Questions on Monitor repair/replacement

[rslaback]

The school district I work at as a tech ed teacher was given a Golden Tee '98 that is converted from a NBA Basketball cabinet.  If we can get it to work the plan is to put it in our student lounge/community center.

Anyway the board appears to work fine as you can play the game via sound.

The monitor in the cabinet is a WG 25K7197.  The Fuse on the board is blown.  If the fuse is replaced it blows on power up.  I have found some assitance in suggesting the HOT is blown.  The screen does have some burn in (my guess is from the NBA use as the burn in pattern doesn't look consistent with Golden Tee). 

A few questions:

If we were to replace the monitor entirely is there anything I need to look for specifically?  Will any 25" CGA monitor work?

The PCB almost looks like it has seen extreme sun damage.  The main board color is an offwhite with green lines only in places.  Is this normal for this monitor?

[grantspain]

that board sounds ok to me,some of the wg k7000 chassis were a cream colour
as for the fuse blowing it could be down to quite a few things
http://www.wellsgardner.com/pdf/Repair/K7000.pdf
this guide is very good indeed,also check the degauss ptc component is not short circuit

if you wanted to change the entire monitor now this size is referred to as 24.8"(dunno why,some crazy law) and i would say any cga(15khz) will do

[Ken Layton]

The 25k7197 is part of the k7000 family and requires operation through an isolation transformer. Williams/Midway Games did wire many (but not all) the cabinets incorrectly. They wired the marquee light fixture, monitor, dollar bill acceptor harness, and switching regulator power supply all across the output of the isolation transformer. This is a big no-no for monitors that need an isolation transformer like the 7197, but perfectly fine for monitors that don't need isolation like the k7400, k7500, U2000, and U5000.

Monitors that need an isolation transformer generally have a 2 wire power cord while monitors that don't need isolation use a 3 wire power cord.

The 25K7400 replaces the 25K7197. The 25K7400 does not need isolation and has a 3 wire power cord. Wells-Gardner sells a special power cord adapter dongle harness that plugs into the k7400 main board and allows you to plug into the cabinets existing 2 wire connector.

[rslaback]

The power leads coming to the monitor from the ps have 3 wires, a purple, purple with (yellow?) tracer and a green.  They are hot, neutral and ground with 110v.  The lead wires from the monitor are black and white with no ground.  I had assumed I would just chassis ground the green.  None of these wires were actually connected when I got the machine.

How can I tell if I have an isolation transformer?  If I don't where would I go about getting that part?

If I do need a new transformer (if one does not already exist) would I be better off just getting a new monitor?

[grantspain]

take some photo's of the inside of the cab around the powers supply and post them here,we should be able to see if you have an isolation transformer

[Mauzy]

If I do need a new transformer (if one does not already exist) would I be better off just getting a new monitor?

new isolation transformer<$20
New monitor of equal size>$300

I think you'll be wanting to do some work on this thing before thinking new monitor...

[rslaback]

Here are some pics of the inside of the cabinet.

[grantspain]

i have a couple of midway cabs wired like that but they have the later free voltage type monitors,i can clearly see that the power supply is being powered from the secondary of the transformer-i can't see if thats the case about the marquee light
i think what Ken said is happening here but the only way i could imagine this is causing a problem is if someone has swapped out the original monitor.
I know that the iso transformer is only meant to have the monitor connected to the secondary(output) and nothing else
i guess you could unplug the power supply and the marquee light to see if the fuse stops blowing

[MonMotha]

Many Midway transformer assemblies from that era had two isolated secondaries.  This appears to be one of them (notice the 4 conductor connector for the purple AC wiring).

One would be used for running the monitor, and the other for "everything else".  Unfortunately, that's not how they wired them.  They wired them as one for the monitor and game power supply and the other running nothing but the marquee light (or other similar silly things).  That configuration will work, though, since the game DC supply isolates its outputs from the AC input (assuming it's not busted), just not exactly the ideal situation.

[rslaback]

The purple and green wiring is actually what goes up to the monitor.  Nothing else is connected to that wiring.

The monitor does appear to not be orginal as the monitor has black and white power leads  there is no formal pigtail just what I assume was field modified connection with wire nuts (the 5 wires were all separate when I got it).

[grantspain]

well i guess all you need to do now is decide whether to repair or replace

[rslaback]

The big thing in the center is the isolation transformer right?  So I just need to trace the HOT issue now?

[grantspain]

yes,its time to follow the wells gardner repair guide

[rslaback]

I attempted to follow the guide.  It wants me to test the HOT (Q11). 

Problem 1.  It is missing.

Problem 2.  Doesn't the fact that the fuse still blows imply another short somewhere?

[grantspain]

looks like someone gave up with this before,
check the following
diodes 19 to 24 with a multimeter on diode test(lift one side of the diode from circuit)
remove the ptc component that switches the degauss
change ic 4 and make sure it matches the correct jumper set up to the schematic
and get yourself a new HOT

is the fuse blowing black or just parting?

[rslaback]

The fuse is blowing black.  I will try to test those out tonight.  I brought the board home with me.

So if this were you and
a. the board were in this shape
b. the tube had some burn in
and c. any repair cost would not be on your dime

would you replace it?  What type of electrical gremlins am I most likely hunting here? 

I don't want to spend tons of time on this but at the same time don't want to jump to a new monitor too quickly either.  A golden tee for the price of a new monitor isn't a bad deal.

[MonMotha]

Check the AC input rectifier diodes.  They can commonly fail shorted, and that will usually cause the input fuse to blow black.  Also disconnect the degauss coil in case it's broken.  Either is an easy (and relatively cheap) fix.

A new monitor will run you ~$300-500 with shipping.  You can sometimes find a deal on a used one for substantially cheaper.  It's definitely worth an hour or so of troubleshooting to try to fix the old one unless the tube is very burned.

[grantspain]

personally i have fixing arcade machines for 23 years professionally so i would fix it,but imo if you do not have experience then just go and get another monitor and save yourself time and possible frustration(not to mention injury)
the things i said to check are easy enough though so worth a final try

there seem to be a lot of crt monitor suppliers in the U.S so you should no problem in getting one
I am pretty sure that golden tee 98 is a 15khz(cga) video signal,i remember working on these quite some ago and the cabs were fitted with Hantarex polo 1 monitors(U.K)

here are some places you can get a monitor and remember its 24.8" now(not 25")
http://alvaamusement.com/_wsn/page5.html
http://www.niemandisplays.com/nieman_video_displays_006.htm
http://www.happcontrols.com/monitors/49305610.htm

[MonMotha]

GT98 is CGA (standard res), just confirming.

I have GT3D and GT2k boards for sale currently, if you're interested.  Should be "plug and play" once you get the cabinet working.

[rslaback]

I should have mentioned this before but there appears to be some additional jumpers on the bottom of the board as well.  There is a jumper from c45 to ground, r75 to c50 (with .01m ceramic cap) and something huge on the right side of the pic.  I am thinking this board might be better left to a pro.

[Mauzy]

Those two caps on the bottom look factory. I know many manufacturers did stuff like that, though I'm not sure of the reason. That jumper wire difinitely doesn't look good.


From a money standpoint, you should look for a new chassis set first. Less than $100 could easily get you a nice working set. They are usually no trouble to install and adjust.

From an ease of repair stand point, maybe you should go for a new monitor, then you won't have the burn in and such. Just be prepared to spend atleast $250 plus shipping for a new monitor.