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Troubleshooting a WG 25k7191 no picture blowing fuse
joej85a:
Hey guys, Im Joe, from NC, new to the board, but been reading for a while. I am having an issue with a Golden Tee 2k cabinet I recently picked up. It has a Wells Gardner 25k7191 monitor in it that has not worked since I purchased it. I have read about the common problems, and visually inspected the board. Blown fuse, cracked Flyback. So I went ahead, ordered a new flyback, fuses, cap kit, IC4, and HOT. I understand the HOTs commonly fail so I wanted to do it as maintenance regardless. I also downloaded the manual for the k7000 series (which is awesome), and have been working with the troubleshooting diagram in it. Here is what I have done:
1. full recap except for cap C55 which I did not realize was not in the cap kit. It visually looks ok, no leaks, not bloated. I have recapped consoles for some time so feel like it is not an install issues (but maybe?!)
2. replaced the HOT
3. replaced IC4
4. replaced the flyback
5. installed new Slowblow 2amp fuse.
Installed back into the cabinet and get immediate fuse blow. No delay, immediate. So referred back to the troubleshooting guide and it says with no hi voltage, and with blow fuse, check for a short on legs 1-4 of IC4 and for a short at the HOT. Leg 1 of my new IC4 shorts to ground. Leg 1 and 3 of the HOT short to ground. I removed the HOT and the leg 1 short to ground on IC4 remains. I removed IC4 as well, and the leg 1 pad still shorts to ground, as does the corresponding pads of the HOT (pad for leg 1 and 3). I am starting to hit a wall as it now just says to look for a cause of the short in the circuit. I have checked the diode bank D19-D22 and they seem to check okay, D23 and D24 however appear to be allowing voltage both directions, but I can't tell if it is feeding back. I did not take them off the board to test.
At this point, I am looking at the retuning cap, c36 cut it is not shorted out. So any help or ideas would be AWESOME!
Thanks guys! and thanks for reading my first post.
grantspain:
so if you isolate the b+ to the flyback and add a 40w lamp to the b+ line as a dummy load does your fuse still blow?
joej85a:
I will have to read up more on the lightbulb test to make sure I do it properly. I have heard people refer to it, but not 100% sure on the details. I’ll get on it and get back with the results. Thanks so much!
grantspain:
any one of the poly caps and the diode around the deflection header will cause the fuse to blow immediately
using this method will prove your b+ supply is correct and there is no issue in the regulation circuit
its the first thing i do on 7000 series chassis when they come in for repair
make sure you use a anti surge fuse also
princess prin prin:
1) Suck solder off pin 2 of the flyback and make sure the pin is no longer touching the pad around it.
2) Measure resistance across pin 1 and 3 of the flyback. Zero ohm/short? If so go to 3.
3) Suck solder off middle pin (COL) of the HOT and here too make sure the pin is no longer touching the pad around it.
4) Measure resistance across pin 1 and 3 of the flyback. Zero ohm/short? If so go to 5.
5) Desolder C36.
6) Measure resistance across pin 1 and 3 of the flyback. Zero ohm/short? If so go to 7.
7) Desolder D18 and C69 and test them out of circuit.