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Help Troubleshooting PT-80 Delay

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Hi everyone, I am trying to troubleshoot my build of a PT-80 Delay from GGG.

Ive poured over my circuit looking for issues and I believe I have fixed up all the dodgy traces etc however still no luck.

I am only getting a dry signal when the effect is on. If I put a probe on Pin 12 of the PT2399 I can hear the effect going. I then trace it from PT2399 Pin 12 up to the 22k resistor however I am not getting any signal on the other side of the resistor. The resistor is reading ok (and at the correct value according to the schematic) on the multimeter.... Im still a noob so little lost as to what the next step would be. ( I wish the schematic and layout had numbered references).

I have double checked all the values and checked for continuity between traces in that area of the PCB. Any tips appreciated  :D

If the signal is at pin12, it should also come out of pin14. All pin voltages on that side (pins 9 to 16) should measure around 2.5v.

Thanks Jim, I have wet signal coming from Pin 14 too. I went through and measured all voltages...


IC1 5v
IC2 2.5v
IC3 18mv
IC4 18mv
IC5 2.8v
IC6 2.5v
IC7 varies between 1v and 2.2v
IC8 varies between 1v and 2.2v
IC9 2.5v
IC10 2.5v
IC11 2.5v
IC12 2.5v
IC13 2.5v
IC14 2.5v
IC15 2.5v
IC16 2.5v


IC1 1v
IC2 1.8v
IC3 1.8v
IC4 4.4mv
IC5 1.8v
IC6 6.4v
IC7 6.4v
IC8 1.8v
IC9 1.8v
IC10 6.3v
IC11 1.8v
IC12 1.8v
IC13 12v
IC14 1.8v
IC15 1.8v
IC16 1.2v


IC1 6V
IC2 6V
IC3 6V
IC5 5.4V
IC6 6V
IC7 6V
IC8 12.1V

Good so far. The PT2399 is happy, the TL072 looks good. Have to admit the 570 compander chip is a mystery to me -  I know what it does but not enough to design with it. Every time I look at its datasheet I get more questions than answers.
Anyway, the next thing after the delay output pin14 is a filter using the only BJT transistor 2N5089. Signal should leave on the emitter and have about 5v DC on it. Signal should be present all the way from the 1uF cap and the x3 10k resistors to the transistor base pin.

Next is 1/2 of the 570 chip which is working as a signal noise reduction expander (loud signal gets more gain than quiet signal and doing the opposite of the compressor action from the other half at the input). Signal goes in on pins 2 & 3 and leaves on pins 6 & 7. The output would have about 6v DC (which it does).

Then signal on lug3 of the delay level pot. On the wiper lug 2 if it's not turned all the way down.

Next is the output mixer 1/2 TL072. You won't get signal on pin 2 but you should on pin1. At this stage, you will also get dry signal mixed in, but if you want, you can disable it by unsoldering one end of the 10k resistor between pins 7 and 2 which is Feed marked [A] on the schematic. This way you can be sure the signal out of pin1 is coming from the delay ok.

Thank again Anotherjim, the PCB transfer image had a pad so close to a ground trace it was bridging. However I have been having issues with the traces lifting while trying to fix this issue. I bought the cheapest PCB blanks from Tayda and was wondering if this was causing me pain. Im gonna etch another PCB and try again.... Ive got all the info I need now to get this pedal rocking so thanks for your work.... Ill come back when Ive got the new PCB populated. I would just buy a fabbed one but the shipping from the US to Australia is insane.


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