Friday, October 21, 2011

Customer support-via email between me and a customer from Belize part 2

Jorges : I had already disconnected the collector from board, and the snubber and diode that goes to pin 1 of fly back and still there is short to that pin from ground. Sir this is hard. Do you think maybe I go check elsewhere else, or is it time to do voltage testing...although there is short?

Humphrey: Components that can short on that line are very few...and the way you put it it’s like the short is after the fly back...These include HOT, snubber capacitor. The yoke (horizontal),  dis- connect the yoke connector at the circuit board and test again...short gone?

Jorges: Sir I have done this. Just in case I also disconnect the lines from board to CRT Neck too. Still there is a Short.

Humphrey: just follow that line removing one leg of the component at a time until the short disappear...Very few components though...and come back to me.

Jorges: Ok Mr. Humphrey, This is what I did. After I check from ground to (secondary) cathode of diode and next way there was a short on the b+. This line goes to pin 2 of FBT. Before it reaches FBT it passes the white resistor 3.9 ohm that got hot. It’s like the surge but this is on the line to pin2 of fly back.

When I disconnect all component after the secondary diode which test good (when I lift one leg) up to Pin2 the short is still there. So I lift pin2 and the short on the line is gone. But when I touch the probe to pin2 that is disconnected it shows short. Because there should be ohms to Pin1 to Pin2, I disconnect the collector of hot from pin one and also the snubber, diode, and another capacitor from this line. If I now touch pin 2 with the probe it still shows short to ground.

I de solder pin1 (collector) and test and Pin1 and Pin2 still show short to ground.

I removed the fly back from board and there is short from the ground pin5 to Pin1 and Pin2 of fly back. Also when the light was blinking (TV was on) there is a tic, tic sound in fly back. I don't understand fly back much, but you can bet sir that I am going over that Chapter in your book again for the fourth time. Thanks.

Humphrey: or could it be the culprit is the fly back  itself?...I smell a rat here... there is no way the B+ pin on the fly back resistance to the ground  have continuity.

Jorges: Thanks for the tip on smelling a rat. I opened the FBT and what do you know, it is leaking all inside. I went to an old TV repair shop and got a used replacement. What do you know, like my teacher I like what my ears heard.. And I had to adjust focus and brightness a bit and I like what my eyes see. Thanks

I find it strange that the HOT is good, since I didn't replace it or the snubber, I tell the owner there is chance TV will only run for a while, but he is in too much hurry to wait for part, so he knows the risk.

This eBook has made me learn in 2 weeks, what I wanted to do for so long. It is so practical and now I am even checking HOT Out from IC's, the Horizontal Yoke, and directly go to suspect Filter Caps on VCC Power IC, Current sense resistor and more. Thank you!!!

Wishing you all the Best Jorges...

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