Need Schematic for Dell/Sony P991 19" CRT Monitor

First try cleaning the spark gap.. Second disconnect the base assembly an see if it arcs whilst disconnected

Kip,

Thanks for the reply. The device that is sparking is a sealed glass bulb. It most closely resembles a neon bulb. It has two soldered in leads and the "spark gap" appears to be inside a gas filled glass cavity. My guess here is that the electrode distance is fixed and that the distance coupled with the type of gas inside the bulb probably determines the breakdown voltage.

As such there is no way to clean the spark gap as you have recommended. I could certainly remove the device and see what happens, or find a replacement. I may even be able to swap it with one of the other devices on the CRT socket board which appear to be the same. I am leery of doing this though right away. I would prefer to test the critical devices first to see is any has drifted out of spec over time. I also would appreciate getting the schematic so that I can confirm the other devices are in fact the same value so could be swapped.

Thanks again. Let me know if you have additional feedback or thoughts. Sorry for not being more clear on the type of voltage surge device being employed.

Bob

Cleaning the spark gap isn't going to fix it. Those monitors are notorious for failing focus dividers on the flyback and capacitors going high esr in the power supply, both of which can cause the focus voltage to go too high and the spark gap to arc over.

In addition the simple check is to make sure the ground pins on the flyback are all good. Rarely on some monitors if the divider resistor ground pin solder connection breaks loose the focus voltage also will go way high.

Thanks. I have visually inspected all the flyback pins and the solder does look good. I can retouch all of them as this is fairly simple with the board out. On the high ESR elecrolytics, which component numbers or do you suggest I check them all? A quick visual inspection did not yield any that appeared to be bulging and I did begin to test ESR on the largest PSU section capacitors, but they checked out low in circuit with the Dick Smith ESR meter.

What I really need is the schematic so I can see what would cause the voltage to be high on that particular protection device. I could then remove leads of suspected resistors, caps, and diodes to test them correctly with my DMM and the ESR meter.

But, unfortunately without the schematic I can only hunt and peck based on tracing the conductor paths and this is extremely difficult due to the density and physical layout (there are several large heat sinks obstructing view/access). This group has always come through for me in the past ... so I remain optimistic that someone will be able to help me out.

Bob

Ok Fine the reason I suggested clean the gap was because I just had one similar on an RCA TV that was in a sort of damp location and cleaning did the trick.Best of luck trouble shooting the Monitor .Most probably a bad IHVT or Focus Network if it has one.

kip

Thanks again for the response. Just wish I had the schematic!

Bob

You don't need a schematic to troubleshoot a bad focus resistor divider.

This might be the info you want:

Hopefully will help with any other potential issues. Be aware that if something happens to corrupt the eeprom that holds the alignment data, you will have to send it off for repair as hte computer interface and software to perform an alignment is not cost effective to buy for only one monitor.

Thanks ... I found my monitor, the Dell P991, on the list and successfully downloaded three .rar files. What application opens these? I thought they would be .pdf and could be read with Adobe Acrobat, but I do not think I have seen a .rar file before. If I can get these open then I can read what is there and see if this is what I need.

Sorry to be such a pain... I do appreciate directing me here. This site did not come up when I did a Google search. It appears to have a lot of info and be from Bulgaria!

Bob

I just plonk rar files into winzip and that works for me -)-)-)

You need winrar to open them..

Thanks. I'll try Winzip first as was suggested, then see if I can find this other app if needed.

Bob

Kip,

Thanks again. I downloaded winrar and also winDJview to open the .DJVU file that was inside the .rar archive. This contained the full service manual and a schematic as well so I think I am good for now.

It never ceases to amaze me how this group always comes through.

successfully