Tempest playing blind

[scottz29]

It honestly sounds like you have a problem with your LV2000 at this point. I would disconnect everything and try the deflection board by itself.

You should get +26v on pin 3 and -26v on pin 6 of P100. If you don't, adjust the respective pots on the lv2000.

Did you check all the diodes on the lv2000 as I suggested?

 

[modessitt]

This is how you measure your HV without an HV probe. You measure your B+ instead and adjust the same pot.

Normally you measure it on pin 5 of P900 (the bottom connector on the HV cage), but it's much easier to just follow that orange wire up to where it connects to the neckboard and measure it there. With your black lead on the frame and your red lead on that spot on the neckboard, you should have +180vdc. If not, adjust your HV pot. Make sure the cage is off so you can reach it easier, and use a plastic adjustment tool if you have one so you don't have to try sticking your hand in there...

 

[modessitt]

BTW - it's easier to measure your +/-26volts by just measuring on the casings of the two frame-mounted transistors on the right side wall (the 2N3716 and 2N3792). One will be the + and the other will be the -...

 

[shirkle]

modessitt- I'll try your recommendations tonight when I return from dinner.

For right now, I replaced the diodes on the LV2000 and rechecked all voltages at the p100 and p900 connectors.
Here's what I got:
P100
p1: +33.1
p2:
p3: +27.9
p4: -5.7
p5: -23.7
p6: 0
p7: -27.1

p900
p1: -5.7
p2: -5.7
p3:0
p4:0
p5:0
p6:0
p7: -23.3
p8:0

Should the fact that pin 5 showed 0.0 be a major concern? Like I said, I'll check it again in a couple hours to confirm it using modessitts suggestions. Those pins were a little tough to get to, so maybe I did mess up measuring (though I was careful)

 

[shirkle]

Ok, modesitt...The transistors on the frame measured -32vdc and -12vdc.

I'm getting nothing on the orange wire. A couple times I tried it and it jumped up to a whopping 5v, but not close to 180.

***One change I've notice, and I'm not sure when this started, is that I now have about 5 very tiny bright spots on the monitor. They are in the direct center and various colors.***

 

[shirkle]

I replaced a few of the transistors on the frame and when I turned it on, I got a bright spot (about a 1/2 wide, very bright) on the screen for about 5-10 seconds before I heard a snap, crackle, and pop in the cabinet...then the spot disappeared.

What was that?

 

[Jeff F]

Damn... I've been keeping up with this thread and I was hoping your last post there was going to be a "success" post.

Just hang in there... eventually it'll work out... eventually.

 

[modessitt]

I replaced a few of the transistors on the frame and when I turned it on, I got a bright spot (about a 1/2 wide, very bright) on the screen for about 5-10 seconds before I heard a snap, crackle, and pop in the cabinet...then the spot disappeared.

What was that?

Check your caps to see if you popped one. If so, check to see if it was in backwards, or the wrong value for that spot. If so, then get a new one and put it in right and try again.

And you should be starting with your b+ turned all the way down, too...

 

[scottz29]

Also recommend sitting at the back of your cabinet watching your boards when you power on.

 

[shirkle]

I usually do, and I have the cabinet set up so that I can see a reflection of the monitor at the same time. Last night, when I noticed something was actually on the screen, it got my attention...then I heard the crackle.

I'm not sure what it was. All of the caps look ok.

I have noticed that the anode cap will not remain on...it loses suction(yes, I cleaned it w/ alcohol) . I don't think it had much to do with this, but wanted to point it out.

I still think I have a bad transistor or two and I'll continue to test them tonight after work. Now that school's starting back up, I have a lot less time to work on it.

 

[scottz29]

I have noticed that the anode cap will not remain on...it loses suction(yes, I cleaned it w/ alcohol) . I don't think it had much to do with this, but wanted to point it out.

Oh wow, that's not a suction cup! There are 2 metal clips that need to be pinched inwards so they fit inside the anode hole. Those clips should be firmly planted inside there.

Generally, I pull the cup back, insert one clip into the hole, then using the pressure of that clip against the glass hole, I can insert the other. Release and make sure both legs are inside and put the cup back down. If you've done that, and the cup still doesn't sit flush against the tube, you need to push the wire further inside that cup so the pressure of the wire leads is pulling the cup down to the tube.

Not 100% sure of the exact purpose of the cup, other than the obvious, to prevent arcing of some 20K volts against other things...

 

[HudsonArcade]

OK- Removed the LV2000 (didn't replace the parts, just removed it), only connected the major connector- same results!!!

You've likely got blown input bridge diodes and/or blown filter caps...

 

[shirkle]

Scott, I'm sorry, I was misleading in the anode cap part of my post. The metal hooks are fine and stay in place, but the suction part I mentioned will not stay put. It pops off afer a couple minutes. The metal hooks remain in the tube, though. I try feeding the wire through it a bit more, but it looks l;ike all of my other monitors....except the cup won't stay attached. No big deal, I hope.

HudsonArcade- I'm not familiar with the parts you're referring to. If you give me a part number or location I can find it, but I'm not sure which diodes are the input bridge diodes, etc. I know what diodes, resistors, caps and all that stuff is and how to test it, but I can't tell exactly what they all do just from looking at the board.

 

[scottz29]

I *think* he's referring to D100-103