Tempest repair: Monitor and AVG

Sinistar

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Spent the last week reading Tempest posts, and it's gotten me a long way. Now it's time to sort some of the more specific problems out....

First, luckily I had 1 semi-working tempest before i started fixing my second, but they are both helping to solve each others problems.

Started with SpotKiller on, no video, no HV or deflection sound, several burnt resistors on the main chassis board, plays blind.

Did a Bob Roberts deluxe: could hear HV crackle, and deflection, but still nothing. No LED lit on the AVG board. Swapped the board from my other working one, BINGO, happy day- working, but with issues (wobbling, unaligned vectors, etc). The HV cage was off, so that may solve the wobbling. The swapped board has some known xy issues that I need to get to- but first:

*NO led lit on the AVG board- ideas where should I start with checking to get some xy out of it?
 
You should be able to run test mode with out the aux board. That will atleast get you the test screen to check the x,y output.

On the Aux board I would measure to make sure you are getting +5 to it. You might have an LED out. There's not much before the LED other than C56, and R2.
 
Spent the last week reading Tempest posts, and it's gotten me a long way. Now it's time to sort some of the more specific problems out....

First, luckily I had 1 semi-working tempest before i started fixing my second, but they are both helping to solve each others problems.

Started with SpotKiller on, no video, no HV or deflection sound, several burnt resistors on the main chassis board, plays blind.

Did a Bob Roberts deluxe: could hear HV crackle, and deflection, but still nothing. No LED lit on the AVG board. Swapped the board from my other working one, BINGO, happy day- working, but with issues (wobbling, unaligned vectors, etc). The HV cage was off, so that may solve the wobbling. The swapped board has some known xy issues that I need to get to- but first:

*NO led lit on the AVG board- ideas where should I start with checking to get some xy out of it?

Have you checked the B+ yet to see if you are getting HV? It should be adjusted to 180 volts. Also, there's a HV cutoff adjustment on some models that needs to be adjusted as per the K6100 manual.

Oh wait, never mind. ha ha
 
Oh wait, never mind. ha ha


Heheh- actually Jehuie, it was many of your threads that got me all past the HV stuff! Thanks to you and your helpers on that. Seeing that monitor power on for the first time in probably 10 years was a real hoot :)
 
board voltage check

Just pulled the voltages from the board with the xy issue:

+5dac= 4.98
-15v=-15.36
xout= -.434
yout=2.73
6.8v=6.96
vctr= .212
All Caps appear to have proper voltage.


So obviously xout is having issues, not sure about the other ones havent ref'd the manual to see what y should be or if thats ok. So no Xout on this board, what to check now?
 
First of all, any comparisons should be done with it in test in the crosshatch. Are you saying that you have no spot killer but no picture ? It's possible you have high voltage but not enough to put up a picture. Also, hate to state the obvious, but if you have no spot killer on and high voltage is present, have you turned up the brightness ?
 
I have 2 Tempests to test with and this is a board issue im dealing with now as both monitors appear to be working right now with the (mostly) working board.

To recap the current state, had a tempest w no monitor working and no led lit on the top pcb. No HV, no static- did a deluxe, had HV, static- no pic, plugged my working board in- and had a working tempest.

So now two working monitors- 1 working board.

The non working board plays blind. I cant see anything out of this board to put it in test mode, i can run the tests fine- but i see nothing on the screen.
 
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well if you aren't getting X out, you really could use a scope. That way you could at least see if you are getting a signal.

Otherwise, start measuring out the voltages on the Tl082 chips at D/E12 and A11. The check your mc1495 at C12

Those are the more common failed parts. Beyond that, it's either A/D or further up the line.
 
well if you aren't getting X out, you really could use a scope.

Yeah, this one really has me getting all the tools, hv and logic probes en route. So how much could I use a scope, not to change topic here, but some of those little pocket scopes look very cool, but at around $80, just wanted to make sure I had more than -say, one use for it, do you use one often?

Ok, checked the pins of those chips- there are some suspect readings:

T082 @ D/E 12
10.11 |-| -15.35
10.11 |-| .654
.659 |-| -.426
15.21 |-| -.426

T082 @ A11 (very suspect of this chip since it differs so much from the one at D/E12)

0.3 pulseing to 0 |-| -15.35
1.0 pulsing to 0 |-| .4 pulsing to 0
1.0 pulsing to 0 |-|.9 pulsing to zero
15.2 |-| .9 pulsing to zero


m1495 @ c12 (a few suspect readings here as well, although may be correct)

15.33 |-| 0.00
-1.31 |-| .006 pulsing to 0
-7.10 |-| -1.135
13.70 |-| 0.00
10.12 |-| 13.96
6.92 |-| 10.12
 
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Well a decent O'scope is invaluable especially checking vector outs.

Compare the x to y, since it sounds like you have Y. The X values will be kinda close.

X= A11, C12, D/E12
Y= D11, C13, D/E13

Just follow the schematics.
 
C12 is off-

Thanks Talon, you're certainly guiding me in the right direction on this.

So I checked the 2 sets of chips against each other and all but C12 seemed ok. C12 though, was wildly off it readings compared against C13. So I ordered the IC from Bob Roberts, will report back once its been swapped.

Thanks again for all the help!



Well a decent O'scope is invaluable especially checking vector outs.

Compare the x to y, since it sounds like you have Y. The X values will be kinda close.

X= A11, C12, D/E12
Y= D11, C13, D/E13

Just follow the schematics.
 
replaced parts update

Ok, so I replaced the IC at c13, which does not seem to be outputting much. The 3rd leg of the chip reads @0.0730 and that is also the same reading I am getting off of the XOUT. Must go further up the board, what should I be checking further up from c13?

Just added a logic probe in the kit, if i can use it in diagnosing this, still shopping for scopes.


Thanks for all the help so far!


(on a positive note, replaced the YLIN pot on my second board, and now have that board at 100%)
 
I'm dead in the water on this Tempest board. Gotten as far as I can get- still no x-out.

Is this one I should give up fixing and send it to someone who knows? Anyone out there that can troubleshoot this board for me, preferably in socal?
 
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