IBM L170 power supply failure

IBM L170 power supply

IBM L170, manufactured in May 2004, model no. 6734-AB1

The screen would turn on fine, but when a signal was applied, the backlight would turn off.

Capacitors C201, C223, C922, C924, C925, C926 had failed. Capacitors C924, C925 and C926 are situated on the 5V rail and were successfully replaced by used 6,3V Chemi-Con KZG and Nichicon HM parts of equivalent capacitance. C201, C223 and C922 are situated on a well-regulated 12V rail. C201 and C223 were collectively replaced by one used 1500µF/16V Chemi-Con KZG (they’re directly in parallel with about 1cm of trace in between). C922 was replaced by another such.

IBM L170 power supply after repairs.

I should end with noting that these are some of my favourite consumer LCD screens ever made. Aside from the the power supply, the build quality is staggering. They weigh six kilograms and ship with a proper, extremely high-quality 100×100 VESA stand that you can bolt onto any monitor you wish, for an instant improvement in stability. They’re screwed together rather than snap-locked, and the serviceability is just staggeringly good all-around.

Acer V193 power supply failure

Acer V193 power supply

Acer V193, manufactured in March 2009, model no. ET.CV3RE.A08

The screen would flash its power LED once and then give up any signs of life until the power cord is pulled and re-inserted.

The 1000µF/10V capacitor C820 had failed. It was replaced by a used Chemi-Con KZG 1500µF/16V. Raising the voltage rating of the capacitor is not necessary, I just used the part I had in stock. All other capacitors measured OK, and were not replaced.

Acer AL1717 power supply failure

Acer AL1717 power supply

Acer AL1717, manufactured in November 2005, model no. ET.1717P.014

The 17″ Acer list on this blog is nearing completion, with the AL1711, AL1716 and now AL1717 down!

The monitor would squeal and flash its power LED, occasionally flashing the backlight for a second or two.

All the larger electrolytic capacitors on the secondary side of the power supply tested bad. The big 2200µF/10V capacitor sits on a well-regulated 5V rail, and was replaced by a used 2200µF/6,3V Rubycon MBZ. The 1000µF/25V capacitors were replaced by various 1000µF/16V units. However, since the 12V rail they’re situated on seems to be poorly regulated and lying at almost 15V unloaded, replacing them with 25V caps is advisable. If the 220µF capacitor above the heatsink is not replaced, the screen will run noisily. Replacing it by a 470µF or 1000µF part will considerably lower the noise emitted by the screen still.

Samsung Syncmaster 206BW power supply failure

Samsung Syncmaster 206BW power supply

The screen would squeal and flash its power LED, showing no other signs of life. The two 1000µF/25V capacitors (C263 and its mate) had failed. They sit on the 13V rail. They were successfully replaced by two used 1500µF/16V Nichicon KZG. All other capacitors tested OK, and were not replaced.

The screen also suffers from a loud buzzing noise when the brightness is turned down. I have not been able to identify the fault, but I believe it to be a fault in the lower CCFL of the panel itself.

Worth noting is that the screen had only logged a run-time of 3000 hours in the service menu before the power supply failed . . .