CurtPalme.com Home Theater Forum

[CZ Eddie]

Bummer.
Nope, arcing isn't normal for new tubes in my experience.

Are you still not getting any crackle, but you are getting heater lights at the back of the tubes?

[Sparky015]

that's right, no crackle, but I get the heater glow at the rear of all three tubes.

This is where I wish I had a set of spare boards and supplies, although my concern is that there is something else wrong that caused this. I'm still holding out that it's the protect circuit that's keeping it from powering up, but I'm at a loss at the two large snaps that I heard and saw.

[cmjohnson]

Do you have ALL your grounding leads and straps connected up properly? And I DO mean ALL of them.

Disconnect any boards that are not totally essential. Unplug the focus board, the astig board, your second input board, your quad input
board if you have one. Astig coils, convergence coils. CMM board. Basically just leave the deflection systems, neck boards, power supplies, CLM, and VIM connected up. The more you eliminate from consideration, the simpler the remaining problem becomes.


Be very sure the G2 lines are hooked up properly, too.

I'd just take it apart and rebuild it slowly and carefully, inspecting everything as I go.


Also, get the neck card jumper data from Tse and make up two jumper plugs. Try out the PJ with only ONE tube installed. If it won't run like that, then something major is wrong. The indicator lights on the CLM will suggest what board(s) are likely to be at fault.

Fortunately, everything's available.

CJ

[km987654]

Sounds like no HV with those symptoms. I would be looking at the HV components.

[Curt Palme]

This is a Marquee from the sound of it. Did you put the ground straps on the tube? I do that once in a while which causes arcing.

It is rare but possible that a tube is bad, I've had a nek crack in transit, but not enough to snap it, so I installed it and there was arcing.

Also possible that there's impurities in the tube, causing arcing in the neck.

I also had a tube where the electron gun came loose in transit, and it was rattling around in the neck, still connected to the pins. that also created a light show.

Note that all these are really rare, but those are possibilities anyways..well, except for the missing ground leads, stupidity runs rampant here in Langley..

[Curt Palme]

This is a Marquee from the sound of it. Did you put the ground straps on the tube? I do that once in a while which causes arcing.

It is rare but possible that a tube is bad, I've had a nek crack in transit, but not enough to snap it, so I installed it and there was arcing.

Also possible that there's impurities in the tube, causing arcing in the neck.

I also had a tube where the electron gun came loose in transit, and it was rattling around in the neck, still connected to the pins. that also created a light show.

Note that all these are really rare, but those are possibilities anyways..well, except for the missing ground leads, stupidity runs rampant here in Langley..

[dvh99]

i dont know if it will hurt but can you put the defl yoke beside the pj and connect it to the vdm and hdm plus the other 2 tubes in a normal way of course.

[Sparky015]

Yes Curt, this is a Marquee. I did not have any of the ground straps connected. I had the heat sink open and was just powering it up for the first time to make sure things worked. Is that what caused my arcing? I had all of the plastic covers over the CPCs off, so the ground strap connecting the top metal cover to the rear cover was dangling. TO be honest, I'm not sure if it was touching the tube or not. The rear ground straps on the neck board cages were also dangling, but not near the tubes. I didn't realize they needed to be in place. I guess I've been playing with fire. I fired up the duds before I removed them this way as well.

When I get home, I will investigate the tube further. I stripped all of the magnetics off it and inspected it and it seems fine. So sounds like the two large snaps are most likely caused by either not having the ground straps connected, or because of impurities in the tube, and that most likely took out my HDM board, which put the pj in protect mode killing the HV? If that is the case, I 'm hunting ghosts trying to find the source of my arc, and I need to concentrate on repairing the HDM.

[Nashou66]

Paul the main ground straps that should be connected are the ones from the Copper tape to the VNB. if those are not connected massive amounts of static electricity builds up and will spark to the closest path. once it was my finger Yeoweee!!!!!

Those will cause the HV to shut off but usually the HV comes back up after a static spark surge. It might have taken out a component on the HDM.

Athanasios

[Sparky015]

Thanks Nash. When it happend, I heard the crackle of the HV on, and then a snap, then a crackle like the HV was re-engaging, then the second snap. HV did not return after that, only an H-fail light. That would seem to indicate a static snap as you describe. The copper tape ground straps were connected, however I reused those ground straps from the dud tubes. Ok, I'm going to say this because I was unsure of myself when I did it, but now I have a feeling the god of stupidity bit me. The tube labels on the new tubes are on the sides of the tube neck. Rather than peeling off the label and moving it to the top out of the way, I put the ground strap over it, thinking the other half of the strap is on the tube on the bottom of the neck.

[Nashou66]

Yes, that is exactly what happens. it should power up again hopefuly, make sure the connection of the aguadag( spelling?) straps are right on the tube. clean the tube well so a good connection is made. The proper tape to use over the copper is an antistatic tape but i just used regular clear Duck Brand packaging tape.

Athanasios

[Sparky015]

Ok, I'm feeling better now. I'm glad this happened because of stupidity, not because of a bad tube. I did use the Kapton tape over the copper tape. Apparently there is a reason the copper tape covers two sides of the tube. Now I know! So now I need to correct the grounding mess I made and move the tube labels to the top, then investigate the HDM. Most likely I blew a transistor or FET, hopefully that's all.

[Sparky015]

Thinking about this a little more from all of the comments. I had the aquadog grounds hooked up (albeit, only half of the strap was on the tube, doh!), and those are connected to the neck board. The neck board is grounded to the neck board cage through the two white grounds. Since I did not have the ground straps connected to the rear heat sink, essentially the tube/neck assembly is still floating in comparison to chassis ground. Static built up on the red tube, had no where to go, so it probably discharged through the deflection yoke.

Does this make sense?

[cmjohnson]

Yeah, that's exactly how it's going to work in that case. Your HDM probably fried, or more specifically, the control ICs on it probably fried.
Most of the high voltage components could have withstood the spike, I'll wager.

BTW,that's aquaDAG, not aquaDOG. A wet mutt has nothing to do with this!

Get another HDM and try it. It'll probably fix the PJ. If not, you'll have a spare HDM for when you DO get it fixed, and having a good
spare HDM is never a bad idea.


CJ

[Sparky015]

aquadog sounds better! It seems my typing has been steadily getting worse.

Thanks CJ. Even though I was a bone head, I suppose this is better than a torched new tube.

It's an ultra HDM, so if anyone has one to sell let me know and a price. Either way, I know I will be troubleshooting tonight. Hopefully the damage is minimal.

[mp20748]

[Curt Palme]

Otherwise I can repair it.

[Curt Palme]

Otherwise I can repair it.

[JustGreg]

[mp20748]

Q501 is on the mini board (daughter board) mounted on the HDM. It's a TO92 transistor that can also be found on either a "Contrast Modulation" or "ACON" board.


http://www.fairchildsemi.com/ds/2N/2N7000.pdf

[CZ Eddie]

[Sparky015]

thanks for the posts guys. I'm diving in tonight, so we'll see what the deal is.