Wells-Gardner K7000 p538 no picture after recap (unsure whether chassis is starting)

[taco_cherub]

Hey Everyone! this is my first restoration project! I'm fairly new to this.

I have a Neo Geo MVS 4-slot cabinet with a Wells-Gardner K7000/P538 chassis. Before the recap, the monitor worked but had vertical foldover and horizontal lines at the top.

I installed a K7000 cap kit from arcadepartsandrepair.com . I also replaced C204 on the neck board with the 4.7µF 250V capacitor supplied in the kit.

After reinstalling the chassis:

• No picture
• No visible orange heater glow in the CRT neck
• I’m not sure whether I hear the normal startup crackle
• The MVS game board and audio work when the monitor chassis is disconnected
• The neck board, yoke, video connector, anode, grounds, and remote board appear connected
• I rechecked the capacitor values, polarity, and solder joints
• Some pads were difficult to get solder to flow onto, but I reworked them with flux

There are several unusual preexisting modifications on the underside of the chassis, including jumper wires, an underside-mounted capacitor, and heavily reworked/discolored solder areas. These were present before the recap, and the monitor worked with them in place, so I did not intentionally change them.

I also had trouble identifying the correct positive and negative orientation for C40. I ultimately installed it according to the c42 fuse orientation, but I would appreciate confirmation of the correct C40 orientation for this P538 chassis.

What should I test next to determine whether the chassis is receiving power and starting properly? Should I begin with the chassis fuse, AC input, C40 orientation, C204 installation, neck-board heater circuit, flyback/HOT, B+ circuit, or continuity through the old jumper repairs?

 

[radicalfaith360]

Check to see if the fuse on your chassis is still good. If it has popped you have a short somewhere. If not, then it could be a very simple fix like something not plugged in correctly when you fired it up. Did you hear static on the first power up after recapping? I have the same chassis on a 25K7131 that I have not worked on yet, so I do not know if the underside is factory or a modification. First thing, test that fuse with your multimeter.

 

[geekmiki]

If it did "work" before the recap then most certainly a broken trace, lifted pad, short, inverted cap.
I learnt it the hard way when recapping a MS8-26 about a year ago. What seemed an easy recap, turned into a nightmare because the chassis are getting old and very sensitive to mechanical stress.
Take a multimeter and check EVERYTHING that you have touched. It's going to be a long and tedious job. Good luck!

 

[radicalfaith360]

I did some homework and the underside of that chassis is field hacked. Remove those wires and caps, then start reflowing solder

 

[duffcon]

Late to the party, but it often happens when new people recap k7000s, they neglect to go over the weak areas in the power section (especially R101 & R89). In your pic I can see R101 is very cold. Basically the chassis is flexed from recapping, these joints are weak and pop. You need to watch "k7000 dead" videos from Mike's arcade monitor repair on youtube. If it worked before you likely have a good power section, but I would check all the things in the videos.

If you are lost, I refurbish k7000s and can rebuild your chassis to better than new condition.