Wells Gardner Capacitor C741

[Luigi]

Hi.

I have an upright Galaxian with an original WG monitor. The picture on the upper side is ok and it gets more blurred the further you look to the bottom of the tube

A friend said that it must be C741. I have the manual from crazykong.com but I'm not sure what kind of capacitor I have to use.

Do I read right`?

C741    0.015   1.5kV

So I guess it is a capacitor with 15mF (milli Farad) that has to stand 1.500Volts 

Am I right? And where can I get such a capacitor?

Thanks 

[shardian]

Maybe if you look at it as 15000 micro-farads, it will make better sense.

EDIT: Nevermind, that is a hell of a voltage isn't it?

[Lutus]

Take a photo of the problem and move this topic over to "monitor/video".  You will get more help from them.

15mF is correct for 0.015F

[Ken Layton]

And the model number of the monitor in question.....??

[Level42]

The Galaxians had WG 4500's originaly. At least mine did.

[Ken Layton]

Galaxian cabinets came equipped with several different monitors during the production run. It could have had a Wells 4500, a Wells 4600, or Electrohome G07. And don't forget Midway was famous for putting the wrong labels on monitors. I've seen many instances where Midway had put Electrohome stickers on Wells monitors and vice-versa
Of course if yours would indeed have a Wells 4500 monitor in it, I wouldn't even bother fixing it IMO.

[Level42]

I agree. Mine has been on the trash-heap for a little less then a year. Although it actually worked, the convergence was a nightmare, and I didn't want to fiddle with that for days...

[Luigi]

Take a photo of the problem and move this topic over to "monitor/video".  You will get more help from them.

15mF is correct for 0.015F

I will do so

Actually I don't know if the capacity is shown in Farads...in the manual there's no unit behind any capacitor so I guess they used that main unit F for all capacitors.....

Pictures later.....

ah...any source or common replacement for such a capacitor??

[MonMotha]

Nobody uses bare farads to rate capacitors, or at least certainly not at those voltages.  Microfarads (uF, or actually the greek letter "mu"F) or picofarads (pF) are the most common for unitless capacitance measurements.  That's probably a 0.015uF (15nF) or a 0.015nF (15pF) capacitor, likely the former.  1.5kV is not an unreasonable rating at 15nF (it is completely unreasonable at 15mF; such a capacitor would be huge).

What kind of cap is it?  Ceramic disc, mylar, silver mica, any of the various monolithic types, etc?  There should be some sort of description in the service manual.

As for replacements, those high voltage caps are sometimes a bit hard to find.  You can check the usual US electronic components distributors (Mouser and Digi-Key are the largest), but your best bet is probably a place that specializes in monitor and old radio repair parts.

[D_Zoot]

ah...any source or common replacement for such a capacitor??

Like arcade monitors, theses types of caps are common in TV's,  often used in the horizontal section as retrace or width tuning.  High frequency, high voltage circuits, hence the kv voltage spec.

In addition to Mouser and Digi-key, places that cater to TV repair should have it,  www.mcminone.com,  www.unicornelectronics.com  are two more places to check if you need.

I too am curious what monitor this is and what the purpose of this cap is that could be causing what sounds like a focus problem.   Anxious to see your pics and hear what model the monitor is.



D

[Luigi]

Hi.

I'm a little confused.

You know, the guy who checked the monitor is really good.....especially with old or vector cabs. He said, that this is the part to be changed.

Then my friend (his hall holds our gameroom) told me that and the other facts I told you.

Yesterday I took a look at the monitor. Unfortunately I forgot my digicam and so I took pictures with my cell phone.....I hope it will be enough.

I attach three pics:

1) the section from the schematics in the Galaxian manual at crazykong.com    I rectangled C741 but I'm wondering about the 4 connectors it seems to have 

2) a (very blurry) picture of C741 so you see the size

3) a (more sharp, but still blurry enough  ) picture of the chassis


I found two places where the chassis has been repaired. In one place there is a burn-hole in the PCB 

I wonder if I should replace the complete monitor 


I think it's a good idea to ask someone who repairs TVs but I need to know the capacity first....as you seen in the first picture there is no unit...no capacitor in the schematisc has a unit.

[Luigi]

I found some 1.5kVDC capacitors at a geman dealer.

Assuming that MonMotha is right I would have to choose the 0,022 uF (third from above ion the picture). As far as I know it is better to use a larger capacity than a smaller.

What do you think?

[Level42]

I think you should do what we Europeans do: Throw out that ancient piece of crap and replace it with a  more modern (CRT !!!) TV-set. Hook it up through SCART and you have the best picture in the world for little money and a lot less hassle.

Check out my Galaxian thread how to do it. Saves a lot of agony and waisted time....

[Ken Layton]

That schematic shows that capacitor to be special. It's a 4 legged one and it's made of polypropylene (that's what the "P.P." means on the schematic).

The correct value is .015 uf @ 1.5kvdc. You'll probably have to order it from Wells-Gardner's parts department.

[Level42]

BYW, this should be in the monitor/video section.....

[Ken Layton]

BYW, this should be in the monitor/video section.....

I was wondering why the mods had not moved this. It should obviously be in the monitor section.

[SirPeale]

BYW, this should be in the monitor/video section.....

I was wondering why the mods had not moved this. It should obviously be in the monitor section.

Next time flag it so we see it sooner!

[Lutus]

How do you flag it?  Just curious because I mentioned it should be moved in like the third post but I have no idea about flagging.

[SirPeale]

Look in the right hand corner of any post.

[Lutus]

Oh, "Report to Moderator"?  Got it.

[qrz]

c741 is a "safety cap".   it can be subbed with a hv type cap of same value and voltage rating .
two .000075uf @ 1600v in parallel would do the same . however , this cap is not ur problem...
usually when this type fails , it goes up in fireworks and results in a doa monitor.

check the 210v boost source . it believe you will find it to be low. likely around 130-140v
c743 ( 10 uF @250v 105 degree )  is the filter cap for the crt drive. a low boost v will result in a darkened pic on left,  ranging to bright on right . it may or not have a series of vertical bars on left .
( rotate this 90 degrees for "vert mounts" )

this cap is a common failure on crt devices, regardless , of make/model.......
it would be a good idea to change any 'lytic that appears buldged or has the insulation peeling back, etc....

qrz

[Luigi]

Sorry for being so late 

We replaced the cap and the picture is ...... ok, we can play but it's not the way it should be. We consider Level42's hint to replace the complete monitor...we'll check out

Sorry for posting in the wrong category.

@qrz: I printed your hints and we will check it out...thanks

[Luigi]

Just wanted to add that it's the 19K4500 chassis.


Another question: there's a little problem with the color blue. When the aliens shoot it's white....when it comes closer to the ground it gets more and more split into a white stripe and a blue stripe...like in the attached picture 

[qrz]

first though was convergence issue . but, looking at the pic ,no.  the white is still white. this would not be the case if truly convergence related.
so, suggest reseating all socketed ic's on the game pcb.  could also be a faulty socket or cold soder joint...

qrz

[Luigi]

@qrz: erm, this is not a screenshot....I drew it with Corel to show you what I mean. I'm not sure if the shot is still white when Blue decides to go its own way .......I'll take a closer look 

[qrz]

 thought it was a screen capture     no problema. 

if it is a convergence issue,  ANY video in the affected areas will  have the "offset"

qrz