So my Aquaboy keeps catching on fire???

[giantrobot]

So here goes. I've built a bunch of MB pedal and love them. I decided to take it to the next level and build an Aquaboy DX. At first I had it setup with BL3208s and it worked great but I wanted some more delay time. So I hunted down some mn3005s off EBay. The guy is in the US, has %100 feedback and tests each chip on video. I cracked open the AB ,switched the jumpers, fired it up and got nothing but dry signal. I reseated the ICs and double checked the jumpers and still got nothing. Then it started smoking!!! R58 melted right if front of my eyes.

Can someone tell me what's going on? I'm scared to turn it on!!! Am I screwed? Any help would be much appreciated.

Thanks

[trickpony]

Per the documentation:
IT IS NOT RECOMMENDED THAT YOU SWITCH BETWEEN THE MN3005 AND MN3205/v3205 ON THE SAME
BOARD. We found this caused problems and resulted in dead boards and/or components. If you want to avoid this, you
should decide before soldering in your jumpers which version it will be.


Did you remember to change the jumpers?

[giantrobot]

Yeah I double checked the jumpers. The Aquaboy DX doc say its alright to switch the ICs. I think I'm gonna switch back to the BLs and see what happens. Can anyone test these MNs for me?

[madbean]

It's okay to switch between the two different BBDs on the ABDX as long as the jumpers are set. Go ahead and remove R58 and jumper it. What's happening is that the it's shooting out current and losing it through heat. A larger value resistor or higher wattage would probably be okay but will also increase the voltage drop on the supply. It should be fine without it. I'll add a note in the build doc. It won't damage anything like your BBDs...just toasted the resistor.

Sorry, that was a poor design choice. You could also replace it with a 1N5817 for extra polarity protection, but jumpering it is fine.


Update: added to build doc and a note made in the Errata section: http://www.madbeanpedals.com/forum/index.php?topic=9190.0

[giantrobot]

Cool thanks brain. I jumpered it and its not catching fire but its still not working with these MN3005s. I switched it back to the BL3208 cofig and its working fine. I figured if it was a relabeled MN I would get some sort delay but get nothing. I guess I got ripped off. That really really sucks! The seller had feedback from people sayin the chips were good. Fail!!!

[giantrobot]

Is there anyway to test these ICs before I dispute it with the seller? Is ther something I'm missing?

[madbean]

Can you tell me more about the MN3005? What voltage were you powering it at? Getting signal into pin7 of BBD1 but not out? How do your voltages look on the MN3005 when the PCB is powered up? Do you have any others that you know to be good that you can use as a reference...even MN3008?

[giantrobot]

Well I I'm running at 9v. I have a Road Rage for running it at 15v but I wanted to test it before I did that. I probed it and I'm getting guitar signal at pin 7 but just get a high pitch whine out of the output pins. The battery is dead on my dmm so I can't get voltages till tomorrow. The only BDDs i have are the bl3208s and some v3205s. It works perfect the the BLs.

Thanks so much for the help!