R18 and IC6 output

[Coe42]

I have a question regarding R18. I read somewhere (old post) that the two middle pins of R18 need to be shorted. Does it still apply to SMT boards? I'm having problems with the output of IC6 (-3.6V) and R18 does nothing (I have shorted the pins). I have the correct values at pins 4 and 7. I checked the diodes and they are correct. I don't know what else to check or do. Also, what should I get at TP3?

Thank you!

David

[Carl-NC]

No, don't short R18. Short R19 and see if the output goes positive. TP3 should be 0V.

[Coe42]

Hi Carl, thank you for your answer, it's good to know somebody is there to help! I'm not home so I cannot do anything right now but from last night, I have 22 mV at TP3, I cut the R18 short without any results, and for R19 I have a 100K resistor. In the parts list there are two R19, one 1M and one 100K. I assumed that the right one was 100K. I'll try this evening shorting R19 and see what I have at TP4. I'll post it later.

Thanks again!

David

[Coe42]

Hi Carl, I shorted R19 and now I can adjust the output of IC6 with R18 from 0.2 to 4.3V (positive this time) but I cannot go lower than 0.2V. Should I leave R19 out? Is 0.2V ok?

Thank you!

[Carl-NC]

100k makes it too low, 0 makes it too high. Somewhere in between will get it right. Try 47k.

[Coe42]

Thanks again Carl, I believe I could have figured it out myself... sorry. I didn't have a 47K so I used a 56K instead and now I can adjust from -0.8 to 2.7V. I think is good enough... Thank you again, I'll go to the next step and hopefully I will be finding metals by the end of this long weekend (if snow melts!!)

I'll keep posting!