Motorola ts907 low hv

[Yamamaya42]

double check the work, that should not have happened R46/R38? check what came out vs what when in, something is not right.

[timmy]

I’m going to double check the resistors I put in. But now I can eliminate L 123 because using the subber I get the same result at the plug on the chassis or lifting the wire on L3 at pin 2 v1 so this leaves L4 or v1 tube socket or caps at v1 since v2 and beyond was good I can’t think of anything else in and around v1.

[timmy]

Here’s the interesting thing wire off L3 subber on pin 2 v1 get a lousy pic but if I put the subber on pin 7 I get a better pic I would think the better pic would have been on pin 2 and no more overheating L42 I get a better pic when the subber is on pin 3 v1

[timmy]

I set up video at test B to set the vertical and horizontal so I lowered the master G1 then as I raised G1 alittle again c91 blew up and shot a flame out of the side of the cap. Is this a bad 130pf cap or what the heck would do this. The cap was a 047 cap a 05 go in instead.

[Yamamaya42]

C91 is in the hv reg line, so I'm not sure what 130pf cap you mean cause there is none in the area.

IF the 6BK4A failed, it could shunt too much voltage to the cap and toast the cathode resistor and cap there, what kind of cap was it?

It may have just been bad/ weak, DO make sure that what ever you replace it with is rated at 1kv or more, and that all other parts in the area are OK and that V17 is not toast.

Remember, when you adjust G1, or brightness, the shunt regulator V17 works to keep the HV stable, so something weird happened here in the area.

[timmy]

Originally Posted by Yamamaya42

C91 is in the hv reg line, so I'm not sure what 130pf cap you mean cause there is none in the area.

IF the 6BK4A failed, it could shunt too much voltage to the cap and toast the cathode resistor and cap there, what kind of cap was it?

It may have just been bad/ weak, DO make sure that what ever you replace it with is rated at 1kv or more, and that all other parts in the area are OK and that V17 is not toast.

Remember, when you adjust G1, or brightness, the shunt regulator V17 works to keep the HV stable, so something weird happened here in the area.

The cap that shot flames out is a 047 630v and the 130pf 6kv is in the same area what came out is the same only 600v. Ok the 130pf is not in that area my mistake

[Yamamaya42]

Originally Posted by timmy

The cap that shot flames out is a 047 630v and the 130pf 6kv is in the same area what came out is the same only 600v. Ok the 130pf is not in that area my mistake

to make it more robust, replace it with at least a 1kv cap, but the same .047 value.

[timmy]

This is what came out but I had put an 047 orange cap.

[timmy]

Well all I have is an orange cap.05 don’t have any .047 ceramic.

[timmy]

This set is nuts surprises everyday I turned the master G1 up alittle then I thought a cap melted down come to find out it wasn’t the caps there was a bright light and hissing kind of noise coming from the corner of where the flyback is yet I find nothing burned no smell when it was burning and if the G1 is up to high focus voltage drops off. Turned it back on and got hv nothing else at this point.

[Yamamaya42]

carbon tracking? solder peaks on the FBT connections?

[timmy]

Originally Posted by Yamamaya42

carbon tracking? solder peaks on the FBT connections?

Well yes I was thinking carbon tracking somewhere maybe on the 6bk4 or between pins because the arcing was at that end at the tube not at the flyback scary stuff coming out of no where.

[Yamamaya42]

the tubes can blow up, remember i had a NOS 6BK4C explode on me. http://suzaku.live-evil.org/1015220040.jpg

[Electronic M]

I wonder if your CRT is getting gassy. Does the neck glow vibrant purple or blue in the dark? When a CRT gets badly gassy it will loose the ability to display video, loose raster, lug down the focus and HV till the flyback screams...

Turning up the G2 is a bad. I have a Setchell Carlson monitor that had a focus problem where it was burning up the focus coil and couldn't achieve good focus or HV....Turns out some idiot had cranked the G2 on the CRT way beyond it's correct setting and the cathode emissions were overloading the focus and HV.... setting the screens to the minimum to achieve a dim horizontal line with vertical deflection disabled and brightness down fixed everything. G2 should always be at the minimum setting for the set to work.

[timmy]

Originally Posted by Electronic M

I wonder if your CRT is getting gassy. Does the neck glow vibrant purple or blue in the dark? When a CRT gets badly gassy it will loose the ability to display video, loose raster, lug down the focus and HV till the flyback screams...

Turning up the G2 is a bad. I have a Setchell Carlson monitor that had a focus problem where it was burning up the focus coil and couldn't achieve good focus or HV....Turns out some idiot had cranked the G2 on the CRT way beyond it's correct setting and the cathode emissions were overloading the focus and HV.... setting the screens to the minimum to achieve a dim horizontal line with vertical deflection disabled and brightness down fixed everything. G2 should always be at the minimum setting for the set to work.

It was the master G1 that I moved and the crt checks out good.