AMC 7135 driver QUESTION!!

[Fiddy]

also how are you measuring the current? testload? how many diodes?

 

[grainde]

Ok here are the photos! Dont laugh!:crackup: As I mentioned all the respective pins on all the 7135 chips are connected and there are no short circuits between the pins!

I just tested using Jufrans test load on pin no. 3 with a Panasonic 18650 (NCR18650A)...

 

[Fiddy]

wow man how much heat did you use?

I know you said it was messy but DAMMM! you might need some practice on these.

Heres a query for you, if you remove the one you added, does the current stay the same? if it does then you have to options, the AMC chip you added is dead, or (unlikely) the traces to that 4th AMC chip position arnt connected or open circuit.

So try another chip if you have 1?

 

[grainde]

Well the first time I put the chip on, the solder was already on the board and I literally touched it on with the iron. Trying to remove it required a fair bit of heat and the 2nd chip I had, already had a dollop of solder on it which didnt want to melt...So yeah a fair bit of heat...How sensitive are the chips? Anyway the first chip I put on was quick and still had the same problem?:thinking:

I think it should be connected, because when I try pin 1 on either the 4th, 3rd or 2nd chip it is connected to pin 1 on the 1st chip. Same with all the other pins?

I already removed a chip twice the current stays at 1050 mA but I can try to get it off again, though Im sure it will stay the same...

The chips I was adding came from another board, so maybe I used too much heat removing them in the first place?:thinking:

Yup will do! Blord very kindly sent me another couple of boards to kil.. erm play with... :beer:

 

[grainde]

Ok is there any way to test the AMC chips I remove from the old board, .ie to see whether they are still working after removal, before I solder them onto the new board? Cheers

Edit: @ Fiddy took the old chip off and current still at 1050 mA. :beer:

 

[justinjja]

Test the resistance between the new chip and one of the old chips on each coresponding pin.
Are they all less than 1ohm?

yes = dead chip
fix by getting a new chip

no = bad solder join or bad pcb
fix by soldering better or connecting a wire between the pins on the new chip and old chip with a small wire


Also, Do you have access to a heat gun?

 

[grainde]

Hey Justinjja chips seem ok; measured resistance on the board though. They were all identical, original untouched and newly added one. Solder joints ok; tested. PCB ok, cos Blord did the same mod with this board. Tried connecting wire...still no good.:gun:

Have now connected and reconnected the 2 new boards from Blord ~5 times and have had the exact same result each time, with the exception of one, where the current went to 1.33 A for a moment, then went back to 1050 mA. I guess you cant solder the chips as Im guessing they are too sensitive to heat. I guess Blord used reflow...and no I dont have a heat gun.

:wtf::tired:

 

[Blord]

I use an ordinary solder iron. Do you have a fine tip for such delicate job ?
You need to make sure every pin is get flowed with tin. I think you have a cold solder point somewhere.

Are you still using your boards ? I have sent you two drivers just in case.

 

[grainde]

Hey Blord I was trying with your boards both of them! :cryyy: I even gently cut the chips from the old board with a very sharp scalpel to avoid heating them too much in the removal step..Yes I have a very fine tip and i did make sure every pin was properly wetted...All electrical contacts are good.

Maybe I need to shift the negative LD out to a different position on the board?? :thinking:

 

[Blord]

Did you omit the Atmel chip ? I have soldered the fourth ic on the board and omit the Atmel chip and I get 1400mA out of it.

 

[grainde]

Anyone know how to test a bare 7135 chip, not attached to the board, so I can remove them and test to see if they are damaged? Ie Does anyone have precise values for the resistance between different pins or a simple test I could perform to check the bare chip? Cheers

 

[grainde]

Did you omit the Atmel chip ? I have soldered the fourth ic on the board and omit the Atmel chip and I get 1400mA out of it.

Missed your post! I tried that before with my old boards and it didnt work, but Ill try again with your boards and check. :beer:

Edit: Interesting I get 1.245 mA! Not quite 1.4 A but its seems to be moving in the right direction! Any ideas why or suggestions how to get to 1.4A? cheers :beer:

Edit 2: Ok just removed the wire bridge and the current is at 1.3 A and have the modes!! Maybe it was something to do with the chip?? Very odd??

 

[Fiddy]

use this to test:

 

[grainde]

Cool thanks will give it a try.

Im currently trying to diagnose why the driver set at 1.4 A and putting out 1.3 A (although it seemed to climb a little approx 1 mA per sec to around 1.4 A) killed my mits 500 the moment I switched it on..bright flash then nothing.. All connections were good no shorts but it still killed my diode. :gun:

Edit: Here are some photos of the modified driver that killed the diode along with a couple of pics of the diode...

 

[BShanahan14rulz]

Looks like it took too much current and poof'd the bond wires :-( Generally speaking, that's a dead one now, although there was a member here who offered to attempt to repair diodes with broken bond wires.

 

[grainde]

Yeah JLSE was offering some repairs if I remember? Anyway Im thinking of trying to reconnect them under a microscope and the tiniest dab of solder possible. Maybe Ill get lucky...:can:

Edit: If anyone could shed some light on what went wrong, that would be fantastic! :beer: