Aquaboy DX - no delay

[sclemmer]

Aquaboy Deluxe - no delay. No matter where I set the bias trimmers, I have no delay.

No part substitutions. I originally intended to run this at 15v but I ended up not going this route. I am not using a diode in D2 per the build doc.

I've only followed the troubleshooting tips in the build doc to try and resolve this.

From the troubleshooting tips in the build doc:

Audio probe pin7 of IC2 to confirm that the compander is working. Yes it is.

Probe pin7 of IC3 to confirm that the first BBD is receiving signal. Confirmed.

Confirm that you have set the jumpers properly for the BBD set you are using and that pins 1
and 5 of each BBD are receiving power/ground appropriate to that device. I'm using MN3005's and the jumpers are set accordingly. My reading on the IC's are
IC 3: pin 1 8.06 - pin 5 3.4
IC 4: pin 1 8.06 - pin 5 3.4

I followed the calibration steps and ended up with 6.7khz on the clock without any noise. I have clock frequency on pins 2 and 6 of IC3 as well.

Any help would be greatly appreciated, I have a lot of money tied up in this and after a failed DirtBag that I didn't troubleshoot, I would really like to get this working.

I've built several MadBean pedals and have not had an issue before (other than the dirtbag). My last two builds were a ZP SDX and a Nautilus. I've checked my joints and things look good, no bridges, no apparent cold joints.

Thanks.

[stecykmi]

try and narrow down where the signal is being lost. to see if it's being lost before or after the 2nd delay stage, probe pin3 and pin4 of IC4 (the output of the mn3005). try adjusting the bias to see if you can get signal.

if you _do_ get signal, the signal is likely being lost in the filter section based around Q3 and Q4. if you _don't_ get signal, check pin7 (the input) of IC4 for signal.

if there is no signal at pin7, probe around R24/R23/C20.

if there is signal at pin7, it may not be biased properly (check the voltage at pin7), or your chip may be bad.

can you confirm both chips are good? try swapping them and check the output pins again.

[madbean]

You should be reading 0v on pin5 of the two BBDs. When you set the jumpers, it connects both of those pins directly to the ground trace.

You can run the ABDX on 9v no problem, and considering you have signal up to the input of the first BBD...well, something is just not right there.

I would spot check some other ground points on the PCB, including the GND pad itself to take some voltage readings. If you are not reading 0v in any spot, then it is a wiring issue. If you read 0v in some spots and not others, then we might need some pics.

[sclemmer]

Thanks for the replies. I'll run through these suggestions later this evening and report back.

[sclemmer]

try and narrow down where the signal is being lost. to see if it's being lost before or after the 2nd delay stage, probe pin3 and pin4 of IC4 (the output of the mn3005). try adjusting the bias to see if you can get signal.

No signal no matter where bias is set.


if you _do_ get signal, the signal is likely being lost in the filter section based around Q3 and Q4. if you _don't_ get signal, check pin7 (the input) of IC4 for signal.

No signal on pin7.

if there is no signal at pin7, probe around R24/R23/C20.

No signal on any of these 3.

if there is signal at pin7, it may not be biased properly (check the voltage at pin7), or your chip may be bad.

Voltage is reading 1.135...

can you confirm both chips are good? try swapping them and check the output pins again.

I've swapped them, they both seem to exhibit the same symptoms.

You should be reading 0v on pin5 of the two BBDs. When you set the jumpers, it connects both of those pins directly to the ground trace.

I checked again and I am reading .008 on pin 5 of both chips.

You can run the ABDX on 9v no problem, and considering you have signal up to the input of the first BBD...well, something is just not right there.

I would spot check some other ground points on the PCB, including the GND pad itself to take some voltage readings. If you are not reading 0v in any spot, then it is a wiring issue. If you read 0v in some spots and not others, then we might need some pics.

I get zero on the ground points when checking against the ground lugs on the switch. Am I checking at the right points? This is the first debug I've done. Also, I have the power jack wired with two wires coming from the ground lug, one is going to the - spot on the board and the other going to one of the ground lugs on the switch.

[madbean]

Sounds like ground it okay. Where did you get the MN3005? Are you sure they are good chips? Have you ever used them before?

[sclemmer]

I bought the MN3005's from eBay from this seller: http://stores.ebay.com/Funkward-Technology?_trksid=p2047675.l2563

According to him they are legit and as far as I can tell from reading around on how to spot fakes they appear legit to me. I have no way of testing them. I think I have some "fake" MN3005 from smallbear that I will try using and see what happens. I'll report back later this evening with my findings.

[madbean]

Yeah, sub in one of those fake Smallbear ones for the first BBD and see if you can get some output. The fakes are MN3008 which will work fine for testing here.

[sclemmer]

Still no delay with the MN3008's, same exact issue.

[jimilee]

Now you gotta pull out the magnifying glass and hunt the solder bridge. It's there somewhere.

[stecykmi]

do you get signal at R18/C17?

[sclemmer]

do you get signal at R18/C17?

Sorry for the late reply, yes, I get signal at both R18 and C17.

[murdog47]

I just finished populating my ABDX a couple of days ago and am having this same issue. Any updates? I've been troubleshooting like mad and I'm stumped.