MAP Adjuster Build Issues

[NelsonATC]

I am building a MAP adjuster according to Dino's instructions, and am having issues. It will only let me fluctuate voltage between 7.8 and 8.1. I originally thought the trim pot was bad, but I replaced it with the same issue. Then I swapped out the voltage adjuster, still the same. The resistor checks out, so now I'm at a loss to figure out the issue. Has anyone else had this issue while building a MAP adjuster, and if so, what fixed it?

Thanks!

Mike

[Cheromaniac]

Sounds like something's wrong with the way you've built your MAP adjuster. Check it against my schematic:



If you elected not to wire an SPDT toggle switch into your system, here's what the schematic should look like:

[NelsonATC]

Matches perfectly. Still not working

[jbxx]

What value trim pot ( 1K ohm ), and what # regulator ( LM317)?
Make sure you get in, out, and grd. correct compare to data sheet. Not much else can go wrong.
J.B.
LM317 datasheet:
http://www.ee.buffalo.edu/courses/elab/LM117.pdf

[jbxx]

Picture of completed circuit please.
J.B.

[NelsonATC]

All components are to spec. Set up according to schematic, Replaced both trimpot and voltage regulator. Same issue

[Cheromaniac]

What value trim pot ( 1K ohm ), and what # regulator ( LM317)?
Make sure you get in, out, and grd. correct compare to data sheet. Not much else can go wrong.
J.B.
LM317 datasheet:
http://www.ee.buffalo.edu/courses/elab/LM117.pdf

The only other thing I can think of is that the fixed resistor might not be 220ohm.

[NelsonATC]

Tested it. it checks out

[W_A_Watson_II]

220 Ohm Resistor should be Red, Red, Brown, Gold. I see Red Red ? Brown.

[NelsonATC]

I will look when i get home, but I tested the resistor with a good multimeter and it checks out at 220.

[NelsonATC]

Red, Red, Yellow, Gold I Think I found my problem!

[W_A_Watson_II]

Yep, I think so.

Red, Red, Yellow, Gold is a 220kΩ 5% Resistor

Red, Red, Brown, Gold is a 220Ω 5% Resistor

[NelsonATC]

That was the issue. Thanks for the help! That's the last time I take the desk jockey's word at RS! Of course if I had my multimeter set correctly, I would have known earlier

[FlyinRyan]

Offtopic....Are you a controller?

[Cheromaniac]

That was the issue. Thanks for the help!

Looks like you'll be buying a few beers.