WG [FIXED] 6012 [B+ actually not stuck at 25v], no picture

alfonzotan

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UPDATE: I was digging in the wrong place. B+ is fine, but still no picture.

Original post follows:

Very weird issue here... I've rebuilt the deflection and HV boards for a WG19K6102 pulled from a Black Widow. Work included:

Deflection:
LV2K installation (twice: on the first one voltages tested fine but the LEDs didn't light, assumption now is the first card just has bad LED installation but I left the second one in).
Replacement of R801 (looked burned), R811 and R810 (measured out of spec), all caps and transistors in spot killer circuit.
Replaced D702 and D602, moved to solder side.
Removed solder side diode mods (see the old 6100 FAQ).

HV:
Replaced HV adjustment pot, all zener diodes, all electrolytic caps and the following resistors due to being burned or testing out of spec: R920, R904, R905, R922, R902, R929, R932, R933.
Moved R907 to solder side.

Reflowed all connector pins on deflection and HV boards. All frame transistors (had to replace a couple) and deflection transistors check out when tested.

Rebuilt per @andrewb's guide. Everything looked good up until the very last steps: HV at the anode is a steady 19.5k dcv, LV measures good at both connection points on the deflection board, there is neck glow and chatter. Spot killer appears to work. But, testing with a known good Tempest board: no picture. And even weirder (although it does explain the no picture): B+ measured at the P323 neck board is stuck at 25v.

Next thing I'll test will be the wire connectivity from the HV to the neck board, but the fact that I'm getting a reading (even if it's not correct) at B+ suggests that's not likely to be the issue.

Would appreciate any suggestions.
 
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If you disconnect the B+ from the load (on the neck PCB) does it come back up to 180?

Looks like lifting the leg of R527 will accomplish the same thing.

1758987019322.png
 
If you disconnect the B+ from the load (on the neck PCB) does it come back up to 180?

Looks like lifting the leg of R527 will accomplish the same thing.

View attachment 850191
Well how about that. I guess I was misreading earlier. Results (both connected and unconnected):

B- (purple wire): -25v
B+ (center orange wire): 180v (I would have sworn yesterday this was 25v, probably a mis-touch of the DMM on my part)
B+ (red wire): 25v.

So I guess I can scratch that one off the list and chalk it up to unfamiliarity with the P323. Still no picture, though...
 
Tell me you also own an oscilloscope. ;)
Don't be silly: of course not.

But let's say I did: what would you use an o-scope to test for in this situation? I'm not worried about the game board right now, I have three known good Tempest boards I can get vectors from (not counting the Black Widow board, which is in an unknown state, unfortunately).
 
Use the scope to track the XYZ signals from source (logic pcb) to "output" (monitor boards) to find where they "stop".

In your case, I might look more carefully at the neck board.
 
Use the scope to track the XYZ signals from source (logic pcb) to "output" (monitor boards) to find where they "stop".

In your case, I might look more carefully at the neck board.
Thanks. I haven't done a thing to the neck board so far, will give it a look next.
 
Lets keep this stupid simple first.. Is the Spot Killer LED lit?

Spot killer appears to work.

So you're saying you see the lite go on and then extinguish when the game is turned on?

Thanks. I haven't done a thing to the neck board so far, will give it a look next.

Bad connections on the red IDC and cold solder are common on all boards so if you've not hit the neck board that's gonna need a once over.

I cant recall if you'll hear chatter with just 1 channel (x or y) working. Make sure that the X and Y input wires from the input connector are actually still connected to the board. The OEM wires are solid core and break easily. I've lost count of how many times I've broken one of those off when I was reinstalling the boards.
 
Lets keep this stupid simple first.. Is the Spot Killer LED lit?



So you're saying you see the lite go on and then extinguish when the game is turned on?



Bad connections on the red IDC and cold solder are common on all boards so if you've not hit the neck board that's gonna need a once over.

I cant recall if you'll hear chatter with just 1 channel (x or y) working. Make sure that the X and Y input wires from the input connector are actually still connected to the board. The OEM wires are solid core and break easily. I've lost count of how many times I've broken one of those off when I was reinstalling the boards.
Spot killer is on when it should be on and off when it should be off.

Neck board is definitely next on the evaluation list.
 
Looks like the focus block is bad. OL reading on the block, measuring directly from the posts inside the HV cage. Simplest fix looks like a flyback replacement.

Are you sure you're going to get a reading on those pots? They are typically in the multi Mohm range anyway so that sorta makes most DMMs think it's Open.

Though if the screen output is low that might do it too. The Screen output on raster chassis is typically 0 - 1.5kv. Most DMMs have a valid range under 1kv so you'll need an HV probe to test that it changes when you twist the knob.
 
Are you sure you're going to get a reading on those pots? They are typically in the multi Mohm range anyway so that sorta makes most DMMs think it's Open.

Though if the screen output is low that might do it too. The Screen output on raster chassis is typically 0 - 1.5kv. Most DMMs have a valid range under 1kv so you'll need an HV probe to test that it changes when you twist the knob.
The meter was set to M Ohms, and still no dice. But it's worth checking the output levels (I do have an HV probe).
 
The meter was set to M Ohms, and still no dice. But it's worth checking the output levels (I do have an HV probe).

You don't have to attach the neck board to the tube when you run the monitor. If you decide to test the Focus output expect 5-10kv.

I test that value with the neckboard off and the HV probe against the lead where it's soldered to the neck socket. Just flip up or pull off the cap. Be careful you don't provide opportunity for an arc though.
 
You don't have to attach the neck board to the tube when you run the monitor. If you decide to test the Focus output expect 5-10kv.

I test that value with the neckboard off and the HV probe against the lead where it's soldered to the neck socket. Just flip up or pull off the cap. Be careful you don't provide opportunity for an arc though.


I've been working with him on this over PM. He's getting a complete open if he measures resistance between the focus and screen pins on the back of the focus block, when it should be showing 40+ Mohms. So his block is bad, and he's likely missing the screen voltage, and maybe focus too (even though he has 19kV at the anode).
 
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