UPDATE: G07 Monitor Issues - Please Help!

[wakerlet]

Hello,

I have a 19" G07 that was taken out of an astro invaders cabinet a few months back.

[dabone]

Just a guess, have you tried reseating your yolk wires with the monitor powered OFF.


( I glanced at the trouble shooting chart over at randy fromms and it doesn't cover that failure.)

Later,
dabone

[Raven..]

Vertical deflection may be out.

[dabone]

But from the pic he has vertical deflection. Just no Horizontial deflection.



Later,
dabone

[Ken Layton]

You probably have a bad width coil (open circuit) or bad solder joints on the width coil.

[wakerlet]

Thank you everyone for your response.   I have a couple of questions of course.

1.  How do I test if it is the deflection?  If it is the horizontal or vertical deflection, how easy might this be to fix?  Should I just contact Bob Roberts?

2. Ken, how do I test the width coil?  More specifically, what is the width coil, lol?  How can I fix this problem?

Thanks again.
-Todd

[Ken Layton]

Here's a picture from Bob Roberts' site. The circled "Width Adjust" is the width coil. The width coil on Electrohomes runs hot and they fail alot. Usually they litterally fall apart and/or the coil shorts/drops in resistance value. They are delicate.

Just replace the width coil anyway as they only cost $10 or so. When replacing, the coil has four terminals: two actually connected to the coil of wire and two that are dummies (strictly for mechanical support). The circuit board is silkscreened with a schematic symbol for a coil and the terminals with the actual coil connect there. It's easy to see which terminals on the coil to use since they are the only ones with wires hooked to them (the dummy terminals have nothing connected).

[Ken Layton]

I just looked a little closer at your picture of your monitor board and your width coil is missing! Somebody took it! 

[wakerlet]

I just looked a little closer at your picture of your monitor board and your width coil is missing! Somebody took it!

[Ken Layton]

Yup, just order one and pop it in and you should be good!

[Raven..]

Nice catch Ken!  Who would have thought somebody would do that?

[wakerlet]

Ken,

I ordered the width coil and installed it.

[Ken Layton]

Yes, by all means resolder the pots (they are delicate, but if broken Bob Roberts sells the replacements). Definitely get a capkit installed before doing anything else. Go to www.dameon.net/BBBB/ and click on "G07 Model CAO" capkit instructions.

[wakerlet]

UPDATE:

Ken,

I installed the cap kit (thanks for the link) and put new solder on all of the pots (except the vsync).  Pluged it in and was able to get the horizontal to sync but not the vertical. 

So in frustration, I quit for the night.  Went down in the morning, turned it on a everything sync'd.  Weird.  30 minutes later vsync was lost and I had a rolling screen again.

OKAY HERE IS THE BAD PART.  So in my sleep deprived state I did not screw in the chassis.  I just placed it in there, stupid, I know.  So trying to adjust the vsync I noticed that if I picked up one side of the chassis, the vertical sync'd.  placing it back down and no sync, up - sync, down-nope.  Interesting.  Okay now I'm thinking I'm, bad connection on the vsync...So I place the board back down, something slips, the bottom of the board hits the frame, POP (or CRACK, insert electrical sounding noise), and the monitor goes blank.  After a little time, I screw in the chassis this time.  plug it back in and nothing

Don't see anything on the board that would pinpoint what blew.  Any tips on finding what I broke?  Or what happened (is assume I grounded something that shouldn't have been.

Thanks for taking on this charity case.

-Todd

[Ken Layton]

Could you have blown the fuse, horizontal output transistor, or voltage regulator transistor?

[ChadTower]

Sounds like something physically broke.  Start assuming that at the very least some solder joints are now broken.

[wakerlet]

Could you have blown the fuse, horizontal output transistor, or voltage regulator transistor?

Thanks I have ordered these parts.  I have one additional question about the v-sync pot.  The wiring for it is really funky.  Can you tell me what the hell they did with it?

Top and bottom pictures attached.

[wakerlet]

Larger top picture.  And where the heck is C501?  I couldn't replace the cap because I didn't find it or C303.  According to Bob I should:

"
-First.. remove C501 & chuck it out.
-Second.. remove C303 & place it in the holes for C501 & solder.
-Third.. clean the solder from the hole between the 2 holes where C303 was removed & fill in the one furthest from the chassis edge with solder.
-Fourth.. put a 10 to 22uf @ 25 volt minimum in the now closer together holes at C303 with the longer positive lead going thru the hole closest to the edge of the chassis PCB & solder.
"
That was hard since I couldn't find either cap.

Thanks much
Todd

[cw]

I worked on one like that not long ago...Its a very early ver of the board from what I could find about it.  I didnt see a way to upgrade the board and just ended up recapping what I could.  Its been up and running for about 2 months and seems to be fine

[Ken Layton]

That vert hold pot is wired correctly from the factory. You have to remember that the G07-CAO (a.k.a. "wide chassis G07") was a home television chassis modified to be an arcade monitor. That small white circuit board attached to the main board with the video input/sync connector is an RGB/sync interface board. This monitor accepts POSITIVE SYNC ONLY (which was what some of the early color video games generated). Modern games (including JAMMA) use NEGATIVE sync.

Disregard all the instructions about C501 and C303 as those caps and that sync upgrade apply ONLY to the regular G07-CBO, not to the wide chassis CAO. By the way the wide chassis uses the same flyback as the normal G07 does.

[dabone]

To get that monitor to sync you will need the following circuit.


Sync from the pc into pin 1 output from pin 2 to the monitor.

If you need seperate syncs just repeat with pins 3 and 4 for the other sync.

http://www.twobits.com/RGB/sync.html


Later,
dabone

[wakerlet]

That vert hold pot is wired correctly from the factory. You have to remember that the G07-CAO (a.k.a. "wide chassis G07") was a home television chassis modified to be an arcade monitor. That small white circuit board attached to the main board with the video input/sync connector is an RGB/sync interface board. This monitor accepts POSITIVE SYNC ONLY (which was what some of the early color video games generated). Modern games (including JAMMA) use NEGATIVE sync.

Thanks much Ken.

God, now I feel stupid.  I'm trying to get this thing to sync with my centipede cocktail which is using negative sync.  No wonder I could not get the thing to stop rolling.    I'm assuming if I get a working CBO chassis, I can use that with the current tube, yes?

[wakerlet]

To get that monitor to sync you will need the following circuit.


Sync from the pc into pin 1 output from pin 2 to the monitor.

If you need seperate syncs just repeat with pins 3 and 4 for the other sync.

http://www.twobits.com/RGB/sync.html

Thanks dabone!

[Ken Layton]

Wakerlet;

Yes, I believe you can use a CBO chassis with this tube and yoke. The only difference appears to be with the circuit board holder clip position and screw bracket on the left side would need to be moved over to the right a few inches to accomidate the narrower chassis & secure it in place.