Carbon composite in place of carbon film

[TinCanAlley]

Originally Posted by DaveWM

good luck with it I hope it fixes the problem. Try the transistor 1st as its just a plug in IIRC.

You read my mind. I have the transistor in front of me and am about to test it. If it tests okay, it goes in and I fire her up. If that doesn't help, I flip her over and start the resistors and diodes.

[DaveWM]

BtW, does your schematic give you voltage readings for that transistor? if so it would not hurt to check them. Make sure you check the notes regarding without signal, line voltage etc...

Be VERY careful reading voltage with SS parts, a slip of a prob can instantly destroy a diode or transistor.

[TinCanAlley]

Originally Posted by DaveWM

BtW, does your schematic give you voltage readings for that transistor? if so it would not hurt to check them. Make sure you check the notes regarding without signal, line voltage etc...

Be VERY careful reading voltage with SS parts, a slip of a prob can instantly destroy a diode or transistor.

Yep, it has the voltages. Is it better to probe the bottom lead of the socket, or try to read directly from the exposed part of the legs of the transistor itself?

[TinCanAlley]

I realize I put this thread in the wrong forum. How do I move it?

[DaveWM]

Originally Posted by TinCanAlley

Yep, it has the voltages. Is it better to probe the bottom lead of the socket, or try to read directly from the exposed part of the legs of the transistor itself?

I find it best to go from top of chassis, get some test prob clips from rat shack, they fit over the tips of reg test probs and have little j hooks that extend and retract, hook up everything with the set off and make sure there are no shorts and that the DMM is in the correct setting, then power up. take readings, power off and remove the clips.

BTW no need to replace anything but the Blanking transistor the others would not account for the jail bars (at least should not).

Don't make too many changes or substitutes. You want to try and diagnose the problem and not shot gun parts at it. If the diode/ blanking transistor/cap/resistors to not resolve it then you are into tough dog territory, and you need someone that has a scope and some real talent to fix it.

I only hope that the target parts are it, again its really just an educated guess.

[TinCanAlley]

Originally Posted by DaveWM

I find it best to go from top of chassis, get some test prob clips from rat shack, they fit over the tips of reg test probs and have little j hooks that extend and retract, hook up everything with the set off and make sure there are no shorts and that the DMM is in the correct setting, then power up. take readings, power off and remove the clips.

BTW no need to replace anything but the Blanking transistor the others would not account for the jail bars (at least should not).

Don't make too many changes or substitutes. You want to try and diagnose the problem and not shot gun parts at it. If the diode/ blanking transistor/cap/resistors to not resolve it then you are into tough dog territory, and you need someone that has a scope and some real talent to fix it.

I only hope that the target parts are it, again its really just an educated guess.

I have those little suckers with the hooks.

I'm going to do the testing.

[TinCanAlley]

Okay, after a total brain fart and leaving the positive lead in the OHM connection, I finally have the numbers.

For the blanking transistor I got 6.8V for the Emitter (SM has 7.19V), Base was 3.9V (SM has 4.43V) and the Collector as 23.4V (SM has 23.5V).

[DaveWM]

those all look pretty good, You can still try the diode (I would just unsolder and check the a DMM compare to the new one) then the resistors. This may be very late question, but do you have the brightness cranked up? or the contrast real low?

[TinCanAlley]

Originally Posted by DaveWM

BtW, does your schematic give you voltage readings for that transistor? if so it would not hurt to check them. Make sure you check the notes regarding without signal, line voltage etc...

Be VERY careful reading voltage with SS parts, a slip of a prob can instantly destroy a diode or transistor.

Well I replaced the transistor and it didn't help. Figured since I was in there I change the other since I had the replacements. I managed to change all of them except for the 3rd Video Amp. When I installed it, there was no picture. I reinstalled the original and it worked fine. The legs on the replacement are not in a row (they in an arc). I know the center back is the base and I had assumed that since the outer two were forward of the base, it would install in the socket that way. Am I wrong? Do I need to bend the legs backwards to rotate and install it?

[DaveWM]

the sams should id the pins of the existing trans or you can look a the schematic to figure it out. then you need to look at the replacement and check the package for what pins are what.