Pentranic chassis and 33" monitor (CH-288?)

[swamprat96]

Just got the chassis back from Joey at Jomac here in Australia. Joey is our resident genius on chassis. He found heaps wrong with it. However I've put it back in and I'm not getting any picture- whereas before I got one but way too dark.

I'm suspecting my work first. I made sure the HV was plugged into the monitor properly,and reattached the degauss and the earth to the neck board. Re attached the 110vac lead and the 6 pin plug from the game. I've measured 110vac at the input to the chassis. I can hear the degauss on power up. I've reattached the neck board and its on good and tight

I can't see any glow at the neck- should I?

I've turned up the brightness and contrast - no luck. I even removed the game input plug expecting at least some sort of response- nothing. I've even looked for a safety/service switch but can't see one

Game is Jurassic Park Lost world- upright. Any suggestions?

[swamprat96]

another thought - as the tube was very dark before the repair could it be that the tube itself is now dead?

[grantspain]

check your connections again,make sure your yoke/remote/power are all connected.check the crt neck for bent pins.check your power input for correct voltage using as multimeter

[swamprat96]

yep just rechecked evrything

[lilshawn]

if you had it shipped i would check carefully around all the larger components to see if something has broken it's solder joint.

flyback, big caps, heat sinks etc...

can you "hear" the high voltage...that annoying high frequency squeal? if not can you hear ANYTHING clicking, ticking, chirping? (other than the degauss)

[gokun]

I've been going through something similar recently with the same chassis, so maybe my situation can help you or give you some ideas...
It is worth noting, however, that an old crappy tube can cause a LOT of problems...dark pic, blurry pic, etc, etc, etc. so just bare that in mind...best case scenario it's always nice to test in another tube that it known to be in good working order....anyways...
is this the dual res? if so, you're sure it's set right?
give it about 10-15 minutes to warm up...
ok, back to my story...
had a chassis that worked but was really old and had been repaired numerous times, so decided to order a replacement just in case.
Got the brand new one in and no pic.
Same symptoms as you in that there was obviously power(could here the degauss,etc) just no pic.
Put the original chassis back in and got pic. Put new one in no pic. no visible damage on the new chassis... Ok....
so long story short, I was able to finally get a picture by making some adjustments to the new chassis...and I recommend you try this first as it's less risky...screen, brightness, contrast...try turning these up slowly and see if you can get a pic. In my case they gave me a very very dark pic when turned up a LOT. but your mileage may vary...suffice it to say you would generally need to do this when replacing a chassis anyways...
so now to the risky part...assuming the basic adjustments don't help....I do NOT recommend this AT ALL, especially on old monitors cause it can damage them very easily...that being said, I adjusted the B+ on the sub power board of the chassis(turned it up a bit) and that brought the pic back within reason such that it could be adjusted most of the rest of the way with the afore mentioned pots. although it is not nearly as bright as the original chassis....still working on that one...lol...anyways, that's my little story...maybe it will help you. or not...but at least i tried lol

[lilshawn]

allot of times the screen on the flyback will be turned right down... guess no one wants to be responsible for burning a tube out....you could check that and see...

[swamprat96]

Sent it back for a rework again- seems there were some cracked traces. Got it back and I have a picture but with these lines (see pic)- any ideas?

The lines are stationery and are wider at the top and the bottom than the middle

[swamprat96]

Doh! Read up and then turned down the screen on the flyback. I'm a dumb a**

[swamprat96]

The screen died again after a very short time.I think I have a shorted Tube. Yeh turned the flyback right up along with the bright and cont- no joy

The tube has -made In Mexico – TCE
89C1UBP/00-7233295-1410
There’s a serial number on the left hand side of the tube 103913 and a sticker above it with the manufactured date- July 1997. There is also a sticker on the neck that has C-11

I sent the chassis back and it runs fine on a test monitor. We suspect that the chassis is not starting because of a dead short somewhere in the tube. Before I replace it are there any basic tests I should do?
 
EDIT- I metered the four wires to the plug that changes the orientation of the tube that go directly to the neck. The blue and the red wire are measuring continuity between them . Is this an issue?

[lilshawn]

they should have some continuity, they are just coils of wire...

one should have very low ohms...maybe 1-2 ohms the other should be low as well but in the 2-10 ohms range.

if you have one that reads near zero....ie (0.2 ohms) then i would suspect something wrong.

but since you had a picture, i'm thinking something else is wrong. if you had a shorted deflection coil, you would have no picture at all for no time at all since the board would fry.

i'm leaning towards a power supply issue with the main board...

i know allot of places say that the chassis tests fine so you will cough up for a new monitor. I had a totally dead chassis sent back to manufacturer...sent back to me still dead. sent it back 3 times each time with a few more components replaced, last time he said they ran it for three days and it worked fine...get it back still dead (exact same problem). had them send me a new chassis and it works fine on the tube. Just goes to show, that even the "professionals" can just throw parts at it and fly blind. I'll bet they never even plugged my board in.

[swamprat96]

I have no picture at all. I did have but it packed in again- and thats when I sent the chassis back. The chassis worked fine under test on a similar size tube

[grantspain]

i had a pentranic monitor do the exact same thing this week and the tube is at fault,i get static/heaters but no picture

[swamprat96]

Yep- sounds similar. So thats it- dead tube?