Repeater Debug

[kierkegaard]

1.What does it do, not do, and sound like?   seems like the guitar isnt passing through, if i touch the pins on a pot then i can hear a local radio being chopped by the effect and the knobs and switches all do what they are suppose to to that signal
2.Name of the circuit = Repeater
3.Source of the circuit (URL of schematic or project) =    https://shop.pedalparts.co.uk/Repeater_-_Vox_Repeat_Percussion/p847124_9673280.aspx
4.Any modifications to the circuit? NO
5.Any parts substitutions? -
6.Positive ground to negative ground conversion? unsure
7.Turn your meter on, set it to the 10V or 20V scale. Remove the battery from the battery clip. Probe the battery terminals with the meter leads before putting it in the clip. What is the out of circuit battery voltage? => 9.2v   using a tester board with 9v power
Now insert the battery into the clip. If your effect is wired so that a plug must be in the input or output jack to turn the battery power on, insert one end of a cord into that jack. Connect the negative/black meter lead to signal ground by clipping the negative/black lead to the outer sleeve of the input or output jack, whichever does not have a plug in it. With the negative lead on signal ground, measure the following:

how do i find the ground on pcb mount jack socket?

Voltage at the circuit board end of the red battery lead =
Voltage at the circuit board end of the black battery lead =

Now, using the original schematic as a reference for which part is which (that is, which transistor is Q1, Q2, etc. and which IC is IC1, IC2, C1, and so on) measure and list the voltage on each pin of every transistor and IC. Just keep the black lead on ground, and touch the pointed end of the red probe to each one in turn. Report the voltages as follows:

Q1
C = 0v
B =  300mv
E =  0v

Q2
C=  620mv
B=  0.8v
E=   3.7v

[duck_arse]

the sleeve is always ground on your jacks. in this circuit, ground is connected to the battery/supply (-) terminal. the pad marked "G", lower centre of the board, where the ribbon connects, is ground.

be so kind as to post some photos of what you have built.

[kierkegaard]

here is some pictures https://imgur.com/gallery/KLSVcex

yeah i was a bit confused about how to check the ground for the questionaire, would i just put both my probes on the ground?

[antonis]

Just put Black probe to ground (or pad marked G on PCB) and Red probe to the point for measurement..

In case of already done it, Q2 voltages are way off..

[kierkegaard]

so yes then?

put my black probe on the ground and then the red probe on the ground to test the voltage there

[antonis]

Then put Black probe to Ground and Red probe to 1 - 9 points and take measurements..
(in case of any - (minus) reading, plz note it..)





P.S.
I think there is a discrepancy between PCB marked OUT/G/9V/IN pads and respective ribbon cable soldering side..

[antonis]

You might got confused, so locate as PCB Ground the pad which is connected to any of C4/C5/C6 ROUND pad..

[kierkegaard]

Aaah ok I see what you are getting at, I was actually asking about this when asking about ground

'Now insert the battery into the clip. If your effect is wired so that a plug must be in the input or output jack to turn the battery power on, insert one end of a cord into that jack. Connect the negative/black meter lead to signal ground by clipping the negative/black lead to the outer sleeve of the input or output jack, whichever does not have a plug in it. With the negative lead on signal ground, measure the following:

Voltage at the circuit board end of the red battery lead =
Voltage at the circuit board end of the black battery lead =

I'm not using a battery lead, it's a powered tester board so wasnt sure where to put the ground probe when testing for the 'voltage at the circuit board end of the black battery lead' because that exact pad is where I'm sourcing my ground for voltage readings

Thanks for the diagram though, I'm pretty sure I took my readings properly as you described but looks like I forgot a transistor!

Will do readings as 1-9 when I'm next in the basement!

[antonis]

Don't bother too much with UJT (Q3)..

Measure voltages around Q2 at first and we'll then proceed to Q1 and Q3..

[kierkegaard]

FYI

I decided to give up on it on account that i had messed so much of it up trying to find the problem it was a mess, decided to take a deep breath and move on

appreciate your time and help, im sure i will be back here for more debugs

in other news, i had another pedal that didnt work i was gonna post on here for a debug but i just sat down and checked through everything properly and reflowed it, found the issue and now it works!

definately learnt to not panic and ake my time going through it all before asking for help

[FUZZZZzzzz]

too bad.. the repeater is a cool little circuit. dont throw it away just yet. a couple of times a year i revisited some projects that didnt work. after a long breather its sometimes easy to find a solution. can be something really easy.