NR90GC Nail Gun controller board repair

[pintglass]

I am in the process of trying to repair a controller board for a Hitachi NR90GC nail gun. The gun has no mechanical reason why it won't work. So I am assuming there's an issue with the PCB.

I've draw a schematic of the pcb by tracing/probing around the board to help try and find out why its not working.

Firstly can you just have a look at the schematic to check if I have made any obvious mistakes.

Secondly can you give me a clue as to what the main IC (U1) could be, as the IC only has the marking of the model number of the nail gun on it. Could it be a custom Chip? There's a few other components that I can't find info on but I can manage without that for now.

Thanks in advance

[petehall347]

c10 c11 dont look too clever

[stj]

the trackside looks like it got wet
why the hell does a nailgun need a microcontroller?

[lotas]

Most likely a re-marked microcontroller (it has internal firmware), its power supply is 3.3v per 1 pin. for 7 pins. - reset.

[sam_sam_sam]

Originally Posted by stj

why the hell does a nailgun need a microcontroller?

Because it needs to know when the nail has left the gun’s guide so it does not jam would be my guess and maybe to know if the tool is jammed so it cuts power to the motor

The battery operated rivet gun that I has a micro controller in it as well because it controls the amount of torque that it sends to the jaws of the tool and tracks the travel of the rod

[stj]

well they are dumb shits because crystals and resonators dont like shocks - like you get with a solenoid hammer mechanism.

check the resonator is resonating.
(and check the soldering on it)

[pintglass]

Originally Posted by sam_sam_sam

Because it needs to know when the nail has left the gun’s guide so it does not jam would be my guess and maybe to know if the tool is jammed so it cuts power to the motor

The battery operated rivet gun that I has a micro controller in it as well because it controls the amount of torque that it sends to the jaws of the tool and tracks the travel of the rod

The nail gun doesn't have any means to sense a nail jam the only sense it has is that the firing mechanism is fully depressed so it knows its pressed against a piece of timber before it fires. Usually if there's a jam the firing mechanism will not depress.
When I've been testing it just this doesn't seem to be working though as the controller seems to fire without sw2 being grounded.

Originally Posted by stj

well they are dumb shits because crystals and resonators dont like shocks - like you get with a solenoid hammer mechanism.

check the resonator is resonating.
(and check the soldering on it)

I will test this but the whole board was encapsulated in some kind of silicone/coating that's why it possible looks like its got wet, but that's impossible due to it having the coating until I scrapped it all of.

[stj]

i noticed the rubber

[Sheppma]

looks like quite a bit of corrosion as well as the damaged chip capacitor, i would give it a thorough clean and try then , you might be lucky

[lotas]

This is not corrosion, the board was coated with silicone sealant.

[pintglass]

Originally Posted by stj

i noticed the rubber

Do you know what it is they use, I was thinking of using silicone to reseal but have read silicone can be acidic so may cause corrosion.

Originally Posted by lotas

Most likely a re-marked microcontroller (it has internal firmware), its power supply is 3.3v per 1 pin. for 7 pins. - reset.

I've drawn a blank trying to find any info on this IC, no micro controllers seem to have VCC on pin 1 and GND on pin 2.

[stj]

Originally Posted by pintglass

Do you know what it is they use, I was thinking of using silicone to reseal but have read silicone can be acidic so may cause corrosion.

i use this:
https://www.ebay.co.uk/itm/125281546908
the 705 one

[redwire]

You can see this uses high voltage capacitive discharge to the gun solenoid.
There is a DC-DC converter, SCR, and HV big film cap. Careful not to get zapped.
I would see if it's first generating HV to charge the cap.

[R_J]

Does it have any sighs of life? are any of the led's lit? does the exhaust fan ever run. Is the fuel cell installed properly.
I have worked on the paslode nail guns and only had to replace broken pistons due to nails hitting something solid and breaking the piston shaft.

[pintglass]

To be honest after some testing I don't think there's anything wrong with the controller board. I originally pulled it all apart as the fan wouldn't run, which caused the board to error.

When I've been testing the board I've had it powered with my bench top power supply and it seems to work fine, the fan runs ok and I get a spark. So I think the issue is that the battery's are shot.
They do seem to charge up ok and do hold a charge, could it be that they can't provide enough power to start the fan.

I'm going to make up a new battery to test when I get chance.