1 volt on input rangemaster pedal

[rangermaster]

Hi again.

I have build a oc44 pnp rangemaster pedal again for a customer. It works great and sounds good. But when i measure on the input(sleeve and tip) i measure about -1 volts. On the output there is like -0.04volts.

Is this normal ? All the parts are new and i already replaced the output and input caps.

Thanks.

[antonis]

Maybe there is some kind of short bypassing input cap..
(-1V is the Base voltage referenced to +9V)

[rangermaster]

Maybe there is some kind of short bypassing input cap..
(-1V is the Base voltage referenced to +9V)

Thanks for the reply. What should be the first thing to look at?

I measure -1v on the OC44 base(470k/68k resistor).

I have a 3 way switch for the input cap. So i can choose between 3 input caps. All caps are leaking some volts in to the input jack. 

[antonis]

Check for continuity between Tip and transistor base..
You might take "some" indication, due to input cap discharge but it should very soon result into "open" circuit..

[rangermaster]

Check for continuity between Tip and transistor base..
You might take "some" indication, due to input cap discharge but it should very soon result into "open" circuit..

-0.06v when measuring from base to tip. +/- -1v when measuring base to sleeve. If that's what you mean. 

[antonis]

Voltage measurement isn't Continuity measurement..

Set DMM to continuity mode, indicated by "diode" / "beep" symbol (or lower resistance scale mode in case of an ancient analog meter)..

[antonis]

I have a 3 way switch for the input cap. So i can choose between 3 input caps. All caps are leaking some volts in to the input jack. 

Have you placed a pull-down resistor..??

[rangermaster]

I have a 3 way switch for the input cap. So i can choose between 3 input caps. All caps are leaking some volts in to the input jack. 

Have you placed a pull-down resistor..??

When i measure that way there is no beep or value. And i have not used pull down resistors..

[anotherjim]

Your DMM has some internal resistance between its probes in voltage mode, depending on its design, anywhere from 1M to 20M ohm; so when attached to your input it is its own pull-down and should discharge the input capacitor to 0v in a short time.
If the voltage remains, then as Antonis suggests, there could be a leakage fault in the input capacitors.
Make sure there's no power supply and measure the capacitors in a high resistance range. Reading should rise to infinity/open.
Double-check you have any electrolytic input capacitor the right way around. For PNP positive ground the + is to the input jack.
However, you should still fit a 1M pull-down resistor. If a NOS axial lead electro cap is used, there is a good chance it will be a little leaky.

[rangermaster]

Ok i'll check but i'm 99% sure everything is wired correctly.

1m Pull down resistors between tip and sleeve right ?

In the attachment is a photo of the board

[anotherjim]

The best place for the pulldown is on the input wire to the board or the input side of the coupling capacitor. If you put it on the input jack then it will disconnect in bypass and let the capacitor build up leakage - which will cause a pop when engaged. The pulldowns job is to keep the capacitor input plate at 0v so it should always be connected.

[rangermaster]

Ah ok like this


But isn't your explanation the same as how i wire it? Tip to +v grounds ? I don't use a stereo jack.. i use a dpdt switch to activate the battery.

[duck_arse]

I measure -1v on the OC44 base(470k/68k resistor).

I have a 3 way switch for the input cap. So i can choose between 3 input caps. All caps are leaking some volts in to the input jack. 

we can't see the switch, or how it is wired, either on your circuit diagram or your layout diagram or your photo.

[rangermaster]

Red lines are ground wires.

1M resistors are going from jack tip to jack sleeve(grounds)




Blue and green are the caps. Going from transistor Base to input.

Sorry for the bad drawings but i only have my phone right now.

[anotherjim]

You don't have a bypass footswitch? Then you can wire the pulldown to the socket tip.
Funny, I've always assumed the "Boost" switch on the original RM was a bypass - but you've used it for something else?

[rangermaster]

You don't have a bypass footswitch? Then you can wire the pulldown to the socket tip.
Funny, I've always assumed the "Boost" switch on the original RM was a bypass - but you've used it for something else?

Footswitch is a 3pdt switch. What you mean exactly ?

[rangermaster]

Switch is wired like this. (Google image)

[anotherjim]

So you do have a bypass switch. That's what I meant before. When you switch the effect out, the input cap on the board is no longer connected to the input socket tip. So the pulldown resister must be fitted on the board. It isn't the same as a resistor on the socket at all - because there's a switch in between.

[rangermaster]

So you do have a bypass switch. That's what I meant before. When you switch the effect out, the input cap on the board is no longer connected to the input socket tip. So the pulldown resister must be fitted on the board. It isn't the same as a resistor on the socket at all - because there's a switch in between.

Ah yeah i understand. Sorry i'm from holland.. have to read things twice 

So 1M resistor from ground to board In lead and one 1M resistor from ground to board out lead.

[rangermaster]

Ok i just did that and no voltages on the jacks.

But when i turn the effect off i have -0.90v on the jacks...