CurtPalme.com Home Theater Forum

[matze584]

Hi all!

Since today i have a serious problem regarding my BD801s ( hm.. both of them )...

I were watching a movie as my projector suddenly showed an error on i2c-Bus which disappeared after about three seconds.
After that, the picture started getting bigger and smaller in both X and Y Axis simultaneous.
I opened the Case and heard a sizzling sound (like a corona-discharge) somewhere between the tubes.

The same projector had a defective focus-board some weeks ago.
It also had this corona-discharge-like sound coming off from it.
After replacing it, things were almost ok. Just on powering on the unit, there was always some arcing
in the Tube-Area. (not the standard electrostatic crisping, but some cracking noise).

Now i decided to unmount the Unit and replace it by my "known good" reserve unit.
But.... as i powered this unit before mounting it on the ceiling, it did almost the same strange things:
- HV Comes up
- typical electrostatic sounds..
- strange whistling (with much higher volume as normally)
- arcing... somewere.

I tried to track the problem down to a particular module, but can't find the reason for the arcing, nor the location.
Removing the EHT-strips of the tubes out of the splitter doesn't show any changes in behavior.

After all, i think its caused by the Quadrupler-Unit / HV-Regulation, as my replacement-BD801 worked
great until i tried the old Focus-Board out of my primary unit with it, to check if it behaves here as in
my primary unit before i ordered a new focus board.
After that i didn't check my replacement unit again but only put in its original focus-board.

May it be, that the Quadrupler and/or HV-Regulation in both units was destroyed by the defective Focus-Board?
What may be a reason for arcing here, even if it arcs without connected EHT on the tubes? (Focus-Network in the
tube sockets ?)

I would be very happy for any hint or idea

Greetings!
Matthias

[rpruen]

Not sure if this helps, but something like this happened to my 701. It turned out to be a focus leak, that had eaten the plastic/bakelite fitting on the back of the tube. You could pull the sockets off the back of the tubes and have a look.

It made a strange quiet arc sound that wasn't easy to locate. Mostly because it was under the tube socket, as in your case disconnecting EHT did not make it go away, but removing the neck board did show it up.

Hopefully others will have some more ideas.

Richard

[Curt Palme]

If you can hear arcing, you should be able to see it. As Richard says, a leaky CRT socket can overload the focus block, shorting it out, but if you do get a picture, then the quad should be OK.

the pix fluctuating in size is indeed the HV changing in value, in your case most likely due to a short/arc somewhere.

Disconnect each red focus lead going to each CRT socket one at a time. If one lead is bad, the other two tubes will work fine/show a good picture once the arcing one is disconnected.

[Curt Palme]

If you can hear arcing, you should be able to see it. As Richard says, a leaky CRT socket can overload the focus block, shorting it out, but if you do get a picture, then the quad should be OK.

the pix fluctuating in size is indeed the HV changing in value, in your case most likely due to a short/arc somewhere.

Disconnect each red focus lead going to each CRT socket one at a time. If one lead is bad, the other two tubes will work fine/show a good picture once the arcing one is disconnected.

[matze584]

Hi !!


Thank you very much for that unbelievable fast response!

So i tried the tip with disconnecting one focus lead after another.
By disconnecting the blue Tube from the focus-block, at least my reserve-unit stopped
arcing! I then removed the blue tube-socket and found a little crack in the bakelite fitting.

But how to solve that problem?
Do i need a new bakelite-part from a burned tube to replace this one? or could i also try to cut out the
burned (and thus conductive) plastic/bakelite using a dremel tool ? (last one works for tube-sockets in
guitar-amplifiers driven with 800V Anode voltage who also like to burn their sockets )

Maybe its (also) inside the socket itself?
The Socket itself looks pretty well from the outside.
Barco unfotunately decided to fill the fokus-resistor-chamber
at the socket with silicone.. so i can't see anything there

Thank you all again! we are near to solve it !

Greetings!
matthias

[Curt Palme]

Replace it. I've got them for $20 plus about $10 shipping. Once HV starts arcing, you're best to change the socket.

email me at curtpalme@shaw.ca and send me a pix of it so I can get you the right one. Anything you try and glue/chip away on that socket will be a temporary repair at best.

[Curt Palme]

Replace it. I've got them for $20 plus about $10 shipping. Once HV starts arcing, you're best to change the socket.

email me at curtpalme@shaw.ca and send me a pix of it so I can get you the right one. Anything you try and glue/chip away on that socket will be a temporary repair at best.

[matze584]

Hi Curt!

Now its anyway a question, wich part is defective here. The bakelite-fitting or the socket itself.
I think we are on the right way, so i would like to try if my main projector is arcing on the blue tube too.
This would hopefully show, that i've burned both sets with the defective focus-board.
After that, i will try to track the problem down to where we know if it is caused by the neckboard/socket-assembly
or by the bakelite-fitting.
I fully agree that any repair on the socket is only a temporary solution, so i will get back to you after i completly understand
the problem to get to the right replacement parts from you
After all, i live in germany and shipping two small parts over the big sea seems to be a bit overkill. Even if we don't know
wich of the two related parts is the defective one.

I'll look after it tomorrow!

Cheers!
Matthias