Aquaboydeluxe mn3205 strange...

[Kivjah]

Hi, all  

I build a Aquaboy deluxe with 2xmn3205.
I would like to say thanks for the very good quality of the PCB.
i calibrate the clock at 7khz for the max delay time and adjust the output of the bbd with scope and a sin wave 500hz 0.6v rms, for the best lower distortion.
I use mn3102 for the clock and a zener 8.2v for d2 and "empty" d3
i use 100k resistor for R55 and 470k for R27  and i have all the time a very clean signal.

There is just something strange :
sometimes when i turn on the power i have no delay and no signal at the output pins of one bbd.
i turn off the power and move the delay time control up and turn on again and that work...
At the start i put this bbd in fisrt and after i change it to second position.  i have all the time the delay signal with the other bbd...
That not critical because it sound very good but That very strange...
Maybe this bbd is fake or work bad but when it work it sound good... If you have a idea....

thanks.

Edit : sorry i post a new topic and there is a similar probleme here ? http://www.madbeanpedals.com/forum/index.php?topic=10638.0

[twin1965]

Hi. There's also this thread: http://www.madbeanpedals.com/forum/index.php?topic=10743.0

He's got two builds that are not passing delay. I've be trying to troubleshoot mine but have very little time at the moment to do it in depth.

Hopefully I can find what the problem is.

Keep on doing your troubleshooting checks and go through the two threads. Maybe something in there will help with your issue.

[Kivjah]

Thank's
I have the same problem of you, and i find a rapid issue for the moment : i turn on two time the delay with a the second time a high clock and it work fast, don't need to wait.
I'll try to reduce or jumper R55 and/or R27, maybe the BBD need a higher signal and/or a high frequency clock (normaly not it can turn on at the lowers frequency clock) for "engage" the delay. Or more current for bias. 

Edit : from Aquaboy PDF : R55 and R27:

"... You may also notice that large resistors  here wi l l pro vide additional current limiting from the two Bias trimpots. If
you are having trouble achieving the correct bias via the tr impots with R55 and R27 then reduce R18 and R26
respectiv ely. This did not seem to be an issue on the prototype builds."

[Scruffie]

Have you guys tried adding D3... might be worth doing.

[twin1965]

I'll try to reduce or jumper R55 and/or R27

Keep us posted on your results.

Have you guys tried adding D3... might be worth doing.

Yes. Worth doing 

[Scruffie]

I'll try to reduce or jumper R55 and/or R27

Keep us posted on your results.

Have you guys tried adding D3... might be worth doing.

Yes. Worth doing 

The BBD doesn't need a high frequency clock (it needs a good square clock wave and a clock frequency to match the delay time).

Did D3 and its cap fix your issue?

[Kivjah]

No that's the same with D3 and/or change R55 value, i think it's maybe a probleme with the clock to "start" the bbd sequency, the vgg voltage is 7,7v. i think that because when i turn up the delay pot to high frequency clock and turn on power, all the time the delay start and work at all frenquency clock after.thanks for your help.
Edit : i have a good square wave signal, saw with scope.

[Scruffie]

Edit: Nevermind...

[Kivjah]

  Ok the delay full work, see in this post :
http://www.madbeanpedals.com/forum/index.php?topic=10638.msg97540#msg97540