpg
gbox_close.jpg
 

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  • RL201-RL207_datasheet.pdf
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KE4EST

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That came out of a Gbox that I got for a good deal cause the transformer was 240V input only. So I never used it took it apart to study the circuit a couple of years ago when I started experimenting with making a DiSEqC decoder.
I did hook up a 120V input transformer and it moved the dish back and forth.
 
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