K7500 Horizontal White Line (vertical collapse?)

mattyams

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I have a customer that has a Golden Tee Fore Complete with a WG K7500. Turns on, speakers make a popping sound every few seconds and the monitor shows a white horizontal line in the middle of the monitor.

I have done a reflow, a recap and replaced R402 which was burnt to a crisp. After doing all that and putting it back in, R402 burnt up again and the white line still exists.

Suggestions? This is the first time I have actually worked on a CRT but I am no stranger to electronics.
 
Well it's in vertical collapse. Now you have to fiqure out if it's the vertical ic or if it's a bad cap around the vertical ic.

Locate the vertical ic, and check out the lines coming theb IC, which by the way is at the right side of the bosrd right in the middle close to the edge. Usually those caps around the front will fail causing collapse.

I have a video on my you tube channel that explain how to check your vertical ic with a scope and check for voltage on it etc.
 
Thanks for the quick response! Would not doing the cap kit eliminate that as an issue though?
 
I am going to get ahold of a vert ic and a few other parts that the k7500 quick guide says to check.
 
And just to be clear I have read thread after thread about the K7500 and the vert issues. I wanted to have one to keep track of the things I have tried.
 
post a pic if you can of the monitor running so we can see what you have.

if your smoking the resister you have a short in that circuit.

it could be your IC or a part over at the flyback.

check all the diodes in that circuit.


if you hit a brick wall, your welcome to send it in.

Peace
Buffett
 
post a pic if you can of the monitor running so we can see what you have.

if your smoking the resister you have a short in that circuit.

it could be your IC or a part over at the flyback.

check all the diodes in that circuit.


if you hit a brick wall, your welcome to send it in.

Peace
Buffett

I have already ordered the replacement vert IC and the diode by the flyback and IC.

Since I have never tested a HOT before I pulled it just to see what it would register. Meter on diode selection, black lead on middle leg on HOT and red lead on outer legs. I get no reading or beeps from continuity. Bad HOT?

I also pulled all the resistors that were in the K7500 service guide listed under no vertical scan. R402 was burnt up (bad). R303 tested at 2.5 ohms (bad? suppose to be 1.2). R627 tested at 91.4k ohms (good).

Lastly, can I test this outside of the monitor? The customer lives a good while away from me and I don't have a truck anymore to haul around monitors and cabs. (Damn kids) What is the safest way?
 
yes replace that resister that is low.

you can use my video to help you test your H.O.T.
https://www.youtube.com/watch?v=XhwuHF-ffpE&list=PLPUz7YHoIxZ97NYckBNCCWP1SZb_qqIhu&index=7

the H.O.T.'s for the 74/75/u5/u2 will test different out of circuit than in circuit.

the method you used with it out of circuit works when it is in the chassis.

out of circuit, it is red lead on the left and black to the center and to the right legs.

Peace
Buffett

Yeah, no readings at all. Sucker is toast.

What about testing chassis without monitor?
 
the only real thing you can test with no tube and yoke is the B+
you can use the bulb method for a load.

to test the rest of the chassis you will need the H.O.T. the tube and yoke.

the chassis requires the yoke for it's load when you are testing it on the bench to see if it comes alive.

if you need a replacement H.O.T. i have tested confirmed working replacements.

Peace
Buffett
 
the only real thing you can test with no tube and yoke is the B+
you can use the bulb method for a load.

to test the rest of the chassis you will need the H.O.T. the tube and yoke.

the chassis requires the yoke for it's load when you are testing it on the bench to see if it comes alive.

if you need a replacement H.O.T. i have tested confirmed working replacements.

Peace
Buffett

Got it. I have what parts I need on order, I will report back my findings.
 
Would it make sense to change U701 while I am at it? I have the NTE replacement for it already.
 
ONLY!! if you have a socket.

this way you can test the new IC and verify that the old IC was bad.

otherwise i do not recommend replacing it.

those pads on that chassis and IC can be lifted pretty easy.

i hate having to repair those.

i rarely see it bad.

Peace
Buffett
 
Alright. Replaced HOT, vert IC, resistor and diode by the flyback and that burnt up resistor. The resistor does not blow anymore however, there is a ticking sound when powering on and no raster.
 
did you replace the insulator behind the H.O.T.?

now you need to do the bulb test on the PS to see where your problem is.

this will tell you if it is in the PS or in the Horizontal circuit and or startup circuit.

if the bulb lights connected to the PS and you can adjust your B+, your PS is good to go.

then your issue is elsewhere.

if the bulb does NOT lite, them you have a problem in the PS somewhere.

the 7500 can be a PAIN to fix when it ticks like this.

do the bulb test and let us know what happens.

Peace
Buffett
 
pull the leg of j12 closest to the width coil.

connect red lead of your meter to the bulb and the jumper.

use the vertical IC heatsink for ground and to the other side of the bulb and your negative lead on your meter.

have your yoke connected to load up the PS and have your anode in the tube or in a GLASS jar.

have your meter set on VDC.

Peace
Buffett
 
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