hi all,

any thoughts on brightness issues w/ a mx5000 north american model?

even at highest setting the screen is a bit "dark."

caps issue? or can i readjust at the pots?

thx in advance,

I will start with your last comment first -- caps issue ? you said, well these sets were produced at a time when the electronics industry was having a lot of problems with Electrolytic Capacitors designed for use in televisions and audio equipment. The two major issues were they either dried out or leaked. However, if everything else with your Beovision MX5000 is working correctly, then it is unlikely to be a capacitor issue.

The problem is going to be associated with the tube, either the cathode drive current or the grid control voltages or the tube itself as follows:-

• If the colour balance (i.e. Redish, Greenish or bluish) of the picture is still perfect and it is truly only a lack of brightness, then I would start by checking the voltage at the control grid of the tube, if it was low then the problem will be either the tube starting to fail or the HT supply has a problem.
• If the colour balance is also not good then it will be one of the RGB current drivers which can be adjusted or the tube starting to fail.

Unless you have an electronics background and know about TV's then this will be a job for your dealer or repairer.

I think caps are definitely a place to start. However one thing I have noticed about my own NTSC MX -- it takes a few minutes to warm up to the final brightness level, appearing quite dim at first.

thx for the replies...

color balance seems fine -the picture is excellent, just rather dark.

regarding "a few minutes to warm up" -mine acts the same way.

furthermore, often when coming out of standby -it takes a while for the picture to even appear. the time varies -a few seconds to a few minutes. sometimes if i change the channel before the pic appears -it will "force" it on.

again, the tv is fine, just very dark and often slow for pic to appear.

You have offered a key piece of extra information in your reply, you said

"regarding "a few minutes to warm up" -mine acts the same way"

Well, that points to a tube heater or supply (normally 6.3 volts) problem and is quite common with tubes, in fact many workshops in days gone by would have a "Tube Re-generator" which would provide a higher voltage to the heaters from a short time to effectively clean the cathodes of the tube which subsequently would provide a much brighter picture.

I would say that based on your subsequent information, I would start by getting the dealer to check that the heater voltage gets to the correct value and rises to teh correct value quickly, if it does, then it will be the tube starting to fail.

Keith Saunders:

I would say that based on your subsequent information, I would start by getting the dealer to check that the heater voltage gets to the correct value and rises to teh correct value quickly, if it does, then it will be the tube starting to fail.

unfortunately (usa) closest dealer is 4+ hours away, and my guess is that they would have little interest in such an old piece. they would likely direct to the reginal repair depot that is same distance. my guess is a local qualified repair shop would be able to help... i have all the mans/schematics for the set.

so, if the heater voltage is good, then tube is bad -and viceversa... -which would be the more desirable situation as far as repair/replacement/costs? bad heater or bad tube? is it worth even bothering?

as always, thanks!

Well, certainly because of the nature of the problem any good TV repair shop should be able to deal with the problem given you have the Service manual etc.

It is certainly worth getting it fixed because these are good TV's, but as always its a cost of repair against replacement which only you can really decide.

per my post here: http://forum.beoworld.org/forums/thread/72951.aspx

Probably some capacitors on the audio/video switching board are beginning leaking. S-Video and RGB use a different signal path than plain composite. Does the tuner works ?

I have written a repair guide for this TV and it is on the reference section of this site.

Good luck!

Best regards,

Jean

 

Just for future reference, we now have the Service Guide available online for the North American NTSC MX 5x00 series. (It's temporarily sorted underneath the regular, European version in the drop-down menus, but I think Van may be fixing that soon. :) )