Any hope on saving this WG K7193 Monitor?

[FritzsCorner]

I just picked up my first arcade cab today http://forum.arcadecontrols.com/index.php/topic,129576.0.html under the assumption that all parts would need to be replaced.  The guy I got it from was pretty sure that it was a non-working cab but I went ahead and got it anyways since it was dirt cheap.  I got it home and fired it up and it seems like the PSU is working, the marquee light powers on, the coin mech lights power on, and the Capcom Game board fan kicks in as well.  The monitor didn't do a thing though, so after following a guide to discharge the monitor (which seemed to not have a charge at all) I started looking around for model numbers underneath all the layers of dust and dirt.  In the process I bumped the neckboard and it looks like I cracked the part that connects to the back of the CRT.  My question for you guys is, based on the very limited information and pictures I have provided, is there enough to go on to determine if this monitor is salvageable or if it just just needs to be replaced completely?

Aaron

[jhobbs]

cracked the part that connects to the back of the CRT

The glass part/gun or just the board?

It looks like the connection to the tube just isn't seated properly.

edit:left off second sentence

[FritzsCorner]

I can't really tell.  Is all the grey stuff around the base where the "crack" is just some sort of sealant and not really a crack? I can't tell what it is but don't want to force anything or make it worse.  I wanted to remove the neckboard, etc. to clean it and see if I can find any other signs of damage.

[lilshawn]

just push it back on. it looks like the plastic part that's normally attached to the neck there has come off.

they have a plastic part that keeps the pins aligned. normally the part stays on the tube, but i have has a few pull off and get stuck in the socket.



if still nothing, come back...you have some diagnosing to do.

[FritzsCorner]

So I pushed it back together and it seems to be seated properly.  At this point I have starting my troubleshooting with the PSU which I have detailed over in the restoration forum here: http://forum.arcadecontrols.com/index.php/topic,129576.msg1325733.html#msg1325733

From what I can tell I have a bad PSU but wouldn't mind a little "peer review" of my troubleshooting steps from someone that knows a bit more than I do on this topic.

Thanks again guys for all your help.

[FritzsCorner]

After working with the guys over in this thread: http://forum.arcadecontrols.com/index.php/topic,129576.msg1325958.html#msg1325958 it looks like the PSU is working fine.  I had a blown fuse on the monitor board which after replacing blows as soon as it is powered on.  I have the specifics in the other thread but wanted to cross post as this may be the better home for this discussion now it has been narrowed down to the monitor. 

[lilshawn]

blown fuse at power on?

sounds like the HOT or the Regulator is toasted.

if you can take out the HOT transistor and light up a 60 watt lightbulb with the B+ regulator, then the HOT is shorted.

if you take out the HOT and put a lightbulb on the regulator and the fuse still bows, then the regulator is shot.

[Furry131]

Fritz.  Check your other thread. I put up some really good info for you.

[FritzsCorner]

Thanks for the tip lilshawn!
Based on feedback that I got from you in this thread and from furry over here: http://forum.arcadecontrols.com/index.php/topic,129576.msg1326000.html#msg1326000 I feel like I have a good idea of what my next steps are. 

I do have a question regarding your suggestion that I try testing the regulator and HOT using a 60 watt light bulb.  Are there any tricks in doing this? I am trying to picture the best way to make the connection between the board and the bulb.

Looking at the location of the regulator and the HOT I think I will need to pull the monitor out of the cab to access these components and then put it back in to do the testing.. unless there is a better method that I am missing. 

Thanks again!

[lilshawn]

Looking at the location of the regulator and the HOT I think I will need to pull the monitor out of the cab to access these components and then put it back in to do the testing.. unless there is a better method that I am missing. 

Thanks again!

you could pull the board and do all your hookups and then place the board back in.

or

pull the monitor out and extend your power connections out of the cabinet.

(you need the isolated power the cabinet provides. don't try to power it directly from an outlet.)

I do have a question regarding your suggestion that I try testing the regulator and HOT using a 60 watt light bulb.  Are there any tricks in doing this? I am trying to picture the best way to make the connection between the board and the bulb.

nope no trick. get yourself a light bulb and a socket with some kind of wire on it..or even a lamp with a plug on it and use a cut off extension cord or replacement end to plug it in. you basically want a light bulb with 2 bare wire ends where you can hook them up to your circuit.

 connect one side to the chassis ground and the other to the output of the regulator, be it with alligator clips or soldering directly to the spot. or lifing the leg out aqnd conneting to that...there's lots of ways of doing it. (depending on which version of regulator your chassis uses depends on what pin is the output. check with www.alldataheet.net for your regulator #'s pinout.)

you more or less need to disconnect the output of the voltage regulator from the rest of the circuit, but still maintain a load on the regulator to ensure it runs. this is what the light bulb does.

if the light bulb comes on strong it's probably good. if nothing or the fuse blows, the regulator is shot. (be sure you use the correct type and rating of fuse. i believe its a 2 amp "slow blow" type)

[FritzsCorner]

First, I just wanted to thank you for taking the time explain things so that a newbie like me can understand! 

So I went ahead and removed the monitor chasis tonight and before I do the Light Bulb test I just wanted to do a simple test with a DMM.  Looking at one of your posts in another thread: http://forum.arcadecontrols.com/index.php/topic,119061.msg1261286.html#msg1261286 you said the following:

what you want to do is put your black probe on the middle leg and then touch either of the 2 outside ones. if either leg reads short(0 ohms) or low resistance (1,2,3,4 ohms etc.) it's bad. it should read really high (1000's of ohms) or open... reverse red and black and test again for good measure. it's not a 100% test but will give you an idea if it's toast or not.

So I went ahead and tried this out myself I was getting 002 on both the left and right legs.  So from what you said, this would be a pretty good indicator that the HOT is toast, is this correct?  If so, at this point is it still worth doing the light bulb test?  I know you said it's not a 100% test but comparing what you say to what I read in a Randy Fromm flowchart for the k7000 it seems to be one of the most common failures that causes the fuse to blow. 

Looking at the chasis I am starting to wonder how I can even remove the HOT to replace it.  it seems to be tightly clamped up against a metal housing making it seem like it would be really hard to get at. 

*Edit* I figured out how to remove the little clip that holds it on. 

I posted a few photo's of my chasis and to the untrained eye it looks like it has undergone some maintenance before.

[MTPPC]

Ugh... late to the party.

[buffett]

did you get it running.

all those parts are there from the factory.

you have a Zenith 25" K7000a chassis to work on.

everything on that chassis can be fixed with the exception of the flyback.
if it is bad you will have to find another working doner.

replace your H.O.T. and check C36, 37, and 38 for shorts.

wild you have it out install a cap kit it needs one after all theses years.

and give the chassis a good re-flow along with the neck board.

Peace
Buffett