VP2030b:delayed start up after replacing caps

[Rob190]

I recently revived a dead VP2030b by replacing the capxon capacitors(3x 180uF 35V, 6x 100uF 25V, 2x 1000uf 6.3V). All of them had the familiar bulge.

Once it's on, the monitor works fine but it takes a very long time to switch on. When the power button is pressed, the green power led lights briefly, then goes out. It then takes several minutes before the monitor turns on.

There aren't any other capxon capacitors and I couldn't see anything else that looked out of the ordinary. Is the delay normal for this monitor? If not what else needs replacing?

Thanks,

Rob.

[pedro]

Re: VP2030belayed start up after replacing caps

I recently revived a dead VP2030b by replacing the capxon capacitors(3x 180uF 35V, 6x 100uF 25V, 2x 1000uf 6.3V). All of them had the familiar bulge.

Once it's on, the monitor works fine but it takes a very long time to switch on. When the power button is pressed, the green power led lights briefly, then goes out. It then takes several minutes before the monitor turns on.

There aren't any other capxon capacitors and I couldn't see anything else that looked out of the ordinary. Is the delay normal for this monitor? If not what else needs replacing?

No, that behaviour is not normal for any monitor. The fact that - after getting all its ducks in line - "the monitor works fine" suggests that the problem is in the power supply section, or maybe the video processing, but not the backlight/inverter area.

Before ripping it open again for the photo session and voltage testing, question time:

1. Did you replace ALL the electrolytics on the power board (except the large one)?

2. What brand/series caps did you use?

3. When you say "the green power led lights briefly, then goes out" roughly how long is it on for, and does it extinguish or go amber/whatever?

[retiredcaps]

Re: VP2030belayed start up after replacing caps

Once it's on, the monitor works fine but it takes a very long time to switch on.

1) This sounds like the caps you didn't replace have high ESR. As the caps warm up, the ESR drops and the circuit functions.

2) Capxon does not have the greatest reputation with members here and are generally a "replace on sight" regardless if they are bulging or not.

3) Capacitors die from age, heat, and shoddy build quality. Capacitors DO NOT have to be visibly bloated in order to bad. They can be out of tolerance uF (a 1000uF measures 20uF) and/or have high ESR (ohm). A multimeter will be insufficient to test for ESR. For that you need an ESR tester which costs between $50 and $300.

Most members here will recommend that you replace ALL capacitors with reputable brands from reputable sellers. Brands like Rubycon, Panasonic, and United Chemicon are suggested. A list of recommended caps can be found at

https://www.badcaps.net/forum/showthread.php?t=2280

4) You can use Panasonic FR/FM/FC series caps for replacements. If your replacement caps are from Radio Shack (or ebay fakes), they will be general purpose caps and not be suitable in a SMPS application which requires low ESR caps.

5) Pedro beat me by 1 minute.

[PlainBill]

Re: VP2030belayed start up after replacing caps

Three words. Start up cap.

PlainBill

[Rob190]

Re: VP2030belayed start up after replacing caps

No, that behaviour is not normal for any monitor. The fact that - after getting all its ducks in line - "the monitor works fine" suggests that the problem is in the power supply section, or maybe the video processing, but not the backlight/inverter area.

Before ripping it open again for the photo session and voltage testing, question time:

1. Did you replace ALL the electrolytics on the power board (except the large one)?

2. What brand/series caps did you use?

3. When you say "the green power led lights briefly, then goes out" roughly how long is it on for, and does it extinguish or go amber/whatever?

1. No, actually nothing on the main power board (i.e. the board when the main supply connects).

2. Panasonic FR series type A and Rubycon ZLJ

3. The green light is on for maybe 1/2 second then goes out. The same problem occurs if the computer turns off the screen. There's an orange light on while the screen is off but when e.g. the mouse is moved to activate the display, the orange light turns off for a couple of minutes and then then monitor comes on.

So you suggest replacing all except the large cap on the main power board? Ok I can try that. Thanks!

[Rob190]

Re: VP2030belayed start up after replacing caps

Replaced all but the large cap on the main power supply board. Unfortunately it didn't make any difference. There is still a delay of a minute or two before the display switches on.

Is there any chance the large capacitor has failed? I've been told by several people that they are very reliable. Or are there any other components that could be so temperature dependent?

[retiredcaps]

Re: VP2030belayed start up after replacing caps

Post top down view pictures of your boards. Follow the instructions in my sig file in post #3. Please do not post inline.

[Rob190]

Re: VP2030belayed start up after replacing caps

Some progress. I tried removing the USB board and that cures the problem. I hadn't replaced any of the caps on that board. There are 6 100uF 25V TEAPO caps. Unfortunately I don't have enough (good quality) caps to try replacing them all right now.

I also timed the delay and it's actually a bit better than before (since replacing the caps on the PSU board, but before removing the USB board). It seems to be about 30 seconds. Sometimes switching it off and on results in another 30 second delay, sometimes it comes on much faster. I can't really see a pattern but I think it's more likely to trigger the delay the longer I leave it switched off.

I also tried measuring the output voltage of the main PSU. After turning on the main switch but before pressing the front button, the 12v/20v give 11.85v and 20.10v. After the button is pressed but before the monitor comes to life the voltages are 11.70v and around 20.10v (can't remember exactly but it didn't change much). Once the display is on, the voltages are 11.95v and again ~20.05v. Removing the USB board doesn't affect these voltages, just the timing.

I can post the pics if that would help but the boards look identical to https://www.badcaps.net/forum/showthread.php?t=8263. Or are you looking for something specific in my boards?

[pedro]

Re: VP2030belayed start up after replacing caps

Or are you looking for something specific in my boards?

We are always looking for something specific in *your* boards - they are the ones with *your* problem. Pictures of someone else's boards are about as useful as sending your neighbour's X-rays to your doctor to find out what is ailing you.

[b700029]

Re: VP2030belayed start up after replacing caps

The green light is on for maybe 1/2 second then goes out. The same problem occurs if the computer turns off the screen. There's an orange light on while the screen is off but when e.g. the mouse is moved to activate the display, the orange light turns off for a couple of minutes and then then monitor comes on.

During this pause, have you tried shining a flashlight at the monitor to see if there is an image? If you can, trace the inverter ON signal to the main board and see if the delay is because the main board is waiting for something first, or if the inverter is taking its time starting up.

Is there anything else on the "USB board"?

[klkmalik]

Re: VP2030belayed start up after replacing caps

I recently revived a dead VP2030b by replacing the capxon capacitors(3x 180uF 35V, 6x 100uF 25V, 2x 1000uf 6.3V). All of them had the familiar bulge.

Once it's on, the monitor works fine but it takes a very long time to switch on. When the power button is pressed, the green power led lights briefly, then goes out. It then takes several minutes before the monitor turns on.

There aren't any other capxon capacitors and I couldn't see anything else that looked out of the ordinary. Is the delay normal for this monitor? If not what else needs replacing?

Thanks,

Rob.

Replace all capacitors, and resolder all invertor area ,high voltage section,I hope it will cure problems

[Rob190]

Re: VP2030belayed start up after replacing caps

Thanks for all the suggestions!

I tried replacing the caps on the USB board but it didn't have any effect. Actually it made it worse and with the USB board connected it now doesn't turn on after 2 minutes. I didn't want to wait any longer in case something was overloaded. I resoldered everything again and rechecked to make sure there weren't any shorts but no change.

With the USB board removed it works fine so I'm going to use it without. I might try debugging the board if I can find out what the connections are. There are only 4 connections, two of which appear to be ground. One will be the supply (5V?). If anyone knows what the other one does I would be grateful.

My current guess at the fault is either the regulator IC on the board (1117L) or a problem with the standby mode in the PSU. I've heard these regulators can fail sometimes. Alternatively it might be that the board is behaving normally but the main PSU can't deliver enough current. I think this is unlikely because there's not much on the USB board compared with the main video board. I suppose there are other possibilities such as the USB board wrongly telling the main video board not to start (is this actually possible?).

Sorry I didn't answer everyone's questions. Regarding what the monitor is waiting for, when it's working ok, you can clearly see the backlight come on before the video starts. When it's not working, there is no backlight. I forgot to check with a torch to see if there was any image. However, when the display turns on, the 'DVI-B' icon appears so I think the sequence is: Delay for 30 seconds, turn on back light, turn on video.

The USB board has 5 USB sockets, the main IC is ISP1520BD USB controller. The regulator is a 1117L (I assume 3.3V).

[b700029]

Re: VP2030belayed start up after replacing caps

Alternatively it might be that the board is behaving normally but the main PSU can't deliver enough current. I think this is unlikely because there's not much on the USB board compared with the main video board. I suppose there are other possibilities such as the USB board wrongly telling the main video board not to start (is this actually possible?).

There could be something shorted/partially shorted there, which is pulling down the supply voltage enough to stop the rest of the monitor powering up. Something eventually heats up and increases its resistance, lowering the current it's drawing and allowing the voltage to go back to a level that lets the rest of the monitor start.

Also, the service manual (Google "vp2030b service manual") has an almost complete schematic.

[Scenic]

Re: VP2030belayed start up after replacing caps

My current guess at the fault is either the regulator IC on the board (1117L) or a problem with the standby mode in the PSU. I've heard these regulators can fail sometimes.

The USB board has 5 USB sockets, the main IC is ISP1520BD USB controller. The regulator is a 1117L (I assume 3.3V).

Check if the 1117 gets really hot fast. I've had that problem on a cheapo external USB hub. The 1117-33 Regulator failed (shorted), got super hot the moment it was plugged in and killed the USB hub IC, which also got finger-burning hot (5V straight to the IC instead of 3.3V). Replacing the 1117 didn't fix it.. IC fried.

If the 1117 failed, there's no point in trying to fix the USB board cause the IC will probably be fried too. Just leave it disconnected if you don't need the USB ports.