Wells Gardner 25K7184 Schematic etc?

[hiperco]

Does anyone have any information on a Wells Gardner 25K7184 Monitor?  I think its from a Lethal Enforcers cabinet, if that rings any bells.  Schematics, pinouts, etc would be most appreciated! 

The board appears to be made by "DBQ", if that helps.

TIA

[Ken Layton]

Hmmmm......something's not right here. 

If the main monitor circuit board says "DBQ" silkscreened  on it then you have a 4900 series Wells-Gardner monitor. A 7000 series monitor will have "P447" silkscreened on it if it's  for a 19" or less tube and "P538" on it if it's for a 25" tube.

Why don't you post a picture of the monitor to clear up the confusion?

[hiperco]

Let me guess..some time in the past the board was replaced.  Maybe that explains why its loose, and I can't for the life of me figure out how it was supposed to be attached 

Here's some pictures.  So what schematic matches this board then? (do you need more pictures to tell?)

The tube is part number A63ABG25X.

The board on the side has a label that says ECC-20380...

[Ken Layton]

Hoo boy somebody has really bastardized that monitor! Looks like they played "mix 'n match" on this one.

You definitely have a K4900 series chassis on a 7191 series frame & tube. Go to mikesarcade.com and download the Wells-Gardner k4900 series manual.

[Grauwulf]

Man oh man! I thought i had it bad with my monitors. At least mine had the right chassis on it with a ton of wrong parts! *lol* Will a 4900 chassis even drive a tube that big?

That also looks suspiciously like a K4915 (25Hz) Medium res chassis. I haven't seen a 4900 series other than that one to have the additional protection board on the side of the frame like that one has.

[hiperco]

Thanks a lot for the replies so far!

Judging from the matching grime all over everything, and the aged caulk that was holding the neckboard on, I think this combination was in service for quite a while.  I'm in the process of setting up a jamma board (High Impact Football - HIF) to see what might be wrong with the monitor. 

Can you explain the ramifications of a medium res chassis board (if it turns out that it is)?   Assuming my HIF game outputs at 15KHz, will the chassis still work properly?  (How can I confirm whether my chassis is a medium res?)

So many questions... Thanks!   

[hiperco]

OK, let me take a little load off the guru's here by answering some of my own questions    (the search button is so nice)

IF the chassis is 25KHz (med res), it won't work correctly with a 15KHz signal.

I strongly suspect that the chassis is set up for 15KHz, since I was told it came from a Lethal Enforcers cabinet (standard res according to KLOV) (and the slight screen burned is mirrored, as it would be for this game being a mirror game).

BUT, is there a way to check 100%?  I have two unknowns right now (my HIF JAMMA game and the monitor).

TIA!

[Ken Layton]

Plug it in and turn it on. If it is the wrong resolution then you will have more than one image folded across horizonally on itself (usually two or three images). DON"T LEAVE THE MONITOR ON LIKE THIS FOR MORE THAN NECESSARY OR IT CAN BE DAMAGED. Just turn it on long enough to see the picture for about a minute.

[Grauwulf]

Well I could be way off base with my assesment of the chassis on your monitor. I'm not an expert, I'm just learning myself.

[hiperco]

OK, well I haven't finished wiring up the JAMMA power yet (And won't tonight, must resist since I stayed up WAY too late last nite, lol).

But I did get power to the monitor.  Here is what is looks like with power off and on.  Without a signal input, does this mean anything (good or bad?)

[Ken Layton]

Well, I looked thru my 4900 manuals and you definitely have a medium res monitor and it's a 25K5515 which is the 25" version of the 4900. The schematic I have is label 25" Medium Resolution Atari. Apparently somebody transplanted your components onto a 7184 frame.

Here's the service manual you can download:

http://atarijeff.com/Arcade/PDF Monitors/Wells Gardner 25k5515 Atari TM-295 1 st Printing Medium Res.pdf

Your picture is showing vertical collapse which would mean you need a capkit (use the 4900 series capkit). Specifically, probably cap # C313 (100 uf @ 160 volts) is bad.

[hiperco]

OK, new cap kit #202 on the way from Zanen.   I really appreciate the help from you guys so far.

Its very intriguing to me that this monitor came from a Lethal Enforcers cabinet, which I can see from two sources runs CGA.  Is it possible that somebody modified this chassis to work with a 15KHz signal?  (I'll find out when/(if?) I get the monitor working and connected to High Impact Football, but the suspense is killing me  )

On another note, do you think the screen burn will be terribly noticable with something displayed on the screen?  (The flash from the camera makes it stand out more so than  under normal lighting).

[Grauwulf]

You may or may not notice the burn as much. I have 3 monitors that you can only see the screen burn at certain times. If you're worried about it, replace the glass that covers your monitor bezel with a piece of glass that is just slightly smoked and it will hide the screen burn.

[hiperco]

OK, new cap kit has arrived.  (Fast shipping from Zanen  )

One question however...C311 is 10uF on my board, and 4.7uF in the kit.  Close enough??  (Its by Q302 on the schematic, vert out transistor)

(BTW, I had scrounged a C313 replacement and put it in over the weekend...didn't help (yet )

[Ken Layton]

According to the schematics for the 4900 and 5515 the 4900 used the 4.7 uf @ 160 volts and the 5515 used the 10 uf @ 160 volts for capacitor C311. Technically you can use the 4.7 uf but you may not the correct vertical height/size range when you adjust the vertical height or vertical size control. It would be better to get the 10 uf @ 160 volt capacitor installed to correctly drive a 25" tube. The 4.7 uf cap was for driving a 19" tube.

[hiperco]

Well, I got the cap kit installed and I was very excited when I found that C310 was bad (the cap installed there was rated for 100V, instead of the specified 160V  ).  However, the bad news is the cap kit didn't make any difference whatsoever in the display. 

Just to re-iterate, the picture above is with NO SIGNAL applied.  If I turn the screen control up, the line in the middle becomes very bright white, which tells me that there is still no vertical sweep (right?).

What's the next most likely problem?  (I have looked carefully for bad solder joints, but haven't found any yet).

[hiperco]

Guess what?  R313 is open (470 Ohm, 7W) 

Think its OK to replace with this one? 

http://www.unicornelex.com/newunicorn/detail.php?itemno=10-6447&

Hmm, maybe a wirewound is not such a good idea...where can I get a replacement carbon?

[Ken Layton]

Yes, that resistor should work and that's an excellent price, too.

[hiperco]

DRAT!

I've suceeded in moving my vertical collapse to the top of the screen, lol.


I replaced R313 (with a double stack of 1K in parallel, Unicorn was out of the 470 ohms).  Good thing I had a stack of 20W there, R313 got VERY hot, suggesting to me that Q302 is on all the time??  (This could explain why R313 was open, in fact the board is discolored in that area from extended baking...)

How likely is it that IC301 is bad?  Or what else should I look for? (I've checked around in that area (diodes etc), haven't found anything yet...)  TIA

[Ken Layton]

If R313 is getting hot then transistor Q302 must be shorted. Maybe Q302 AND Q303 are both shorted!

[hiperco]

Both of the transistors checked ok (not shorted with ohmmeter, diode check ok base to emitter and base to collector..) 

It appears Unicorn has IC301 replacement (any experience with using NTE1471 as cross?).  Perhaps I'll put one in (although somewhat pricy at close to $8 a pop...)  Unless you don't think it wil help?

[hiperco]

In a desperation move I replaced Q302/303 eeven though they didn't measure bad.  No difference.

Q302/303 are on all the time.  Not sure how 

[Ken Layton]

It's possible for IC301 to be bad. NTE replacement components are excellent parts.

[hiperco]

OK, I ended up having to order NTE1471 from mouser.com, Unicorn doesn't stock.

It doesn't look like IC301 is doing much of anything related to the vertical section (I looked with a scope),so I'm hopeful that a new one will get me going.  (The vertical output transistors are on all the time, putting nearly 130V across R313 all the time (~34Watts!)....no wonder its hot!)

Thanks a lot Ken for your advice so far, I'd never be this far without your help 

[hiperco]

Well, it seems that perhaps I have fixed it (I didn't need to replace IC301)

Its almost embarassing to admit what the last problem was...but since you all know I am a newbie at this (this is the first monitor I've ever looked at from the rear  ) I'll explain.

It didn't make any sense that R313 was burning up, so I poked and prodded it until the problem revealed itself.

The vertical position pot was turned all the way to the end (perhaps by me, but I think maybe it was like that when I I got the monitor).  Somehow this shorted out the pot,  putting one side of the vertical deflection coil just about at ground, turns on Q302 all the time, and for some reason causes IC301 to not switch Q303 (and also gets R313 extremely hot!)

So, now to try to get this beast working with a PC video card

It sure looks like this thing is switching at 15Khz, which makes sense from the game it came from but doesn't make sense from the standpoint of this being a medium res monitor.  I guess I'll try a 15KHz input and see what happens...watch this space 

[hiperco]

It really works!  Hooked it to a Trident Blade (original) (at 15KHz, btw.  Strange!)

Thanks again Ken for your help!

I'm hoping I can improve the picture quality with some tweaks, I'll probably start another thread for that topic