Echo Base - a new PT2399 delay

[fegg]

the mod mentioned was just for the 1M LFO pot.

However, I am using only 100k lin pots for all the pots in the echbase.

For the delay-time, just throw in a 100k pot. You'll get the possibility to get longer delays, no adjustments needed.

sweet thanks.

[slacker]

On this picture it looks like your opamps are the wrong way round. On that layout the opamps are upside down compared to the other 2 chips, so looking at the board with the slanted corners at the top the spot, which normally tells you where pin 1 is, should be bottom right of the chip.
Unfortunately if you've put them in the wrong way round you've probably killed them 

[mikemaddux]

I do love them blue boards!

I could be optic-illusion, but from the pics I'd say look at the area's I marked below:


I looks like there are some shorts there. There may be more, I did just a quick scan.

Thanks for the help!
The lower left one is a jumper that is arched over the trace.  I forgot to put the jumper in under the IC 

Ill look at the other two tonight when I get home.  I know, chances are its probably a shoddy soldering job on my part.

this is a little OT but does anyone know if I can get a fine pencil tip that will screw on to my soldering iron? 
My regular one just isnt cutting it for tight boards like this one.

[Auke Haarsma]

your welcome.

Please also check Slackers post about the IC's being oriented incorrectly. I just looked at the pic, Slackers looked at the layout!

[mikemaddux]

your welcome.

Please also check Slackers post about the IC's being oriented incorrectly. I just looked at the pic, Slackers looked at the layout!

" I just looked at the pic, Slackers looked at the layout!"
I dont quite get what you are trying to say...

[davent]

your welcome.

Please also check Slackers post about the IC's being oriented incorrectly. I just looked at the pic, Slackers looked at the layout!

" I just looked at the pic, Slackers looked at the layout!"
I dont quite get what you are trying to say...

Hi Mike,

He just means that he didn't compare the layout to your picture so didn't notice the TL072's were installed the wrong way around.

Take care,
dave

[mikemaddux]

I now see what he was saying, I had missed slacker's earlier post.

I switched around the TL072s and am now getting bypassed signal and a slightly lower volume uneffected signal when the effect is on.

Ill search around the 20 some odd pages in the post to debug this problem tomorrow.

Ive got to say this board is driving me nuts.  I may have to scrap it and start over.

[Barcode80]

there is a good chance the tl072 chips are blown since they were in backwards. You may need to replace those...

[Auke Haarsma]

pin voltages would help debugging!

[slacker]

Yeah check your voltages against the ones on page 4 of this thread that should help figure out what's wrong.

[mikemaddux]

looking at the board, component side up, with the cut corners at the top.

top right TL072
8.75
2.66
0.28
0.00
0.28
8.72
8.75
9.36

bottom left TL072
8.29
4.06
0.28
0.41
5.67
0.28
8.32
8.92

PT2399
0.20
0.10
3-16 0.00

CD4066
0.16
0.16
0.00
0.00
0.00
0.82
0.00
9.25
9.25
0.16
0.16
7.67
8.81
9.39

This thing seems really screwed up...

[Auke Haarsma]

doesn't look good indeed...

what's coming out of the 7805? (voltage reg)

[kierc]

Do you have to use that 7805? or can you use a 78L05?

[Auke Haarsma]

I always mix those up   7805 and 78L05 should both do the trick. 7805 is overkill though.

[slacker]

Yeah a 78L05 will be fine, I used a 7805 because I had some lying around.

[slacker]

Mike, something is very wrong there, looks like there's a problem with the voltage regulator, because you're not getting 5 volts anywhere.
Try pulling all the ICs and then measure the voltage on all 3 pins of the regulator, with the layout how you had it for your other measurements you should get 9 volts on the top pin, 0 on the middle, and 5 volts on the bottom. It might also help to look at the the layout here the red traces should be 9 volts and the orange ones 5 volts.
If you still don't get 5 volts where you should it probably means you've got a short somewhere, pulling the 5 volts down, in which case the regulator will probably be hot. Or you've got the regulator in the wrong way.
If you do get 5 volts with the ICs removed then the most likely thing is that you didn't replace the TL072s and they have been damaged by putting them in the wrong way round and are shorting the 5 volts out.

[mikemaddux]

I did replace the ICs when you said to.

The 7805 i used was getting hot when I first built this.  I assumed I had it the wrong way and rotated it 180 degrees.  Just to be clear, that was b4 I posted my problem on here.

[mikemaddux]

I dont get any voltage out of any pins of the 7805.

I had purchased this board and when I changed the orientation of the 7805 one of the solder pads fell off. 
Could it be an issue with a low quality board?

So have I now fried all the new ICs I put in there?

[Auke Haarsma]

I don't think it is a low quality board (it is from John right?). However, a board can be damaged during soldering. Happens to me sometimes too. Doesn't mean the board cannot be used anymore. You just have to make sure the connection that is damaged gets restored.

Here are some points to check to help you debug.



The yellow area (1) is the main +9V line. Here is where the 9V enters the PCB. Measure here. Do you get +9V ?

Next, go to yello area (2). This is where the 9V gets to the 5V regulator. I can see now that the area is damaged. Check that the pin makes contact with the 9V trace. From your report I expect that that there is a problem here.

If there is no contact, you can swap in a new regulator and bent the pin for 9V to the trace. That's how I often solve these issues.

Now check blue (3). This should be reading 0V since it is connected to ground. Does it read 0V?

Finally check pink (4). This is where you would expect 5V coming out of the regulator.

Your voltagereadings do suggest there is more wrong than just the 5V reg. However, I'd say first try to fix/verify this.

[mikemaddux]

update:

I checked the solder joints on my 7805 regulator, the damaged joint had come loose again so I soldered it back in place and
1) I am getting 8.1 at the input
2) It was damaged as you thought and like I said above I reslodered that joint and I am getting 8.1 at that junction
3) I am getting 0.00 at the ground connection
4) The regulator is outputing 5.08 at this point.

I checked all these with the chips removed.  I removed the battery and replaced all the chips.  I pluged the battery back in and smelled that smell we all dread the most.  I felt all the chips and the top right TL072 was very hot and I removed it immediately.

Since it was plugged into my demo amp it started producing a strange circuit bent type chirping noise.  all the pots respond and slow the pitch/speed/volume.....

Thanks for the help everyone.  Auke, great walkthrough.  BTW I wasnt implying anything about John's PCB etching abilities.  He is the man when it comes to etching, Ive completed two of his other boards successfully.  I was more asking about separation of copper from PCBs without applied pressure as ive never had this happen before.

Ill reply with pin voltages.  Thanks again.