6100 Z Amp 100% and not adjustable

FlapJ4cks

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Rebuilding another 6100 here and I have one that has the Z-Amp at maximum and the brightness control on the flyback doesn't really do anything...

I suspected ZD902 initially, so I've replaced all the zener diodes on the P316/HV unit with no luck...

Maybe something on the neckboard?

 
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Check this connector on the neck board. If it is not connected, a super bright picture is the result.

6100_037_Neck_brd_conn_800x600.jpg


Bill B.
 
Going to try swapping in known good working HV boards and neckboards tonight to see if I can at least narrow down which board the issue is in...
 
Check the wiring very carefully, particularly the red and white wires going from the back of the HV focus and screen adjustment knob block, to the neck board.

Pull the rubber boots off the back of the block. Pull the red and white wires off and pinch the connectors slightly to make sure they fit on the posts snugly, then replace the wires and boots.

Check the red and white wires where they go into and out of the 2-pin molex on the HV cage. They often break inside the connector (where the wires meet the pins), and are hanging by a thread. Disassemble and solder them back together if necessary.

Also, check where the red and white wires connect to the neck board. The red one often breaks where it connects to the board. The white one goes into the neck connector, but you can pop the end of the connector off and check it.
 
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D501 on the neckboard open? Should measure close to 180v on both sides.

Also, from the FAQ:

• R515 (broken wire to R531)
• C503 (reversed; may toast R527)
 
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D501 on the neckbeard open? Should measure close to 180v on both sides.

Also, from the FAQ:

• R515 (broken wire to R531)
• C503 (reversed; may toast R527)

Thanks for the tip! Busy week, but I'll definitely check this when I get back to it this weekend.
 
Check the wiring very carefully, particularly the red and white wires going from the back of the HV focus and screen adjustment knob block, to the neck board.

Pull the rubber boots off the back of the block. Pull the red and white wires off and pinch the connectors slightly to make sure they fit on the posts snugly, then replace the wires and boots.

Check the red and white wires where they go into and out of the 2-pin molex on the HV cage. They often break inside the connector (where the wires meet the pins), and are hanging by a thread. Disassemble and solder them back together if necessary.

Also, check where the red and white wires connect to the neck board. The red one often breaks where it connects to the board. The white one goes into the neck connector, but you can pop the end of the connector off and check it.

Pulled the boots, tightened the crimps and verified solid connections. They both seem good and this appears to be a fairly new flyback transformer as its shiny new white and the pins under the boots look brand new. Also double checked the molex connections and the seem good as well. Unsoldered & resoldered all the wires that are direct to PCB connections and toned through to verify.

I couldn't figure out how to pop the white cap off the neck connector, and I didnt want to force it so I didnt check that. :(

D501 on the neckboard open? Should measure close to 180v on both sides.

Also, from the FAQ:

• R515 (broken wire to R531)
• C503 (reversed; may toast R527)

Pulled D501 and tested it good. R515 metered correctly as well.

Still need to pull C503 and check its polarity and correct install.

Also accidentally discovered the degauss coil/spring was a rusty crumbled mess inside the housing when I tugged it a little at the bottom where its grounded and a large chunk of rusty spring just pulled straight out. :(

That might explain the huge divergence in the red, green & blue guns in the image... https://imgur.com/eP7jhgi

Any place to get a replacement? Back to the drawing board..
 
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If it's a spring, it's the dag spring, not the degaussing coil. Two separate things. The degaussing coil plugs into the left rear corner of the deflection board.

The dag spring is the ground for the tube. That's important. You don't want to run the monitor without it. You can make a new one with just a piece of the old spring (even a short rusty one) and some solder braid. I've repaired a few this way.
 
If it's a spring, it's the dag spring, not the degaussing coil. Two separate things. The degaussing coil plugs into the left rear corner of the deflection board.

The dag spring is the ground for the tube. That's important. You don't want to run the monitor without it. You can make a new one with just a piece of the old spring (even a short rusty one) and some solder braid. I've repaired a few this way.

Yep thats what it is and I should have said. :) ...grounded to the chassis next to the HV cage. It looks like it hasn't been able to carry an electron for several decades as most of it is dust.. Could it have damaged other components being on without it?
 
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Yep thats what it is and I should have said. :) ...grounded to the chassis next to the HV cage. It looks like it hasn't been able to carry an electron for several decades as most of it is dust.. Could it have damaged other components being on without it?


Can't say, as I've never tried running one without it. But without a ground reference, I can't see how the tube is going to work properly. But if nothing was arcing, sparking, or smoking, you might be ok. You definitely want to fix it though, and then see where you're at.

You just need to find a small piece of spring, roughly similar to the old one, maybe take one off a dead TV, or find one somewhere. You just need it to hold a little bit of tension, then you can make a new ground strap out of copper solder braid/wick.

Stretch the solder braid across the tube, fasten it to the frame on one end (any way you can), and use the spring on the other end to hold it tight against the tube.

The back of the tube is conductive aquadag ('dag') paint, and that strap basically just connects the dag to the frame, to ground it. You want to make sure the dag isn't peeling off, and is clean where the strap contacts it. You can wipe it down with a damp paper towel if needed. The dag on 6100's won't dissolve, though it's basically like pencil graphite, so you might see a small amount rub off onto the paper towel, so you don't want to scrub it off. Just wipe off any dirt or rusty bits from the old spring.
 
You just need to find a small piece of spring, roughly similar to the old one, maybe take one off a dead TV, or find one somewhere. You just need it to hold a little bit of tension, then you can make a new ground strap out of copper solder braid/wick.

Stretch the solder braid across the tube, fasten it to the frame on one end (any way you can), and use the spring on the other end to hold it tight against the tube.

The spring I'm replacing is pretty much dust and in about 100 pieces. Could you guesstimate the size (length & diameter) that a replacement spring should be? Or just short enough to apply some tension to the braid vs. stretched all the way across the back?
 
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I finally got around to this again... I soldered 2 light springs on each end of a solder braid and stretched it across the back of the tube across the aquadag with the springs connected to the shielding. I then soldered the grounding wire to the middle of the braid and anchored it to the chassis as before.

Firing her up didn't change the behavior any.

Even more bizarrely, I also tried swapping the neck board with a known good neck board from my Tempest and I actually got zero picture; almost like there was no HV.

I swapped back to the original neckboard and fired her up and get the same results as before. :/

I didnt notice before but at about :23 notice how the picture scales up on its own? That provide any clues?

Digging back into the FAQ again now for insights...

 
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In Bill's pic he mentioned this connector being off and you saying it was on.

I just rebuilt both the deflection board and the HV recently and while moving this connector one of the wires just FELL OUT. When I went to test the other, it popped out with barely any tension. I re-pinned and everything was AOK.

6100_037_Neck_brd_conn_800x600.jpg


Bill B.[/QUOTE]
 
In Bill's pic he mentioned this connector being off and you saying it was on.

I just rebuilt both the deflection board and the HV recently and while moving this connector one of the wires just FELL OUT. When I went to test the other, it popped out with barely any tension. I re-pinned and everything was AOK.

No, those pins are definitely well connected. I get good continuity from the back side solder-pads of the pins on the neckboard through to the P900 pins on the HV cage.
 
Do you have another color vector game that you can swap monitor to isolate it? Kinda looks like a Tempest PCB problem but not 100% sure on that.


Andrew
 
Do you have another color vector game that you can swap monitor to isolate it? Kinda looks like a Tempest PCB problem but not 100% sure on that.

Andrew

Yeah, Tempest runs fine on the monitor in it's cabinet. This is a spare 6100 destined for a reproduction Q cabinet some day.

edit: Additional findings

The B+ never goes about 165v; even with the adjustment pot in HV cage wide open. When it goes to the title screen that really pushes the transistors, the voltage drops to the low 140s to upper 130s.
 
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