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benobo wrote:

madbean wrote:Also, those MAX chips usually only tolerate a max of 12v (I think they are rated at 10v) so if a larger DC supply was plugged in it could have damaged it.

Can I replace the MAx1044 with a 7660scpa? I believe it's cool but just want to double check/


thanks

Yup!

7660scpa;

9.11
4.56
0
-4.34
-8.79
4.57
7.03
9.11

tl074

pin 4 :9.10

pin 11: -8.97

all other pins 0 v

benobo wrote:7660scpa;

9.11
4.56
0
-4.34
-8.79
4.57
7.03
9.11

tl074

pin 4 :9.10

pin 11: -8.97

all other pins 0 v

We have a winner! It's a split rail supply and the bias is ground. You've at least partially fixed the problem.

What you can do at this point: use an audio probe on the various pins of the compander and the two BBDs to see if the signal is being passed or not. It COULD be that you signal is going through the compander but suddenly absent at BBD1 or BB2. If so, then it could be a case of needing to re-bias via the trimpots.

I believe that pins 8-16 on the NE570 are being used for the compressor portion of the circuit, based on the voltages. You should probe those pins first.

Morning All,

I suppose Nashville is still in the Dark. London is, but for a different reason.

First, a big Thank to Madbean for his help on this bad boy . I have replace the Max1044, and now I have got SOUND ! but no Delay at all . I am going to check the BBD and NE570N.

B

benobo wrote:Morning All,

I suppose Nashville is still in the Dark. London is, but for a different reason.

First, a big Thank to Madbean for his help on this bad boy . I have replace the Max1044, and now I have got SOUND ! but no Delay at all . I am going to check the BBD and NE570N.

B

You're in London? If you get stuck, i'll happily check it over for cost of postage there and back.

But for now, give us your new voltages

Thanks for your offer scuffie

voltage reading for

NE570N, V3102 and both V3205 are the same than readings above

B

TL074;

pins:
1
3
5
7
8
10
11
12
14

all connected to ground

madbean wrote:What you can do at this point: use an audio probe on the various pins of the compander and the two BBDs to see if the signal is being passed or not. It COULD be that you signal is going through the compander but suddenly absent at BBD1 or BB2. If so, then it could be a case of needing to re-bias via the trimpots.

I believe that pins 8-16 on the NE570 are being used for the compressor portion of the circuit, based on the voltages. You should probe those pins first.

Hi Madbean,

I am using the audio probe. On pins 8 and 16 of NE570N, the amp stops buzzing.

on BBD 1 there is a hiss on pins :2-3-4-6 and 7
BBD 2 , hiss on pins :2-3-4 and 6

thanks

using the audio probe on pins 11-12-14 and 15 of NE570N, there is a "Shiiiiiiiiiiiiiiiiiiii" detuned radio like sound.

Thanks

Benobo

madbean wrote:

benobo wrote:V3205 (1)

0
3.92
4.80
4.80
8.47
3.91
4.63
6.82


V3205 (2)


0
3.92
4.52
4.52
8.47
3.91
4.47
6.82

8.47v is on the high end of the maximum supply for the v3205, but they might still work this way. You'd have to trace it back to how the VDD supply is done...usually an 8.2v zener, but here they might have just used a resistor or two. Other than that the voltages look okay.

Do you have an audio probe?

8.47 should be fine, the max supply is 10V, the optimal voltage is related to noise/input distortion.

Pins 2 & 6 show the clock's doing its job...

Pin 8 is a bit low, but I guess that's probably just how it's set up, still... something to keep an eye on, other than that as bean says, they look fine so for now we'll rule out the 3102 or 3205s being injured.

6,7,10,11,14,15 are the pins to check on the 570 I think i'm right in saying, but ignore it for now, finding the signal on the TL074 will be more important as it'll be at the input/output of the effect.

Check pins 1,7,8 & 14 on it for audio.

When it comes to checking the BBD, you're only interested in signal being on Pins 3,4 & 7.

Yeah, pin7 on the v3205 is the input and 3 and 4 are the two delay line outputs. So, if you have input but no output you will need to adjust one of those bias trimmers until you hear an actual delay signal.

Scruffie--thanks for the clarification on supply voltage.

Scruffie wrote:

madbean wrote:

benobo wrote:V3205 (1)

0
3.92
4.80
4.80
8.47
3.91
4.63
6.82


V3205 (2)


0
3.92
4.52
4.52
8.47
3.91
4.47
6.82

8.47v is on the high end of the maximum supply for the v3205, but they might still work this way. You'd have to trace it back to how the VDD supply is done...usually an 8.2v zener, but here they might have just used a resistor or two. Other than that the voltages look okay.

Do you have an audio probe?

8.47 should be fine, the max supply is 10V, the optimal voltage is related to noise/input distortion.

Pins 2 & 6 show the clock's doing its job...

Pin 8 is a bit low, but I guess that's probably just how it's set up, still... something to keep an eye on, other than that as bean says, they look fine so for now we'll rule out the 3102 or 3205s being injured.

6,7,10,11,14,15 are the pins to check on the 570 I think i'm right in saying, but ignore it for now, finding the signal on the TL074 will be more important as it'll be at the input/output of the effect.

Check pins 1,7,8 & 14 on it for audio.

When it comes to checking the BBD, you're only interested in signal being on Pins 3,4 & 7.

Hello All,

I have used an audio probe, following this instructions : https://www.diystompboxes.com/pedals/debug.html.

Could you, please guys, let me know what the different sounds I heard mean?

On some pins : "Shhhhhhh" detuned radio like sound. (on the NE570N)
on other pins: a high pitch hiss. (on V 3205)

So, if I understand you both well, I just have to re-calibrate the Bias on the V 3205. I am going to give a go then.

Thanks again for your time.

Scruffie: If I send it to you, would you have the will or time to trace the ECHO?

High pitched whine on the 3205 is likely the clock signal, that's a good sign.
Hiss... I wont deny, my Compander knowledge is lacking, probably normal though.

I'm not sure about the bias being off, the voltages look fine for it and there's no reason it should have unbiased itself really, then again it can't hurt to try if you know which trims are which.

Much as i'd love to trace it, while I can debug a delay i've never tried my hand at a full trace so you'd have just as much luck as I would.