msdstc
Active member
Just got home, setting things up, I'll report back.
K7000 static, but no neck glow after shorting.
- Thread starter msdstc
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Just got home, setting things up, I'll report back.
mecha
Well-known member
yes for posterity, to anyone reading, you should always redo the solder connections to the 2 ground wires at the neckboard. meaning you remove them, clean the solder pad, cut off the stripped ends of the wires, strip them again, and solder them back onto the pad.
from the flip flopping of chassis between tubes to keep games running in their coin operated past lives the wires get beat up and the exposed stranded wire will eventually fray and break off.
msdstc
Active member
msdstc
Active member
mecha
Well-known member
green: heater assembly and flyback power tap
red: R213 where heater voltage comes in
blue: the heater return path to ground
R213 is .68 ohm 2W, if it's open or high resistance that can cause your lack of voltage presence. but also if you didn't fix the ground wire connection back to the heatsink wall there won't be a return path for the heater and it just won't work.
red: R213 where heater voltage comes in
blue: the heater return path to ground
R213 is .68 ohm 2W, if it's open or high resistance that can cause your lack of voltage presence. but also if you didn't fix the ground wire connection back to the heatsink wall there won't be a return path for the heater and it just won't work.
msdstc
Active member
I fixed the ground wire cleaned it up, stripped it and resoldered. I posted a pic above but I just don't even have r213 on th board.
mecha
Well-known member
measure voltage at that jumper that some knucklehead installed against the monitor frame. if no voltage is present then you knocked out the 6.3V AC tap off the flyback and will thus need a new one. that resistor would have functioned as a fuse and gone open if you shorted anything. that won't work with a 0 ohm jumper connection.
msdstc
Active member
Should I reinstall the original resistor? What do you think caused them to make that choice?
mecha
Well-known member
I don't know... people do silly hacks.
msdstc
Active member
Alright I'm getting 0 off that jumper.
mecha
Well-known member
make sure the 2 plugs with white and blue wires don't have any barbecued wires also
msdstc
Active member
Dumb question incoming. Will the barbecue be on the board itself or on the wires? There is a tiny bit of wire peeking through some of the insulation, but it just looks like it was nicked at some point.
msdstc
Active member
Also do I need a new flyback? Or something else?
mecha
Well-known member
pictures
the flyback outputs 6.3V AC, which goes through one of those white/blue wire harnesses to the neckboard, through R213, to pin 10 and pin 9 goes to ground. either the flyback is no longer outputting that voltage and needs to be replaced or you have a bad ground connection to the neckboard.
I don't know what you arced, but if you looked at the underside of the deflection board you would see visible char marks if you did.
msdstc
Active member
Forgot to grab the pic earlier but I did an inspection and the wires look fine, no scorch marks anywhere on the bottom or top of board. Anyway to test the flyback directly?
I think you're troubleshooting at step 3 or 4. You need to start at step 1. Anytime a fuse pops, you don't just put in a new one and carry on. You need to proof out the power section before you do anything else. Watch Zenomorp's videos on K7000 Blown fuse T/S (Mike's amateur arcade repair on youtube).
M K L
Well-known member
This is a K7000A and the heater goes through another resistor (3 in parallel in fact) before going to the neckboard.
Measure resistance from A to J. It should be very low, 2-3ohm. If it reads open, check every point in between until you find where the circuit is open.
If everything tests good, check if you have 12V and 24V. It's more likely that the flyback isn't working at all (no secondary voltages) rather than the heater winding inside the flyback being open.
Measure resistance from A to J. It should be very low, 2-3ohm. If it reads open, check every point in between until you find where the circuit is open.
If everything tests good, check if you have 12V and 24V. It's more likely that the flyback isn't working at all (no secondary voltages) rather than the heater winding inside the flyback being open.
msdstc
Active member
ok awesome thanks a ton I'll do this when I get a chance. is there a way to test the heater by placing the probes directly on the neck pins itself just in case?
mecha
Well-known member
oh cock, you're right. the trace colors did seem a little off. lol
good looking out again as always
Yes, with a blue ring tester.
Yes, you can measure the 6.3VAC heater voltage across the two heater neck pins, but most multimeters can't accurately read the 15kHz AC voltage produced by the heater circuit (for example, my Fluke 117 can't do it). You'll need a pretty serious professional grade multimeter (like a Fluke 87) in order to do that. Ask me how I know.
