BLF SRK FET Board discussion thread

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JohnnyMac
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BLF SRK FET Board discussion thread

I am SOOO frustrated right now and discouraged.  I ordered a couple of the BLF SRK FET drivers from Mtn ELectronics.  One for a Terminator mod and a second for a future SRK mod.

Last night I was working on the Terminator mod figuring it should be straight forward.  Man was I wrong.  Anyway, I removed the original driver, fit the new one by trimming a hair off the tabs, soldered the LED- wires to the LED- pads on the driver.  Soldered the LED+ wires to the LED+ pads on the driver.  Tested the 4 wires for the electronic switch and confirmed which two are for the switch momentary and which provide power for the green and red LEDs.  After double checking the switch leads with a continuity test on my DMM, I soldered those two wires to the switch pads on the new driver.  Should be good now, no?

NOPE!  I have nothing!  Nada! Zip! Zilch!  What am I missing here, folks?  Has anyone else had any issue with this?  Is there something else that needs to be done with the driver that I'm not aware of?  THe negative conatact ring should go through to the inner negative pads and traces.  Same with the positive center pad.  I'm about to completely give up on modding any of this crap, that's how frustrated I am. Yell

Edited by: JohnnyMac on 06/24/2014 - 13:35
comfychair
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Did you bridge the SW+ pad to the appropriate pad? Should be 'P2' (MCU pin #2 correlates to the old Nanjg's star #4) as shown in the pic for that firmware.

http://75.65.123.78/driverhacks/srk-dd-detail.jpg

JohnnyMac
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comfychair wrote:

Did you bridge the SW+ pad to the appropriate pad? Should be 'P2' (MCU pin #2 correlates to the old Nanjg's star #4) as shown in the pic for that firmware.

http://75.65.123.78/driverhacks/srk-dd-detail.jpg

Thanks, Comfy!  I had no clue that that was to be done.  I think Richard should post a link to a simple tutorial or instruction on the proper connections.  I had a similar issue with my Convoy S2 mod using the 17mm FET driver.  I had no moon low and after writing to me he told me there is a bug and the one leg of the Tiny13 needs to be soldered to the ground ring.  Stuff like that should be on the page.

Anyway, what is the difference between p2 & p3 pads?  Also, since the switch is simply a momentary connection I don't think there is a positive and a negative to it.  Does it really matter?  I did swap the switch wires when I was trying to figure out the lack of light last night but since I didn't bridge to  P2 it didn't make a difference.

comfychair
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The firmware can be written to use any of the 3 pins that the old Nanjg used for the stars. Most code writers use pin #2/star #4, but some use pin #3/star #3. If you got it from RMM it'll need to go to P2.

No, polarity doesn't matter, all the switch does is connect the trace going to the MCU to ground when pressed.

Easiest way I found to deal with the tiny little jumper pad is to just strip one of the wires a bit longer so it can be laid across both the main SW+ pad and the jumper at the same time. It's no fun trying to use a separate piece of wire to bridge it. I have a request in to have the boards updated with two completely separate SW+ pads, one for each MCU pin, and then you'd just attach the switch wire to whichever pad went to whichever pin you needed.

http://75.65.123.78/blf-srk/switch1.jpg

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Oh, another thing to check...

The OSHpark boards are thinner than every other SRK board I have seen, so it might be pressed too far into the head and not making contact between the battery tube and the driver's ground ring. I add 4 lumps of solder on the topside and file them down to the same thickness as the original SRK boards.

http://75.65.123.78/blf-srk/Dsc07619.jpg

leaftye
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Fwiw, I'm looking at a SRK board from Richard with P3 bridged.  I haven't tested it yet though.

 

Is that E07 one of those new SMD capacitors?  I was wanting to try those instead of an aluminum electrolytic canister capacitor.  It'd just be for aesthetics, although I've read that they're supposed to last much longer...which is meaningly in my lights since they'll be retired or upgraded long before a capacitor dries up.

The low mode should be lower.

Reviews: Efan IMR18350 700mAh 10.5A, <a href="http://

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Nope, 5A/40V schottky diode, only required when using the inductor to get nicer low modes. Flyback diode, freewheeling diode? Whatever it is. I mostly just know how to copy other stuff that seems to work, anything other than that I come up with is most likely due to the Blind Squirrel Syndrome.

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comfychair wrote:

Oh, another thing to check...

The OSHpark boards are thinner than every other SRK board I have seen, so it might be pressed too far into the head and not making contact between the battery tube and the driver's ground ring. I add 4 lumps of solder on the topside and file them down to the same thickness as the original SRK boards.

http://75.65.123.78/blf-srk/Dsc07619.jpg

Thanks for all the assistance, Comfy! Smile

Yeah, I found that the driver board is a tad too small in diameter for the Terminator vs the SRK.  I soldered tinned copper wire to the top edge of the PCB then filed then down to an even height and also so the driver fits snug in the head without any gap.  At one point I thought maybe the gap was causing the exposed edge of the battery tube form contacting the ground ring on the driver.  After soldering this was not the case but now I know it's because of the switch P2 pad.  You da man!!

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Damnit!  No good, Comfy. Sad  I soldered that P2 bad to the main switch pad and nothing.  Checked continuity from the two and all is good.  Tried the P3 pad instead...nothing! Switched it back to the P2 and tested continuity.  Good.  P3 no continuity. Good.  Checked the board thickness to make sure my soldering on the edge of the ground ring was thick enough to reach the battery tube.  Even thicker...check.

Next I popped a 14500 into a cell holder and connected the leads to the LED leads to make sure the polarity is good and the LEDs work.  Check.  They light up beautifully.  Something in the driver is not working properly.  Current isn't getting from the contacts on the driver to the LED contact pads.  I took a pic in it;s current state hoping you might see something off about it.  Any thoughts would be appreciated.  Right-click the image and open in new tab to see the full size.

Werner
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Are the positive led wires connected to battery+?

leaftye
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Why doesn't yours have a capacitor?   I don't think that would stop it from lighting up at all though.  Maybe a bad solder?  I'd try holding down the chips while testing.

The low mode should be lower.

Reviews: Efan IMR18350 700mAh 10.5A, <a href="http://

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Werner wrote:
Are the positive led wires connected to battery+?
That Batt+ pad on the LED side is connected to the anode pad on the cell side.  The LED+ pads should be as well.  I wonder if I need to connect a wire from the Batt+ pad to the L1 pad? I was wondering what that Batt+ pad was there for.  There needs to be some decent instructions to go with these things.  For complete drivers they are missing a lot of important details that someone who wasn't a member here wouldn't begin to know how to figure out.
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Yes if not using an inducer you need to jumper it, use something large like a piece of braid or a larger piece of single strand AC wire (like romex).

 

Always remember SPC Joey Riley, KIA 11/24/14.

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Is there anything similar you have to do with the other RMM SRK driver? I can’t get mine to work either. Or is it just solder and play (so to speak)?

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It’s labeled to have an inductor there. If you don’t use the inductor it needs to be bridged. There are a few threads going up with separate discussions of each board and where they exist I add links to them. Much development and discussion goes on in the Oshpark projects thread where it gets lost in the noise. I have mentioned before the need to have separate discussion threads for each board(or at least each family of boards) and that is being done slowly but these are all new enough that that hasn’t been done for all of them. I’m sure Rich will do what he can to add info on his site as well so thanks for pointing this out.

Now that Werner has found your answer if you would like to retitle this thread it could become the needed discussion thread for the SRK FET board.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

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Cereal_killer wrote:
Yes if not using an inducer you need to jumper it, use something large like a piece of braid or a larger piece of single strand AC wire (like romex).
Ok...so to be clear, I need to jumper the Batt+ pad to the L1 pad?

Rufusbduck wrote:
Now that Werner has found your answer if you would like to retitle this thread it could become the needed discussion thread for the SRK FET board.I'd be happy to.  What would be the best title for it?

Oh!  Thanks for all the help guys!!  I will let you know tonight if it works finally. Cool

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JohnnyMac wrote:
Ok…so to be clear, I need to jumper the Batt+ pad to the L1 pad

Yes the two pads that look like T’s laid on their sides facing each other., that will get you going.

 

Always remember SPC Joey Riley, KIA 11/24/14.

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Yes, BAT and LED+ must be connected with something, either a jumper or an inductor. Big schottky diode at D2 is not needed if not using an inductor.

with inductor:

http://75.65.123.78/blf-srk/Dsc07617.jpg

without inductor: (ignore wires going off to bottom left, those are for bench testing only, removed before installation)

http://75.65.123.78/blf-srk/Dsc07592.jpg

If Richard is selling these as 'assembled' and complete ready-to-run, they should also really have that jumper installed as well. (For some reason he's against using the inductor/diode parts, I don't understand his reasoning for not using them and he doesn't understand my reasoning for them, I can only tell you I use them because they give a much nicer low end and allow lower sub-1-lumen lows even with reasonable minimum PWM values.)

 

The big electrolytic cap is no longer needed, that was to patch the issue of whiny noise when using older versions of firmware, no longer needed when using the silent fast-PWM firmwares.

leaftye
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Does that reduce maximum output?  He's mentioned a mod that would allow much lower lows.  

The low mode should be lower.

Reviews: Efan IMR18350 700mAh 10.5A, <a href="http://

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Reduction in max output depends on which inductor you pick, both the DC current rating and the inductance rating. Comparing ~15A-rated 0.58uH inductor to a ~15A-rated 1.2Uh inductor, the 0.56 will have less damping effect on the lowest modes but also the least impact on the straight DC 100% mode. The 1.2uH will give a lower low but with slightly less output on 100% mode. But it's in the range of a few milliohms. With a ~4mOhm Rds(on) FET you can afford to sacrifice a little at the top end and not see a big hit in total output.

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comfychair wrote:

Yes, BAT and LED+ must be connected with something, either a jumper or an inductor. Big schottky diode at D2 is not needed if not using an inductor.

with inductor:

http://75.65.123.78/blf-srk/Dsc07617.jpg

without inductor: (ignore wires going off to bottom left, those are for bench testing only, removed before installation)

http://75.65.123.78/blf-srk/Dsc07592.jpg

If Richard is selling these as 'assembled' and complete ready-to-run, they should also really have that jumper installed as well. (For some reason he's against using the inductor/diode parts, I don't understand his reasoning for not using them and he doesn't understand my reasoning for them, I can only tell you I use them because they give a much nicer low end and allow lower sub-1-lumen lows even with reasonable minimum PWM values.)

 

The big electrolytic cap is no longer needed, that was to patch the issue of whiny noise when using older versions of firmware, no longer needed when using the silent fast-PWM firmwares.

I don't know if you know just how relieved to have this finally working!  I was about to completely give up on my modding skills and be so discouraged that I stop again for a while.  I can't WAIT to see some impressive results for once!

On a side note, I tried modding my TR-S700 with a couple of the FETs Richard sells (it's a FET driver to start with) hoping they would allow more current to the emitters but I only gained just under 200 lumens.  Still only 3745 OTF with 7 LEDs and 3*26650.  Not at all what I was hoping to see. Sad

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http://www.digikey.com/product-detail/en/ETQ-P6F0R6BFA/PCD1393CT-ND/308387 or http://www.digikey.com/product-detail/en/ETQ-P6F1R2HFA/PCD1307CT-ND/281422, I found both on ebay for much cheaper. Anything with similar specs will do the same job, and we tried to lay out the inductor pads on the board to be compatible with just about anything in that size range regardless of manufacturer. Lots of stuff out there that will work.

This is the diode needed at D2 if using the inductor - http://www.digikey.com/product-detail/en/MBRS540T3G/MBRS540T3GOSCT-ND/91... - or, again, something of similar specs. It just needs to be able to shunt the leftovers stored in the inductor when the FET is turned off via PWM in the less-than-100% modes.

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JohnnyMac wrote:

On a side note, I tried modding my TR-S700 with a couple of the FETs Richard sells (it's a FET driver to start with) hoping they would allow more current to the emitters but I only gained just under 200 lumens.  Still only 3745 OTF with 7 LEDs and 3*26650.  Not at all what I was hoping to see. Sad

Multi-cell buck or boost drivers don't rely on the ultra-low resistance FETs anything like a single cell direct drive driver does. Multi-cell stuff has enough voltage overhead that a high resistance FET is easily compensated for.

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comfychair wrote:

JohnnyMac wrote:

On a side note, I tried modding my TR-S700 with a couple of the FETs Richard sells (it's a FET driver to start with) hoping they would allow more current to the emitters but I only gained just under 200 lumens.  Still only 3745 OTF with 7 LEDs and 3*26650.  Not at all what I was hoping to see. Sad

Multi-cell buck or boost drivers don't rely on the ultra-low resistance FETs anything like a single cell direct drive driver does. Multi-cell stuff has enough voltage overhead that a high resistance FET is easily compensated for.

Same voltage as an SRK as they are parallel cells.
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Thanks.  That's what I needed to know to build one of my SRK's.  I had been wondering why the C+ pad was so big.  Now it makes sense.  It needs to be able to handle different things.  I'll place an order on Digikey tonight.  

The low mode should be lower.

Reviews: Efan IMR18350 700mAh 10.5A, <a href="http://

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JohnnyMac wrote:

comfychair wrote:

JohnnyMac wrote:

On a side note, I tried modding my TR-S700 with a couple of the FETs Richard sells (it's a FET driver to start with) hoping they would allow more current to the emitters but I only gained just under 200 lumens.  Still only 3745 OTF with 7 LEDs and 3*26650.  Not at all what I was hoping to see. Sad

Multi-cell buck or boost drivers don't rely on the ultra-low resistance FETs anything like a single cell direct drive driver does. Multi-cell stuff has enough voltage overhead that a high resistance FET is easily compensated for.

Same voltage as an SRK as they are parallel cells.

How are the LEDs wired? Got any pics of the driver innards?

JohnnyMac
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comfychair wrote:

JohnnyMac wrote:

comfychair wrote:

JohnnyMac wrote:

On a side note, I tried modding my TR-S700 with a couple of the FETs Richard sells (it's a FET driver to start with) hoping they would allow more current to the emitters but I only gained just under 200 lumens.  Still only 3745 OTF with 7 LEDs and 3*26650.  Not at all what I was hoping to see. Sad

Multi-cell buck or boost drivers don't rely on the ultra-low resistance FETs anything like a single cell direct drive driver does. Multi-cell stuff has enough voltage overhead that a high resistance FET is easily compensated for.

Same voltage as an SRK as they are parallel cells.

How are the LEDs wired? Got any pics of the driver innards?

The emitters are wired in parallel.  Here is a pic of the emitters on the sink:

Here is the driver.  At the time of the pic I'd already upgraded the LED wiring and bridged the sense resistor pads but IIRC they were always empty but don't hold me to that.  Since the pic I've replaced the two FETS with two 70N02 FETS.  Marginal gains with either mod.

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Thanks Johnny, the link is in.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

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Cereal_killer wrote:
Yes if not using an inducer you need to jumper it, use something large like a piece of braid or a larger piece of single strand AC wire (like romex).
Yup, just saw that in the picture…no inductor, jumper the pads
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Ebay seller 'rfextra' has lots of goodies, if you don't need a large enough quantity to get the price breaks from Digikey or Mouser. The big diodes are fairly cheap at retail in small numbers, the inductors are not.

IRF 60V/3A Schottky Rectifier 30BQ060TR,SMC,Qty.50 - $6.99
http://www.ebay.com/itm/150201700078

Coilcraft 1.2uH 12.3A Power Inductor MLC1260-122MLC, RoHS, Qty.10pcs - $6.99
http://www.ebay.com/itm/181286346884

Coilcraft 0.8uH 12.4A Power Inductor MLC1250-801MLC, Qty. 10pcs - $6.99
http://www.ebay.com/itm/160974587402

Coilcraft 0.68uH 12A Power Inductor DO3316P-681HC, Qty. 10pcs - $5.99
http://www.ebay.com/itm/160664715456

Panasonic 1.2uH 14.2A Power Inductor ETQP6F1R2HFA. Qty. 5pcs - $4.99
http://www.ebay.com/itm/400433611169

Panasonic 0.58uH 19A Power Inductor ETQP6F0R6BFA, RoHS. Qty. 5pcs - $4.99
http://www.ebay.com/itm/400257620168

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OK. I'm about to flip my shit! Soldered the pads and still nothing.  Examined all the soldering points on the chips and they appear to be OK. Checked switch continuity yet again and it beeps when I press the button. What the hell is going on here???  Apply power directly to the LED pads and it lights up. Has anyone ever got a defective board from RMM? I'm at my wits end with this issue. Yell

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