Hello,
i bought an Compaq Presario CDS 522. Nice little Computer.
The Problem is when you turn on the Computer, no Picture appears but the PC works in the background. The CRT monitor is running but there is no writing or anything like that on it. It has no HDD but you can boot MS-DOS with a floppy disk.
If someone has a solution or can help me in any other way, I would be very grateful.
THX
MFG
Jonsey74
Most likely the CRT section has died. Could be many reasons but most likely capacitors in the CRT PSU and mainboard sections are bad. If you know anything about TV or Monitor repair then you might be able to fix it.
Other wise you have to figure out a way to route the motherboard video to an external monitor...
Personally I avoid those "all in one" type PC and Mac's just for this reason.
Sorry but cannot offer any more help because I have never worked on an "all in one" before.
Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun
Folk have replaced the CRT with LCDs on these...
There's a glitch in the matrix.
A founding member of the 286 appreciation society.
Apparently 32-bit is dead and nobody likes P4s.
Of course, as always, I'm open to correction...😉
Horun wrote on 2021-05-26, 01:26:Most likely the CRT section has died. Could be many reasons but most likely capacitors in the CRT PSU and mainboard sections are […]
Most likely the CRT section has died. Could be many reasons but most likely capacitors in the CRT PSU and mainboard sections are bad. If you know anything about TV or Monitor repair then you might be able to fix it.
Other wise you have to figure out a way to route the motherboard video to an external monitor...
Personally I avoid those "all in one" type PC and Mac's just for this reason.
Sorry but cannot offer any more help because I have never worked on an "all in one" before.
The tube works. It gets lighter after a while. And when you perform a reset, you can tell by a brief flash. It could also be that the onboard chip of the graphics card is defective.
Caluser2000 wrote on 2021-05-26, 05:47:Folk have replaced the CRT with LCDs on these...
This is not an option for me at the moment.
Is HV present? This usually casues electrostatic charge buildup on the front of CRT and hair tends to be attracted to it. If you can feel HV then there should be a picture even if it's too low - it would only make it dimmer and not streched across entire screen.
Then there's a few more electrodes in the CRT neck that need correct voltages, like first grid (which can cut off the picture entirely) and focusing. And then there's the cathode drivers, I doubt all 3 colors would just die but perhaps the common voltage rail they need is missing somehow.
BTW the missing/incorrect voltages on the CRT can also be caused by brightness/contrast pots going open. Those should be tested as well, treated with contact/cleaner or replaced if needed. Lastly most multi-mode monitors have some logic circuitry to disable screen if they don't like the input signal frequency - thac rarely goes bad but a dry electrolytic or two could cause it to malfunction.
Deunan wrote on 2021-05-27, 10:00:Is HV present? This usually casues electrostatic charge buildup on the front of CRT and hair tends to be attracted to it. If you can feel HV then there should be a picture even if it's too low - it would only make it dimmer and not streched across entire screen.
Then there's a few more electrodes in the CRT neck that need correct voltages, like first grid (which can cut off the picture entirely) and focusing. And then there's the cathode drivers, I doubt all 3 colors would just die but perhaps the common voltage rail they need is missing somehow.BTW the missing/incorrect voltages on the CRT can also be caused by brightness/contrast pots going open. Those should be tested as well, treated with contact/cleaner or replaced if needed. Lastly most multi-mode monitors have some logic circuitry to disable screen if they don't like the input signal frequency - thac rarely goes bad but a dry electrolytic or two could cause it to malfunction.
Yes, high voltage is there and if you come near the tube or touch it, it crackles.
Attached is a picture from the PC. You can see that the monitor works.
How does the monitor connect to the video card. I have a presarrio 4402 and I had a similar issue that turned out to be a damaged VGA cable. I had it replaced it's been solid ever since. On the 4402 all the monitor connections are external like a standard desktop/tower.
Jonsey74 wrote on 2021-05-27, 22:02:Yes, high voltage is there and if you come near the tube or touch it, it crackles.
Attached is a picture from the PC. You can see that the monitor works.
OK, with the photo it's obvious HV is present and both deflection circuits work.
I see buttons, does this monitor have on-screen menu display (OSD)? Can that be shown? If so it would be a great way to test if the basic CRT drive works properly or not. Note that some monitors can disable the OSD if there is no signal input.
Is there an auxiliary signal input to the monitor? Or, as mentioned above, is it connected to the mobo via external cable? If so try another VGA signal source, could be a video card issue after all. Preferably test with different cable.
There are pots inside behind the monitor to make adjustments on these. You need quite a long insulate sflat bladed screw driver to get at them.
There's a glitch in the matrix.
A founding member of the 286 appreciation society.
Apparently 32-bit is dead and nobody likes P4s.
Of course, as always, I'm open to correction...😉
chrismeyer6 wrote on 2021-05-27, 22:49:How does the monitor connect to the video card. I have a presarrio 4402 and I had a similar issue that turned out to be a damaged VGA cable. I had it replaced it's been solid ever since. On the 4402 all the monitor connections are external like a standard desktop/tower.
Internally, the graphics are transmitted via an onboard chipset.
Deunan wrote on 2021-05-28, 08:31:OK, with the photo it's obvious HV is present and both deflection circuits work. […]
Jonsey74 wrote on 2021-05-27, 22:02:Yes, high voltage is there and if you come near the tube or touch it, it crackles.
Attached is a picture from the PC. You can see that the monitor works.OK, with the photo it's obvious HV is present and both deflection circuits work.
I see buttons, does this monitor have on-screen menu display (OSD)? Can that be shown? If so it would be a great way to test if the basic CRT drive works properly or not. Note that some monitors can disable the OSD if there is no signal input.
Is there an auxiliary signal input to the monitor? Or, as mentioned above, is it connected to the mobo via external cable? If so try another VGA signal source, could be a video card issue after all. Preferably test with different cable.
This monitor has no OSD. The monitor is internally connected to the mainboard.
And at the moment I don't have an ISA graphics card to test whether it would work with an external monitor.
Caluser2000 wrote on 2021-05-28, 10:01:There are pots inside behind the monitor to make adjustments on these. You need quite a long insulate sflat bladed screw driver to get at them.
Can you explain that to me in more detail? I would not like to adjust anything if I do not know what and why.
Jonsey74 wrote on 2021-05-30, 21:46:Caluser2000 wrote on 2021-05-28, 10:01:There are pots inside behind the monitor to make adjustments on these. You need quite a long insulate sflat bladed screw driver to get at them.
Can you explain that to me in more detail? I would not like to adjust anything if I do not know what and why.
Just look down in front of the rear RF shield and you should see them from memory, which isn't that great lately..
When I had my CDS524 I adjust the screen so the image covered the whole screen.
There's a glitch in the matrix.
A founding member of the 286 appreciation society.
Apparently 32-bit is dead and nobody likes P4s.
Of course, as always, I'm open to correction...😉
Jonsey74 wrote on 2021-05-30, 21:44:This monitor has no OSD. The monitor is internally connected to the mainboard.
And at the moment I don't have an ISA graphics card to test whether it would work with an external monitor.
Hm, that thick cable looks like VGA, but it's probably terminated on both ends with customized PCB connectors. It might be possible to figure out what the wires do, excactly - for ground, RGB and sync signals. I would expect the RGB to actually have these wire colors. With that it mighe be possible to drive the monitor from external source, like another PC with VGA. Well, that's assuming it has no extra VGA connector on the back for that purpose.
Caluser2000 wrote on 2021-05-30, 21:58:Jonsey74 wrote on 2021-05-30, 21:46:Caluser2000 wrote on 2021-05-28, 10:01:There are pots inside behind the monitor to make adjustments on these. You need quite a long insulate sflat bladed screw driver to get at them.
Can you explain that to me in more detail? I would not like to adjust anything if I do not know what and why.
Just look down in front of the rear RF shield and you should see them from memory, which isn't that great lately..
When I had my CDS524 I adjust the screen so the image covered the whole screen.
Is that what you meant and what exactly should I adjust now?
Deunan wrote on 2021-05-30, 22:57:Jonsey74 wrote on 2021-05-30, 21:44:This monitor has no OSD. The monitor is internally connected to the mainboard.
And at the moment I don't have an ISA graphics card to test whether it would work with an external monitor.Hm, that thick cable looks like VGA, but it's probably terminated on both ends with customized PCB connectors. It might be possible to figure out what the wires do, excactly - for ground, RGB and sync signals. I would expect the RGB to actually have these wire colors. With that it mighe be possible to drive the monitor from external source, like another PC with VGA. Well, that's assuming it has no extra VGA connector on the back for that purpose.
It doesn't have an external connector for a monitor and I don't want to damage the cable. But maybe another solution can be found.
The operating description of the of the pots is silk screened next them on the pcb. I found the best thing was have the system on a chair. Facing a mirror, adjusting the pots while viewing the crt in the mirror(just remember the image reversed from what it is on the actule crt) and adjusted to suit. As I mentioned earlier I use a loooong insulated screw driver to adjust the pots. At first I was a bit nervious because of the voltage inside. After a while I got quite comfortable and adjust the screen to where I wanted.
There's a glitch in the matrix.
A founding member of the 286 appreciation society.
Apparently 32-bit is dead and nobody likes P4s.
Of course, as always, I'm open to correction...😉
These pots shouldn't have any life-threatening voltages on them but a full-plastic adjustment tool is a good idea anyway, if for no other reason than reducing risk of damage or injury if it accidently ends up being shoved into wrong spot.
Preferably mark original pot position, or use the photo you've made, and just turn them a bit and return to original setting. Just to loosen them up a bit. Might help and it's easy and safe to do.
Jonsey74 wrote on 2021-05-25, 20:16:Hello, […]
Hello,
i bought an Compaq Presario CDS 522. Nice little Computer.
The Problem is when you turn on the Computer, no Picture appears but the PC works in the background. The CRT monitor is running but there is no writing or anything like that on it. It has no HDD but you can boot MS-DOS with a floppy disk.
If someone has a solution or can help me in any other way, I would be very grateful.THX
MFGJonsey74
Hi Jonsey, if you still have your Compaq with the same problem, maybe I have a solution for you (or maybe to other people with the same problem).
You need to keep in mind that working on these computer monitors can be EXTREMELY DANGEROUS, so proceed at your own risk!
Before touching anything, safely check and if necessary discharge the power supply main big capacitors and high voltage from the CRT... there are plenty of info on how to do that over the internet....
I recently bought one of these all in ones (524) with the exact same problem. On my computer the problem was related to the CRT neck board (the small board that attaches to the tube), there was a 100uF 25V small capacitor that was shorted and thus preventing any video output to the screen.
Maybe that could also be the problem with your computer, I think it's worth a try.
Check all capacitors in the CRT neck board with a multimeter in the Ohms scale and see if there are any with very low resistance (you must remove them from the board or lift one of the legs first), or just change them by new ones.
Hope that helps
