News:

Forum may be experiencing issues.

Main Menu

Harbinger 2 lamp not pulsing

Started by wstimson, September 16, 2019, 05:38:09 PM

Previous topic - Next topic

wstimson

I put together a Harbinger two, and everything is working right except that the lamp is always on instead of pulsing.  If you manually cover and uncover the LDRs it sounds awesome.  :)  The voltages all look pretty close except for Q12, which has the correct value for C, but B and E are way low (like around 1v each).  So I suspect that is the culprit, but I don't have any more MPSA13s here to swap with... so while I'm ordering more of those I thought I'd see if anyone else has any suggestions.  I also triple checked the values of the caps and resistors in that part of the schematic and they are all correct. However, C20 and C21 I had to use some older 1uF caps that I "reclaimed" from another board, since I was also out of those... so I'll be replacing those as well if swapping out Q12 doesn't end up fixing it.  Any other ideas or suggestions for what to look at would be welcomed.

Thanks!

wstimson

Well, I replaced the MPSA13 and no change in the voltage.  I tried a different speed pot, and replaced the 1uF caps (C19, 20, and 21) and no change.  The voltages on the other transistors look correct, so the last thing I can think of is that I managed to damage the NSL-32s.  I don't have any others to try, so I ordered another pair from smallbear.  Should be here this week and we'll see if that fixes it.  In the meantime if anyone has any other ideas, I'm all ears.  :-)

Thanks!