Author Topic: I need help with my WG 25k7191 - no video, with power, good fuses (Read 8770 times)

Cyberflexx · « **on:** January 22, 2006, 12:52:34 am »

I am a newbie, very new to arcades so please be patient with me...

I have the 25k7191 in my neo geo machine.. i have a new transformer, verified 129 volts going into the monitor chassis. the suction cup isnt dryrotted or loose or anything, flyback not cracked, the fuse is good.. earth ground good, no cracks in the tube- some burnin though.. i reseated the RGB/Sync connectors and reseated the jamma connector, have a new noise filter installed too...

the monitor chassis looks good, no bulging caps, no burnt places, but a little dusty from yrs of age. no chips in the back of the monitor, nothing looks wrong with it, just wont show video, no hum sound either...

i verified the earth ground is on the frame and continuity tested it to the main ground in the power circuit.

Is there anyway to test this monitor without using another PCB since i dont have one??

Any suggestions, thoughts on why this isnt working?

Thanks in advance..

Ken Layton · « **Reply #1 on:** January 22, 2006, 01:09:01 am »

Visit this site: www.jstookey.com/arcade/WG_25k7191/

Also be sure your monitor has had a recent capkit installed as well as inspected for bad solder joints.

If this is a later production run with a "remote adjustments" board be sure it's plugged in. To attempt powering up the monitor without a remote adjustment board plugged in will damage the monitor. I don't think yours is one of these later ones though.

Cyberflexx · « **Reply #2 on:** January 22, 2006, 01:12:04 am »

it has a remote board, i had it disconnected during one power up to see if that would allow it to come on.. i did notice the remote board didnt have the RGB Pots on it, but it has the vert hold and stuff...

You think its toast?

Ken Layton · « **Reply #3 on:** January 22, 2006, 01:54:41 am »

Any monitor that uses a remote adjustment board will never power up without it being connected.

Install a fresh capkit and check for bad solder joints.

Cyberflexx · « **Reply #4 on:** January 22, 2006, 03:11:30 pm »

Thanks for the advice...Now on to a million questions

Do you think the tube is good? It does have a little burn in that I can see if the light hits it right, Anyway to cure that?

Do you think it would be wise and less headache just to get a new chassis with remote board?

Where is the cheapest place to get these parts and their part numbers?

Does anyone here have a working used chassis for the 25k7191 they would be willing to sell for a good price?

Do TV repair shops normally work on arcade monitors or do they shun them?

Thanks again!

Cyberflexx · « **Reply #5 on:** January 22, 2006, 03:43:27 pm »

Is this monitor the same as the WG7000?? Been searching the net for parts and penn-ray has flybacks on sale!

Thanks

Nipedley · « **Reply #6 on:** January 22, 2006, 05:39:21 pm »

It's a 7000 series, though I'm not sure if they all use the same flybacks, Ken can answer that for you =).
My local tv repair shop wouldn't step near my monitor, even though it's run by my uncle.. tsk

Ken Layton · « **Reply #7 on:** January 22, 2006, 07:54:03 pm »

The 7191 and k7000 are the same and use the same flybacks. Yes, I know that flybacks for these are on sale for dirt cheap right now at Penn-Ray. I just ordered a bunch for my friend Steve Mildenberger. Electrohome flybacks are also on sale too. You won't find a cheaper price ever on these.

Mario · « **Reply #8 on:** January 22, 2006, 10:48:21 pm »

Quote from: Ken Layton on January 22, 2006, 07:54:03 pm

The 7191 and k7000 are the same and use the same flybacks. Yes, I know that flybacks for these are on sale for dirt cheap right now at Penn-Ray. I just ordered a bunch for my friend Steve Mildenberger. Electrohome flybacks are also on sale too. You won't find a cheaper price ever on these.

Does the 7194 use the same flyback, too?

Thanks.

Mario

Ken Layton · « **Reply #9 on:** January 23, 2006, 01:32:43 am »

SirPeale · « **Reply #10 on:** January 23, 2006, 02:50:17 pm »

Will these work on the 19" model as well?

Ken Layton · « **Reply #11 on:** January 23, 2006, 11:36:22 pm »

Cyberflexx · « **Reply #12 on:** January 25, 2006, 06:33:31 pm »

I went to discharge the flyback, and when i put the screw driver under the anode cap ( suction cup looking thing) I did not get a snap. I popped the anode off and checked voltage and it was not charged.. Could this mean the flyback transformer is bad or some other circuit? How hard are the 8-liner.com chassis board to install?
I think i might just order one of those if I cant track down the problem of this board

Ken Layton · « **Reply #13 on:** January 25, 2006, 11:13:47 pm »

If you decide to use a replacement chassis, then visit this site for more info:

http://home.earthlink.net/~arcadeparts/index.html

Cyberflexx · « **Reply #14 on:** January 26, 2006, 10:40:40 pm »

Ken,

Thanks for the fast replies and help...

I ordered a flyback and cap-kit from Penn-Ray today.. shouldnt take long to get here as I am in WV and penn-ray.com is in PA. I'll replace all the caps before i put on the new flyback since the old flyback might be good.. I am also going to check voltages on R301 ceramic resistor and if that is good, i'll check the voltage on R103 and also check the solder points throughout the board..

Does that sound like a good start on the next troubleshooting steps?

Ken Layton · « **Reply #15 on:** January 27, 2006, 12:01:26 am »

Yes, sounds good.

Cyberflexx · « **Reply #16 on:** January 30, 2006, 07:33:44 pm »

Ken
I pulled off the neckboard, and the tube looks good, i also checked the bottom of the chassis and all the solder points looks good and shiny..
I did notice my fuse was blown and i thought it wasnt...

Any thoughts on what to check? and should i put it all back together and try another fuse? it might have been blown before i even began to work on it..
or do you think i should just cap kit it when i get my parts and then go from there?

thanks

Mario · « **Reply #17 on:** January 30, 2006, 09:53:20 pm »

Quote from: Cyberflexx on January 25, 2006, 06:33:31 pm

I went to discharge the flyback, and when i put the screw driver under the anode cap ( suction cup looking thing) I did not get a snap.

I had the same thing happen to two monitors in the past week. No pop at all. This was when shorting the anode to the monitor frame.

I'm very concerned that the monitor really wasn't discharged. One of the monitors was used the previous day, so I expected that there has to be a charge there.

Ken (or anyone else), can I really be sure it's discharged? I'd rather be sure than zapped.

Mario

grantspain · « **Reply #18 on:** January 31, 2006, 10:39:06 am »

dont know if its the same with some of your monitors(we dont have vision pro/happ in u.k as a rule)but all modern monitors i have worked on tend to have a discharge circuit for the ht(but still be cautious) so you probably wont get a ht arc,so it should not be anything to worry about.
once you have worked on alot of monitors you tend to hear if its running ok
e.g a fizz on the screen when switched on(static-means you got ht),if frequency or adjustment on holds is incorrect you get unstable whistle-sounds like a fax.
another good sign if you dont have a picture is when you switch off the screen you should get a flash-this usually denotes that there is either picture/color adjustment problem,no signal from game board,or on board color generator chip faulty such as an lm1203n.
anyway if your not sure your tube is discharged or not then just short your anode cap and entry to earth using either 2 screwdrivers shorted together in a v-shape(dont put your fingers on the metal of the screwdrivers like one of my trainees did when doing this-he shot across the workshop like a scud missile) or make a lead using a croc clip,some hi amp insulated wire and an insulated probe.
please beware dont damage the paint around the anode cap and keep away from the earth when discharging.hope this helps

SirPeale · « **Reply #19 on:** January 31, 2006, 06:21:42 pm »

Quote from: Mario on January 30, 2006, 09:53:20 pm

Ken (or anyone else), can I really be sure it's discharged? I'd rather be sure than zapped.

You'll be fine. Even if you're zapped, it won't be much. Don't sweat it. These days I don't usually even bother discharging.

Just don't pull it off when it's still on.

Cyberflexx · « **Reply #20 on:** February 01, 2006, 09:53:02 pm »

I installed the capkit, and new flyback... i powered it up and the fuse blew... i checked Q11 again and put the ground lead of my meter to the frame and the red lead to the base and it checked good with continuity as did the emitter and collector. I checked D19-23 and the only one that gave me a weird reading was D23. it would go to a high number then go back to 1. What are the values of D19-23? I was not for sure how to check the IC4 or IC3. I am just a novice in electronic repairs so thank you for being so patient.

I didnt have much time to tinker with the monitor this evening. The wife always seem to have me doing something right about the time i head to the garage..

Ken Layton · « **Reply #21 on:** February 02, 2006, 12:43:58 am »

Remember the horizontal output transistor requires a mica insulator behind it to insulate it from the metal frame.

Check for a shorted capacitor C36 and diodes under the metal frame that Q11 bolts to. Also check for a shorted diode D18.

Oh yes, almost forgot: Early production runs of this chassis had the value of the fuse silkscreened wrong on the parts side of the main circuit board. It should be 2 amp slo-blo, but the early run still had it saying 1.5 amp slo-blo

grantspain · « **Reply #22 on:** February 02, 2006, 02:11:42 pm »

if i have a monitor blowing fuse on power up the first thing i do is disconnect the degauss coil,then remove the ptc componant-if it still blows the fuse i then go on to check the input diodes/bridge rectifier circuit,then any transistors on the primary input.things like h.o.t and caps further in the circuit tend to give trip faults rather than fuse blows.obviously you have checked your ac input wires are in the correct place-anyway a fuse blowing straight away points towards a direct short to earth usually on the monitor psu primary input,usually a power diode.

Ken Layton · « **Reply #23 on:** February 03, 2006, 12:05:11 am »

I've seen that black box-like capacitor right next to the fuseholder short circuit and blow the fuse.

Cyberflexx · « **Reply #24 on:** February 04, 2006, 01:08:52 pm »

The blackbox cap .1uf seems OK.. i replaced d18 and the original d18 was good.. i checked d20-24 and they were good as well... I cant find IC4 or the HOT anywhere local. i put in a 2amp fuse and the monitor will hummmm for a few sec then the fuse will blow with a flash of light... BTW I had the degausing wires unplugged ... any suggestions? I am kind of getting discouraged with this board..

grantspain · « **Reply #25 on:** February 04, 2006, 01:52:49 pm »

i was talking with a friend today who is a bit of a wiz on the wells gardner,he said that if you switch on without the adjustment control board it will blow the crap out of the monitor psu,you could be looking at a multitude of componants-might be worth just sending this to the pros as i think its gonna be a real difficult job.

Cyberflexx · « **Reply #26 on:** February 05, 2006, 12:28:51 pm »

Ken,
I pulled the HOT from the board and put in a fuse and plugged it all up.. the fuse blew.. so wouldnt this eliminate the HOT being the problem??

Any other suggestions?

grantspain · « **Reply #27 on:** February 05, 2006, 01:51:08 pm »

well like i said you gotta a problem on the monitor psu,big job im afraid

Ken Layton · « **Reply #28 on:** February 06, 2006, 11:05:01 am »

Did you check C36 for shorted condition?

Luckydevil · « **Reply #29 on:** February 06, 2006, 11:27:01 am »

cyberflexxx- I called WG and cancelled the repairs to my chassis. I figured you were right about just buying a new chassis instead of having them fix an old one.

I just ordered a new chassis from Alva Amusement (Ken's recommendation). It was only $88 for the chassis + shipping. It's worth it to me just to get the new chassis, troubleshooting those things is a pain in the ass.

Alva Amusement: http://alvaamusement.com/

Cyberflexx · « **Reply #30 on:** February 06, 2006, 11:56:06 am »

I'm tired of fighting with this one.. if C36 is shorted, i'm just going to order from Alva..

Ken, would this be the right board? The Wei-Ya Model WY826HR 25inch Chassis V=9.6ohms 10 pins.
My monitor is a WG 25K7191

Thanks

Luckydevil · « **Reply #31 on:** February 06, 2006, 02:46:45 pm »

Cyberflexxx- I spoke with the guys at Alva and they said for my 25" WG25K7193 I needed the 825H. They also said that the 825H comes with the remote so I guess technically it is the 825HR.

I think you would need the same chassis.

Cyberflexx · « **Reply #32 on:** February 06, 2006, 04:30:20 pm »

Is the WG 25k7191 a standard resolution monitor? I called Alva Amusements and she told me to double check.. The lady was really nice on the phone..

Oh, what is the value of C36 in microfarads and volts.... i'll replace it tonight and if it still blows fuses, i'm giving up..

Luckydevil · « **Reply #33 on:** February 06, 2006, 04:46:04 pm »

Your monitor is standard resolution.

Here is a blurb on Bob Roberts' page about the C36. Shoot him an email and he can give you the values of it.

http://homearcade.org/BBBB/csc.html

Ken Layton · « **Reply #34 on:** February 06, 2006, 06:05:09 pm »

C36 is a special type of capacitor. If it proves to be bad then order it from Bob Roberts.

As I've mentioned several times in other threads, the 7191, 7193, 7194, 7196, 7197 are all the same chassis.

Cyberflexx · « **Reply #35 on:** February 06, 2006, 06:23:36 pm »

I noticed my board has a diff. cap soldered to the bottom of it.. same value as the one on bob roberts page on how to replace this cap.. i assume someone did this mod and left the old cap inplace.. could this be causing the issue?

Ken Layton · « **Reply #36 on:** February 06, 2006, 07:07:03 pm »

The k7000 series (which yours is part of) had several foil side parts added by the factory. Don't even think of touching them. Leave them be.


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