Aquaboy DX clean signal but no delay

[murdog47]

[Scruffie]

Hmm... I might be off, this is just a tiny hunch but something about those chips makes me think one of those might be real and the other looks suspect... but it's incredibly close, might just be the photos. They could still both just be dead or fakes though, good fakes though.

But just for the hell of it, try swapping the positions of the chips and see if with the other first you get delay.

If not, have to dig some more.

[murdog47]

Switched them up and got the same result with both. Anyone out there willing to verify my MN3005's if I ship them to you? I'm pretty sure they are the problem but want to make sure before I go any further.

[Haxman]

Hey,

I just finished my ABDX project with the MN3008 chips and MN3101 clock running at approximately 12V.

I have the same problem as murdog47. I got Dry Audio passing but no Delay.
There is signal passing at Pin 7 of IC2 and Pin 7 of IC3 but only a high-pitched whine coming out at Pins 3 and 4 of the Delay IC. The BIAS1 pot seems to have no effect whatsoever.

I'm reading the following Voltages:

IC1 LF353N
Pin 1 -> 6,3V
Pin 2 -> 6,3V
Pin 3 -> 6,3V
Pin 4 -> 0V
Pin 5 -> 6,3V
Pin 6 -> 6,3V
Pin 7 -> 6,3V
Pin 8 -> 12V

IC2 SA571N
Pin 1 -> 1,0V   Pin 9 -> 1,8V
Pin 2 -> 1,8V   Pin 10 -> 4,9V
Pin 3 -> 1,8V   Pin 11 -> 4,9V
Pin 4 -> 0V      Pin 12 -> 1,8V
Pin 5 -> 1,8V   Pin 13 -> 12,4V
Pin 6 -> 1,8V   Pin 14 -> 1,8V
Pin 7 -> 5,2V   Pin 15 -> 1,8V
Pin 8 -> 1,8V   Pin 16 -> 1,0V

IC3 MN3008
Pin 1 -> 11,4V
Pin 2 -> 5,7V
Pin 3 -> 8,8V
Pin 4 -> 8,8V
Pin 5 -> 0V
Pin 6 -> 5,6V
Pin 7 -> 5,3V
Pin 8 -> 10,5V

IC5 MN3101
Pin 1 -> 11,4V
Pin 2 -> 5,6V
Pin 3 -> 0V
Pin 4 -> 5,6V
Pin 5 -> 5,4V
Pin 6 -> 5,7V
Pin 7 -> 5,6V
Pin 8 -> 10,5V

IC6 TL062
unstable except the V+ supply

Could the problem be dead Delay chips? Or could this whine at pins 3 and 4 have another cause?

Greetings Haxman

[murdog47]

Mine have been verified as bad chips  Sounds like you may have the same problem. Don't rule them out though until you get then checked.

[murdog47]

Ok, I got some MN3005 fakes from smallbear to use and I am getting the same symptoms. I am still reading good voltages as far as I can tell but still only clean signal and no delay. Signal at BBD pin 7 but not 3 or 4. I've decided to attach some pictures. Is there something I'm missing??

[midwayfair]

I think you're supposed to omit the diode on the clock chip.

Could be bad news. I think it blew mine.

[murdog47]

DOH! Thanks Jon!!...been pulling out what left I have of hair! This one got past me in the build docs.

[murdog47]

That was in fact the problem!! Cut out D3 and I am now getting signal through pins 3 and 4 on the BBD's. New issue though is that I'm not getting much delay out of it. Some delay but not much more than a slap back.

[Droogie]

Don't know if you ever solved this, and it might be a shot in the dark, but yesterday I plugged mine in to a 250 mA supply and didn't get delay. Switched over to a 400mA and it worked like a charm... (v3205 version at 9 volts)