Tokyo Marui MP5 NGRS SMD identification

[mightyjebus]

Internet team assemble...

 

So I've got a broken NGRS MP5 here and it's blown a component which looks like a diode and I'm struggling to identify the numbers. If someone has better eyesight than me or has a MP5 board lying on their bench can you confirm the markings on the diode.

 

So far I've got

30aS 1913 or 1915

30eS 1913 or 1915

306S 1913 or 1915

308S 1913 or 1915

30 something else S 1913 or 1915

[Sewdhull]

That diode ( or variant thereof) is for reverse polarity protection in case you connect the battery the wrong way round. It will only work if you also have a fuse in the circuit and that fuse blows, no blown fuse and the diode blows , then the circuit dies of reverse polarity. 

 

If you remove it and connect things up correctly and the unit works then replace that diode, if you want protection again, with the highest current diode that fits in the space, smd or otherwise. If it doesnt work then your mosfet control circuitry is probs fried.

 

The 1913 is an imperial case size, .19inch by .13inch, you can measure the component to verify. The equivalent is 4833 in metric

[Sewdhull]

heres a chinese website with half decent pics, 

 

http://www.wargamehk.com/cgf/viewthread.php?tid=191848&extra=page%3D1

 

It's possible that its a TVS or zener in a dual role, but it is across the battery so its use is very limited, maybe over voltage protection for AB too

 

Looks like 308S or 30BS and the size is slightly different 19 0 something

[mightyjebus]

Cheers for the link. some good photos.

 

I managed to zoom in a bit more and it looks to be 306S 1913. It looks to me like the battery was plugged in backwards and it fired the board. I've got the broken diode, a chip on the other side is fried so badly I can't see any markings, plus the 3 mosfets are dead and it got so hot it moved their position and delaminated the board. basically it's goosed.

 

Just need to find a manual now to get the part number for the M system ECU and then start talking to some Japanese contacts to see if they are available. Thankfully it's not my AEG

 

[mightyjebus]

Anyone good at identifying SMD components? I think this is a transistor but not 100% sure if it is and what type it is. Any help would be appreciated.

[Sewdhull]

It's a zener diode mate. 25 to 2.5v

 

Likely 9v or 16v depending on what it's doing.

[mightyjebus]

buggered if I can find a 5-pin Zener. It's off the MP5 ECU and probably only needs to handle the TM 7.4v lipo so I'd imagine the 9v would work if I could find one

 

[Sewdhull]

Me too, not a zener. I've looked at the lists again, there's some voltage regs in 5 pin.

 

More than one sadly.

 

https://smd.yooneed.one/code5931.html

 

That's your y1s and whilst they are mostly zeners, there's a few regulator, detecting, etc ics in 5 pin.

I've looked at a few of them and we need to know the connections.

 

If you know which pins get volts etc you can look at the pin outs from the data sheets in alldata or some such.

 

It's likely a generic variety since there's so little info on the package.

 

Do you have that bit of the circuit written out?

[mightyjebus]

4 hours ago, Sewdhull said:

 

 

Do you have that bit of the circuit written out?

 No but I've got another MP5 here. I'll plug a battery in and see what's happening on the pin-outs of the 5 pins.

[mightyjebus]

ok, still can't identify the mystery Y1. I traced the tracks on the faulty board and below are the results.

pins 1 & 3 are chained together and end up at the programmable PIC16 IC. Pin 4 is ground and pins 2 and 5 go to the Gates on the Mosfet. I think pins 1&3 enable Y1 which puts a voltage on the mosfet gates allowing the mosfet to pass current. Basically when you pull the trigger, pin 28 goes high which tells the mosfets to fire via Y1. This also makes sense with the 3 round burst as the PIC will be programmed to stay open on pin 28 for a time duration (3 rounds worth).

 

Could Y1 be an amplifier?

[Pseudotectonic]

I guess it is a SOT-553, ROHM EMY1

 

https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/emy1t2r-e.pdf

 

(fake?): http://www.1688eric.com/product.aspx?id=360852

[mightyjebus]

weirdly I ordered some UMY1NTR's when I ordered the other blown diode replacement. I'll fit them both when they arrive and update. might be useful for other people that have a blown ECU.

[mightyjebus]

So the parts arrived and I fitted the new diode and amp and.... it still doesn't work but it's not all bad news.

 

I can connect a battery and go into dry fire mode and it happily flashes blue however as soon as I pull the trigger in either mode it turns solid red. I stripped it back down and I found that one of the mosfets has a short between source and drain. I think I missed that when checking the board. I've ordered some however it's from Aliexpress and no where else seems to have the SM4391NSKP mosfet even listed on their site.

 

When they turn up I'll replace all 3 and see what happens.

 

On another note, I found that if you get a solid red light followed by 3 quick red flashes then you have a motor issue.

[mightyjebus]

so the new Mosfets turned up and I replaced the knackered one. Still get the red light of death however I've stripped the board out again and found another 2 shorted resistors and a Cap showing open circuit. Now need to order these parts and fit them.

 

I've got to say that working on the MP5 is quite nice as it strips down really easily.

[mightyjebus]

so good news and bad news. I replaced a few more parts and managed to fix the ECU. It ran for about 1 mags worth of BB's and died again once I did a bit of rapid semi auto.

 

*EDIT*

So I stripped it down again and luckily the motor connector had come away from the motor and once reattached the MP5 is now running fine. I'll give it a run out next weekend to see if it holds up.

 

It's looking like I fixed the ECU. 

Edited March 17 by mightyjebus

[Sewdhull]

Good job