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Old 05-29-2022, 11:10 AM   #40
Join Date: Mar 2022
City & State: Altea
My Country: Spain
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Posts: 35
Default Re: Cyberpower CP900EPFCLCD - F03 Error

Originally Posted by Per Hansson View Post
Ok, so with these values it looks to me like your incoming line voltage is 233VAC
Since you measured 227v in series with the bulb this is the voltage it drops.
So therefore your measurements of 5VAC show the remaining AC (not being dropped) i.e. it points to the short.
Well, that must be the current issue, indeed.

Originally Posted by Per Hansson View Post
In this case you are reading a very low voltage on the bridge rectifier of only 3.96VAC and 5.361VAC in C22 before it.
This points to the bridge rectifier or something after it being shorted.
I would remove the bridge rectifier from the board and test both again:
This will help narrow down where the issue lies.
I removed the bridge rectifier and, when I connected everything to mains, the light bulb was off. Then measured the voltage. This time, I was getting 230.8V into both inputs for the DB107 bridge rectifier. I suppose that means that everything before it should be working fine, right?

Originally Posted by Per Hansson View Post
As for the voltage difference in C5 and C6 that is because one is connected from phase to neutral (230vac side).
And the other between neutral and ground side (this should in a perfect world read as 0vac but a low voltage like you see here is normal).
Ahh, understood. I didn't know that was the correct value I should get.

Originally Posted by Per Hansson View Post
As for K1 and the capacitor C7 I don't see how they are connected but I would ignore them for now, the goal is to get power to the Viper chip first.
In any case I'm 99% sure that the voltage generated by the Viper is used to control the relay so there is no point going down that path (yet)
Alright, let's check the right part later on.

It took me some time to respond cause I was about to receive a package with the fuse replacements and some extra DB107. I replaced the DB107 with a new one, and when I connected everything again, the light bulb was on, and the values back like last time.

I disconnected it and thought an idea. I removed the viper22a from the socket, and got a few more measures. First, the bulb was off (probably because part of the circuit was not accessible). The DC output from the rectifier had 316.2V DC. The C3 capacitor measured 316.2V, and C14 between 40 to 50V, but couldn't write it down cause while using the probes, I must have shorted something, and fried the 550ohm resistor and C14 probably. Probably it wasn't a very good idea removing the viper, but at least isolates a bit where the short is.

Then, from now on, what do you recommend me to do? Should I replace the blown components and try again, or remove some of them to try to find the faulty section?

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