Go7-CBO issue

starfighter2

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I have a g07 that when powered on you can hear the monitor start up but there is no high voltage to the tube. I can put my hand over the picture and there is no static. I test with high voltage probe and there is no voltage in the anode cup. I have check the fuses and 4 didoes (bridge rectifier) which look good. I have changed the caps, both hot bottle transitors, and the flyback, still the same start up sound with no picture. I also tried another tube with no luck. Any ideas on what to test or try next?
 
I do have 110 at the blug.

Also, I have not checked the b+ and don't know how. Can someone tell me what to do and what I should see as results and I will try it.
 
If you have the Electrohome G07 manual, page 05 has the test point and adjustment point called out in Figure 01. Just grab your DMM and check it out.


On a G07 it's measured from the tab on R901, closest to the tube..

If you don't have a copy of the manual let me know I can probably post it somewhere (or you can do a search within the forum I'm sure it's been posted somehwere).
 
I hate to be stupid but don't see it in the manual. I have a copy of the Electrohome G07 13in and 19in Color Raster.pdf. Don't see one specific for the CBO version. any help in identifing the section would be appreciated.
 
I hate to be stupid but don't see it in the manual. I have a copy of the Electrohome G07 13in and 19in Color Raster.pdf. Don't see one specific for the CBO version. any help in identifing the section would be appreciated.
R901 is the large, white ceramic resistor mounted on the left side of the chassis.
 
here

go7-1.jpg
 
thanks, so then next question is how to test. I see the test point in the picture.

1. What should it mesure? is it a range?
2. if it does not mesure the voltage provided, I assume that I turn the pot to get the correct mesurement?
3. What if I cannot reach the messurement by changing the pot? do I need a new Pot or other part?
4. most important how would you folks test this while the monitor is on. Do you pull the chasis? if so does it sit on something. O an worried about destroying componets by shorting them or me getting shocked. I don't test commponets while the monitor is on that is why I ask for the best approach.
Thanks
 
I'll post a "how to" when i get home tonight. If you have some alligator clips that will come in handy. I can't remember off the top of my head but, i was thinking it should read somewhere around +137VDC (or I could be thinking of something else). I'll check the manual to make sure. If you're only getting like +90VDC you have "this" problem and if you have something crazy like +175VDC then you have "that" problem. Sorry, I don't remember this stuff off the top of my head. I'll check the manual when I get home from work. I'll also post the Troubleshooting Flowchart for that monitor. It helped me with a lot of problems on one of my monitors.
 
I'll post a "how to" when i get home tonight. If you have some alligator clips that will come in handy. I can't remember off the top of my head but, i was thinking it should read somewhere around +137VDC (or I could be thinking of something else). I'll check the manual to make sure. If you're only getting like +90VDC you have "this" problem and if you have something crazy like +175VDC then you have "that" problem. Sorry, I don't remember this stuff off the top of my head. I'll check the manual when I get home from work. I'll also post the Troubleshooting Flowchart for that monitor. It helped me with a lot of problems on one of my monitors.

Randy Fromm severely frowns upon his flow charts being posted. FYI

120vdc......

Correct

Positive lead on the tab closest to the tube
Negative lead on ground
Meter set for 200vdc
 
ok, so I connected the red lead to the tab closest to the monitor on the large white resitor on the left and the black to the chasis. turned on the tube, heard the tube "bounch sound" but got zero "0" vcd. also checked in ACD and zero. then turned of the power and tryed again making sure everything was secure. this time nothing, no sound. checked the fuses and the small fuse does not have continuity. so I will need to change that after dinner buy unsoldering that one and puting in another one.
 
Don't bother yet. If it's blown, it blew for a reason:

1) bad horizontal output transistor.

2) bad flyback.

3) bad voltage regulator

these are the "usual" causes. Check them before throwing a fuse at it and blowing it for no reason.
 
The HOT is the 2SD869 bottle cap transistor next to the fly and the reg is the 2SC1106 bottle cap transistor on the left hand side of the chassis.
 
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