Broken Dell 1800FP Power Supply - when and when not to resolder?

[PlainBill]

Re: Broken Dell 1800FP Power Supply - when and when not to resolder?

The browning around D903 and D906 appears to be flux. Components with heat sinks present a problem in manufacturing. The heat sink must be attached when the component is soldered of it won't be at the right height. But heat sinks interfere with the wave solder process, so these are often hand soldered afterward. And sometimes someone doesn't bother removing the flux.

None of the joints on D903 look particularly healthy. And given what you (probably) got ripped off for the directions, you might as well resolder every one of the pins mentioned. Even if it takes you 2 minutes a pin, it's a quick job.

I've attached a touched up picture indicating the separate areas. Mainly you are concerned about the leads of D903, etc.

NOW, the facts of life. Just because poor solder joints on T901 and D903 and D906 are a common cause of failures on these power supplies doesn't mean that they are the ONLY cause of failure.

PlainBill

[maverick530]

I own a Dell 1800FP whose Power supply (LG part #:6870T445D10 2003.05.07) is bad. I know this because I have replaced it with a known good power supply and the monitor works fine. I want to fix the power supply so I can have 2 monitors.

1st, I purchased fix it instructions that say to resolder the transistor connections at T901, but my connections there look stellar (perfect). Do you think I can skip this step?

2nd, upon visual inspection of D903, I'm not sure which sections should connect to each other after I'm done. Should just A&B be touching with solder? or just A or what? How does one know without a schematic? Could the browning between the top 3 connections be shorting out the cirucuit?

3rd, there's a lot of other browning on the board (not listed in the instructions of things to resolder) where it looks like the solder got runny. Might these need to be "resoldered" as well?

Thanks for any and all help,