My machine has a working, but not very good looking CRT.At some point someone did a tube swap.. There is upside down pacman burn in - and two sizes of it. Centipede had a swoop in the playfield from the top left down and parts were off the sides..
Research and friendly advice says - recap the monitor (replace all of the electrolytic capacitors) and swap the tube. People who restore arcade machines and monitors do this all the time - the wealth of information available is insane.
So - I'm not even going to attempt to come up with a *tutorial* so to speak. I am going to describe my CRT work from the perspective of a guy who has a reasonably good grasp of electronics, circuits and no fear of jumping into things. But this is my first one.
Not the nicest - but its what I have for now. I'll have the chassis recapped and back together before I find a donor TV. Once I find a new CRT - I'll replace it.
Here is the standard inside of the chassis - many years of dust and crud. I took pictures of everything with many closeups. These are pretty well documented - I downloaded the manual for this CRT - A Wells-Gardner K4600. There were a number of YouTube videos on this specific model. I can say - most of the people working on them didn't care for the design..
I'll say I was quite nervous about the shock hazards inside the CRT. Every video out there shows you how to pop the anode (suction cup) off the CRT and drain any voltage using a screwdriver with a wire on. Once I understood that it is essentially discharging a big capacitor - it made more sense. Find some videos and pop that anode connector right off! Nothing to fear
The next set of videos I watched were a bit astonishing.. Grab your CRT and give it a bath - literally! But after watching about 5-6 of them.. It wasn't a scam. Most of them used Simple Green - which I just do not like the smell of. One guy used this stuff - Krud Kutter - available at Home Depot. He raved about it. I have to say - it really worked great cleaning up the boards. It will likely replace some of our other under-the-sink cleaners.
Here it all is - soak it down real good - let is set and wash away.. freaky..
I used warm running water and a soft bristle paint brush to clean in and around components. Once you get past the
not-common sense of washing the inside of a TV.. Use common sense and brush and clean - but be somewhat delicate with it all..
The hand brush I did use on the backside of the boards. It cleaned up 40 year old flux and other crud on the solder side of the board. Be careful as well if there are jumpers and resistors on the back.
On the neck board - there is a black ground and the red wire soldered on under a white removable cap. It goes back to the flyback transformer. The black wire went to the ground wire on the tube. The simplest way to remove the neck board was to desolder them. Guys on the videos did it and it wasn't a big deal.
Neck board before.
Neck board after..
On the main board - there is one little delicate part to be aware of. The little red coil hanging out on the right. It can be removed from a holder that is part of the chassis. Some of the videos they desolder it. Just don't break it!
Main board before:
Main board after:
One thing in the "wash your TV videos" that I didn't care for was they basically sat them out in the sun to dry.. (except for one guy).. USE COMPRESSED AIR! A compressor will blow out every little bit of water out of every little nook and cranny.. Do not blow apart your boards - again - be careful. Just use some air to get the water out.
Now - I love tools - I really love tools. There is nothing better than having the right tool for the job. Replacing all of the capacitors (and reflowing pins.. I will touch on that later) requires removing old solder. There are a bunch of ways to do it
- Heat the old part and push it through the board
- Use a solder wick and soak up the old stuff
- Use a bulb style solder removal tool
- Use a pump style removal tool
orGet something that is fun and easy to use. I had a 5 day tangent just reading up and watching videos on these machines. As with anything else - you can spend as much as you want. But finding a sweet spot for the non-pro is where I was at. In the end - this was ~$140 and it really works very well. The vast majority of the caps just fell out of the board after sucking up the solder.. The others required a slight tug. ZD-985 Desoldering station.
I have a descent multimeter - I think it was ~$50 at Home Depot when I got it. But while I was at it I decided to upgrade and demote my old one to my secondary tool set that stays at the camp. I now get why everyone likes the Fluke meters. You can feel the quality immediately when you pick it up..
While I was replacing the capacitors - I tested the old one coming out AND the new one going in. My reasoning was simple:
- Play with the new meter
- See if there were any *really bad* capacitors coming out
- Make sure I identified the correct one going in AND check its tolerance for comparison to the originals
Checking the caps coming out and going in also slowed me down and made sure I double and triple checked my work. Many of the caps coming out were off by 20%-30%. All of the new ones going in were within 10% and more often within 5%.
Here is the desoldering tool heating up a solder pad. Once it gets liquid (2-4 seconds) hit the trigger and it sucks it all up..
Both pads in C608 desoldered. Pops right out..
To get the new one in and keep it tight to the board - there are a bunch of ways to do it.
My first few I held one lead in place with an alligator clip, trimmed the other lead, soldered it and then clipped the remaining long lead and soldered it.
Eventually I just bent the leads outward just enough to hold the capacitor in place, then clipped and soldered. I'm going to hit this board again with water/cleaner to remove the flux.
The recap kit these guys provided was complete. One thing you will bump into - not every board has every capacitor. I had about 5 left over. If your original board didn't have it - then don't add it! I used the sheet as a checklist and went through each one in order.
Pretty much every recapping video said - reflow all of the connector joints. Meaning any place there is an edge connector, the 40 year old solder is likely failing or will fail. At first glance I checked my boards and figured.. naaahh.... these joints are all good. Why fix what isn't broken..
Upon further review I noticed a hair line at this connector. Took a pic and blew it up. The guys who do it all the time know what they are talking about. 4,5,6 show the failing joints very clearly. 1,2,3 certainly are suspect.
For reflowing the solder - some of the video guys just heated it up and added a little fresh. The guys who really seemed to be experts recommended REMOVING the solder and adding all fresh. This is the route I chose. The desoldering gun didn't fit over these flat tabs, but it did remove a majority of the old solder.
Reflowed..
I was also warned about this style of connector. If you have a matching connector, use it to hold the pins so they do not fall out. I do not...
So I used a binder clip. Desolder and resolder 1 or 2 at a time so that there is a fixed pin to help hold the others steady.
There were some large diameter pins for the connectors in the center of the board. My gun came with 3 tips, small, medium and large. Medium is perfect for the caps. But large was too small to get over these pins so that I could desolder and reflow them. My solution was a 3/32" drill bit to drill open the hole in the tip enough to get over the pin AND allow solder to be sucked up around it. My large tip is now XL.
Here is a board all recapped.
I've finished all of the recapping and reflowing of the pins.
Next up will be washing the tube and chassis and putting it all back together.