SOLVED Simulcast quiet/thin sound

[okstateblues]

Thanks up front for any help. Everything works but it is super quiet even at 100 percent on the knobs.

 

[Mcknib]

All your values and orientation look correct

Post a pic of your offboard wiring to jacks switch etc

It could be a number of things most likely the usual cold solder joint in the audio path, on the jacks or 3PDT incorrect wiring etc

Is it ok bypassed

 

[okstateblues]

Yes works bypassed but sounds really low volume wise when engaged. I'll get pictures of the back tonight.

 

[Mcknib]

Daft as it seems are guitar and amp levels all up in to in etc

Its more to see your wiring to the jacks and 3PDT and to make sure nothing's shorting on the enclosure etc

 

[okstateblues]

Pic 1

 

[okstateblues]

Pic

 

[okstateblues]

2

 

[Mcknib]

Looks wired correctly when you stick a jack in the out socket is the tip clear of the back of that B25K pot

 

[okstateblues]

Yes it clears. However I did notice that the green wire going from my footswitch to board isnt all the way thru the hole on the board. May need to reheat and coax it further through. Would the burnt insulation have an impact?

 

[Mcknib]

Not unless it shorts on something like the lid

Yes just heat your solder joint for around 4 seconds and gently push your wire through

do you have low volume throughtout the tone pot rotation the one I built had a couple of blank spots at the beginning and end of the tone pot rotation @Chuck came up with a solution that worked

One thing I can't check is your transistor pinout what did you use for the OC71

I'd personally get the audio probe out to find where you loose volume

 

[okstateblues]

Yes volume is low throughout entire rotation. The transistor is a mullard oc71 from digikey if memory serves me right.

 

[Mcknib]

Do you have an audio probe? there's nothing obvious that I can see the OC71 looks correct from what I can see should have a red dot on the collector, audio probing the circuit will get you to the problem area pretty quickly

 

[okstateblues]

I have the page bookmarked for building one but have yet to build one. I will get a better picture once I make it home.

 

[okstateblues]

1

 

[okstateblues]

2

 

[Mcknib]

Here's a PDF explaining how to use one etc

https://drive.google.com/file/d/1T9OsJ0riQhm1QFWPfNQ5q5guikuFKDRN/view?usp=sharing

You can make a quick one like this with a mono jack, solder a 100n to 1uf film cap to the tip lug with a bit of solid core wire soldered to the other cap leg and solder a piece of wire with a croc clip to the ground lug

 

[okstateblues]

The red dot looks like it is closest to the left leg on the OC 71

 

[Mcknib]

That's correct red dot = collector, base in the middle and emitter goes to the pad with the small tag on the silkscreen, some metal can type transistors have a small metal tag on the body indicating the emitter pin

Does your level pot act like a level pot ie goes off when you turn it down etc and nothing you can see is touching the bare metal enclosure

The reason I ask all this is from your description you do get effected signal which would indicate a high resistance to the signal making it through the circuit which could be a dry solder joint in circuit etc etc so whilst you wait to construct your audio probe I'd reflow the joints indicated in red and make sure all of them are good, obviously take care with the 3PDT lugs you don't want to heat them for too long

The fact you get bypass signal tells us the wiring to the jacks is ok doesn't tell us much else

 

[okstateblues]

Yes pots do act properly when rotated. Overall sound is just really low. I'll reflow tomorrow and report back.

 

[okstateblues]

Reflowed those points and still no change. Audio probe in progress. I'll have to order parts so it will be a while as I'm in remote usa