Tempest playing blind

shirkle

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Just picked up a nonworking Tempest. It plays blind.

What I've figured out so far is that someone already installed an LV2000 and at some point may have done a Zanen kit on it.
Two fuses were blown when I got it(f100 and f101). I replaced both but nothing changed. What would have caused those to blow?

The LED on the deflection PCB is not lit.
The LEDs on the LV2000 are not lit.

I have a new zanen kit (seller included it), but I'm not sure I want to go through 3-4 hours of soldering if someone already did this and it didn't solve the problem.

What else can I check before moving forward?
 
Are your other two fuses good? Verified that you have power coming TO the monitor from the power brick? Try turning up your brightness?
 
Yes, all fuses are now good.

I assume there is power coming to the monitor because I can see that faint glow in the neck.
 
I just tested continuity between the 6 transistors mounted on the frame and the frame itself to see if anything was shorted. My results were consistent, but I'm not sure if it tells me much or not.
Every one of them showed continuity between the transistor case and the frame. The all also showed continuity between 2 of the 'legs' and the frame. The one leg on each that did not show continuity was the one with the either blue or green wire coming from it.

I thought there should be no continuity at all because that would short it out.


Also, turning brightness all the way up made no change.
 
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That's not good at all. You should not have any continuity between anything on those transistors and the monitor chassis. If you disconnect the wiring harnesses that go between the main monitor PCB and those transistors does it change your measurements?

I guess maybe the person before you didn't think they needed the mica insulators?
 
Interestingly, the insulators are there. So, I unplugged the main connector but there is still continuity.
Next, I unplugged the small red connectors that come from the pairs of transistors and each time the continuity stopped. So, the transistors themselves aren't causing the short, but there is a short somewhere. I just don't know where and I didn't see anything obvious. I'll be taking the monitor out later today or tomorrow to investigate.

Anything else I should check for first?
 
You're not reading a short with the connectors in place. What you are doing is reading a very low value part that is under 20 ohms.

Of greater concern is why your low voltage section isn't powering up. For a properly working 6100 in a tempest, the spot killer LED should come on for a second when turned on, then turn off. If it's not doing even that, then there is a problem.

Have you pulled the deflection board and inspected it for cold solder joints? That black PTC part directly behind P100 is well known for this...
 
If it's not too big a pain for you to take the monitor out I'd definitely work on it that way. I just fixed a wg6101 and as soon as I took it out of the machine I had a couple things just jump right out at me. Way easier to work on on the bench imho.

I'm sure someone else here will jump in with suggestions... but personally I'd just start tracing back from the pin that you are getting the continuity with the chassis on and see where it leads you. Sounds like a catastrophic failure of some common part.

Good luck! :beerchug:

(edit... see... I knew someone would jump in... with a better suggestion... :D)
 
I pulled the boards today and no cold solder joints jumped out at me. I looked pretty closely. I'm planning on installing the Zanen kit today/tonight.

Also, originally I posted that two fuses were blown: F100 and F101. I replaced them and both have blown again. What would cause that?

I'm going to do that kit, but I'm not going to turn it on until I know what made those fuses blow. I don't want to waste my time on that kit if I'm just going to riun the components on power-up.

Also, is it normal for these monitors to have serious burn in the center of the screen. I'm not talking about a light gray burn in, I'm talking about black spots where it looks like the phosphor is gone. They are tiny, but I've never seen that before.
Anyway...back to those fuses :)
 
Zanen kit complete. Same result. FUSES STILL BLOWING.

Any thoughts?
 
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1) Unplug all the connectors to the deflection board except for the big one.
2) Fuses blow?
3) Connect P100 only.
4) Fuses blow?
5) Connect each connector one at a time and check to see if fuses blow.

Let us know how far you get before you start blowing fuses...
 
Well, that was a pretty short-lived experiment. :/

I only had the main connector and the degaussing coil connected and it blew both fuses almost immediately. I guess I didn't follow your directions exactly by leaving the coil connected....would that make a difference?

Otherwise, where do we go from here?

If you can't tell, this is my first 6100 experience.
 
Possibly. if the degauss coil is shorted to the frame, it might blow the fuse. Unplug it. And if that doesn't work, unplug the HV unit and try again. If it still blows, doublecheck what voltage is coming to the monitor from the power brick...
 
Will do....unfortunately it'll have to wait until tomorrow. I'm fresh out of fuses. Thanks for your help so far- it's greatly appreciated.
 
OK, big connector only(not even the HV connectors) and the fuses blew immediately.
The spot killer LED came on and one of the LV2000 LEDs came on briefly before fading out.

Does that mean that the voltage coming into the monitor is too high? A PCB problem?

8 fuses down. Let's keep a tally.
 
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According to the schematic I found, the voltage coming into those fuses should be 25v. I just put a meter to them and they came out at 25.9 and 26v at the connector. That seems to be within the acceptable range. Why are these fuses blowing then?

After checking more voltages in the cabinet (PCB and Audio Regulator) the only ones that seemed way off were the 36vac on the Audio reg board. They were only coming in at 19.8vac. I'm not sure if those are supposed to be added together to get 36v (39.6, which isn't off by too much), but I have a feeling they are.

All other PCB readings were dead on.
 
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Get your meter out and measure all the diodes near those fuses, and then check the transistor in the back on the heat sinks...
 
Is there a way to measure those diodes since they are in circuit, or do I have to desolder them and remove them to measure them? I'm a little rusty on that stuff. Sorry for being a pain, but what measurement should I get on the diodes and transistor?
 
Just measure them for shorts. Yes, you can test them in circuit. if any register as a short, remove one leg and retest....
 
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