I spent Saturday evening fixing my monitor. Yes, it's a strange thing to publish here but I enjoyed doing it. Only a geek can understand the excitment of taking on the inner workings of a 22" CRT with it's thousands of deadly volts and x-ray warnings. Also, this post will be commited to the information superhighway forever and may help other people searching for a fix.

The VM Pro 510 (A201HT) gradually stopped working over the course of a few weeks. The first signs of a fault were when the PC powered up. If in standby mode (orange LED) the monitor would initially sense a video signal and switch on (green LED). However, as the fault became worse, the monitor would fail as it switched on and reverted to standby mode. In the end it would fail to even enter standby mode and stopped responding to the on/off switch.

Click Read More for more...

The fault is mentioned on a few web sites, and a number of causes are suggested. The most useful information is at Monitor repair forum. A Richard B gives these words of advice to a few people whose monitor failed like mine (first reply to one that also poped and smoked);

- "Hi your problem is caused by C932 this is in the HT feedback circuit and goes low in value and more importantly high esr, this lets the psu go too high output especially from cold start.

Now something has died either the HOT Q503 has gone S/C but sometimes one of its parallel diodes D501, D502, D511 if so it will have taken out axial fuse R961, the other item that can die under this condition is the video output IC this takes with it an axial fuse in the 80V line I can not remember if this is on the video PCB or the Main PCB."

- "The capacitor is the main rason for failure of this model and others with a sinilar chassis."

- "Always change C932 10uF 50V on Iiyama before replacing Video output IC.
For white picture check for fuse in 80V rail to video output IC."

As my fault seemed to match the description of a failing capacitor, I chose to try the simple fix first and replace just C932. The only part it required was one 10 uF 50 V Electrolytic capacitor, this was 12p from Maplin. Fitting it was fidly, but simple.

• First I shorted the plug terminals to disipate any charge (not sure how advisable that is, but probably more advisable than an electric shock). Then remove the base, plastic case and front facia.
• With the monitor resting on it's screen, remove all of the x-ray shielding from the back and sides. Loosen the top screw clip securing the gun circuit board to the end of the tube. Then pull the whole gun circuit boad off of the tube, the plug is large and required a firm pull. I took care not to disturb the tuning magnets. Slacken the cable ties and move things around to provide a bit more room.
• Unscrew the main circuit board from it's chassis. There are about 8 screws along its top edge and sides. The board should then be free to lean forward. Looking through a chassis hole above the power plug you should be able to see a label for C932. The two solder pads site one above the other with an idicator on the positive capacitor leg. It is also simple to locate on the component side of the board, above a small transformer.
• With the main board leant forward there should be enough room to gain access with a soldering iron and tools. Unsolder the old capacitor, in my case there were no obvious signs of failier or bulging. Remove excess solder using a solder-sucker or copper braid. Then poke in the new capacitor, taking note of it's polarity, and resolder.
• Put everything back together and test it.

The monitor worked perfectly after the fix, standby and video sensing was as good as new. Hopefully someome else will find this info useful and rescue their broken monitor. The VM Pro 510 is a great monitor, it seems a shame to landfill something that cost many hundreds of pounds when new when a silly fault makes it unusable.