No video on WG K7000 after cap kit.

[Numbski]

As the subject suggests.  Installed a cap kit from Bob Roberts last weekend.  Hooked everything back up (as best I can tell anyway) and no video.  The tube doesn't even appear to be firing up.

I have a troubleshooting document, but I think I what I need to start with is a reference to make sure I have all of the proper power hookups and most importantly, cables between the main board and the board attached to the video tube.  I'm no video expert by any degree here, and I don't own an oscope.

Something that bothers me - there were some jumped traces on the bottom of the board, and places where it looked like the leads had separated from the circuit board itself.  Worries me.  It worked before, but the picture was too wide and some colors were bleeding, so I replaced all of the capacitors but three (they weren't in the kit) and replaced the width capacitor.

Help?  Any references to what cables get plugged where to make sure I don't have a wiring issue, and anything I can do to ensure I'm getting power where it should be going would be helpful.  I guess the next step would be to take the board back out of the cabinet and double check all of my solders...

[Ken Layton]

Make sure all capacitors were put in correctly: correct value for each location and correct polarity. Did you remember to cut off the excess leads after soldering? Did you triple check all soldering?

[Numbski]

Yes and yes, but I'll pull it and check again.  My confidence level on where I've plugged all of the wires has plummeted though...escpecially one with a 1-conductor molex on it.

The fact that I can't tell that the tube is getting power or not has my concern most.  Hard to have a picture with  no power.

[Kevin Mullins]

That one conductor molex sounds like one that goes to the neckboard.

Do you have 120v going to the monitor?
Since it seems to do nothing, start there.

If you can take a picture of any plugs you're uncertain about that would help us identify them.

[Numbski]

Sorry to go all silent on this.  I've been very ill, and changed jobs too.

Anyway, the monitor doesn't fire up.  I'm getting ready to discharge the tube and unhook the mainboard again.  Here's the one conductor molex I was talking about:


Bigger pics

And the opposite end of that wire on the mainboard:

Bigger pics

[SirPeale]

That one wire won't keep the monitor from firing up.  Don't worry about it.

[Numbski]

Did some more testing.  I show 125.2V AC coming in from the mains to the monitor's mainboard, and then there's a 2-conductor molex near the rear/center of the mainboard that appears to be power outbound to the tube, and I get about ~145V AC coming out from there to the tube, so it at least looks like the monitor is getting power.

[Numbski]

There's also a bare pin on the mainboard labelled "TP 3" that no wire is currently hooked to.  I'm hoping that means "test point 3", and that it isn't required, but I don't recall whether something was hooked to it originally or not.

I really, REALLY should have taken a picture of all of the connection points prior to unhooking this.

[Arm123]

Sorry to hear this...  I have had similar problems when recapping a badly beaten up chassis.

Which is why i always replace a few in the same area and fire up the monitor again.  This is only if the chassis is in bad shape, so at least you can narrow down where the problem is.  I suppose this is good practice for people the dont regularly do servicing.

I know this doesnt help you now, but…

Dont get down on your self though, keep looking and you will find out where you went wrong.   

[Numbski]

Well, now I'm having trouble getting audio out of my speakers from any of my game boards...hard to fathom that the two things are related, but I wanted to confirm I wasn't going batty - but I can't.  Gah.

One problem at a time....

[qrz]

service manual here : www.wgec.com/pdf/Service/K7000.pdf   ( 17meg file )

it has pics of board layout which should help .
 the wire to which you were referring is the screen grid.
 not connecting this wire would not result in a doa monitor . but, it would result in NO pic.....
check the integrity of traces near the replaced components , etc......

qrz

[Numbski]

The filament on the back of the tube (right next to the neckboard) *should* light up, shouldn't it?  It doesn't in my case.

Also, there's a plastic box with a single wire running into it that I had to open up and de-solder to remove the mainboard, then re-solder to hook everything back up.  Anyone know what that is?  The box was on the neckboard.

[qrz]

that is where the focus lead enters the crt socket . this wire will carry around 6-12kv ( depending on screen size)when set is on .

no filament most likely means no h sweep operation... triple check previous work.
( i STILL miss things from time to time- it happens !!)

qrz

[ChadTower]

This happened to me once on the same monitor.  I went over my caps, the connectors, etc for a week.  Finally I noticed that when I put the neckboard back onto the CRT socket I bent a pin.  Check that. 

[Ken Layton]

The filament on the back of the tube (right next to the neckboard) *should* light up, shouldn't it?  It doesn't in my case.

Also, there's a plastic box with a single wire running into it that I had to open up and de-solder to remove the mainboard, then re-solder to hook everything back up.  Anyone know what that is?  The box was on the neckboard.

You don't unsolder anything to take the boards out!

Neckboard unplugs from the tube after carefully slicing through the glob of white silicone glue the factory put on the neckboard tube socket to keep it from scooting off during shipment.


The tube filament should light up if the monitor is going through normal startup. Get out your high voltage probe and measure the high voltage. It should be a steady voltage between 19,000 and 24,000 volts. If it climbs rapidly and falls to zero then the B+ voltage regulator IC is bad.

[Karetaker]

Double check your solders again. Make sure you didn't bleed one into another. If you're unsure clean the solder out with wick and make sure. If it was working and you capped it and now it's not, I'm thinking it's something along those lines. Listen to the monitor when you first fire it up. Can you hear the high voltage whine if only for a second?

[Numbski]

Two things -

1.  I got the neckboard off the tube.  Thanks for the tip on the glue.   I can clean off the neckboard now (made a point to clean of the mainboard with cotton swaps and alcohol last time).

2.  Where are the high voltage test points, and will a multimeter work?  I'm presuming this is DC voltage I'm testing for.

[qrz]

2nd anode and focus voltage are in the Kv range. this is well above safety limits of a multimeter .
use an HV probe only .
holding a neon bulb near the flyback will provide a visual indication of hv pulses.

a decent multimeter will be adequate for measuring the lower voltages present.

follow the schematic .....

qrz

[Numbski]

Wait, high voltage probe?  Do you mean like the greenlee test lamps?  I have a pair of those laying around too, but I thought those were only for testing AC, like to make sure an outlet has the right breaker kicked, etc.

[qrz]

a hv probe is a device designed for the direct measurement on the 2nd anode voltage of a crt .

just above the handle is a meter that will read up to 50kv. beyond the meter is a series of "corona rings".
these rings are designed to minimize the the shock hazzard of the user. the plastic tube from the rings to the exposed tip houses the hv resistor (99.98 MEG ohms for 50uA meter) . the resistor limits current from tip to
ground clip.
>>>>>  NEVER touch a probe to any crt without FIRST securing the ground clip .<<<<<

failure to observe this suggestion may result in a painful reminder , or DEATH with operating chassis
there IS sufficient current available in color crt hv sections to kill...

no probe  ?   well, you can still test for flyback operation without making any circuitry contact.
simply hold a neon bulb ( ne22) near the xformer . the bulb will glow in the em field produced by an operating flyback. 

do not fear electricity - but, give it the respect it demands.

qrz

[Numbski]

I'm about ready to give up on this thing.

I've double and triple-checked all of my solders.  There are traces that have lifted off the board a bit but were jumped prior to my work.  I'm getting nothing from holding a neon bulb near the flyback. :\  (Presuming the flyback is basically the neck of the tube...)

I hate to go buying a new monitor because I hosed up the board, but I'm running out of ideas.  Is there someone that does repair on these kinds of boards that I could send it out?

[qrz]

the flyback is the high voltage transformer ......

am a electronics tech . so yes, i could work on it if u wish ... fire off a pm and we'll go from there - qrz