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BLM software or hardware bug

9 posts in this topic

I have a strange issue with my newly built BLM:
When I start the SEQV4 and select all 16 steps in the selected Track (G1T1), then switch to the length layer and then to the velocity layer the BLM stalls with the "pattern" showed on the picture.
I have to unplug it to fix it.
Besides that everything works as supposed. In test mode I can lit all led at once.  I have the PICF184685 so I suppose the brown out reset is not the issue and I run the newest firmware (project_with_4_mapped_ains)
Before I put everything in the case I want to be sure it's not a hardware bug.

Any ideas what my problem is?

Thanks Michael

 

IMG_2600.JPG

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Can you measure the main power rail voltage in this state? E.g. using the J3 jumper? Just on the weekend I was happily switching between layers (you should get a kind of VU meter display).

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No problem on my unit replicating your test conditions. I have a 2A PSU for the SEQ, adafruit Verter regulator inline inside the case, Schottky diodes piggybacked and 8 mapped AIN, with unused AINs jumpered. 

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Everything works fine as long as I don't activate more than 10 steps (and not choosing too many at the boarder eg. steps 1,2,3 or 14,15,16) and I get the "VU meter display".

Like that the voltage drops down to 4.4v

if i lit all 16 steps it stalls with 4.25v

just checked my PSU: it's a cheap cellphone usb adapter with 1A. :blush: too little?

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sounds like too little! :)

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ok my bad. at least it's easy to fix!

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One trick might be to disconnect the SEQ's LCDs to do the test, perhaps that way you can determine if the PSU is strong enough or if the problem is present on the BLM side with the low voltage.

Can you mention if you have Schottkys installed?

The way I have connected my PSU (old F1 Core) is to remove the 5V linear Vreg and insert SPSU 0V on pin 2 and +5V on pin 3. 

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I just powered my SEQ with my Lab PSU and everything works perfect!
thanks and sorry for the noise. still in the early beginning with electronics....


I haven't yet soldered the Schottkys. My transistors are soldered with very little tin and I still haven't found a neat way to bridge the gap.
Is it possible to bend down the pins of the Schottkys or will they break easily?

 

 

 

 

 

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Great to hear it's solved!

I was just wondering if the transistors switch off faster (which they should using Schottkys) if the current draw and thus +5V rail drop is less. I would check to see if the slight ghosting annoys you before undertaking this. I remember that the legs of my Schottkys were a bit too short to bend; perhaps a clipped resistor leg could help (carefully trimmed shorter after soldering)? But in my build I just loaded on the solder until a suitable blob formed.

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