CurtPalme.com Home Theater Forum

[Afro Steve]

OK guys - i have a good one for you all!

I bought a cheap Seleco 800 with a busted Green tube. It uses Sony MSP tubes.

I had a set of near new Sony MS tubes, carefully cut them out of their aluminium surrounds, and fixed them into the surrounds from the MSP tubes.

Everything fits mechanically, but the tubes are not rated for the 800. I have fired up the projector and everything works as it should, good picture etc, apart from everything is just a little too bright!

Now the best way i can explain it is that even when lowering the G2 voltage adjusters to the minimum, i still can't lower it enough! as you may expect when changing the contrast via the remote, it doesn't really do anything at all!

Now what i presume is that the G2 voltage (or a different voltage) is a little higher in this projector than the lower spec Selecos which is where the Sony MS tubes came from, so does anybody have any ideas about how to lower this voltage either moding the neck boards or maybe the supply voltage to high voltage transformer?

It should be easier trying to get rid of too much voltage rather than not having enough in the first place!

I have plenty of spare parts from lower spec seleco - inc neck boards, power supplys, hv splitters etc... So shout some ideas at me!! At the end of the day, it may go into the bin after having caught fire etc, or with the regret of not having tried anything!

If pictures are wanted of what has been done so far, let me know

Thanks in advance for you help,

Steve

[Nashou66]

Do you have any schematics for the Seleco neck boards? I assume the Cathode cut off voltage for the two types of tubes are different by quite a bit.

I think id start there but I am no expert. TSE would know more on that aspect of tube operation. But no one here is really Seleco experts as there are not many
around.

Athanasios

[Afro Steve]

No i dont have any sort of schematic, if some one can point me in the right direction that could be handy! I will have a dig around and see what i can find. If some detailed pictures of the neck boards would help then i could post them up? Infact any neck board schematic for any projector using Sony MS tubes surley would be of some help!

I'm not sure it's a specific Seleco problem as such - it's more replacing tubes with different tubes. i think that the Barco 801 uses the same sony msp tubes?

I will see if i can take some photo's of the tube faces and maybe i'm missing something simple or a bit more obvious.

Thankyou for your reply

Steve

[Ile]

Isn't 07MS tube physically smaller than 07MSP?

I have thought that
07MP and MSP are same sized.
SD187 and 07MS are same sized, but bit smaller than MP/MSP.

But that shouldn't be problem if you got it installed.

Barco 800/500 works fine with all these tube types, only tubes hardware and lenses are bigger for 07MP and MSP.
Brightness goes SD187->07MS->07MP->07MSP, so actually your new green should be brighter than red and blue.

I guess that your Seleco have problem with green cut off, that caused original green tube to broke.
Swap green neck board with red and see if problem follows.
Or replace neck board with same part number from your part machine, it's probably not same in lower end Seleco.

Don't use projector with bright raster longer than it's needed to see if repair helps.

If it's neck board and it use VPH06 or VPJ06 main transistor, I should have one.

[Afro Steve]

"Isn't 07MS tube physically smaller than 07MSP?
I have thought that 07MP and MSP are same sized.
SD187 and 07MS are same sized, but bit smaller than MP/MSP."

Oh yes - you are right (it's been quite a while since i changed the tubes!)

I was wrong, they were not Sony MSP tubes - they are some completly different number, i will find out when i get home and let you know.

"Barco 800/500 works fine with all these tube types, only tubes hardware and lenses are bigger for 07MP and MSP.
Brightness goes SD187->07MS->07MP->07MSP, so actually your new green should be brighter than red and blue."

You may have misunderstood - I have replaced all the tubes, so i now have a full set of 07MS tubes in the Seleco 800. All the tubes are working to the same brightness, but if i dim any tube it seems to affect the other tubes brightness!?

"I guess that your Seleco have problem with green cut off, that caused original green tube to broke.
Swap green neck board with red and see if problem follows.
Or replace neck board with same part number from your part machine, it's probably not same in lower end Seleco."

I'm not sure what the green cut of does or how it works but you could be right? The main transistor on the seleco 800 Neck board is: C4686a
http://www.toshiba.com/taec/components2/Datasheet_Sync//66/7834.pdf

Can you explain how the cut of works?

The cables that feed the neck boards on the seleco 800 are different to the lower 400 / 500 so i can't swap them from an earlier set unless i find out what all the cables do? That may work but i would need help!
I think that the main transistor from the lower spec selecos are different by quite a bit i will try get some photo's up for you of each neck board as no doubt that may give you some ideas?

So if the High voltage is different between the two projectors, are you saying that it should not matter? I think its like swapping three 07ms tube for three SD187 tubes??

Thanks again

Steve