U5000 upgraded transistors possible?

BobsterD

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Has anyone ever decided to use a more durable/upgraded transistors for the U5000 neckboard Q506,7,8 (2n3904) Q509,10,11 (2n3906) and Q503,4,5 (2sc3782) and even upgraded sinks on those?
 
why what's it doing, burning them out? I run U5000s in a commercial setting and they hold up fine. just had dim tubes on my Blitz twins... rejuved one (K7500), gotta do the U5000 next. the original neckboard on the U5000 had traces lifting on the neck transistors, with intermittent missing green and such.

took a scrap chassis lot from ebay and transferred all the parts over and did whatever jumper mods were necessary and haven't had any issues since.

I didn't know you could use different transistors, always thought they had to be a perfect match since they're such delicate components.

someone recently made mention of putting bigger heatsinks on theirs, not sure what came of that. does anybody know if thermal paste like Arctic Silver Ceramique would be good to add, or do they have mica insulators inside? I never tried pulling them off, always afraid I'll break the legs or something worse.
 
Received this monitor as a basket case with a game purchase, and after a cap kit, fly, all of the service kits, changing the neckboard tansistors I get a great picture...for about 5 minutes then things heat up and I start getting color problems, usually starting with green. Q503,4 & 5 all are quite hot even with the stock sinks with a bit of thermal grease as well.

Let it cool for a bit and the whole thing starts again. It's like the parts are being "overdriven" somehow.
 
could be a tube issue, but i strongly suspect solder issues and or cooked traces at or around the three color drive transistors and resistors on the neckboard..

if you cant fix whats messed up, you might want to check with chad at www.arcadecup.com , for awhile he had new neckboards... dont know if he still does or not..
 
could be a tube issue, but i strongly suspect solder issues and or cooked traces at or around the three color drive transistors and resistors on the neckboard..

Yeah, I'm thinking like you. I had to do quite a bit of repair on the traces around the drive transistors but I may need to look a bit deeper for more.....
 
I've seen a few different setups for the neckboards on the U5000s and the K7500 (which uses the same neckboard)

the one U5000 I replaced the neckboard on with one I got from a scrap chassis lot actually had a capacitor running from what I believe was the ground on the green drive and running to the CRT ground pin. I wasn't able to get those to solder at the CRT ground pin without the damn pin falling out repeatedly, lol. so I left it off, didn't seem to affect the performance any.

there was another on the K7500 neck that I borrowed for a few months that has a resistor in the heat circuit. the picture looked fine for medium res with my Sportstation, but as soon as I pulled it to use in another cab for Zombie Revenge (which I ran in scaled down mode for standard res) the picture looked absolutely horrible. it was too dark.

the tube on that U5000 inevitably, even after I made my neckboard swap and some other repairs, had a weak red and what appears to be a blue short (I have it turned all the way down and it still has a blue tint)

it's common for these monitors to have major piece of shit Zenith tubes, and typically with a ton of mileage on them.

if you know anyone in the area that has a rejuvenator, I'd go that route first.

otherwise, I have a few more neckboards. one of these days when I start to get caught up more I'll try testing out all those junk chassis I bought and see if any of them actually work.
 
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