SOLVED Duo-Phase side A clipping to Rate

[irvmuller]

Just finished building the Duo-Phase. Side B works perfectly but side A is not giving me effect and is making a tick-tick-tick sound that goes at the same speed as the rate.

I did sub in 2n5088 because I didn’t have any 4401s but I’m doubtful that’s causing the issue.

Please, give me your thoughts.

 

[irvmuller]

Does this look like it could be the culprit to anyone else? I remember using a needle nose to turn it and thinking I may have handled it too roughly.

 

[Coda]

Have you adjusted the trimpot for that side of the pedal?…

 

[irvmuller]

Have you adjusted the trimpot for that side of the pedal?…

I have. The LEDs and Trimpots are working correctly on both sides.

 

[Coda]

I have. The LEDs and Trimpots are working correctly on both sides.

So you weren’t able to dial the clock noise out using the trimpot. Next question: how valid are your ICs? Can you post some voltage readings?…

 

[irvmuller]

So you weren’t able to dial the clock noise out using the trimpot. Next question: how valid are your ICs? Can you post some voltage readings?…

TL072s I got from pedalpcb when I bought the pcb. The two 1044scpa I got from mouser. I can change them out when I get home though and see if that helps.

 

[Coda]

TL072s I got from pedalpcb when I bought the pcb. The two 1044scpa I got from mouser. I can change them out when I get home though and see if that helps.

I didn’t mean valid as in they weren’t trustworthy (though I think there are fake 72’s around), I misspoke. I meant something like “let’s see if everything is right with the IC’s”…

 

[irvmuller]

I’ll put up voltage readings tomorrow.

 

[PJS]

Does this look like it could be the culprit to anyone else? I remember using a needle nose to turn it and thinking I may have handled it too roughly.

If you are concerned, I would measure the resistance with light on it, and then covered (with a finger maybe) and compare the results with one (or more) of the others. If the results are consistent it's probably fine.

 

[irvmuller]

Ok, some new info. I checked all chips on both sides. Since B works perfectly I compared it to A (the side working incorrectly) to see if there were big differences. Chip 3 on side A really stands out to me as being off. That same chip is connected to the LDR I was worried about! I changed out the chip and got the exact same results so I’m thinking it could be something leading to IC3A.

I did compare resistance on the LDR and it seems to be in line with the others.

let me know what you guys think. And the more input the better. There are a lot more people in here more knowledgeable than me!

 

[irvmuller]

Checked under the board where IC4 is and sure enough, there’s my problem. Would’ve saved myself a lot of time if I did that first. At least I got to work on some old skills and knew exactly where to look first!

I NEVER make this mistake.

Thanks for all the help guys!

 

[PJS]

So been there done that