Echo base debugging

[guidoilieff]

The input audio just reaches past the first 100n capacitor, then its just like white noise delayed anyware. Time, Feedback and Mod Depth affects the output so pt2389 seems to work fine.
LED doesnt light up.

I replaced the 240k resistor next to the Mod Depth with a 220k, the 470p cap on pin 15 of pt2399 I replaced it with 561p and the 1u cap coming out pin 2 of the second tl072 I replaced it with a 105 film capacitor rated for 100v.

tails and bypass doesnt seems to make any difference.

Then I replaced the 2n5089 with a 3904, the bc560 with a bc559 and I used a 78l05.
(the voltages at pins 3 and 6 of the tl072 that connects with the 5v regulator output is 7.5/8v)

I used a stereo 50k pot that I think I wired correctly  http://www.bestronusa.com/images_products/PTC-503T6S.jpg

Schem
http://static1.squarespace.com/static/54696a3ee4b05a85cbfe56e5/t/5469759be4b05145d3fd695e/1416197531945/Echo-Base-build-PDF-updated-051810.pdf

Layout


power: 8.75v

tl072 1:
1-8.45 |  8-8.75
2-8      |  7-8.10
3-7.45 |  6-8.47
4-0      |  5-7.85

tl072 2:
1-7.20 |  8-7.85
2-2.2   |  7-2.15
3-7.78 |  6-7.75
4-0.80 |  5-5.37

3904:                 BC559:              78l05:
E:0                     E:0                     IN:8.75
B:0.63               B:2.31                GND: 0
C:1.50               C:2.85                OUT:7.80

MC14066:

1-7.22  |  14-8.78
2-7.27  |  13-8.58
3-0.45  |  12-1.82
4-0.45  |  11-7.67
5-0       |  10-6.57
6-0.75  |  9-0
7-0       |  8-8.72


PT2399

1-7.80  |  16-3.90
2-3.89  |  15-3.80
3-0       |   14-3.94
4-0       |   13-3.91
5-4.79  |  12-3.91
6-3.89  |  11-3.91
7-3.80   |  10-3.91
8-3.7/8 |  9-3.91


Thanks

[guidoilieff]

and I used a 1n4007 instead a 1n4001 that I think it wont do any harm.

[Tightpants]

Looks like your 5V regulator is not working properly, I would start by investigating that. Check to see if the regulator is the right way round (the clue is that your measured output voltage is only slightly less than the input voltage - if you connect a 7805 regulator the wrong way round the built in protection diode becomes forward biased and the apparent output voltage goes up within a diode drop of the input). If it is the right way round then remove all the chips and check the voltage at the regulator output. If it is not 5V then either the regulator is fried or you have a solder bridge somewhere. I doubt the PT2399 will be OK after giving it nearly 8V but you might get lucky.
Good luck anyway!

[mcknib]

As Pat says the 7805 and the 78L05 have different pinouts just turn it the other way and providing you've no other errors like a zapped PT2399 all should be good although from the datasheet the absolute maximum voltage rating for the chip is 6.5v but you never know! There is some fairly inaccurate info in the datasheets for this chip.

Not trying to be a smart ass here but any circuits I build that use regulators or charge pumps I always check what's coming out of them before I let it loose on the rest of the circuit I've frazzled a few chips in my time so I'm a wee bit cautious these days! Hopefully yours will be ok.

[guidoilieff]

Looks like your 5V regulator is not working properly, I would start by investigating that. Check to see if the regulator is the right way round ....

As Pat says the 7805 and the 78L05 have different pinouts just turn it the other way and providing you've no other errors like a zapped PT2399 all should be good....

The 5v regulator is not the problem. I already swapped the pins. As I said, the voltages at pins 3 and 6 of the tl072 that connects with the 5v regulator output is 7.5/8v. I tested it without the 5v regulator.  I checked resistor and cap values and orientation.

[guidoilieff]

some pictures


https://farm1.staticflickr.com/683/20331970263_5f91ef45e1_o.jpg (never mid the led)

https://farm1.staticflickr.com/619/20766251619_fdd0983c8e_o.jpg (out of focus)

https://farm6.staticflickr.com/5695/20764956040_fdefcc68bf_o.jpg (made from 2 pictures)

[mcknib]

The 5v regulator is not the problem. I already swapped the pins. As I said, the voltages at pins 3 and 6 of the tl072 that connects with the 5v regulator output is 7.5/8v. I tested it without the 5v regulator.  I checked resistor and cap values and orientation.

Sorry I'm slightly confused so with the regulator in circuit you're still not getting 5v output or not?
have you tested the regulator on a breadboard or some other way to see if it's ok?

I don't follow when you say the regulator's not the problem how do you know it's not the regulator or it's socket solder joints?

[anotherjim]

With the regulator out, continuity test between the orange and red traces on the board. Somehow, the +9v feed is getting fed directly to the +5v regulated supply. Be prepared for the possibility that the PT2399 may have been damaged by the excessive voltage.

[slacker]

I would remove all the chips so that you don't damage them any more than they already might be. Then measure the voltages on the orange traces on the layout, these must all be 5 Volts. If they aren't then the problem is either with the regulator, it's broken or in the circuit the wrong way round or there is a short between the orange traces and the red 9 Volts ones. You can test for this by removing the regulator and then measuring the voltage on the orange traces it should be 0.

EDIT: Jim beat me to it

[guidoilieff]

I started over and it was the first tl072. I dont know why but it was damaged from scratch. The pt2399 survived!
I cant believe I made all those measurements for a bad ic.


Thanks everyone!

[guidoilieff]

Actually the led won't turn on at all. The ic pin is 0v. Already tried inverting the led.

[slacker]

Try removing the LED and then measure the voltage on pin 9 of the CD4066, with the delay on you should get 9 volts with the delay bypassed you should get 0 volts, also measure pin 8 this should be 9 volts in both settings. If you don't get those voltages check all the connections to pins 6, 8 and 9 of the CD4066 and all the components connected to them. If you get the right voltages then you either have a problem with the connections to the LED or a broken LED.

[guidoilieff]

Modulation works fine, but that pin is 0v. I tested the led and its fine and there is nothing else connected to that pin. Could it be that it only works with super bright leds or something like that?

[slacker]

It should work with any LED, even if the problem was just the LED not lighting up there would still be 2 or 3 volts on pin 10 when the delay was on. Try removing the CD4066 and use a piece of wire to connect pins 8 and 9 on the socket, that should make the LED light up. Pin 6 controls the CD4066 switch that turns the LED on and off so the problem could be there, check that pin 6 is not shorted to ground. If it isn't then with the CD4066 in the socket and the effect powered on connect pin 6 to 9 volts that should turn the LED on, if it doesn't then you have bad connection to pin 6 or the 10M resistor or the CD4066 is bad.