U5000, No Blue

Kyrosfear

Well-known member

Donor 4 years: 2012, 2018, 2020, 2025
Joined
Apr 4, 2012
Messages
3,074
Reaction score
36
Location
Pennsylvania
Gentlemen,
I have a U5000 and it needed a cap kit (had some wavy lines across the picture). The colors, however, were fine. Following the cap kit, I hooked it up and turned it on. The picture was gorgeous and just when I was in the middle of my "another one bites the dust routine" the blue gun started to flicker. This occurred quickly at first, until ultimately it was out all together. My first thought was a cold solder joint, although the proximity of this issue and my just completing the cap kit seemed more than coincidental. I played with all of my connections and tweeked my neck board. I also turned off the game and let it cool, then fired it back up. No blue, no flicker. My best guess is still a cold solder joint, or a mediocre soldering job somewhere along the blue path that quickly failed once it got hot. What do you think? Thanks in advance.
 
I should also mention that I searched for this issue and found only this thread.

http://forums.arcade-museum.com/showthread.php?t=67209&highlight=u5000+blue

I wanted to create my own post because this issue specifically began for me after I did the cap kit. I did not have time last night to work on this chassis, but I will tonight when I get off work. At that time I am going to reflow the blue path. Besides reflowing P201, what else do you suggest?
 
I think you're definitely on the right path with a cold solder joint. Flip the chassis over and look it over carefully. Touch up & reflow ANY solder that looks questionable - especially since it only takes a second. Also keep your eye out for broken traces and/or lifted (or lifting) solder pads as these will break the connection.

If by some odd coincidence, this problem isn't chassis related, you could check out the tube to eliminate that from the equation. Do you have access to a tube rejuvenator? Connecting your tube to a rejuvenator can tell you a lot about the condition of the tube (i.e. each gun) and the life of it. It will also help you quickly deduce if it's the tube or chassis.

But (like you) my bet is on the chassis based on your description.
 
my bet is that it is a broken trace on the neck board transistor.

almost all the U5000, 7400, 7500 chassis i have worked on, i have had to reinforce the traces to the next point of contact in both directions on those models.

Peace
Buffett
 
my bet is that it is a broken trace on the neck board transistor.

almost all the U5000, 7400, 7500 chassis i have worked on, i have had to reinforce the traces to the next point of contact in both directions on those models.

Peace
Buffett

+1

The blue signal goes into the chassis, but immediately goes to the neckboard, there is NO processing of the blue signal on the main chassis. It is all on the neckboard. That said, check that the blue signal path makes it to the neckboard, ohm meter does the job! I also made a picture I use to follow the color path (will post), as Buffett said, the larger power transistor is a key failure point, very likely when you were capping the chassis, you may have bumped the transistor which are very weakly held by traces alone. I did a thread on fixing a neckboard a while back.
http://forums.arcade-museum.com/showthread.php?t=242287

There are actually 2 transistors that handle each color, a resistor and then the IC on the neckboard does color processing. I'll add my neckboard aid I use in a few.
 
Last edited:
Let me update this thread to add information to the search archives. I ended up reflowing the entire chassis and neck board last night and the problem is fixed. The picture looks great again. (Proceeding with "Another One Bites the Dust" routine).

Now I want to address what Buffett and Tek said. Included in what I reflowed were several traces that had been repaired previously by someone else (jumpered with capacitor leads across broken traces). These looked awful when I started and I had to do a lot of cleaning and resoldering to make them acceptable. Technically, I do not know where the issue originated because I attacked the whole thing before retrying it, but I would suggest to anyone with this issue to do some reflowing, focusing on the neck board. Also, check the neck board traces as mine obviously had issues here in the past and these knowledgeable gentlemen have seen it several times before. Thanks for the help guys.

Buffett, you are quickly becoming my best friend.
 
Back
Top Bottom