WG 4900 help!

[Beretta]

ok so i've got this WG 4900 series that was in a joust cabinet (original monitor)

i bought it with the seller fore warning me it had no picture, but that he did not know what the cause was.

the cabinet door was in bad shape and screwed down.. so i did'nt take a look at it before transport.

getting it home i noticed the cardboard on the neck board had been cut, and the anode cap had been removed.

someone has clearly messed with this monitor.

to make things worse the chassis was unscrewed and laying loose on the frame, in my unprofessional opinion it does'nt look like the tube or chassis was damaged during transport though.

the project im putting to together is on a thin budget about 300 bucks (-75 to get the cab home)

buying a new monitor probably is'nt in the budget as a quick list of what i need i've only got about 50 bucks wiggle room here.

the tube has HEAVY burn in and i've been reading about tube swaps and this is something i'd consider if the chassis is still good, as i can get tv's without to much trouble.

but first i need to know what works and what does'nt on this monitor.


so where should i start? how can i tell if the chassis is still good (and a canidate for tube swap).. should i hook up the anode cap and give it the old "smoke test" or is there a way to test the chassis separately without a tube?


i've attached pictures below, i can take more of specific angles if needed reading basics of monitors i have a grasp on the major components but do'nt know how to test or diagnose them.

so i need advice on how to proceed, if all else fails i'll be going with a TV for this project although i'd prefer to use the arcade monitor instead of a tv's s-video.

also the isolation transformer is kinda rough looking with some rust, do these go bad? what should i do about that if anything, also i thought these had 2 ac in and 2 ac out, this one has quite a few wires coming off it.. also attached picture below.

[Kevin Mullins]

so where should i start? how can i tell if the chassis is still good (and a canidate for tube swap).. should i hook up the anode cap and give it the old "smoke test" or is there a way to test the chassis separately without a tube?

Unless you just want to send it to someone, then yes.....you'll have to hook it up and just see what it does or does not do. Otherwise no-one can really help with any kind of troubleshooting.
Most likely will need at a minimum a capacitor kit as they look mostly original in your pics.

A piece of tinted plexi does wonders for screen burn.
A tube swap can be tricky at times, but very possible.

also the isolation transformer is kinda rough looking with some rust, do these go bad? what should i do about that if anything, also i thought these had 2 ac in and 2 ac out, this one has quite a few wires coming off it.. also attached picture below.

That "rust" is nothing..... rarely ever effects anything. Take a small wire brush to it if it concerns you.
Those older Williams had multiple output taps because they produced several different voltages for the original power supply, etc.
You'll only need to be concerned with what is currently going to the monitor and the switching power supply.

[Beretta]

thanks, ok so hooking the anode cap back up, i just squeeze it a little and work it back into the hole?

or is there a particular method to it?

[Kevin Mullins]

I usually fold the "suction cup" back in half and insert one of the tangs and then push it sideways to insert the other tang.

You should also discharge the tube to be certain it hasn't built up a charge first.

And also be sure to mount or at least set the chassis in place where it belongs so that nothing is touching something it shouldn't be.

[Beretta]

ok heres what i did.

1. i put the chasis back in it's mounting and found 2 machine screws that fit, so it's secure.

2.  i took your advice and tried to discharge, i wired the screw driver to the frame using some 14ga household electrical wire i had laying around, stuck it in the hole.. nothing happen.

i then stuck the right prong in the hole, pushed right, then put the left prong in the hole.. it was'nt a death grip tight.. im not sure how snug these things are suppose to be but it did'nt seem like it was gonna come out, it moved but did'nt appear to wanan come out pulling straight on on it gently.

i quickly traced the wires back the jamma, it's a mess but it looks like it's going to the right spots (the jamma connector actually had label on it which was nice) but it was very close quarters so i can only say it was going "close" to where should be, i assumed it correct, the guy who sold it supposedly it did work at one time so i have no reason to believe the rgb ground and sync for the monitor is wrong.

3. i traced the wires for the monitors power going down to the transformer.. which btw has my head spinning i tought these things had in and out, not 20 connections coming off it.

it's goin got the transformer and thats about all i know.. i hate the mess of wires down there, it's got a connector coming off of it btw, with about 10 pins on it, going to nothing it's been zip tied neatly.

4. i put a blanket over the cabinet and grabed the fire extinguisher, better save then sorry.

flipping the switch nothing happen.. not even sound.. and i heard it playing attract sound when i powered it up at the guys place so i know the board works.. so at this point im thinking something did'nt make the move or i fried something.

long story short i traced the audio back to the jamma and double checked the speakers.. boards working again..

the monitor however is dead.. and i mean dead, no neck glow, no flicker, no spark, not even a whimper of high freq noise, if i did'nt know better i'd say it was'nt plugged in.

5. so i turn off the machine, unplug the monitor from it's little molex connector..

i plug the game back in and took a multi meter to it, well i know the monitor is getting power thats for sure, whats more it reads 130 volts AC, that struct me odd.. the frame says 120v 60hz on it's sticker.

i then checked the outlet it was plunged into.. it says 119volt (which is within normal range)

at this point im inclined to believe some how something is wrong with the transformer and it has FIRED this monitor.. but maybe im getting away from my self here..

where should i go from here?

P.S i should mention that after i unplugged the machine i tried to discharge the monitor again just to see if the tube got any juice.

granted i've never discharged amonitor till today but i heard nothing.. i stuck the screw driver under the cap and wiggled it around.. all i heard was the scraping sound of the screw driver and the anode cap.. no zap,bang,fizzle.

[Kevin Mullins]

Check the fuse on the chassis.

May be in need of a good ol' cap kit / transistor checking.

[Beretta]

ok i'll check the fuse tomorrow.. although if it is the fuse then there must be another problem.. in my exp a fuse does'nt blow unless there a problem.

btw what about the 130v ac i got coming into the monitor.. is'nt that a problem?

EDIT: oh and i know recapping the monitor will fix a lot of display problems, but does it usually get bad enough that the monitor wont even attempt to power up?

[Beretta]

ok checked the fuse, i had to cut the rubber protective sleeve off of it.. btw it's soldiered in theres no socket

it's blown for sure, nice black mark in the middle and i can't see the wire inside.


thats really not the interesting part though..

i barely bumped what looked to be a ceramic capacitor catty corner to the fuse, and it crumbled into about 5 pieces.

i think thats what it was only the lower half is still attached to the board..

unforunately i did not have my camera with me so i could'nt take a picture, my previous pictures do not show it but i found one i had taken that was VERY close to it, i also found a large shot of a 4900 chassis and marked it.

i know this will have to be replaced can anyone tell me exactly what it is? i think it's a ceramic capacitor, and white type i need?

also any theories as to how this happen and what the odds are the rest the chassis is still usable? looks like what ever happen was pretty serious.

or should i just give up now?

btw i need confirmation on the 130v im getting coming into the monitor.. i can't believe 130 volts would be healthy when it clearly says 120 @ 60hz on the sticker.

[Kevin Mullins]

TH501 resistor is a "thermistor" which controls the degauss coil.
If the coil or that thermistor were shorted it could cause the fuse to blow.

But so could a bad Horizontal Output transistor and bad caps.

The thermistor isn't immediately needed to further troubleshoot. But you'll want it when you get things back up and running for degaussing. I don't know off-hand the equivelant replacement. (I usually rob them off other stuff when needed)

I would start with a cap kit and checking the H.O.T and see if it is shorted.
There are some diodes that could be shorted in the power supply section as well.
I would also do a good thorough check over the entire chassis and neckboard for bad solder joints while you're at it.

Your 130v is fine.... you're measuring it with no load and that chassis is actually supposed to be rated from 108v to 132v according to the manual.

[Beretta]

thanks for your help btw if i had'nt mentioned it yet.

ya now that you point it out i notice it in the manual as well 108-132..

first things first gotta find some fuses i know i got some around here some where but you can never find stuff when you need it   

i usually just use my multi meter to take voltage readings and continuity..

but if i remember right ot test diodes, resisters and transistors you can't properly test those while in a circuit can you? that means im gonna have to do some desoldering, ick 

i'll disconnect the chassis and bring to work on it.. i guess we'll take it from there.
i dont mind putting the time in if i got a good shot of having a working monitor, what do you think the odds are?

btw whats the best source for cap kits? preferably one thats not gonna charge me 10+ min shipping on 5 or 6 dollars worth of capacitors.