hi there.
i have bought from jipsey market one not working UPS for learning purposes.

Have checked 4 MOSFETs on the heat sink and they`re good. In pdf of that ic i see
DC parameters
Load regulation
Ripple rejection

Which of tests to apply to see if the ic is faulty at all?
The more beautiful question - how?

thanks

 

Do you have more than 14V on the input?
Do you have 12V on the output?
If yes to both then it is working.

 

I will look for some guide if there`s such but i do know that sometimes one guide from two pages cannot tell me how to fix a device

 

1.57 input 0.8 output

3 fuses ok
c31 23,2 uf c1 71.5uf from 100uf/replaced before measuring voltage/

edit :
guardian 1500ap

 

The problem is that there isn't enough voltage on the input. It needs to be at least 14V.

 

If we exclude not charged batteries what to do?

 

What is the input connected to?

 

i should find a schematic.
R31 and mosfet a1020

 

Does the A1020 look like this? If so it's a normal PNP transistor.

 

yes it looks like that but its labeled Q7.

 

Hello,

The Q is for all types of transistors:
https://en.wikipedia.org/wiki/Reference_designator

Bertus

 

yes it looks like that but its labeled Q7.

Which of its pins is connected to the 7812 input?

 

the middle one

 

What voltage is on pin 1 of the transistor, the emitter?

 

l7812cv 1st to middle 0.120; third to middle 0000

the bipollar to minus of the input :
1 2 3
0.89/0.87/1.705

 

There is not enough voltage on the emitter of Q7, pin 1. So now the question is what is connected to that?

 

the middle pin of irf3205 and the same pin of the next irf3205. There are 2 heat sinks with x 4 mosfets. These 2 mosfet are from the 4 that i have tested.

thanks

just for info...
https://ibb.co/Jdbg4CZ
https://ibb.co/kgKBDsB

 

Now it's going to get impossible without a schematic.

 

Can you help me find it? you probably pay for some sites that offer schematics. i have written the device trademark and model upper in the thread.

edit

new photos from Iphone`s cam :
https://ibb.co/bJVnSBX
https://ibb.co/B2hfs1M

 

There's plenty of sites with the user manual but I didn't find a service manual or schematic.