Compaq Contura laptop PSU output is high

[ckrtech]

OK, guys. This one should be fun and out of the typical ATX zone a bit!

This is a power supply for a 486 Compaq laptop. There are a couple of issues
1: There is a bit of an open in the power cord. Tough to get a reading from the barrel, but when I do...
2: The output is around 22 volts.

The Max output is apparently supposed to be 18.5v according to the casing.

Now I suppose I could try to repair the open to get a stable "22v" at the barrel connector and plug it into the laptop - and goodness knows the condition of the laptop - but I was hoping maybe you PSU guys could share some thoughts on this little guy.

He is about 24 years old.

The component bolted to the heatsink to the right of the transformer (output side) with label CR3, I can't quite make out. It looks like:

30
892M
-> <- (couple of diode arrows point at each other)

[momaka]

Re: Compaq Contura laptop PSU output is high

What series are those Nichicon capacitors? PR? PL?

Old Nichicon PR caps like to leak from the bottom and cause all sorts of issues.

That said, the 22 odd volts you read at the output may or may not be an issue. I've seen numerous genuine "18.5V" HP adapters read 19.5-20V before and it wasn't a coincidence - they were designed like that (or most likely re-labeled 19.5V adapters). I doubt your laptop will have any issues with 22V, as the caps at the input inside the laptop are usually rated at least 25V (the next lower value is 16V, but that wouldn't be any good for an 18V adapter).

So first check what series of Nichicon caps you have. If not PR, then fix the open-circuit issue with the barrel and see what voltage you get from the adapter. Then see if it can power on the laptop. It looks like a well-built power adapter, so it is likely to be okay, even with the caps being this old.

[jazzie366]

Re: Compaq Contura laptop PSU output is high

What series are those Nichicon capacitors? PR? PL?

Old Nichicon PR caps like to leak from the bottom and cause all sorts of issues.

That said, the 22 odd volts you read at the output may or may not be an issue. I've seen numerous genuine "18.5V" HP adapters read 19.5-20V before and it wasn't a coincidence - they were designed like that (or most likely re-labeled 19.5V adapters). I doubt your laptop will have any issues with 22V, as the caps at the input inside the laptop are usually rated at least 25V (the next lower value is 16V, but that wouldn't be any good for an 18V adapter).

So first check what series of Nichicon caps you have. If not PR, then fix the open-circuit issue with the barrel and see what voltage you get from the adapter. Then see if it can power on the laptop. It looks like a well-built power adapter, so it is likely to be okay, even with the caps being this old.

Nichicon PL do this as well.

I second this, also depending on the regulation that voltage may drop with a load.