CurtPalme.com Home Theater Forum

[Motobias]

Yesterday im picked up a dirt cheap 808 which was dead when i got it and looked horrible from the outside.
Anyway...took the set home and tubes are brilliant i would rate at least 8-9, 2300h on the set !
i had to change the smps fuse and the replace the g2 board because it kept shutting the unit off after a few seconds.
g2 board from my other 808 brought it back to life and it was doing fine.
adjusted g2 voltages and 17v reference and kept it running for an hour with computer attached to it playing videos.
then i thought i should add convergence...and first change it from front ceiling to front table mode - then the trouble started !

setting the single switch for ceiling/table made the set power up but not bringing up the status screen, also locking all remote controls and bringing up a rcu error - wtf ?!?
setting the switch back, everything was fine...
then i changed the front/back switches...same problem - wtf ?!?

operated the switches a couple of times - did not change a thing !
then i got myself pcb cleaner and sprayed the switches, waited couple of minutes and cleaned them out with compressed air.
that transported the cleaner AND some murky liquid out of the switches... smelled like rotten water and wouldn't evaporate...
so it can only be WATER ?!

everything else in the set is looking fine and there is no clear evidence that the set has been sitting outside and/or that it got moisture inside !


i think the switches are gone or badly corroded, causing the error in the controller but can't really verify that.

has anyone ever had a similar problem and/or got it fixed somehow ?
how are the pins laid out, so i can check the continuity of the switches and their resistance ?
is there a way to unsolder the switches without taking the main pcb out of the unit(opening the bottom) ?

got some pictures of the set...not the actual problem
at the very bottom...


http://www.facebook.com/media/set/?set=a.10150403825268502.446567.738343501&type=3&l=f1324298fa

all help appreciated

[Ile]

[Motobias]

hmm...cleaned switches as good as possible from the top...because getting the main pcb out will be a pain in the ass and i hope i don't have to ! (includes unsoldering wires - pretty sure about that)
checked for bad solder joints on deflection boards and cleaned contacts aswell...nothing !
weird thing is that either front/back or ceiling/table will cause the same problem and i think that at least the single multi contact switch for ceiling/table should be good...
could it be a firmware issue ?

[Decibel]

You could replace the frame (motherboard) because could be bad a reverse scan switch, but the disassemble motherboard is very difficult.
So if you have another 808 ... swap all better boards and better tubes into this other chassis and try.
I had a reverse scan switch bad in a my projector and it was impossible to found.

[Motobias]

ok the switches seem to be alright...
they are pulling either hsi or vsi on the controller to ground
in my working configuration (front/ceiling) hsi is pulled down and vsi is up.
if i change either horizontal or vertikal i am getting the error!

hsi vsi
down up WORKING
up up ERROR
down down ERROR
up down ERROR

ERRRRRRRRR !!!!

i am thinking about just setting the switches and cut/short the cables according to my needs...but that's not the way !!!
so am i facing a controller problem ? maybe the diodes next to the pin headers ?!
i am getting a second controller beginning of next week and will try that...

[Decibel]

There are four switches.

This is the positioning for the different mounting configurations

[Motobias]

aaaaaaaaaaah i'm not stupid !
JEEEEEEEZEEEZ

[Motobias]

vsi and hsi end up on the 80c32 standby processor... can this one go bad ?
maybe i changed a switch without making sure that the standby voltage was completely gone or off...

CUUUURT help me in my misery !

[barclay66]

Hi,

I know that such a problem can be PITA. Nevertheless I would suggest that You stop for the moment and wait for the controller You're getting next week. By swapping it You could rule out a lot of potential problems at the same time. And You could make things worse in the meantime. In fact, I think that the controller is the least probable cause.
If You take a look at the Frame schematics You will see that the switches are directly connected between the H-Deflection / V-Deflection Boards and the Deflection Yoke connectors. They are used to switch the polarity of the Deflection signals as needed. So we can expect that the entire Deflection current will go across them and that can be a significant amount of current (even soldered yoke connections or plugs sometimes simply burn away). Any kind of contact weakness will most likely result in contact burn and additional failures.
I have a complete Barco Graphics 808 in parts (I took apart a set with dead tubes). So if You need some measurements for comparision or even the complete Frame I could be of help.
BTW: No soldering is needed in order to swap a Frame as long as You swap the HV-Splitter together with it!

Regards,
barclay66

[Motobias]

oh yes...it is a PITA
the switch contacts for the deflection yokes seem to be alright and won't cause such a problem...unless they cause a scan fail signal, but that on the other hand would cause a different behaviour !
where are you located in germany ?
crt owners need to stick together

[barclay66]

[Decibel]

[Motobias]

here's what i found

[Motobias]

ok...i must admit i haven't tried harder so far.
today i damaged my little finger with an angle grinder, so i get to think about this issue a bit more.
as i can not access the projector atm and i only have a second faulty controller, it's all about clever ideas now
i think i will cut the cable that tell the controller how the switches are set and see what it does.
of course it won't have the right information about where left/right and up/down is, but it might fix the problem that the projector will not start up.
if this fixes it, the according chip on the controller is bad, or the controller screwed alltogether !

my first bg808 will serve as a donation device anyway, as the green is to bad to use... or in case the mainboard is bad, i'll switch over the green tube and all good boards into it...but if the cotroller is bad, i am back where is started.

i still have my xg135 which will be the first choice to put in, the green tube is my only concern !

[gjaky]

The question is why is it important for the controller board how is it mounted? For example on my PG xtra I have to set in the menu how the pj is mounted, but that is only affects the astig drive, every other connector needed to be set manually for the right operation, all yoke have a two pin connector so from projector side there is no way to find out how are the yokes connected. I think your idea should work, the only thing you have to find out is which functions are inverted by software (like the astig in the case of NEC), if you find them you have to reverse those corresponding yokes and that's all.


Is a new controller board expensive?

[km987654]

[Curt Palme]

Yes, I have had a controller board bad in an old BG800 many years ago. It wouldn't work with the V scan switch in one position because of that one wire that connects to the control board. I spent hours trying to figure it out back then.

I would change the controller board. I've got them at $50 plus about $20 shipping, but I'm out of town until Oct 18.

[Curt Palme]

Yes, I have had a controller board bad in an old BG800 many years ago. It wouldn't work with the V scan switch in one position because of that one wire that connects to the control board. I spent hours trying to figure it out back then.

I would change the controller board. I've got them at $50 plus about $20 shipping, but I'm out of town until Oct 18.

[Motobias]

ok...it's the controller !
switched the controller over into another 808 with short in controller board and tried to fire it up - same problem !
set the switches accordingly and it came right up...
changed eeproms over, works but same issue.
so somehow the controller is bad...

now i am stuck with two dead graphics 808
one dead controller, another one with this issue and one bad smps !
any suggestions on how to repair a shorted controller ?
anyone got circuit diagrams for the controller ?

[Motobias]

i just cut the hsi and vsi cable to the controller and set the switches for front/table.
weird thing is that the software somehow senses it right but then of course mixes up top/bottom and left/right
well at least it's working now...somehow

i blew another smps aswell and it's now just blowing every main input fuse - damn !

not that much luck with barcos, but i am still trying