Another Dead K7000

[Chopper79]

K7000 19", was working perfect 3 weeks ago. Now dead with no neck glow and no B+ voltage.

Fuse not blowing
Hot tests ok
Safety cap tests ok
D18 -D12 ok
Ceramic fuses removed and tested ok.

Looks like replacement flyback and cap kit already done.

125v input voltage ok.

I'm at a total loss on this one. Only thing I haven't checked is the voltage regulator.

It was working perfect and only switched off for 3 weeks.

Any ideas?

 

[gunblade]

you need to see what the b+ is doing

 

[Chopper79]

you need to see what the b+ is doing

B+ is dead. Showing no volts.

 

[gunblade]

ok look for broken tracks on r101 and read r89

 

[Chopper79]

Ok, went over a few suspect joints, but nothing obvious. B+ is now showing 127 volts DC (At blue cable end) and 167 volts dc (At red cable end)

Still blank screen. Can see a faint glow from neck if lights turned off.

 

[gunblade]

it should be 123v on a 19"

 

[Chopper79]

it should be 123v on a 19"

What would be next to check?

 

[gunblade]

i reckon its going to be the flyback, i had a chassis recently with your exact fault and the flyback was almost new
only way to prove it is replace the flyback
personally the first thing i would do is dummy load the HOT , check b+ and if still above 123v then desolder b+ pin on flyback and dummy load the b+ line

 

[Chopper79]

i reckon its going to be the flyback, i had a chassis recently with your exact fault and the flyback was almost new
only way to prove it is replace the flyback
personally the first thing i would do is dummy load the HOT , check b+ and if still above 123v then desolder b+ pin on flyback and dummy load the b+ line

Thanks for your help grant. I'll get one on order.

 

[Chopper79]

Just an update. I found the red wire from the flyback going into the neck socket, couldn't have been soldered in properly, as it broke off removing the neck board. I stripped it back, and resoldered properly, and now when monitor on, I get a bright horizontal white line through the screen.

 

[gunblade]

as in a vertical collapse? a line going left to right and tube mounted like a tv horizontally?

 

[Chopper79]

as in a vertical collapse? a line going left to right and tube mounted like a tv horizontally?

Yes correct

 

[gunblade]

you would need to check the 24v to the vertical ic

 

[Chopper79]

you would need to check the 24v to the vertical ic

I have 24.2v on pin 6 of IC3.

 

[gunblade]

check yoke connector with a meter

 

[Chopper79]

check yoke connector with a meter

All good

 

[gunblade]

then you need to look at replacing the vertical ic

 

[Chopper79]

Replaced IC3 vertical IC, no change! I can hear a faint hissing noise coming from anode cap. When powered off, no charge on anode cap, as always check with screwdriver, but nothing. Can literally power off, and just pull cap off, without discharging! This chassis is becoming a Nightmare!!!

 

[gunblade]

you checked your vertical size pot is not broken?

 

[Chopper79]

you checked your vertical size pot is not broken?

Yes. Removed it and tested ok.