CF-29 back light repair successful! Huge thanks to "toughasnails" for the help!

This repair was done on the 10k hour unit that the touchscreen stopped working on. I managed, somehow or another, to kill the back light.

Toughasnails provided me with some info that helped me determine that a cf-28 doorstop had 3 of the chips I needed to fix this unit, although I only needed one.

I thought that I had read somewhere here that you DO NOT want to unplug the connector that contains the wires for the touchscreen and inverter supply with the unit plugged in and the battery installed.

I found that whatever I did, which was probably the above, killed an OR gate that feeds the PWM signal to the inverter board.

In any case, it's now working.

One thing, working with surface mount components takes a steady hand!

Here are a couple of pics of the component removed and the new installed, the bottom chip:

 

Good job, glad we could help you out. Steady hands...30 years ago but not now

 

More info! Like specific part numbers for Mouser or Digikey and PLEASE STICKY THIS!!!

 

I will tell you that this job requires a little knowledge of being able to work on surface mount components. It can be done, but the right iron tip is imperative along with a steady hand and some magnification helps.

The part number from Newark is MC74VHC1G32DFT2G.

I'm going to suggest that anyone that may have a component that needs to be replaced will probably want to have someone with experience in doing this to complete it.

 

For me, desoldering is the most difficult part. I do very little SMD stuff. I have an ultra thin 12watt iron that works decent.

 

Thanks for the part number! AND VERY TRUE! Unfortunately, I am the one others come to when they break their toys... I don't particularly like doing surface mount repairs, but I am good at them.

Sometimes carefully breaking the parts off, is the key. Sometimes. This is a judgment call as it can lift traces damaging them. I usually desolder as much as possible first with my bulb sucker type Radio Shack desoldering iron. Tip: If you do any decent amount of work, replace this iron regularly. I have to replace mine every year or so. After sucking as much of the solder as quickly possible, then usally breakign the part off can be accomplished a little more safetly. Then clean the pads up and remove any bits left behind.

Using an ESD safe work station to reassemble, really helps, especially if it is temperature controlled. If you don't know what ESD safe means, then walk away now LOL!

I have changeable tips on my station, so that helps too. I still hate doing surface mount stuff. But when fixing a bit like this is a $1 or less part and half an hour, it makes up for the trouble! :thumbsup: