Pentranic 1014 missing green

[DamagedGoods]

wondering what could cause the loss of the color green.
also when fired up only blue is showing until I adjust the red either way and it comes back.
the chassis is marked CH-203.

I't's not the game either all colors are fine on another monitor.

And I also soldered the green directly to the board and still no change whether connected or not.
so somewhere along the green there is something amiss.

[grantspain]

could be bad pots hence the issue with red,green could could be drive transistor

[DamagedGoods]

so I'm guessing the drive transistor would be next to the gain pots on the board since there's a transistor for each one but not sure how to test them.

I get the same reading between C and E for all three transistors of 772 but I thought I was supposed to get no reading at all if it's good or are they all bad.

this can't be right since I checked all the transistors and all but one gives a reading between C and E so I think my thinking is backwards and I found 1 bad instead of 8 or so bad ones.

[grantspain]

you really need the schematic to fault find this,once you id the green drive circuit you can start swapping the transistor from blue to green etc
pentranic did suffer from drive transistor problems

[DamagedGoods]

yea I'm gonna try swapping them around then.
the schematics that are available are kind a mix between the 688 and the 203 chassis so half of what I see isn't even on this board or even the same board.
besides that I also found different revisions of the 203 that don't match up at all.

have no idea how to read them so i'm just following the lines from point a to b.

funny thing is I took A class in high school for electronics but the only thing I remember is what the symbols mean.

[lilshawn]

pentranics where notorious for running the drive transistors really hot... a fan mounted to the frame to circulate air really helps.

also check the solder... especially with the large load resistors. the solder gets all yucky and plasticizes... makes the connection cruddy.

[DamagedGoods]

swapped the blue and green transistor and still no green but I do still have blue so it's not that.
I guess i'll just check everything out along the green path until I find something bad.

Or I'll just keep buying monitors until I get one that works.

Edit:
what I thought was the drive transistors wasn't since "notorious for running the drive transistors really hot..."
It's the ones with the heatsink just didn't think it was them since only 2 have them and was looking for 3 alike and in a row.
green is shot assuming it goes B G R.
who needs schematics

Edit #2:
where should I check B+ voltage I'm assuming the big cap with the 14" on it.
and also what should it be.

[lilshawn]

swapped the blue and green transistor and still no green but I do still have blue so it's not that.
I guess i'll just check everything out along the green path until I find something bad.

Or I'll just keep buying monitors until I get one that works.

Edit:
what I thought was the drive transistors wasn't since "notorious for running the drive transistors really hot..."
It's the ones with the heatsink just didn't think it was them since only 2 have them and was looking for 3 alike and in a row.
green is shot assuming it goes B G R.
who needs schematics

none of this.

that little circuit board attached to the end of the picture tube... that will have the transistors on it

[DamagedGoods]

now it makes sense.
couldn't find them in the schematic because there marked Q 911, Q912 and Q913
but on this chassis it's Q 711 etc..

hmm they all appear to be bad
only .15 cents A piece so not A big deal

[TopJimmyCooks]

How'd it turn out?  Got exactly the same problem on a wg monitor I'm getting ready to try my luck on. 

[DamagedGoods]

never got around to fixing it.
have 3 new transistors just sitting here waiting.
lost all 3 colors after switching the blue and green transistors.
red was on it's way out so I expected that it was bad along with the green.

still need to get new pots for the neck board.

I'll get to it once I get the pots.
bought A new monitor so kind of lost interest at the moment.

been reading up on electronics in the meantime.
the videos from here are a good start.