View Full Version : Help with a CRT

August 28th, 2009, 09:52 PM
It's not super vintage, but your guys' past posts have been extremely helpful and technical. Hoping someone might be able to point me in the right direction.

I have a Philips 201b4 monitor. It's a very nice 21" CRT with BNC connectors for great color. I love it to death, better than any LCD panel I've ever used. Call me old fashioned, but I dislike LCDs because I'm limited to only 1 resolution.

It's developed an anomaly and I was wondering if anyone here might have an idea what's going on with it. After prolonged used, the right side starts to flicker. It'll start at the bottom right corner, then gradually move upward to the top right corner.

I've ruled out any electromagnetic interference. Even went as far as to take it into work with me and hook it up in the library to a different machine. I've tried different cables, different computers, different locations. I'm pretty sure it's an internal problem.

If I leave it unplugged for about a week the flickering goes away. However, after a few days of use the flickering returns.

CRTs are so difficult to find now, I was wondering if this is something I can get fixed.

August 29th, 2009, 06:19 AM
Give it a whack on the side. If it clears up then you have a bad solder joint.

Outside of that you probably have a cap going south.

August 29th, 2009, 06:36 AM
Judging from your discription, I think the problem is most likely in the vertical oscillator. Some capcitors seem leaking. I use to just replace all the electrolytic capacitors. I think nowaday you can just remove the circuit card and do it.


August 29th, 2009, 08:47 AM
Those are both good ideas, thanks. I'll see what happens.

I downloaded the service manual and took it apart once to see if there was anything noticeable. The circuit board does separate from the main CRT with a few screws and the cables.

I need to get a soldering iron (never thought I'd need one of those) because I can also use it to replace the capacitors on a dead white iMac at work.

August 29th, 2009, 10:52 AM
If you're in the USA try mouser.com for the caps. They have no minimum order, an excellent website with links to data sheets, AND they have HUGE amounts of stocked components.

Once you buy from them you'll get this HUGE paper catalog which makes things even easier to research.

I love it that they have physical sizes listed on the web and on paper for the parts. If I'm building cap kits for different boards those help me determine which ones are the right size to fit around other components in the circuit. (Important when ordering caps for a WG 7000 series arcade monitor!)