Diagnosing / Repairing UPS KIT

Hi guys, site is going on very slow so I think we should keep threads alive...

as I have installed new kit and module, my old kit is lying in store... so I got time to test it so yesterday I connected it with battery and tested voltage at biasing points B1 & B2 but saw 0 volts on both points... No other thing was connected .. only battery + and -....
Also then I removed it from battery and connected mains 220v points to wapda and still nothing happens... only a slight spark I see when connect to mains but nothing else... no relays clicking on or off or any such thing...
I suspect when I tested kit in ups by removing biasing wires one by one then something happened with kit as it became dead at that time...
any idea what could be wrong? I want to use this kit to learn and practice so will want to revive it if any controller, octocoupler or any component is damaged... How to test? @Ijaz Ahmed, @aurangzebhaque...
Kit is "Lahore electronics D101"
Many Thanks

"If you try and take apart a cat to see how it works, the first thing have on your hands is a non working cat" :-)

[quote="nasirjavaid, post:, topic:"]
I connected it with battery and tested voltage at biasing points B1 & B2 but saw 0 volts on both points... No other thing was connected .. only battery + and -....
[/quote]

1) Even if there is something coming out at B1 and B2, it will be some kind of waveform and you may not see any voltage level.

2) There is almost always a 2-pin connector for a panel switch on such UPS kits. This switch should also be connected for the kit to function.

[quote="nasirjavaid, post:, topic:"]
Also then I removed it from battery and connected mains 220v points to wapda and still nothing happens... only a slight spark I see when connect to mains but nothing else... no relays clicking on or off or any such thing..
[/quote]

Again if switch is not connected, it will do nothing. If you connect switch and battery (without 220VAC) then you should see some waveforms on B1 and B2. During this time, if you connect 220VAC, the waveforms should disappear and charging relay should click (in some kits).

[quote="nasirjavaid, post:, topic:"]
Kit is "Lahore electronics D101"
[/quote]

They are all copy of each other.

At last my wait is over...thank you so much for detailed reply. you are right about the cat but what if cat is already dead and we dissect it ;)

I have already shorted the switch with a wire.

1- I was told that when connecting kit with battery and putting black meter probe on battery -ve and red on B1 or B2, I should see some voltage (1-3 volts).

2- as stated above I already shorted the switch.

I have not yet tried connecting battery and mains simultaneously. Should I?

When connecting main I hear no click.

Now as I investigated, I need to test diod near battery terminals on kit for short (checked and it is fine) and biasing transistors (red prob on base and black on emitter and collector for diode function- I guess??)

Any other tips are highly appreciated.

[quote=", post:, topic:"]

"If you try and take apart a cat to see how it works, the first thing have on your hands is a non working cat" :-)

[/quote]

Almost fell off the chair laughing.. :D

You can sit back now :P

[quote=“nasirjavaid, post:3, topic:21775”]

1- I was told that when connecting kit with battery and putting black meter probe on battery -ve and red on B1 or B2, I should see some voltage (1-3 volts).

[/quote]

That's true because at B1 and B2, there are pulses (whose max voltage is equal to battery voltage) and the meter shows average value of those pulses. So did you see any voltage at B1 and B2 or there is nothing at all ?

Alternatively you can measure frequency at B1 and B2 if your meter has frequency measurement. Some kits may be looking at the feedback from 220V generated by transformer (in invetrer mode) and may immediately stop generating PWM (the pulses on B1 and B2) if there is no feedback. Maybe the same is happening in your case. The feedback is necessary to adjust the PWM so that 220V can be maintained under varying load / varying battery voltage conditions.

[quote="nasirjavaid, post:3, topic:21775"]

I have not yet tried connecting battery and mains simultaneously. Should I?

When connecting main I hear no click.

[/quote]

You should first be able to get something at B1 and B2. Connecting battery and 220V I/P simultaneously wouldn't help. I think your kit needs feedback. If that is the case, you need to make the full setup including transistors, transformer and correct wiring.

[quote="nasirjavaid, post:3, topic:21775"]

Now as I investigated, I need to test diod near battery terminals on kit for short (checked and it is fine) and biasing transistors (red prob on base and black on emitter and collector for diode function- I guess??)

Any other tips are highly appreciated.

[/quote]

Look at the picture, the components in small red circles are related to power for the kit. The component on heatsink looks like a voltage regulator. Please check it's part number.Then the components in big red circle are drive circuit for external power transistors / MOSFETs which are on heatsink plates.

I would suggest you to check the part number of the main controller IC, look at the datasheet of this part and find it's VCC anf GND pins. Then attach battery to the kit and measure if this controller IC is getting it's power or not. Mostly these type of controllers are 5V devices.

[quote=", post:6, topic:21775"]

That's true because at B1 and B2, there are pulses (whose max voltage is equal to battery voltage) and the meter shows average value of those pulses. So did you see any voltage at B1 and B2 or there is nothing at all ?

I see nothing at B1 and B2 in any case.

Alternatively you can measure frequency at B1 and B2 if your meter has frequency measurement. Some kits may be looking at the feedback from 220V generated by transformer (in invetrer mode) and may immediately stop generating PWM (the pulses on B1 and B2) if there is no feedback. Maybe the same is happening in your case. The feedback is necessary to adjust the PWM so that 220V can be maintained under varying load / varying battery voltage conditions.

I have purchased UNI-T 203 clamp meter last week after my UNI-T 50 got lcd broken :( ...... it can measure Hz I think with clamp... can I use it to measure ? and how?

You should first be able to get something at B1 and B2. Connecting battery and 220V I/P simultaneously wouldn't help. I think your kit needs feedback. If that is the case, you need to make the full setup including transistors, transformer and correct wiring.

hmmm.... for that I think I will have to purchase a separate transformer as my current ups has now been shifted to IC-105 kit and 2kw module :) so don't wanna hurt him in my learning process.

Look at the picture, the components in small red circles are related to power for the kit. The component on heatsink looks like a voltage regulator. Please check it's part number.Then the components in big red circle are drive circuit for external power transistors / MOSFETs which are on heatsink plates.

I would suggest you to check the part number of the main controller IC, look at the datasheet of this part and find it's VCC anf GND pins. Then attach battery to the kit and measure if this controller IC is getting it's power or not. Mostly these type of controllers are 5V devices.

I will test as per your instructions and mention part number here also.

Thanks for your feedback, I am now learning new things about this stuff and feeling excited.

[/quote]

[quote=“nasirjavaid, post:5, topic:21775”]

You can sit back now :P

[/quote]

Hey farhan, are you back on chair now :P .......... I saw http://picse.edu.pk/ is near naqsha stop... you think it will help if I join them for ups repairing course? I m interested.

either spend time with any electrician, as his Chotaa....or you can join the course..

the art of repairing anything is the skill you have in fine soldering..if you can solder well, you can do anything in ups easily.

I would love to become chhota but that requires much time but I only have time in evening or at weekends... so looks like I will have to join the course... you UPS guy was asking for 50K for teaching ups repairing :rolleyes:

[quote=“nasirjavaid, post:7, topic:21775”]

[/quote]

Dear Ijaz,

parts numbers are as below... I will be testing the ic stuff soon for voltage at pins

YD 7805 transistor (you are right its voltage regulator)

PIC 16F54

LM 339N

Capacitor 35v 680uF

[quote=“nasirjavaid, post:10, topic:21775”]

I would love to become chhota but that requires much time but I only have time in evening or at weekends... so looks like I will have to join the course... you UPS guy was asking for 50K for teaching ups repairing :rolleyes:

[/quote]

his work is very good, his theories and concepts are purely mental.. donot listen to him..just get your works done and leave ASAP.

[quote=“farhan_ds, post:12, topic:21775”]

his work is very good, his theories and concepts are purely mental.. donot listen to him..just get your works done and leave ASAP.

[/quote]

Yeah, listened from one ear and let it go from other :P

well... he agreed to help in theory and troubleshooting for pure sake of knowledge and if I won't use this to make money... and I agreed :)

Found the cause of kit not cutting off on low battery settings. The LOW BATT trimpot is missing ground resistor as shown in figure. The moron who made kit missed this important part. :angry: ...Most probably it was the cause behind my battery damage as it drained till 8 volts many times without being noticed. :(

It can bee seen from red rectangle in the pic below.

[quote=“nasirjavaid, post:14, topic:21775”]

Found the cause of kit not cutting off on low battery settings. The LOW BATT trimpot is missing ground resistor as shown in figure. The moron who made kit missed this important part. :angry: ...Most probably it was the cause behind my battery damage as it drained till 8 volts many times without being noticed. :(

It can bee seen from red rectangle in the pic below.

[/quote]

That's a great catch. Congratulations

Thanks... learning with the help of you guys always here at WP :)