Hey everyone,

I've two 50" Toshiba RPTVs for arcade games (Sega Megalo 2) with some
issues.

I've never repaired RPTVs before, although have done plenty of arcade
monitor repair. I'd basically need some info on these beasts before I
accidentally try fixing something that isn't broken.

Does anyone have schematics for these? The model numbers a P502SG
and P500GKB

The problems I am having with them:

-Convergence... far off... probably convergence ics need changing,
though those are the least of my worries as I can get them locally. I
don't have a remote for them yet so can't even try to adjust it, and
it might only be because the convergence rings on the crt necks are
loose as heck.

-Geometry errors! I am getting asymmetrical geometry errors that are
different for each colour. Green seems okay, Red image is pulled
upwards in the right upper corner, and blue is the same way in the
upper left corner. Is this something that can be adjusted in the
service menu, or are there only symmetrical adjustment options ?
(Meaning that the red image is only distorted in the upper right hand
corner, and all other corners seem to be fine, thus I'm not sure it
could be fixed by adjusting linearity as lin adjustments do
symmetrical changes.)

The geometry errors are my main concern as I've no idea what would
cause asymmetrical image distortion, never seen such happen in regular
CRTs. Capacitor faults are what cause most of the problems there but
they usually cause distortion on both ends of the picture be it
vertical or horizontal problems.

On the same note does anyone have any info on rptv CRT
interchangeability ? I'm specifically wondering if the crt tubes
themselves can be changed between different makes and models like
regular CRT monitors? (Meaning if the tube has the same number of pins
and the same yoke resistances/inductivity)

Thanks for any and all help guys!

On Sun, 26 Dec 2010 13:14:24 -0800, József Bucher wrote:

Hey everyone,

I've two 50" Toshiba RPTVs for arcade games (Sega Megalo 2) with some
issues.

I've never repaired RPTVs before, although have done plenty of arcade
monitor repair. I'd basically need some info on these beasts before I
accidentally try fixing something that isn't broken.

Does anyone have schematics for these? The model numbers a P502SG and
P500GKB

The problems I am having with them:

-Convergence... far off... probably convergence ics need changing,
though those are the least of my worries as I can get them locally. I
don't have a remote for them yet so can't even try to adjust it, and it
might only be because the convergence rings on the crt necks are loose
as heck.

-Geometry errors! I am getting asymmetrical geometry errors that are
different for each colour. Green seems okay, Red image is pulled upwards
in the right upper corner, and blue is the same way in the upper left
corner. Is this something that can be adjusted in the service menu, or
are there only symmetrical adjustment options ? (Meaning that the red
image is only distorted in the upper right hand corner, and all other
corners seem to be fine, thus I'm not sure it could be fixed by
adjusting linearity as lin adjustments do symmetrical changes.)

The geometry errors are my main concern as I've no idea what would cause
asymmetrical image distortion, never seen such happen in regular CRTs.
Capacitor faults are what cause most of the problems there but they
usually cause distortion on both ends of the picture be it vertical or
horizontal problems.

On the same note does anyone have any info on rptv CRT
interchangeability ? I'm specifically wondering if the crt tubes
themselves can be changed between different makes and models like
regular CRT monitors? (Meaning if the tube has the same number of pins
and the same yoke resistances/inductivity)

Thanks for any and all help guys!


Educated guess: If you suspect convergence ICs most of the other
anomalies may be linked to the convergence processing. I would replace
those first, find a service man alignment and go from there. You gotta
start somewhere.


--
Live Fast, Die Young and Leave a Pretty Corpse

On Dec 26, 4:14*pm, József Bucher wrote:


The geometry errors are my main concern as I've no idea what would
cause asymmetrical image distortion, never seen such happen in regular
CRTs.

Don't worry about the geometry, just correct the convergence problem
and all will be well..

I pulled the power/convergence boards out of both today, and could see
nothing wrong. The thing has STK392-020 convergence ICs, or at least
had. One (the same location on both boards) has been replaced with an
stk392-040. I checked all the resistors, as i understand that
convergence IC fault results in burnt resistors, but none test open,
actually everything seems to be fine. There are burnmarks on the power
supply board around a diode on both power supplies, but the diode
isn't shorted and neither are any of the resistors around.

Is there a definitive way of testing the convergence ics themselves? I
suspect that the previous owner tried to fix the projectors but onyl
replaced one of the two ics and then wondered why it didn't work... or
somesuch... so I'd like to test the ics themselves... 4 of these
things would be a slight waste of money... (Can get them locally and
if I buy 3 or more I get a discount, but wouldn't like to buy them if
it turns out they're not at fault...)


One more question... how do you discharge the crts in these things?
The suction cups seem to be completely glued in with silicone from the
factory...

On dec. 27, 14:04, Stroonz wrote:
On Dec 26, 4:14*pm, József Bucher wrote:



The geometry errors are my main concern as I've no idea what would
cause asymmetrical image distortion, never seen such happen in regular
CRTs.

Don't worry about the geometry, just correct the convergence problem
and all will be well..

On Dec 27, 3:14*pm, József Bucher wrote:
I pulled the power/convergence boards out of both today, and could see
nothing wrong. The thing has STK392-020 convergence ICs, or at least
had. One (the same location on both boards) has been replaced with an
stk392-040. I checked all the resistors, as i understand that
convergence IC fault results in burnt resistors, but none test open,
actually everything seems to be fine. There are burnmarks on the power
supply board around a diode on both power supplies, but the diode
isn't shorted and neither are any of the resistors around.

Is there a definitive way of testing the convergence ics themselves? I
suspect that the previous owner tried to fix the projectors but onyl
replaced one of the two ics and then wondered why it didn't work... or
somesuch... so I'd like to test the ics themselves... 4 of these
things would be a slight waste of money... (Can get them locally and
if I buy 3 or more I get a discount, but wouldn't like to buy them if
it turns out they're not at fault...)

One more question... how do you discharge the crts in these things?
The suction cups seem to be completely glued in with silicone from the
factory...

On dec. 27, 14:04, Stroonz wrote:



On Dec 26, 4:14*pm, József Bucher wrote:

The geometry errors are my main concern as I've no idea what would
cause asymmetrical image distortion, never seen such happen in regular
CRTs.

Don't worry about the geometry, just correct the convergence problem
and all will be well..- Hide quoted text -

- Show quoted text -

To discharge the CRT High Voltaage, use a pair of grounded pliers
holding a hatpin in the pliers and go thru the rubber, or better yet
go between the glass and the rubber. Can't help with the convergence.

I know how to discharge a crt, but since these are glued in, I thought
there may be a trick to it like simply de-attaching the HV line from
the flyback and grounding it there instead of having to remove every
single cup just so I can get out the other board aswell. Thing is I
didn't want to tear out the suction cups, but oh well. (And no I'm not
plannign to mess around too much with the video board, but since I'm
doing arcade restorations here, I clean even the pcbs.)

Anyways... I took the plunge... 4pcs of STK392-040 and some other
parts I've been waiting to get are on their way... this wasn't a cheap
order... 110 USD with next day shipping. (Four STKs, one hantarex
flyback and a handful of capacitors... pricey...)

We'll see what happens when I replace the ICs tomorrow.

On dec. 28, 05:44, " wrote:
On Dec 27, 3:14*pm, József Bucher wrote:





I pulled the power/convergence boards out of both today, and could see
nothing wrong. The thing has STK392-020 convergence ICs, or at least
had. One (the same location on both boards) has been replaced with an
stk392-040. I checked all the resistors, as i understand that
convergence IC fault results in burnt resistors, but none test open,
actually everything seems to be fine. There are burnmarks on the power
supply board around a diode on both power supplies, but the diode
isn't shorted and neither are any of the resistors around.

Is there a definitive way of testing the convergence ics themselves? I
suspect that the previous owner tried to fix the projectors but onyl
replaced one of the two ics and then wondered why it didn't work... or
somesuch... so I'd like to test the ics themselves... 4 of these
things would be a slight waste of money... (Can get them locally and
if I buy 3 or more I get a discount, but wouldn't like to buy them if
it turns out they're not at fault...)

One more question... how do you discharge the crts in these things?
The suction cups seem to be completely glued in with silicone from the
factory...

On dec. 27, 14:04, Stroonz wrote:

On Dec 26, 4:14*pm, József Bucher wrote:

The geometry errors are my main concern as I've no idea what would
cause asymmetrical image distortion, never seen such happen in regular
CRTs.

Don't worry about the geometry, just correct the convergence problem
and all will be well..- Hide quoted text -

- Show quoted text -

To discharge the CRT High Voltaage, use a pair of grounded pliers
holding a hatpin in the pliers and go thru the rubber, *or better yet
go between the glass and the rubber. *Can't help with the convergence.

On Dec 28, 8:03*am, József Bucher wrote:
I know how to discharge a crt, but since these are glued in, I thought
there may be a trick to it like simply de-attaching the HV line from
the flyback and grounding it there instead of having to remove every
single cup just so I can get out the other board aswell. Thing is I
didn't want to tear out the suction cups, but oh well. (And no I'm not
plannign to mess around too much with the video board, but since I'm
doing arcade restorations here, I clean even the pcbs.)

Anyways... I took the plunge... 4pcs of STK392-040 and some other
parts I've been waiting to get are on their way... this wasn't a cheap
order... *110 USD with next day shipping. (Four STKs, one hantarex
flyback and a handful of capacitors... pricey...)

We'll see what happens when I replace the ICs tomorrow.

On dec. 28, 05:44, " wrote:



On Dec 27, 3:14*pm, József Bucher wrote:

I pulled the power/convergence boards out of both today, and could see
nothing wrong. The thing has STK392-020 convergence ICs, or at least
had. One (the same location on both boards) has been replaced with an
stk392-040. I checked all the resistors, as i understand that
convergence IC fault results in burnt resistors, but none test open,
actually everything seems to be fine. There are burnmarks on the power
supply board around a diode on both power supplies, but the diode
isn't shorted and neither are any of the resistors around.

Is there a definitive way of testing the convergence ics themselves? I
suspect that the previous owner tried to fix the projectors but onyl
replaced one of the two ics and then wondered why it didn't work... or
somesuch... so I'd like to test the ics themselves... 4 of these
things would be a slight waste of money... (Can get them locally and
if I buy 3 or more I get a discount, but wouldn't like to buy them if
it turns out they're not at fault...)

One more question... how do you discharge the crts in these things?
The suction cups seem to be completely glued in with silicone from the
factory...

On dec. 27, 14:04, Stroonz wrote:

On Dec 26, 4:14*pm, József Bucher wrote:

The geometry errors are my main concern as I've no idea what would
cause asymmetrical image distortion, never seen such happen in regular
CRTs.

Don't worry about the geometry, just correct the convergence problem
and all will be well..- Hide quoted text -

- Show quoted text -

To discharge the CRT High Voltaage, use a pair of grounded pliers
holding a hatpin in the pliers and go thru the rubber, *or better yet
go between the glass and the rubber. *Can't help with the convergence..- Hide quoted text -

- Show quoted text -

Keep us informed of your progress (or lack thereof).

Unfortunately it's a lackthereof...

Since these two projectors share the same power/convergence output
boards, I replaced the convergence ics on one, and tested both with
it. Also replaced -all- electrolytics on the board, checked all the
resistors, even replaced three caps in the powersupply section that
seemed dodgy.

-No- change whatsoever. Since I don't have a remote yet I can't test
if convergence adjustments actually work. I checked power supply
outputs on the resistors near the STKs, and +35,-35,+15,-15 volt
supplies all check out to within .1 volts. Checked 12 volts on the
power board, it seems slightly low, but since 12 volts is usually
unregulated, I'm pretty sure 10.8 volts is fine.

At this point either the STKs are not getting good control signals, or
the problem lies on the deflection board.

Any tips/tricks you guys have? Maybe I forgot about something? I hear
pico fuses mentioned a lot, but could not for the life of me find
anything remotely resembling a fuse on the convergence output board.
The only fuses I found were on the powersupply board and they all
checked fine.

Does anyone perhaps work in the industry and have schematics for this
thing? I'm pretty sure Toshiba used these in commercial RPTvs too.
Also does anyone have any documentation on how to calibrate the output
levels evenly on these things?

Any and all help would be appreciated. I'm pretty steamed at tossing
out that much money on the ics right now...

On dec. 29, 05:44, " wrote:
On Dec 28, 8:03*am, József Bucher wrote:





I know how to discharge a crt, but since these are glued in, I thought
there may be a trick to it like simply de-attaching the HV line from
the flyback and grounding it there instead of having to remove every
single cup just so I can get out the other board aswell. Thing is I
didn't want to tear out the suction cups, but oh well. (And no I'm not
plannign to mess around too much with the video board, but since I'm
doing arcade restorations here, I clean even the pcbs.)

Anyways... I took the plunge... 4pcs of STK392-040 and some other
parts I've been waiting to get are on their way... this wasn't a cheap
order... *110 USD with next day shipping. (Four STKs, one hantarex
flyback and a handful of capacitors... pricey...)

We'll see what happens when I replace the ICs tomorrow.

On dec. 28, 05:44, " wrote:

On Dec 27, 3:14*pm, József Bucher wrote:

I pulled the power/convergence boards out of both today, and could see
nothing wrong. The thing has STK392-020 convergence ICs, or at least
had. One (the same location on both boards) has been replaced with an
stk392-040. I checked all the resistors, as i understand that
convergence IC fault results in burnt resistors, but none test open,
actually everything seems to be fine. There are burnmarks on the power
supply board around a diode on both power supplies, but the diode
isn't shorted and neither are any of the resistors around.

Is there a definitive way of testing the convergence ics themselves? I
suspect that the previous owner tried to fix the projectors but onyl
replaced one of the two ics and then wondered why it didn't work... or
somesuch... so I'd like to test the ics themselves... 4 of these
things would be a slight waste of money... (Can get them locally and
if I buy 3 or more I get a discount, but wouldn't like to buy them if
it turns out they're not at fault...)

One more question... how do you discharge the crts in these things?
The suction cups seem to be completely glued in with silicone from the
factory...

On dec. 27, 14:04, Stroonz wrote:

On Dec 26, 4:14*pm, József Bucher wrote:

The geometry errors are my main concern as I've no idea what would
cause asymmetrical image distortion, never seen such happen in regular
CRTs.

Don't worry about the geometry, just correct the convergence problem
and all will be well..- Hide quoted text -

- Show quoted text -

To discharge the CRT High Voltaage, use a pair of grounded pliers
holding a hatpin in the pliers and go thru the rubber, *or better yet
go between the glass and the rubber. *Can't help with the convergence.- Hide quoted text -

- Show quoted text -

Keep us informed of your progress (or lack thereof).