Author Topic: wells gardner k4915 help (Read 7600 times)

rfr341 · « **on:** April 19, 2006, 12:36:25 am »

Hi there I was wondering if anyone can help me out. I just got a wells gardner 19k4915 medium resolution chassis and I can't get it to work. When I turn on the game I can hear the game sounds but get no picture on the screen. I have replaced the IC501 with one from another 4900 chassis and put in a new C507 cap but have had no luck. I am not getting a glow in the neck of the tube so I don't think power is reaching it. I know the monitor tube works because it has worked in the past. Anyone have any ideas for me as to what to try next?

Thanks

Ken Layton · « **Reply #1 on:** April 19, 2006, 12:54:25 am »

First thing is: Has this monitor had a fresh capkit installed? If not then start with that.

Second thing is: This chassis is well known for many bad solder joints so look closely all around the main circuit board and resolder any bad joints encountered.

rfr341 · « **Reply #2 on:** April 19, 2006, 01:16:54 am »

Thanks Ken for your quick reply. I have checked the board for any bad solder joints but it all looks good. I have ordered a capkit for it and I am just waiting for it to arrive in the mail which I am hoping will be this week.If that doesn't work what else should I look for? I do have some old 4900 chassis laying around which I use for parts, do you think I should take a fly back transformer from one of them and replace the fly back on the 4915? Another quick question regarding another used game I just got. I went to plug it in and the tube caught on fire inside and when I unplugged it the fire went out and the neck of the tube fell off, what could have caused this to happen?

Ken Layton · « **Reply #3 on:** April 19, 2006, 02:21:03 am »

The neck of the picture tube was probably cracked and the tube is now destroyed.

rfr341 · « **Reply #4 on:** May 02, 2006, 06:56:29 pm »

I installed a new cap kit for the chassis and still the montior is not working. I still don't see a glow from the neck of the monitor, what should I try next? I am thinking replacing the fly back. Any other ideas for me?

SirPeale · « **Reply #5 on:** May 02, 2006, 07:02:38 pm »

You check the fuse? I mean with a multimeter, not visually.

rfr341 · « **Reply #6 on:** May 02, 2006, 08:22:39 pm »

I have checked the fuse with a mulitmeter and I have no problems there. I have replaced the fly back transformer and that didn't fix my problem, I am still not getting anything on the screen. If anyone has any suggestions what to do next they would be greatly appreciated. Thanks

SirPeale · « **Reply #7 on:** May 02, 2006, 09:52:29 pm »

Have you checked the B+? Check the voltage on both sides of the large white wire wound resistor.

Also, if you can get ahold of a cap tester, start checking caps to see if they're good or not.

rfr341 · « **Reply #8 on:** May 02, 2006, 11:42:48 pm »

I have managed to get the monitor to work, I changed a few transistors that looked in rough shape and doing that I now have the glow from the back of the neck of the tube. Now my problem is that on the monitor screen I am getting a thin horizontal line across the center of the screen( monitor is vertically mounted), I have tried to adjust it on the back but am having no luck. What could be causing this problem?

Thanks

Ken Layton · « **Reply #9 on:** May 03, 2006, 12:55:12 am »

Broken width coil? Bad solder joints on width coil? Bad solder joints on yoke connector on monitor main board?

SirPeale · « **Reply #10 on:** May 03, 2006, 08:05:45 am »

Quote from: Ken Layton on May 03, 2006, 12:55:12 am

Broken width coil? Bad solder joints on width coil? Bad solder joints on yoke connector on monitor main board?

Yeah, but he said it was vertically mounted, so wouldn't that be in the vertical circuit, if the line is horizontal?

Ken Layton · « **Reply #11 on:** May 03, 2006, 10:06:43 am »

A thin horizontal line in a vertically mounted monitor would be a horiz problem.

rfr341 · « **Reply #12 on:** May 03, 2006, 02:01:44 pm »

I checked the width coil and it looked good but I still replaced it with another one and am still getting the same problem. I also checked the solder joints on the width coil and yoke connection on the board and they also look good. Any other suggstions?
Thanks

Ken Layton · « **Reply #13 on:** May 03, 2006, 05:54:19 pm »

Check the yoke with an ohmmeter to make sure that one of the windings is not open circuit.

SirPeale · « **Reply #14 on:** May 03, 2006, 07:17:36 pm »

Editing my post, as the info on it is dead wrong. Don't want to confuse someone.

rfr341 · « **Reply #15 on:** May 03, 2006, 08:18:09 pm »

The problem I am having is like the bottom picture Peale sent.

rfr341 · « **Reply #16 on:** May 03, 2006, 10:57:04 pm »

How do I check the yoke with an ohmeter? I am new to this stuff so I am learning as I go along. Also the horizontal output transistor gets very hot, could that be part of the problem?

Kevin Mullins · « **Reply #17 on:** May 05, 2006, 12:50:47 pm »

I remember something about the 4900's have common problems with the IC on them. (IC301) (deflection problems)
Even though you may have swapped it once, try another one. Since you're pulling from other boards, etc.

Oh, and make sure ya do the cap kit when you get it ......
(if you haven't already)

rfr341 · « **Reply #18 on:** May 06, 2006, 03:03:42 am »

I have done the cap kit with no luck and today I swapped the IC301 from another board but I will try to change the IC301 again and see if that works. Thanks Kevin for the info about the IC301.

Kevin Mullins · « **Reply #19 on:** May 06, 2006, 03:45:41 pm »

I just looked at Randy Fromm's flowchart.....
You should also check transistors Q302 and Q303 also resistor R313.

rfr341 · « **Reply #20 on:** May 07, 2006, 12:32:51 pm »

I have replaced the Q302, Q303 and resistor R313 and still have had no luck. I also have Randy Fromm's flowchart and I have done everything on the chart but with no luck. I have found a few hairline cracks in the board could that cause this problem?

Kevin Mullins · « **Reply #21 on:** May 07, 2006, 01:56:59 pm »

If the hairline cracks are running across some traces it could...... double check the continuity of all the traces that the cracks seem to run across.

rfr341 · « **Reply #22 on:** May 07, 2006, 05:58:01 pm »

I have checked the traces that the cracks seem to run across and they all seem fine. I am not sure if this could be the cause but I will run it by eveyone and see what you think. The game is APB and it is suppose to have a medium resolution monitor but when I got the game someone had switched the original monitor and chassis and put in a standrad chassis and a new tube. I was getting double image and was told that I needed a wells gardner k4915 medium chassis to replace the standard chassis which was a wells gardner k4914, so I went out and found a k4915 on ebay and this is the chassis I am working on right now. I was told that the tube that is in there would work with the medium chassis even though the tube was connected to a standard chassis. Does it matter what type of tube you use or do all tubes work with standard and medium chassis? Could this be causing my problems? Any info you guys have would be greatly appreciated.
Thanks

Kevin Mullins · « **Reply #23 on:** May 07, 2006, 08:32:05 pm »

APB is medium resolution.
WG k4915 is medium resolution.
So you're good there......

The only difference between a standard res tube and a medium res tube might just be the deflection yoke. (the coil winding around the neck)
Nothing to do with the glass portion.
I'm not sure what the actual impedance (ohms)should be on your yoke for a medium res.
The part number should be 9A2843-001 , if you can find that somewhere on it.
None the less..... this has nothing to do with a total horizontal failure you have.

You would still be able to get FULL SCREEN picture of some sort even on a standard resolution monitor, it would just be scrambled.

rfr341 · « **Reply #24 on:** May 07, 2006, 09:02:33 pm »

Thanks Kevin for your advice and I will check the number on the yoke.If you have any more ideas for me to try please pass them on. Now I just want to make sure because I have been told 2 diffrent things from people. Someone has told me I am having a vertical deflection problem and another person said I am having a horizontal deflection problem, my monitor is mounted vertically and the line is running horizontally through the screen which is vertically mounted. So wouldn't this be a vertical deflection problem because if you rotated the monitor to horizontal position the line would be running vertically through the screen. Which one is correct? Thanks to everyone for there help and if you have any more ideas for me to try please pass them on because this problem is getting frusturating.

Kevin Mullins · « **Reply #25 on:** May 07, 2006, 09:35:42 pm »

A monitors horizontal and vertical axis are determined as if it were horizontally mounted just like a PC, a TV, or anything mounted horiztally.
Vertical axis is the shorter length side of the monitor.
Horizontal axis is the longer length side.
Whether you mount it sideways (vertically) or not, this doesn't change the axis.

So in your case turn your head sideways and look at it.

Now.......
Since the picture is squished inward from the left and inward from the right creating the line in the middle, it is squished along the "horizontal axis". (creating a vertical line)

You have a horizontal failure.

Kevin Mullins · « **Reply #26 on:** May 07, 2006, 09:43:33 pm »

Have you looked at L352 to see if it is broken or bad solder?

Kevin Mullins · « **Reply #27 on:** May 07, 2006, 09:46:14 pm »

Is the jumper for LEFT - CENTER - RIGHT plugged in?

rfr341 · « **Reply #28 on:** May 07, 2006, 11:22:21 pm »

I have already checked the L352 and it looks good and the jumper is plugged in. I was looking at the pcb board and noticed that it was missing a few resistors that were suppose to be there according to the chassis manual, so I replaced the missing resistors. I turned the game on and the line is not there anymore but now I have a dot in the middle of the screen. What could have caused this?

Kevin Mullins · « **Reply #29 on:** May 07, 2006, 11:43:45 pm »

Did it look as if those resistors had been previously taken out by someone before you got the chassis?

Where were they located?

Some boards had revisions done and there may be some slight variations out there.

The white dot doesn't sound healthy, don't run it too long like that.

rfr341 · « **Reply #30 on:** May 08, 2006, 01:14:31 am »

I did look like there had been resistors there before, they were located at R310,R379 & R385. The dot in the middle of the screen is gone but now I have a live running vertically up the screen. I noticed that on the yoke connection on the board that one of the solder joints for the horizontal had pulled of the board and the trace had pulled up also so I tried to fix that and there seems continuity across it. When I was messing around with it I did manage to get the game picture on the screen but it was rolling so I was trying to adjust it and then it went back to the vertical line on the screen and I haven't been able to get the graphics back. For a few seconds there I thought I had figured it out, so close yet so far.

Kevin Mullins · « **Reply #31 on:** May 08, 2006, 08:41:20 am »

Defineately check all four pins and the connector for the yoke.......
Sounds like you may be onto something there.

It's amazing what a little wiggle test will tell ya.

Ken Layton · « **Reply #32 on:** May 08, 2006, 11:53:57 am »

A medium res monitor has a different yoke than a standard res one.

Kevin Mullins · « **Reply #33 on:** May 08, 2006, 12:26:39 pm »

Thanks Ken . . . . figured so.
Just wish I had some specs to give him to check.
Sounds like he might have a mis-match of parts. (tube-yoke-chassis)

rfr341 · « **Reply #34 on:** May 08, 2006, 12:28:46 pm »

I am not going to give up on trying to get this monitor to work yet but if I need to get a replacement monitor what would be my best choice of medium resolution monitor to get and where would be a good place to get it from.

Ken Layton · « **Reply #35 on:** May 08, 2006, 12:43:21 pm »

It's harder and harder to find a dedicated medium resolution monitor manufactured brand new today. What you will likely find is "multi-sync" game monitors which will work fine, but cost more (naturally).

rfr341 · « **Reply #36 on:** May 08, 2006, 12:45:28 pm »

I am just checking out monitors on HAPP's website and they have a wells gardner 19" K7500 medium resolution monitor would that be a good monitor and would that work with APB if I decide to go that route and replace the monitor.

rfr341 · « **Reply #37 on:** May 10, 2006, 10:04:43 pm »

Well I measured R503 and the voltage is 152vdc when it should be between 130-145vdc. I also measured the voltage at IC501 and they are high also. Does anyone have an idea why these reading are higher than they should be.
Thanks

Kevin Mullins · « **Reply #38 on:** May 15, 2006, 11:50:00 am »

Is this what you get at TP91?
That doesn't sound terribly high.... could be a difference in line voltage from the wall.

And I believe you should have the same voltage at pin 9 on the flyback.

Check out Q352 H.O.T. (2SD870)
(diode testing) (power off)


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