Dish Network VIP622 Power Supply Ticking

[cheebster]

Hi ! I have a psu, coming from a vip622 (or bell 9242, equivalent) receiver that doesn't fire up. It ticks on startup, i can see 166vdc up to some point on the board, but it doesn't fire up.

This is the second power supply i've had doing the exact same problem, the other one i had was brand new, and it was doing the same if it can be of any help in the diagnostic of the issue (ruling out badcaps, i guess?)

Visually i don't see much, here is a picture of the psu itself and the schematics from the receiver schematic.

The pcb has a crack from the user doing a rough removal from the unit, but traces have been properly fixed under the pcb, it's very clear to see the damage.

Anyone has any pointer on where to start on this one ? thanks !!

[aaronwt6]

Re: Dish Network VIP622 Power Supply Ticking

Not sure where you are located but I think I have one of these I could send to you cheap. PM me if you want.

[cheebster]

Re: Dish Network VIP622 Power Supply Ticking

Hi there ! I will send a pm right now. thank you !!!

[aaronwt6]

Re: Dish Network VIP622 Power Supply Ticking

Replied. Didn't realize you were in Canada. Figured maybe you could find one up north for cheaper but I don't see a single one on Ebay. Let me know and I can have it out to you.

[budm]

Re: Dish Network VIP622 Power Supply Ticking

If the new one is doing the same thing, then it may be due to too much current draw by the load also, so it goes into shutdown/restart mode (ticking).

[cheebster]

Re: Dish Network VIP622 Power Supply Ticking

The new one was in a new receiver, it's another case than this one ! no load on the psu's, they're alone on the bench.

[Khron]

Re: Dish Network VIP622 Power Supply Ticking

What series are all those Chemicon caps? KZG's seem to be known for being a bit "allergic" to heat, and failing with no visible signs...

[PeteS in CA]

Re: Dish Network VIP622 Power Supply Ticking

Like Khron, I was noticing that most of the O/P caps look like NCC/UCC. A couple look like Panasonic FC. While there could be a PWM IC behind the switch device heatsink, I'm guessing that's a self-oscillating discontinuous flyback. The clue that it's a flyback is that there is no output inductor (those ferrite rod inductors are usually for suppressing spike noise). In a flyback the transformer primary functions as the output inductor.

[Khron]

Re: Dish Network VIP622 Power Supply Ticking

I think it's quite safe to assume that pretty much all the cheapo and/or low-power PSU's (up to 50-100w) are flybacks. In this case, you can pretty clearly see the components of the RCD-snubber across the transformer's primary winding (CR6 diode / R5 / C28-29) And i'd "vote" for a surface-mounted PWM on the bottom of the board.

[rogfanther]

Re: Dish Network VIP622 Power Supply Ticking

Considering this, could the culprit be just one of those two caps, the blue and the orange ones, like in a 3882 psu ?

[Khron]

Re: Dish Network VIP622 Power Supply Ticking

That orange one may well be a Chemicon RX which is pretty "vintage" (or at least i know i have a few orange-sleeved 13x40mm RX's and i've yet to find a datasheet for them).

[PeteS in CA]

Re: Dish Network VIP622 Power Supply Ticking

The RX series was NCC/UCC's main miniature low ESR series in the late 70s and early 80s (the corresponding larger low ESR series was the RZ, also with an orange sleeve). I seriously doubt something that ancient and obsolete would be used for a satellite receiver P/S.

[cheebster]

Re: Dish Network VIP622 Power Supply Ticking

Here is a picture of the bottom of the board

I was trying to follow the discussion, but it seems a little out of my league..

[cheebster]

Re: Dish Network VIP622 Power Supply Ticking

The orange is a chemicon gxe, the blue is a rubycon xe30. All of the chemicon's are KZE, and 2 rubycon ZL's.

On the bottom the smd ic is a ST 38438, EZ805.

I have 2 donor boards with different problems as well..

One was the new one from a 9242 that i killed by soldering with power applied ( can CLEARLY see the damage) and another one is ticking in loop trying to fire up.

So basically, 3 psu's, none working. I've poked around a lot using my multimeter checking for bad diodes, checking a lot of stuff but it didn't go anywhere. I just can't seem to find anything that seems bad, but they don't fire up.

[Uniballer]

Re: Dish Network VIP622 Power Supply Ticking

I just can't seem to find anything that seems bad, but they don't fire up.

That is about the point when I download the relevant data sheets, float the old analog scope, and start probing [NOTE: I do not recommend that anyone bypass safety grounding, etc.]. Do you have a schematic? There is clearly a chip (U1) that looks like it could be a PWM controller on the bottom of the board, but I can't read the part number. Get the data sheet, read it until you understand what it should be doing, and see what is actually happening.

[cheebster]

Re: Dish Network VIP622 Power Supply Ticking

Problem is that i don't have a scope and even if i had one i have no clue how to use one..

I should get one someday. All i have, is a good fluke 115..

[rogfanther]

Re: Dish Network VIP622 Power Supply Ticking

Just to rule out the possibility : replace those two caps, the blue and the orange.

Also, a photo of the underside of the psu would help.

[cheebster]

Re: Dish Network VIP622 Power Supply Ticking

rogfanter, okay. I've posted the picture already just 3 posts up ?

https://www.badcaps.net/forum/showpo...9&postcount=13

[budm]

Re: Dish Network VIP622 Power Supply Ticking

ST UC3843, try replacing those two start up caps or heat them with hair dryer to see if the power supply will start up normally.
Please verify if it is 3843b, not 38438
https://cdn.badcaps-static.com/pdfs/...9eef16428b.pdf

[cheebster]

Re: Dish Network VIP622 Power Supply Ticking

Which caps are the start up caps ? It's a 3843B.