monitor fault colour

[robertg]

hi i am a new user with a small problem please please could some one shed some light to why my monitor has gone from good colour to purple shown in the pics below

[grantspain]

looks like your red drive transistor on the tube base gone short,depending on what type of monitor you have,compare the readings from all your drive transistors to find which it is.i have had exactly the same problem on a hantarex in a ridge racer.the only other thing i can think it would be is a lopti fault but i doubt that judging from your photo.

[robertg]

there are no markings on the monitor to give away what it is but i am guessing its a hantarex how many transistors are there to check thanks for your help

[grantspain]

You should find 3 with heat sinks,these are your color drive transisors.If you post a photo of your chassis I could probably tell you what it is.Remember judging by the age of this monitor you should be looking for dry joints,broken pcb tracks but i think the problem lies on the tube neck board,concentrate around there.One last thing check the adjustment pots on the neck board turn them one by one to find which is not working,i think you will find the red cut off is not operating,you can then trace that pot to the output of the faulty transistor by following the track,all the best.

[robertg]

pics there is not much on the neck card that i can see any more help would be great i have check and resolderd the points on the neck card but nothing has changed really doing my head in thanks again for any help

[robertg]

pics

[robertg]

pics

[robertg]

last pics

again any help offered is brilliant :-)

[grantspain]

My good god you have a very early hanterax 900 monitor i have not seen one of those since about 1988 when i was an apprentice,its a miracle it still works.i will look for the schematics for this chassis as i dont think the drive transistors were on the tube neck card,i will let you know what i find as soon as poss.

[robertg]

i would be very very greatfull in any help you can offer i really want to get this working again

[grantspain]

Im still looking for the schematics for your 900,but try this for me please-you have 3 coloured wires going from the neck board to the chassis they are red/green/blue these are your colour signal to the guns in the tube,try disconnecting the red wire then repower your cab-if your screen remains exactly the same im afraid you will have a tube fault-if your picture only shows blue and green then it is definetly the red drive transistor,keep me posted.

[robertg]

hi i have tried that and now it has gone grey ish well i think that's the colour i have attached pictures of the results thank you very much so far

[Harry Potter]

From the first pics, it looks like his green is actully gone.

[grantspain]

ok your missing both green and red now,good now im sure the tube is fine-there is something you could try now very simple way to prove your transistors at fault,we now know that your blue drive transistor and gun are perfect from this you could prove the fault,you can swap the wires around to prove where the fault lies ie put the green wire from the chassis to the blue wire from the neck tube(if it was me i would cut the wires half way down and put them in a connector strip then you could swap wires easy) every time you get a blue picture it shows your drive transistor is running.Now judging from your last picture you have no green drive at all and judging from your previous pictures seems that your red is too high either by adjustment or by transistor fault,cant remember if you said you had checked for dry joints on your chassis-i do remember the 900 series suffered dry joints on the neck tube card-please check for these first as its the most logical answer,then we can look at the drive transistors-you can do that by following your r/g/b wires from the neck board to the chassis and then with a meter follow to transistors then compare readings of transistor on ohms if one is faulty it will be obvious because the readings between the legs should be the same.If i do manage to find the schematics i will tell which transistors to look at.

[robertg]

i have checked every joint on the neck board and re soldered them just in case i will change the the wires around now and see what happens

[robertg]

OK it did what expected while i was doing the change over i checked the main board for dry joints and resolded them for good luck but when i put the leads back it went back to normal with the red tinge so i am guessing like the rest of you that there is something wrong with the green colour now i tested the transistors the best i could and the resistores around them and they all seem to be giving out the same measurement what now  and again thank you very much for all the help so far 

[grantspain]

The reason i said to swap the wires from the chassis to the neck was to eliminate a possible fault away from the drive transistors,i have seen faults like this before on old monitors and it is important to prove the guns in the tube are working correctly therefore if you swapped your green input on the neck tube to your blue output of the chassis then you should have a green picture,this should be the same for each input-this then proves your tube is perfect then we can look at the possible chassis faults-this exactly how i go about fault finding with old kit otherwise you will just go around in circles-the point is to eliminate as much as possible as quickly as possible,you still have to check your input colours from the game board this is another possible angle again the same process applies-swapping wires ,im sure we will get to the bottom of this problem.happy hunting amigo.

[robertg]

ill have another go switching the colours around this is all new to me great way to learn i am very greatfull for all the help