K7000 Chassis, Blows Fuse, Extra Wiring?

Yes. C69 is already there. The jumper is in fact its leg.
 
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Yes. C69 is already there. The jumper is in fact its leg.
Right the polycap in the area marked c36 has the value of c69; i've seen this with the 4 legged version (crippled cowpacitor) and a 2 leg, but there has always been a c36 somewhere else. I've seen c36 placed in the position of d18 with d18 underneath and i've seen examples of c38 placed near the flyback or yoke like @mecha pictured.

So basically my question is:

1) Is this ok to leave as is?
2) if no, should I add a C36 on top like a standard setup and remove the jumper on the right here (or not):

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The cap in location C69 acts as C36, i.e. the flyback or retrace cap (one leg to HOT collector, other leg to ground) and since it's 6.2nF which is the value of C36 on a 19" chassis, I suspect they tried to convert a 25" chassis to a 19" even though the voltage regulator looks like a STR3130 to me and not a STR3123.

Anyway, for a 25" you leave the 6.2nF cap where it is (as that's the value of C69 on a 25"), remove the jumper and put a 3.6nF cap in the location C36 (currently not populated). And of course you make sure the voltage regulator is a 130V one.
 
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So I did all of that and when I powered it up, I have 130vdc on R301. I can hear the High Voltage startup, but I would describe it as "weak". There is no raster, even with the flyback cranked up.

I ran out of time to work on it, but I did notice that the collector on Q11 (HOT) didn't seem to have 130vdc measured on the metal tab on the back of the IC. Because this chassis has the same voltage divider, it has a wire on the HOT collector and ran up to the board on top of the heatsync, which also did not have 130vdc. My meter was pulsing with 0v readout, so I was going to probe the flyback underneath to see if it was present on pins 1&2.
 
There's no DC voltage on the daughterboard. You would need an oscilloscope. Same with the HOT collector but here the pulse is mighty high so oscilloscope and 100:1 probe. But why not check the DC voltage outputs of the flyback? 12V, 24V and if you have a HV probe the anode voltage too. If those are spot on it would mean the flyback is driven correctly.
 
So my c36/69 setup is now like the picture above. If I bridge the other two legs near the heatsync the HV starts up, but goes into shutdown after a second.

So i probed underneath the flyback. I have 130vdc on pin 2 of the flyback and pin 3 on the neckboard, as well. I have +24vdc on pin 4 of the flyback all the way to pin 6 of IC3 so we should have vertical deflection. We have neckglow and I can hear HV startup when powered up. I know that the heater is dc but I get a rolling number when measuring that way. If I measure dc, I get 1.8v on the heater circuit measured on the flyback pin 9 and also on the neckboard. Compared to a working K7000, it's the same value so I know the heater is getting the correct voltage. Still the same issue, no picture at all, screen pot is all the way up, contrast and black level pots all the way up. I check continuity from the pots on the remote board to the main board and we're good.

This is so weird. I'm tempted to pull the flyback; someone put a newer one in, but I have no idea where it's from. I wonder if this might be shutdown, but typically wouldn't the b+ be 160v?

Probably should do my own thread at this point :)
 
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Another finding. I though I turned everything up before, but I went ahead and cranked the flyback, contrast and brightness and I can actually see something:

IMG_0179.jpeg

Given screen and focus are both flyback, this may be the cause. This flyback is a newer version, but I have no idea how old or if this was a dud out of the gate.
 
Afternoon all,

I am back from taking a mental break on this project. Quick update, after much frustration, I sent my board back to @zenomorp for repair. He did a greta job and ended up making a video of the repair. Turns out I was the victim of conductive thermal paste under the HOT.

I installed the freshly repaired board, checked all connections and plugged her in. Popped the main board fuse after about five seconds. Almost the same issue as I was experiencing before but the screen actually started to come alive in that short amount of time. We know the board was good to go when I got it back as is was tested on his monitor before shipment. Looked and functioned great. Zenomorp asked me to check the resistance across the horizontal winding, red and blue wire. Thinking if the resistance was around 50 ohms then the chassis is not original to the tube....swapped along the way. To our amazement, the reading was closer to 2 ohms. I verified I have an isolation transformer in line, made sure both tabs of the anode were in place and secure.

Today I tore into the chassis to see what failed and it appears the voltage regulator ST30130 has shorted out. Zenomorp suggested a post an update to get some feedback. Attached the last part of our communication before I stuck my head in the sand.

Thank you all,

Jay

Screenshot 2024-12-07 at 2.25.51 PM.png

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Jay, let's go back to the beginning. What game is this running in? It worked for hours on my test bench with no issue.
 
Jay, let's go back to the beginning. What game is this running in? It worked for hours on my test bench with no issue.
Afternoon Sir. This is a stand up Hard Drivin game. I went back through the video you made on my original chassis problem to help with troubleshooting. Looks like the VR let go when I hooked it up to the monitor. Pins 3 & 4 are shorted, only 2 ohms on the 180 ohm resistor.
 
Hard drivin' is medium res. You can't use a 25" standard res K7000 on that game. You need a K5515, NT-2515, or a K7500. If you're running a standard res K7000 on a medium res yoke, that would explain your issue. Post some pics of the entire monitor and frame.
 

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Hard drivin' is medium res. You can't use a 25" standard res K7000 on that game. You need a K5515, NT-2515, or a K7500. If you're running a standard res K7000 on a medium res yoke, that would explain your issue. Post some pics of the entire monitor and frame.
had one of those at a location years ago, it had a K7000A in it. I don't know the breakdown for which versions of the game run standard or medium res. here's pictures of the game and the chassis I yoinked out of it. we have a couple decommissioned Race Drivin's at work, I'm uncertain what they have in them.

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had one of those at a location years ago, it had a K7000A in it. I don't know the breakdown for which versions of the game run standard or medium res. here's pictures of the game and the chassis I yoinked out of it. we have a couple decommissioned Race Drivin's at work, I'm uncertain what they have in them.

View attachment 786128

View attachment 786129
Hmm.
 
Hard drivin' is medium res. You can't use a 25" standard res K7000 on that game. You need a K5515, NT-2515, or a K7500. If you're running a standard res K7000 on a medium res yoke, that would explain your issue. Post some pics of the entire monitor and frame.
Here you go. Thanks for the help!
 

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Inspected the tube today as I have read reports of shorted windings that have caused issues. Posting my readings below for reference.

Red to Blue = 1.7 Ohms
Yellow to Brown = 10.7 Ohms
Red to Yellow = Consistent rise in Ohms upwards of 25 Ohms
Red to Brown = Consistent rise in Ohms upwards of 25 Ohms
Blue to Yellow = Consistent rise in Ohms upwards of 25 Ohms
Blue to Brown = Consistent rise in Ohms upwards of 25 Ohms
 
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