CurtPalme.com Home Theater Forum

[skippyar]

Hello fellow CRTers hope all is well.


Picked up this champ from a car-boot and was told it came from a pub which is quite evident. Chap who sold it basically said it did work but the pub roof leaked and it got wet then stopped working. He then put it in an airing cupboard to dry out. (I swear to God that's what he said.)

So it's had a rough ride. Anyway, healthy and safety on full alert whilst testing it.

Replaced blown fuse within mains connector molding, that blew "something" on the SMPS board. I traced tested and replaced a resistor, powered again blew another resistor on the switching board so replaced. Tried again blew even more components prior to the switching board.

I took the SMPS board to the workbench and removed the heatsink which reveal a cracked transistor H7NA90FI.

I've cleaned all the messed up and was wondering before attempting to replace everything if there is a stockist for this board.

It's only a hobby project to challenge myself to repair, in the event I simply can't get it going I could offer it up to someone more proficient or needing spares.

I'm no expert but if my Barco 500 Data is entry level, I don't know what this one qualifies as. (It has Delta TAC4 lenses I'm sure they're optical plastic.)

Any info would be grateful.

** DIAL UP - 7 graphics follow **

[Curt Palme]

This appears to be a very common problem on the Selecos, blowing up of the power supply. I've only had three Selecos through here, and two had the same problem that your set does.

Zero parts or schematics available from what I know of. Funny though, I just had a guy email me from California that wants to dump two Selecos, an 800 and a 410. I told him that I wasn't interested, but if he wanted to give them away, to post in the buy/sell section. Not sure if the 410 has the same power supply as yours, but I'd suspect that they are close. So keep an eye out on the buy/sell section to see if he posts them.

The set is on par with the BArco 500, but the TAC4 lenses are worse than what should have come with the Barco.

[Curt Palme]

This appears to be a very common problem on the Selecos, blowing up of the power supply. I've only had three Selecos through here, and two had the same problem that your set does.

Zero parts or schematics available from what I know of. Funny though, I just had a guy email me from California that wants to dump two Selecos, an 800 and a 410. I told him that I wasn't interested, but if he wanted to give them away, to post in the buy/sell section. Not sure if the 410 has the same power supply as yours, but I'd suspect that they are close. So keep an eye out on the buy/sell section to see if he posts them.

The set is on par with the BArco 500, but the TAC4 lenses are worse than what should have come with the Barco.

[macgyver655]

Ahhhh....the sweet smell of burnt electronics. I can look at that charred soot and imagine the illustrious fragrance.

[stefuel]

I think I sent Curt 2 of the 3 that he's had. One of them was working and the other had a supply problem like that but it was sooo bad that it actually had a hole burned into the circuit board. It looked like somebody poked a smokin hot welding rod through it.

[skippyar]

Thanks for the comments guys.

@macgyver655: The fragrance is pretty bad and lingers.

@stefuel: The faults are dramatic. Which is my main concern why and always in the same place. I think its all stemmed from the cracked H7NA90FI.

@curt: Shame, schematics would really help, all I can do is trace and compare component values. The H7NA90FI (the cracked transistor) is $8 (10UKP) alone, of course this could become a costly process especially if things keep blowing. (which is why I've got the eye guard on. )

I wouldn't mind so much if I had a large supply of spares as I'd gladly keep replacing components until the issue was resolved. Though it would just be easier to swap out the board.

I haven't tried yet but wondered if I can just work on this board alone to isolate it from damaging elsewhere (more seriously the EHT ); without schematics I can't determine if it needs to be interconnected (dependent) to power on.

I don't suppose any gurus would know of an alternate to H7NA90FI: http://www.electronicrepair.org.uk/osCommerce/product_info.php?products_id=55&language=en from "N-CH M-FET 900V 4.5A isowatt218 package" googling ISOWATT218 returns BU808DFI Transistor which are available on Ebay of a couple of bucks.

Need to ensure this fault doesn't creep too close to the transformers, otherwise I will be knackered.


...eastbound and down loaded up and crting

[macgyver655]

[skippyar]

@macgyver655: Thanks very much, well deducted!

Greatly appreciated.

[macgyver655]

And if you dont mind buying from hong kong: http://shop.ebay.com/i.html?_nkw=900v+4.7a+mosfet&_sacat=0&_odkw=sth7na90fi&_osacat=0&_trksid=p3286.c0.m270.l1313


But I would be very skeptical.

[RaWsHaRk]

[skippyar]

@RaWsHaRk: https://www.curtpalme.com/forum_archived/viewtopic.php@t=23467.html


I don't think this unit was ever rain on, or that was responsible for its failings. On reflection after talking to the guy he mentioned selling stuff at car boots he'd find in bins; that in itself summarises the calibre of personality. I believe he simply claimed it *did* worked to validate a sell...

Dismantling the SVP last night I noticed there's no water marks nor electrical based shorts from such. What I did find was a blank 'Tested for electrical safety' sticker and that someone had disconnected one of the heat sensors on this unit.

If it did live in a pub perhaps the atmosphere tripped the heat sensor shutting down the unit, so removing it might explain the heat tarnished SMPS board and cracked Rectifier that I'm incline lend to overheating failure.

(You could resurface a motorway with the cigarette tar inside.)

I suspect when it first failed it blew the fuse and damaged the Rectifier, me replacing the fuse and firing back up probably further compounded the original fault.