Rangemaster Failure - RATS!

[GreenEye]

:cry:

"Finished" my rangemaster clone today from GGG.  The bypass feature works great!  Unfortunately, when the effect is switched on, there's a teeny tiny signal that decreases to nothing when the level is turned up.   :evil:  Mine is the positive ground one (for now).

Stupid question #1:  which connectors on the 3PDT foot switch (Aron's blue one) are supposed to register on the multimeter when the unit is on, and which ones when the unit is off?  I get about half registering all together.  I'd really like to know what happens to the signal inside of that thing - the external loops and amount of connectors is perplexing.  Most of the board appears to be working, but something with that switch seems screwy.

#2:  I get readings on both side of my canister caps with my MM, but with my polys, only one side -what gives?  If the signal goes into one side, shouldn't it come out the other?  I even tried substituting 2 different ceramic input caps too - again, nothing on the output side.  #$#@@%%@$!

Enough debugging for today...

[petemoore]

Geo tech of...Rangemaster
 Have you tested the transistor voltages?
 GEO Article on bypass techniques has pics 'n such about bypass switching.
 Pen, Paper, a wire free switch, DMM set to beep mode: map the switch..you'll discover two sides and a middle.

[GreenEye]

Thanks for the help.

I think the problem lies in that (1) I'm doing a postive ground circuit, which seems to have different wiring and circuit flow then what the FAQs often describe, and (2) GGG's wiring diagram for the 3PDT switch is not even remotely close to what Aron shows for his blue switches.  I mean wires are going to totally different connections.  To do up what Aron shows, I'd have to desolder several wires and start from scratch for the off board connections.  ARrrrrggghghh.

[Hal]

oh man debugging sucks

hahahahaha
okkkkk first suggestion - wire it up without the switch, outside the box, and see if it works, before you tackle the switch - one more thing to rule out.

Obviously, to do that, you go input jack hot to effects input, and effects out to out jack hot....

for + grounding, you don't need a new layout....just switch the orientation of the battery, and all electro caps.  (and any diodes if there were any, but there aren't)

[STOMPmole]

GreenEye,
I just built the Rangemaster w/Aron's blue SPDT switch and positive ground and can say that his diagram DOES work.

One thing to note about Aron's diagram for 3PDT wiring is that the black line across the top of the circuit board block diagram is ground (it can be easy to confuse it with '+' where the wires cross...especially if you are looking at the diagram in black and white instead of color.

Another thing to look at is your wiring of the switch terminals...those terminals are very close together and I had some trouble (that required debugging) with wire strands shorting to the next nearest terminal post.

One last thing to check is the wiring of the pot.  I wired it like the diagram and it ended up being reversed (decreasing volume as you turn the knob clockwise).  You turned the pot all the way counter-clockwise and still don't have any effect signal, correct?

[remmelt]

the entirely different way of wiring the switch connects the input (or output) of the effect to ground to avoid oscilation, but only when it's off, ofcourse.

good luck!

[theaxeman]

HI!

Just yesterday I finished my RM clone, i also used the GGG posotive ground schem, but i built on perfboard, added pulldown resisitors and a input cap switch, it seems to be working absolutley fine. There was one point when i put the pot in backwards!  :lol:  But i fixed it.

I'd just check for shorts and loose conections and check the tranny voltages.  

Good Look!    

Rob

[petemoore]

When I test Rmaster
 check for connection to NOT be between +and - of batt clip
 cheep transistor
 out of box
 no switch
 no jacks
 on tested test jig...just cardboard box on top and box with jacks underneath all connections with alligator clips [Gnd, in and out]
 you have not failed, your success has merely been postponed.

[saros141]

Yup, you'll get it.  It's passing audio so you're close.  Check the orientation of the transistor, do you have the collector wired to where the emitter should be and vice versa?  Check the potentiometer's orientation too, the wiper might be wired up right but the other two lugs might be reversed.

One thing I'm learning to do is, when it doesn't work right away, take a deep breath/take a break.  It's too easy to just dive in and start changing all kinds of things which might not even be wrong.  It's harder to think clearly when I'm frustrated.

[GreenEye]

Thanks for the tips and encouragement!  I fell into the depths of despair for a bit there.  I think working outside of the case will prove to be much easier.  

I'm going to print out everyone's advise and try it all.  I'm also going to try the makeshift audio probe.

[RDV]

For ?#1, in one position of the switch the middle row of contacts connect to the top row, in the other position the middle row of contacts connect to the bottom row.

HTH

RDV

[petemoore]

I thought that went there...
 I've had to silently say that many times about an error on the board.
 I'll just sit there with the schematic and the board, turning the board from one side to the other...looking from the side, with my eye inline with a row to determine if 'that' lead is actually going to the center socket pin...etc...then I get the DMM beep mode and confirm bottom to top board connections [actually I practice leaving enough lead atop the board for DMM probe access...holding the probe to a blob on the bottom of the board to veryfy a socket pin conection is rediculous].
 I pull everything from the sockets, Then I check resistances that don't have an alternate current path through the circuit, or pull/cut one end of a resistor connection if I feel an overwhelming need to  check that resistor.
 I must have used thousands of resistors, and found one bad...so I figure somewhere near 999 out of a thousand [disregarding reading errors] the color code resistance is the resistance in the resistor within tolerance.

[GreenEye]

Well, I went ahead and tied up test leads w/alligator clips for the off-board wires.  Left out the LED, the DC jack, and the footswitch.  Tried it out, and it seemed to work pretty good.  I used Small Bear's schematic and layout for the Tweak-O as supplemental guides.

I found it to be a very subtle effect.  I did tests with 3 input caps:  0.0047 uF polyester, 0.0047 uF ceramic, and 0.0068uF ceramic.  I liked the 0.0068 a lot.

I did have the pot wired backwards.  I didn't realize the pot actually was able to turn the volume down to zero.  I thought the pot was more of a drive then a level.

In addition, I originally tried to use a radio shack LED with a built-in resistor.  Well, the resistor is on the "wrong" wire for positive ground wiring!!  I guess that's the newbie price I paid.  I'll have to save that for a negative ground project.

Now if it all just works in the box....[another day]

[STOMPmole]

GreenEye,

It shouldn't make a difference WHAT LED leg (wire) the resistor is on as long as you hook up the polarity correctly for the LED.

[GreenEye]

I fixed it and made it work! WOO HOO!!    

I did leave out the DC jack, out of fear of the many problems my radio shack adaptor would have brought me, and also to make some space.

Stomp:  thanks; slowly, I'm learning (although I had gone ahead and did a lot of wire splicing)  :oops:

I find that my rangemaster is not so much a treble booster, as a bass reducer - same thing I suppose.  I would recommend it for single coil pickups, or lower output/single-space humbuckers.  I guess when this thing was in production, single coils were the norm, so I can see how this unit would have been useful.  It works better in different p/up positions and with my different tube amps, so I think I'll find some useful sounds.

[STOMPmole]

I think it works really well with a somewhat bassy guit/amp combo like a LesPaul/JTM45.  My favorite sound with the strat is using a Fender amp and a 0.01mF input cap.  The stock value input cap is slightly too trebly.  If you like Black Sabbath put a switch so you can change the input cap to
0.15mF; that will give you that bassy, over the top, distorted tone like on 'Iron Man' or 'Paranoid'.  With the full-range 0.15mF input cap it reminds me of a weak (not as distorted) fuzz face.