compaq monitor

[pete g]

hi, i'am working on a model PE1160-chassis FS7550/V7550. this an old crt based monitor that has given great service. at the moment it shows a small image both horiz and vert. i've been scouring the internet for a schematic and parts list, to no avail.there is a clue, R446 is burnt. can't find the trouble. does this ring a bell with anyone? any help would help. thanks. p.s. i've fixed a lot of tv's, not too many monitors.

[truenorth]

It is somewhat against my normal principal to try and discourage someone that wishes to restore/refurbish something to do otherwise. However unless there is great nostalgia or an unquenchable  desire to repair this CRT monitor i would wonder why you would want to do so. I have 3-4 CRT monitors i would gladly give away to anyone that wanted them to avoid them going to landfills. Many second hand stores also practically give them away. LCD monitors have come way down in price that even if you do have the expertise to repair the unit it will still cost you something and your time (unless either of the 2 previously stated situations exist) has to be worth something. I did do a search on the internet for the model you stated  but the number of hits was extremely low (under 6) and they were all in non english languages. Sorry i wasn't of more assistance.truenorth

[pete g]

hi truenorth, i understand what you are saying. however, let me say that i'am not that impressed with lcd monitors. i'am a retired field technician. i worked for all the major manufaturers. the idea of tossing a piece of electronic equipment is so against my nature that i feel i have to repair instead of replace. i know that sounds old fashioned, but there you have it. the idea that you repair is so ingrained in me. my time is no longer a factor(thank god), i still get a big kick out of repairing things. at 73 years of age, i guess i won't change anytime soon. i do want to thank you for your response. regards pete g.

[truenorth]

Having  a big advantage over me in advanced years (one year) and as a subscriber to the very same notion as can be readily demonstrated by my penchant for buying old items at garage sales (currently computers )with a view to restoration. I can absolutely relate to your position (hence my earlier stated reservation of my advice). If it turns out to be a vacuum tube issue sometime ago i remember reading that the Russians were actively trying to buy all the vacuum tubes that they could lay their hands on. So if that be so perhaps some searching within a Russian based search engine might find them. Don't know to what extent CRT monitors use vacuum tubes though.I find that LCD displays are generally sharper and of course the units occupy far less space than CRT's and therefore allow more options for their placement. good luck,truenorth

[pete g]

the only tube in a crt based monitor is the crt(pix tube). the monitor in question lasted 8 years before it required any kind of service. during that time it was on almost 24 hours a day. there is no lcd monitor now or probably ever that will give that kind of troublefree service. so, while they may be a little sharper and the current technology does not mean there better. however i think we're straying from the original purpose of this post. namely, what the *censored* is wrong with it? pg

[BC_Programmer]

the magneto-restriction coil and/or the flyback transformer that powers it has failed.

[quaxo]

I mean absolutely no disrespect with this post, Pete, and I certainly hope you take none. However, there are components inside CRT monitors that retain a charge even long after they've been unplugged. A charge strong enough to kill a person.

I always recommend that if someone really wants to save their CRT for whatever reason, that they take it to someone who is trained and qualified to do so. The fact that you're actually asking how to locate the problem or repair a CRT (or to try to find the problem) would lead me to believe that you aren't trained and qualified to repair one. I understand that you apparently know a lot about electronics, but if you aren't completely familiar with how to service a CRT monitor, please don't attempt to.

If you must repair the monitor, please find someone trained and qualified to diagnose and repair the monitor.

[pete g]

 i have repaired many crt based equipment and only once in 30 years was i ever shocked due to my own stupidity. inside almost all tv's and monitors there are bleeder circuits that discharge hi value capacitors. there are only one or two scenarios when you can be seriously shocked. having said that, it is a good idea to discharge p/s caps. also you want to be careful when you disconnect the crt anode, its a good idea to discharge it. if you want to talk about getting killed you should look into servicing microwave ovens. not being careful with them will kill you. as far as asking for help on the forum two things come to mind one is i can't find a service manual and two i'am just being lazy. what will probably happen is i'll get into fixing the monitor and it will get fixed. by the way, i just finished repairing a 50 inch zenith plasma.

[quaxo]

Ok, fair enough. I always assume people don't know what they're doing when they poke around inside certain things, usually it's true. You seem well aware of the risks, so I won't bother you further.

I'm not trained or qualified to give you advice on how to fix it, so I'll *censored* out now.

[truenorth]

pete g, This will probably be my last kick at this can. Given that you desire a service manual or schematic for the monitor here is a link to one of those sites i referred to in my earlier post that supposedly is dealing with a person seeking the same thing for that crt model. I do see references to the model within the post . However if there is something within it that gives you what you are seeking i cannot tell. Maybe you can see something. It does seem to be a sight devoted to your type of issue (amongst adverts for many other non related stuff). Have a look and maybe it will lead to some assistance or an alternative place to post your question. truenorth
http://translate.google.ca/translate?hl=en&sl=es&u=http://www.dtforum.net/index.php%3Ftopic%3D107780.msg1010925198%3Btopicseen&ei=SXPmTf3mF5SRgQfXjK2iCw&sa=X&oi=translate&ct=result&resnum=6&ved=0CEkQ7gEwBQ&prev=/search%3Fq%3Dcompaq%2BPE1160-chassis%2BFS7550/V7550.%26hl%3Den%26client%3Dopera%26rls%3Den%26channel%3Dsuggest%26biw%3D1246%26bih%3D842%26prmd%3Divns
This is the link to the "translated" page that is in another language. truenorth

[Salmon Trout]

In TVs since about 1950 and all CRT monitors, the EHT to a CRT anode is derived from a flyback transformer and is rarely if ever lethal; the current capability is measured in microamps. I have had a couple of 25 kV "belts" from colour TVs back in the day. Very nasty, and never to be forgotten. On the other hand, the 2 kV anode supply in a microwave oven is derived from the AC mains and the current capability is appropriate for the power rating of the oven, so that a 1,000 Watt oven will have a supply capable of delivering half an amp without even getting into a sweat. This is, of course potentially lethal. Also microwave ovens have an HT reservoir capacitor which can hold a charge for months and which can also kill.

[Salmon Trout]

If both vertical and horizontal scan amplitude is reduced, I think I would probably start looking around the power supply.

[pete g]

trunorth thanks for your efforts. salmon trout right on, could be low bplus. when i solve this i'll post. that is, if anyones interested. bye from s.florida.