Since the circuit is powered from +9V and 0V ground, all voltage measurements are made with the red voltmeter probe with the black probe always connected to 0V ground.
Please measure and post the battery voltage with it powering the circuit.

Thanks you, I will make a note of that to remember in future

 

A lot of the vintage pedals were "positive ground". These typically were based on PNP germanium transistors. This one is a negative ground but may cause problems with chained with positive ground pedals that are externally powered (not battery.

Thanknyou for your help. This pedal is normally in a rig with other pedals with an external power supply. I am currently only using the 9v to test on a bench. Having said that the previous point still applies that this has been working in that rig for a year so I do think it is down to the output rotating.

 

The problem could have occurred because you (or someone) rotated the cable as they plugged/unplugged a cable. There are no tabs on your DIY box to prevent the jacks from rotating during use. So, it is very possibly a recent issue after it has been working a long time. Check for contact when the cable is plugged in.

Good point, it is possible that the input rotated and contacted with the LED. One of the first things I did was to tighten all of the ports so they no longer spin so I don't want to slacken them off to test this, but it does look possible.

 

This circuit is AC coupled all through from Q1 to Q4. Hence it is a simple circuit to trouble shoot.
I will be away from the computer for the rest of the day. Someone else can do the circuit simulation and provide you with the expected voltages at all points in the circuit.

Here are the simulated DC voltages on Q4.



Like I said, unsolder Q4 and measure the voltages on the PCB pads where Q4 belongs.
I am fairly certain that Q4 is bad and needs to be replaced. But before going and get more replacements let's check out the rest of the circuit.

 

This circuit is AC coupled all through from Q1 to Q4. Hence it is a simple circuit to trouble shoot.
I will be away from the computer for the rest of the day. Someone else can do the circuit simulation and provide you with the expected voltages at all points in the circuit.

Here are the simulated DC voltages on Q4.

View attachment 281537

Like I said, unsolder Q4 and measure the voltages on the PCB pads where Q4 belongs.
I am fairly certain that Q4 is bad and needs to be replaced. But before going and get more replacements let's check out the rest of the circuit.

Not a problem and thanks again for your help and the effort you are putting in. So with Q4 removed, board is reading
0v, 1.6 and 8.6

 

As I look at the photos I see a lot of what might be solder bridges across the very narrow gaps, and at least one apparent cold soldered joint. That might be part of the problem, or maybe not.

 

I take back my analysis on Q4. It might be ok after all.
Leave Q4 off the board for now. Measure these voltages as related to the emitter, base and collector of Q1, Q2, and Q3.
You will have to zoom in to read the voltages.



As it turns out, Q1, Q2, and Q3 are biased with the same value resistors. Hence the voltages should be similar.
I have reduced the battery voltage from 9V to 8.6V to match the values you have provided.



Yes, there appears to be some solder bridges on the bottom side of the board. Check over the solder joints carefully and clean them up with a hot soldering iron and some solder flux. In general, you used too much solder and did not leave the soldering iron tip on the joint long enough. The molten solder should flow easily and leave behind a small shiny smooth dome around the pad.

 

So with Q4 removed, board is reading
0v, 1.6 and 8.6

I asked twice for the loaded battery voltage to see if it is 8.6V which it must be since the transistor is removed and the collector resistor is connected to it. The base voltage is correct.

 

I asked twice for the loaded battery voltage to see if it is 8.6V which it must be since the transistor is removed and the collector resistor is connected to it. The base voltage is correct.

Sorry don't know how I missed this, apologies.

 

Right I am going to have to order flux as I have missed placed mine. I'll setsome time a side this week to complete the work and get back to you.

Thanks again to everyone who is offering advice.

 

Here are some guidelines on proper soldering techniques.

 

I have not seen any images of the wires to the connectors, nor have I seen any circuit drawings showing the connections to that switch, which has a LOT OF WIRES ON IT. My guess right now is that there is a wrong connection made when it was re-soldered. Not part of the circuit board. So I am thinking that the problem is not where you are looking for it.

 

Right I am going to have to order flux as I have missed placed mine. I'll setsome time a side this week to complete the work and get back to you.

Thanks again to everyone who is offering advice.

To remove excess solder you will need a solder sucker or some solder wick.

 

I have not seen any images of the wires to the connectors, nor have I seen any circuit drawings showing the connections to that switch, which has a LOT OF WIRES ON IT. My guess right now is that there is a wrong connection made when it was re-soldered. Not part of the circuit board. So I am thinking that the problem is not where you are looking for it.

Hello, I did check the drawing when I noticed that this cable was disconnected. The drawing is part of the pdf instructions I uploaded in response to another reply. I'm hoping that I haven't got it wrong but the pdf may clear up your concerns. Thank you for your input

* Pdf is part of reply at 17:15 yesterday

Moderator edit: Times are given in local time. pdf can be found on post #11.

 

I looked at that PDF and I see a poor wiring diagram with no circuit schematic showing the connectors or the switch. And the pictures of the connectors seem to be unclear and worthless.

 

I looked at that PDF and I see a poor wiring diagram with no circuit schematic showing the connectors or the switch. And the pictures of the connectors seem to be unclear and worthless.

Ok, well thank you for your help. That is the best I have, and my knowledge only extends as far as the instructions that I received when I bought it. If I can find anything else I will let you know