Road Rage 2014

[dujuarez]

I populated the board for -9volt D1, D2, C1,C2,C6,C7,R1. And have omitted the rest. Do I need to add the charge Pump?

[spin]

Yes, if you take a look at the schem, you'll see -9 is coming from pin 5 of the IC.

[dujuarez]

Ok, I've now added the charge pump (7660scpa, jumpered BST) but when I check with a meter, I can see the +9v coming in from the DC jack but when I measure at the -9 G points I get a reading of 0.01 Volts. I then tried measuring at the IC 3 ground and 5 -9 Volt and I get the same reading.

Please help.

Thanks

[RobA]

It sounds like you've got the right parts on now. These are the things I'd check.

Check the orientation of all your polarized parts and the IC.

Look for solder bridges between parts, check with a continuity setting on your DMM.

What are the voltages on the rest of the pins on the IC (pins 1, 2, 4, ?

If those don't help, can you get a good photo of both sides of the board?

[dujuarez]

I believe that I have it working now. I'm able to get the correct -9v. But I'm getting a slight hum in bypass mode and extremely loud hum when the board is engaged. I understand that I will be getting some hum from the pedal not being in a box, but maybe it's because I have Q1 connected to breadboard to try different transistors. I found something unusual when was checking for continuity of the potentiometer. Normally what I do is check continuity from the board to each lug of the pot. Then I place a probe on the wiper from the board and the other probe on lug 1 for example, then I move the pot and listen to the tone from the meter. When I do this I'll hear the tone when the pot is turned all the way up and loss audio when I turn it down. Now I hear the tone with the pot fully on and when I lower the pot the tone is distorted.

These are the Voltages

Pin 1   +4.05
Pin 2   +4.64
Pin 3   0.00
Pin 4   -4.32
Pin 5   +8.97
Pin 6   +5.51
Pin 7   +4.06
Pin 8   -8.96


Thanks

[RobA]

I think you've got the numbers reversed on pins 5 through 8. Beside that, Pin 1 should be connected through the jumper directly to pin 8 (your number 5). So, it should be sitting at +8.96. That could be the cause of the noise you hear if it is a pretty high pitch. The boost circuit won't turn on if pin 1 is at too low a voltage so the frequency of the clock could be down in the audible range. Check the continuity between pins 1 and 8 (8 being the pin directly across the IC from 1).

Which pedal are you using this with?

[dujuarez]

Sorry about that error. I measured straight across and no in a u-shaped manner. So the correct numbers for 5 through 8 are:
pin 5 - -9.00
pin 6 - +4.10
pin 7 - +5.64
pin 8 - +9.00
I checked continuity, and I'm getting continuity between pins 1-5, 2-5, 3-5 and 4-5. I went back to check continuity again, just to make sure I have the right pin order. But now I'm not getting anything. When I check pins 1-5 for example I get short beep, then no sound at all.

The pedal is the old Rangemaster circuit. I've upload pictures.

David

[dujuarez]

Additional pictures(learning how to reduce and post pics)

[dujuarez]

More

[RobA]

Sorry about that error. I measured straight across and no in a u-shaped manner. So the correct numbers for 5 through 8 are:
pin 5 - -9.00
pin 6 - +4.10
pin 7 - +5.64
pin 8 - +9.00
I checked continuity, and I'm getting continuity between pins 1-5, 2-5, 3-5 and 4-5. I went back to check continuity again, just to make sure I have the right pin order. But now I'm not getting anything. When I check pins 1-5 for example I get short beep, then no sound at all.

The pedal is the old Rangemaster circuit. I've upload pictures.

David

That U-shaped numbering scheme is weird, but all DIP IC's seem to do it that way.

The only pins that should have continuity are pin 1 with pin 8 and that should be made through the jumper. One thing to check is that there is no connection between pin 6 and ground. It looks like it is OK in the photo, but check for continuity just in case because this can do weird things to the charge pump. Since you are getting the right output voltage, I'd assume the rest of the connections are OK. The main thing is that low voltage on pin 1. It should be sitting at the same voltage as pin 8 since they should be connected right together. This also might be the source of your hum since it can take the charge pump out of frequency boost mode and bring the clock down into an audible range.

I can't see anything on the PCB, but you might want to reflow the solder for pins 1 and 8 and the jumper connections (be careful not to let the jumper fall out when reflowing) and then check the voltage on pin 1 again.

To make sure we are talking about the right thing here, how high pitched is the hum/whine. The unboosted charge pump clock could be anywhere from about 3kHz to 10kHz. Although, even then you could have some interactions with something else that might make the pitch lower. Still that's another good indication that it is likely to be the boost connection that's a problem.

As a temporary test, you could hold a wire directly from pin 1 to pin 8 to make the connection and see if the noise goes away and the voltage is at the right point.

[dujuarez]

I was having trouble trying to get the proper continuity from pin 1 to pin 8, that I gave up and built another Road Rage. I'm thinking that I might have ruined the IC. Once I finished the new Road Rage it worked fine. Continuity and voltage checked out. I'm still getting the hum, but it's not high pitched. It's more tuned to open D on guitar. Sounds similar to a guitar cord plugged into the amp and grounding the tip and sleeve. I believe it has something to do with the Rangemaster.  I will go over the circuit tomorrow and see if I find anything.

Thank you.