Was the board tested before you did the swap? It’s possible you have a bad or mis programmed mcu. I’ve fried a few boards myself without understanding how or why. Keep trying and keep looking up threads that date from around this time as this was discussed for a few months.
Yes, this was a new “generic” NANJG 8x7135 from FT (this is the one with the mode groups via clicking in low mode) and I tested it before removing the 7135s.
One problem is the pics in the original (comfy’s) NANJG-92 thread OP are gone. Plus I’m still confused about something: Even though the pics are gone, I followed that original thread, and I could have sworn that the original mod had the 3 pin FET upside down and the 70n02/3 and AOD510 FETs were mentioned in the thread, so it seems like the AOD510 like I have should be mounted upside down.
Jim
EDIT: The other thing that makes it hard to check/remember is that the link to the FET in the OP of that thread is no longer existing also :(…
EDIT 2: Can someone who has this working post some pics, especially showing which cap to remove and where to put the cap?
I’ve spent the morning going back in time and found This post by WarHawk-AVG (post 44) that mentions it. I’ll look some more to see if I can find some other info. I’d suggest you google the different fets and compare gate pin locations, that’s what determines FET orientation.
Ohaya, do you recall This post or wight’s response ? A bit earlier in the thread he also mentioned that he thought it possible that a higher value cap should be used to absorb the spike but basically if it ain’t Atmel, it ain’t cookin’.
Hi,
Here’s some pics of my testing board.
Showing the top, AOD510 soldered to other 7135 position because pulled pad off other position:
Top view (you can see the missing solder pad):
Bottom view:
No, I don’t remember that post specifically - wish I had done this back then when comfy and wight were around :(…
Re. Atmel, do you mean that if the MCU isn’t Atmel that this FET conversion won’t work? I have to check that. As I said, the board I’m using is one of the “generic NANJG” drivers from FT. I was hoping to use that because it does mode switching by clicking rather than using the stars.
EDIT: That post you mentioned was about whether the MCU from a NANJG could be used on the BLFDD board, rather than about NANJG-92.
EDIT 2: One of the things that is really bothering me is why when I scope the FET pins, I get no (or constant) signal? In other words, it’s like the MCU is not working. Either that, or there’s a short to something like +V that I’m not finding
If the FET is This one then your hook up looks right. I don’t know why a different mcu should make a difference except in not being able to reflash it but WTHDIK. It may be that the different mcu is unable to charge the gate on the FET or it may be fried. To test that you could reinstall a 7135 to check it. On boards where I killed 7135’s the mcu was still able to drive the led in different modes but all were variations of moon.
Is the white wire soldered only to the ground ring or is there a via under the tip of it that connects to the led- trace?
Was just about to reinstall 7135. If that works I’ll try w a different type of nanjg, from illumn.
I think the conversion should work but not if you switch the mcu to a different board with different I/O hook ups and you wouldn’t be able to reprogram it.
Lots of members I miss too, those and others.
Hard to tell from the pic but to me it looks like the white wire might be soldered to both gnd and led- which would bypass the FET and lock it in DD.
It is another driver than the 105C, but with the AK-47 I have an original NANJG version that uses a different Attiny pin for the 7135gate than a generic version sold by Banggood. So the lay-out is not always preserved.
Perhaps a bit useful, here's a stereo picture and a stereo gif that I posted in comfy's thread, they are still there, these are the original 105C board an Vishay FET from the OP of comfy's thread:
RBD, djozz,
If I remove the FET and solder one of the 7135 in, and move the emitter - wire to the normal place on the driver, I get modes.
If I remove the 7135 (again) and solder in FET, and move the emitter - wire to the FET tab, I get no modes.
The white wire is only there to make it easy for me to test, i.e., I hook the - of my bench supply to that white wire and the + from my bench supply to the spring to test. It’s only soldered to the ground ring on the battery side of the driver board (I’ll double check but that was my intention)…
EDIT: I think that I’m concluding that the boards I have don’t work with FETs. The MCU has no markings so I can’t tell if it’s an Atmel.
Hah! So the original mod DID use a 3-pin FET (looking at your images), right? Now I know I’m not going crazy!
But, do you know which FET was used, because in the original the FET was positioned with the ground tab on top (upside down) so I think the Gate pin for whatever FET was used must be the opposite side/end from the AOD510?
That sounds indeed like this FETdoes not work well with the 105C gate-signal, in other words: that goes way beyond my expertise. Rufusbduck, RMM or dthoang know more about FET's.
The original FET wax referred to as Vishay 70N02 . Here's a picture of it right side up, by RMM:
Btw, the middle tab sticking out afaik is also the drain, directly connected to the big tab on the other side.
@ ohaya;
I have successfully swapped out the 7135's for a 70N02 fet on the generic FT board, so I know it will work, at least with that fet.
In fact, I think it was the first fet mod I did back when this was being pioneered by ComfyChair.
It's hard to tell from your photo - do you still have the diode there (hidden by the positive lead)?
Hi,
All I did was remove the 8 7135s, solder in the FET, then move the black wire to the tab of the FET. I remember there was some add’l steps, I think about moving a capacitor, but whas a diode suppose to be moved also? Would not moving those cause the thing not to work with the FET?
Yes, the diode has to be there - I just couldn't see it in your pictures.
What you have done should work, as long as nothing is broken, & it plays nice with that particular fet.
The cap mod was specifically for the feedback/voltage spike that was causing the attiny to reset, but your not dealing with the attiny on the FT generic board, so who knows if it'd good/bad/necessary?
FmC,
The driver I have is FT part#1127403. Is yours the same?