Magnus Dallas Rangemaster not "boosting"

[Squirrel Murphy]

I built the Magnus Rangemaster according to this schematic and an OC-44 at about hfe=65. I did this one because it's an NPN circuit and has 3 tone options one of which matches the original circuit.

I think it's working properly except that it's just under unity at full pot. I think it's supposed be unity at about 9 and boost from there up. I checked for a reversed transistor and it's not reversed.

Voltage at the collector is supposed to be about -6.6 to -7.2V but it's not. I have this:

C = 0.595
B = 8.85
E = 8.90

One thing I noticed that is that I have 9.5V volts at the bottom R4 junction, but zero on the left leg of C5. I didn't have non-polar caps for C5 and C6 so I used electrolytic polarized caps. I installed them with + facing the voltage source (to the right in both cases). But seeing as I have no voltage left of C5, maybe it's in backwards?

I wanted to check with the experts here before reversing the caps because I heard that it can cause damage if they are in backwards.

Alternately, I could have screwed up the whole +/- thing pretty easily. I tried to trust the schematic and not over-think it. 

Thanks for any help.

[PRR]

That's a layout, for building. Not a Schematic, for thinking.

Did you see a schematic in your travels?

What little I worked-out looks wrong. The Boost pot should go to the EMITTER, not the Collector. Polarity is also dubious.

[Cozybuilder]

Here's a Rangemaster schematic. It looks like your layout just adds  a couple of caps and a SPDT (on-off-on) switch for changing the tone with the input caps. Like Paul says, the layout seems off.



Edit-
The Magnus layout uses a negative ground for the enclosure, while the circuit card uses positive ground. Be sure the circuit card does not short on anything in the enclosure. Some clear photos of your build would be helpful.

[Squirrel Murphy]

What little I worked-out looks wrong.

Like Paul says, the layout seems off.

Magnus said it was verified and I know others have built it, so I went for it even though the positive/negative thing definitely confuses me. I'll PM him directly for input.

Here's a Rangemaster schematic.

This is a negative ground for the enclosure, while the circuit uses positive ground.

The Magnus is designed as a center-negative circuit vs the original Rangemaster which was center-positive. I don't know how this happens exactly, but it's good for me and my power adapters. I must say that the enclosure wiring seemed a little strange to me but it does seems to work.

Looking at the schematic you posted, I have both C5 and C6 oriented right (negative side facing pot lug #1 for C5, and facing the emitter for C6). Unless.... errr.... I'm supposed to flip them because it's now negative ground circuit... in which can I have them backwards?

I can post some pics tomorrow. Appreciate the help. I feel like I'm 95% of the way there and as always, learning a boatload as I go...

[antonis]

I think there is a wiring mistake..

GND of OUT jack should go (via 3PDT switch) to junction of R1 & R2 and NOT to C4..

C4 shoud go to OUT with lug 1 disconected from OUT...

[Cozybuilder]

The labelling on the Magnus layout makes it a little difficult, but it looks to me like the output jack tip goes to center left pin (3PDT), the circuit output is the upper left pin and connects to C4. Input jack tip is connected to center pin, and circuit input is the upper center pin connected to C2 and the associated input cap parallel options.

Be sure you are plugging the guitar into the Input jack, and the amp to the output jack- its easy to reverse if wiring the box in accordance to the way its drawn since the box will be upside down!

[Squirrel Murphy]

Maybe I should create a schematic that matches the layout to help me answer some these questions. It's a little unclear to me from the drawing which jack lugs are tip, ring, and sleeve and exactly where the grounds connect on and off/board. I see the blue lines as in/out and how they connect jack/switch/board. I wired green lines as ground on the jacks/switch and also connected to the board as shown. It's not clear to me exactly how the ground-bus connects off-board.

The labelling on the Magnus layout makes it a little difficult, but it looks to me like the output jack tip goes to center left pin (3PDT), the circuit output is the upper left pin and connects to C4. Input jack tip is connected to center pin, and circuit input is the upper center pin connected to C2 and the associated input cap parallel options.

This is exactly my understanding as well.

[Cozybuilder]

Instead of labelling ground connections (which adds to confusion in the Magnus), the power source gives you 0V and 9V, so label your drawing that way. I think you'll find it easier to follow.

There are lots of different jack styles- use your multimeter to verify jack lugs to tip, sleeve, and ring.

[Squirrel Murphy]

There are lots of different jack styles- use your multimeter to verify jack lugs to tip, sleeve, and ring.

I stared it down and worked it out (tip to in/out = blue lines, sleeve to ground = green lines, ring to battery negative = black line). Pretty sure I wired it this way, but it's now clear to me why.

I think there is a wiring mistake..

GND of OUT jack should go (via 3PDT switch) to junction of R1 & R2 and NOT to C4..

C4 shoud go to OUT with lug 1 disconected from OUT...

Ooooh. I totally see this now. As I said earlier, I couldn't understand where the board ground-bus connected off-board. I see it now. I'll try moving the green line to R1/R2.

The schematic cozy posted is super informative... helped me decode the layout.

[Magnus]

Hello,
its my layout and its verified.

I have used the schematic posted in this thread as a basic
and reversed the polarity for a negative-ground circuit.
An rc-network at the dc-jack prevents "motorboating" while using a wallwart.
I have built it two times, one OC44-version and one OC71-version
like you can see on the right side of the layout ;-)

I think there is a wiring mistake..
GND of OUT jack should go (via 3PDT switch) to junction of R1 & R2 and NOT to C4..
C4 shoud go to OUT with lug 1 disconected from OUT...

No, its just negative ground ;-)

@Squirrel Murphy:
Try to get non-polarized-caps where they have to be installed, maybe thats it.

Have you installed the three solder bridges on the pcb?

...and post some pictures of your build please!


Greetings
Magnus

[antonis]

I think there is a wiring mistake..
GND of OUT jack should go (via 3PDT switch) to junction of R1 & R2 and NOT to C4..
C4 shoud go to OUT with lug 1 disconected from OUT...

No, its just negative ground ;-)

If so, then I insist on the above written..

[slacker]

I don't know if it helps but here's a schematic of the layout minus the 3PDT. Just realised the input cap switch is wrong and the in out jacks are the wrong way round but the important bits are correct.



The layout looks correct to me just a bit confusing, it confused me anyway, because some of the ground wires are hidden by text.

[Squirrel Murphy]

I don't know if it helps but here's a schematic of the layout

Yes it helps me alot. I studied it, compared to my marked up version of the original schematic Cozy posted, plus my marked up version of Mag's layout. Then I made my own so I could really understand it.



I moved C5 to the top because it connects to R3 and the pot... but now I'm confused because C5+ is supposed to connect to battery + which is on the bottom where you had it. This confuses me greatly. If R1, R2, C6+, and R4 all connect to ground, then the same rail along the bottom also connects to C5+... but then it all also connects to battery + through R4. If I didn't add R4, then 9V+ is connected to the ground bus. My head hurts. I also don't show Pot-1 and R3 directly grounded like you did (and I see on the layout too)... and this bugs me too because if makes me feel that C5 is grounded on both sides...

Anyway, thank you guys for being patient with me.

As for capacitor orientation, I think I'm OK: in the original schematic, C5 and C6 (the two 47uF ones) are shown a polarized with + legs facing ground. So that schem is positive ground, right? +9V battery goes to input ring and negative battery goes to C5 (negative leg), R3, and Pot1. All opposite of the Magnus negative ground version. This tells me that C5 is oriented correctly for the Magnus circuit (+ to the right, - to the left in the layout). Same logic for C6. So I think the caps are OK the way I installed them.

Someone told me to check the pot and make sure it's sized right.... it's an A10K.

If it matters, I installed 22uf for C6 (approx 25uf at Mag's recommendation and versus 47uF on the original). I used 0.01uF for C4 like the original circuit.

Try to get non-polarized-caps where they have to be installed, maybe thats it.

Have you installed the three solder bridges on the pcb?

...and post some pictures of your build please!

I don't have an np caps that size, but I can order some I guess. I expect it should work anyway as long as I have them in right.

Solder bridges: I built on pad-per-hole perfboard. I just soldered nodes directly together where they were close (eg. node at C1+C2+C3+R2+R3). I used lead wires to connect across multiple holes (e.g., that same node connecting to Q1-base). In other places where I had some distance to cover, I used jumper wires on top of the board (e.g., Q1-emitter+R1 are soldered together and then jumpered to C6). I jumpered all the way from Pot-1 to the ground-wire coming off the board since it's only a 2-node connection. It's very possible I made a mistake by doing it this way.

pics in the next post...

[Squirrel Murphy]

Pics. Sorry they are not great or easy to see. For the bottom of the board, it's lifted out and flipped toward the toggle switch. C1, 2, and 3 connections to the toggle switch are along column L. Pot connections along the top right and tranny sockets on the far right column Y.

Not my best work, but so far it seems solid and quiet.

Oh... and C7 isn't there. I haven't put it on yet. But I did put R4 on (top far left). Errr... crap I hope that's not my issue. I assumed that since C7 is for power noise reduction it was OK to skip for the moment. The LED CLR (R5) is also on there... far left middle, row H.

[Ben Lyman]

I tried to copy this in DIYLC, omitting the off board components and all the extra "dots" because they confuse my eyes and brain.
I think the bottom of the board (note reverse image) should go like this:


Top like this with the jumpers and components:


Here's everything with x-ray vision:


I see you've done it a little differently but maybe this can help you spot a missing link or something.
Good luck!

[Squirrel Murphy]

I see you've done it a little differently but maybe this can help you spot a missing link or something.

Thanks! I'll go through it soup to nuts tonight.

I tend to allow for creative latitude with layouts and I'm sure that gets me into trouble. Example: I don't see why that zig-zag trace plus jumper from Pot-1 to the other side of the board is needed. I'm more inclined to find a hole next to the Pot1-R3-C5 junction and solder the off-board wire right there. I didn't in this case, but I used the same logic in several other places.

Think I might switch to PCBs for a while to keep me out of trouble...

[PRR]

> My head hurts.

Agree.

The battery-only polarities, for PNP transistor, are clearly like this:

https://s10.postimg.org/a77gm3nah/Squirrel_Murphy.gif

If you want to use this on a common wall-wart with other pedals, without smoke, it gets more head-hurting.

[Magnus]

Hello,

@Squirrel Murphy:

You have drawed a mixed version-schematic
of positive and negative-ground, there are some small errors.

If R1, R2, C6+, and R4 all connect to ground

They aren't connected to ground.
R1, R2, R4, C5 (+), C6 (+) and C7 (+) are connected to the battery-plus-pole.

I also don't show Pot-1 and R3 directly grounded like you did (and I see on the layout too)... and this bugs me too because if makes me feel that C5 is grounded on both sides...

Pot 1, R3 and C5 (-) are the only three connections which are grounded.

As for capacitor orientation, I think I'm OK: in the original schematic, C5 and C6 (the two 47uF ones) are shown a polarized with + legs facing ground. So that schem is positive ground, right? +9V battery goes to input ring and negative battery goes to C5 (negative leg), R3, and Pot1. All opposite of the Magnus negative ground version.

That's right.

This tells me that C5 is oriented correctly for the Magnus circuit (+ to the right, - to the left in the layout). Same logic for C6. So I think the caps are OK the way I installed them.

I think you did it right.

Someone told me to check the pot and make sure it's sized right.... it's an A10K.

Yes, 10kOhm Audio (logarithmic).

If it matters, I installed 22uf for C6 (approx 25uf at Mag's recommendation and versus 47uF on the original). I used 0.01uF for C4 like the original circuit.

22uF is authentic enough for the OC44-version since every cap has a tolerance.

I don't have an np caps that size, but I can order some I guess. I expect it should work anyway as long as I have them in right.

I have seen that you have the two right polarized-caps, I thought you had polarized ones for the input-caps too, but you don't - so everything is fine ;-)

Solder bridges: I built on pad-per-hole perfboard. I just soldered nodes directly together where they were close (eg. node at C1+C2+C3+R2+R3). I used lead wires to connect across multiple holes (e.g., that same node connecting to Q1-base). In other places where I had some distance to cover, I used jumper wires on top of the board (e.g., Q1-emitter+R1 are soldered together and then jumpered to C6). I jumpered all the way from Pot-1 to the ground-wire coming off the board since it's only a 2-node connection. It's very possible I made a mistake by doing it this way.

If you are sure you did it right - no problem with that.

Oh... and C7 isn't there. I haven't put it on yet. But I did put R4 on (top far left). Errr... crap I hope that's not my issue. I assumed that since C7 is for power noise reduction it was OK to skip for the moment. The LED CLR (R5) is also on there... far left middle, row H.

That's no problem, C7 is only needed for quiet wallwart-use, if you want to use one add it later.

I don't see why that zig-zag trace plus jumper from Pot-1 to the other side of the board is needed.

That's a cosmetical thing.
In the enclosure the pcb is above the jacks
and so theres no wire going on top of the pcb and over the parts.

Think I might switch to PCBs for a while to keep me out of trouble...

Yes, an etched pcb is much easier, you don't get a knot in your head...

btw:
The input-capacitor-switch has to be an ON-OFF-ON-type,
so in the middle position theres no connection
and in the two side-positions always two caps are added.

Here's the corrected schematic:



Greetings
Magnus

[Squirrel Murphy]

They aren't connected to ground.
R1, R2, R4, C5 (+), C6 (+) and C7 (+) are connected to the battery-plus-pole.
Pot 1, R3 and C5 (-) are the only three connections which are grounded.

OK. I see it now. C5 connects to the top through the ground. It makes sense to me now.

If you are sure you did it right - no problem with that.

Well, clearly I've made a mistake somewhere! 
I'm comfortable with my logic. It's probably a solder bridge or bad/weak solder joint but so far I can't find it. Everything seems to test OK.

You know, I get a degraded continuity beep from C to B legs on the tranny. Does that sound right? I assume that I should have continuity but it's through R3 and the pot so it's degraded. I've looked closely and I did not accidentally bridge C to B with solder.

I'll keep working it until I find the problem. I have enough parts to build another one... so maybe I'll do it on the breadboard as a model and work backwards. Thanks for all your help. And thanks for the very cool layout diagram. It's very nice.

The input-capacitor-switch has to be an ON-OFF-ON-type,
so in the middle position theres no connection
and in the two side-positions always two caps are added.

Yes, it is. And it tests properly (left 2 on, then middle only, then the right 2).

Here's the corrected schematic:

Fixed my original which I made with DigiKey's SchemeIt:

[Magnus]

Hello,

You know, I get a degraded continuity beep from C to B legs on the tranny. Does that sound right?

Sorry - I don't know but maybe another guy here can tell you more about those measuring-data...

I'll keep working it until I find the problem.

That's DIY

I have enough parts to build another one... so maybe I'll do it on the breadboard as a model and work backwards.

Good idea!

Thanks for all your help.

No problem, always again

And thanks for the very cool layout diagram. It's very nice.

Thank you

Fixed my original which I made with DigiKey's SchemeIt

Perfect!

Did you try another transistor?

btw: Don't solder germanium-transistors, they don't like too much heat...

Please let me know how your project goes


Greetings and good luck!
Magnus