Seems ok, apart from the screen

i built up the kit today, control board and smr-4.
most of it went without a hitch, though i have to get my solder-sucker back from a friend so i can swap one mistake i made - i got two trim pots in the wrong places (R3 & R34), doh!
anyway, i tested the control board with a multimeter before attaching the screen, but once i had built the smr-4 and connected them together, the screen on the control board doesn’t show anything…
it lights up but there’s no text.
i’m getting sound, i just don’t know what i’m doing with it as i can’t see anything!
could anyone point me in some areas i should check/test please???

thanks in advance!


Try adjusting the contrast with R21 (Step 13 of the Building Instructions)

oh yes, 'should have said i’d done this - wound it counter clockwise until it clicks and then wound it back a few turns, but i don’t see anything :frowning:
thanks though!

Did you try the whole range? And; ist it a 5K Trimmer? Sorry for that stupid questions, but me, myself and I managed to put in a Cap the wrong way…

When you say it lights up, do you mean:

  • that the backlight LED is lit but the screen is dark -> contrast is too high in the negative direction
  • that the backlight LED is lit and that the first line of the screen is fully lit, but no readable text-> one of the data pins is incorrectly soldered
  • that the backlight LED is lit and that the screen is fully lit -> contrast is too low in the positive direction

Have you tried adjusting the trimmer in the other direction? Maybe it’s a bug in the assembly instructions and I mixed up CCW and CW?

ah, just tried this the other way (whilst you were posting your reply, pichenettes) and have got text!
thanks, am happy now :slight_smile:
just need to swap the trimpots round now, oh and read the instructions so i understand how it all works!
i’ll be back for more, no doubt…
mr sync24

Ah, i See the Instructions state at Step 4.2 “You can mount it in either orientations.”. Shown is Screw to the back, so if you turn it the other way you have to change CCW with CW?? Will have to think about that after my 2nd coffe…