Aquaboy -- every problem imaginable

[midwayfair]

Oh lordy. I'm not sure this is really a tech help thread or an opportunity to laugh at me ...

1. Modulation isn't modulating -- the LFO isn't functioning. Somehow I have 15v on pins 1 and 5 .... even though pins 2, 3, etc don't have voltages that high. The chip is socketted and I tried another. No weird continuity or anything.

2. Delay is extremely distorted at pin 3 of the BBD and extremely low level. The bias range where I get any sound at all is very, very tiny. That part might be normal I guess ...

3. Signal is further attenuated at pin 3 of IC 4, and even more distorted.

4. My clock has to be dialed almost all the way CCW to get any signal on pin 3. Hallway is very loud clock noise and no audio. Since the biasing instructions have the clock STARTING at halfway, I'm assuming this isn't normal.

5. I have good signal from the compander going into pin 2 of the BBD, and I have the distorted repeats with almost no delay going into the post-bbd buffers, and I have signal when it hits the compander -- but then the signal completely disappears at pins 10 and 11. 100% dead on those pins.

Using 3005s tested by Gtr2 as genuine ... And the accompanying parts.

This is so many problems I don't even know which to start with.

------------------
Voltages:
-IC1 is correct and working.

-Compander:
1 - 1v
2 - 1.8v
3 - 1.8v
4 - Ground
5 - 1.8v
6 - 1.8v
7 - 3.1v
8 - 1.8v
9 - 1.8v
10 - 4.6 (?)
11 - 4.6 (?)
12 - 1.8v
13 - 15v supply
14 - 1.8v
15 - 1.8v
16 - 1v

Clock
1 - 13.3v
2 - 6.6v
3 - Ground
4 - 6.6v
5 - 6v
6 - 6.6v
7 - 6.4v
8 - 12.6

BBD chips:
IC3
1 - 13.3v
2 - 6.6v
3 - 9.7v
4 - 9.7v
5 - Ground
6 - 6.6v
7 - 4.5v
8 - 12.6v

IC4 - Same except
3 - 9.2v
4 - 9.4v
7 - 3.9v

IC 6
1 - 14.25v
2 - 1.3v
3 - 8.6
4 - ground
5 - 14.1 (not identical to 1 in any switch position)
6 - 9
7 - 9
8 - 15v

Delay lug 1 - 2.9v

Anode of

Top-side picture:

[gitaar0]

Hi Jon,

Just some suggestions and questions to have a starting point:

The lfo can be viewed as a separate problem for now.

If you have a distorted signal at pin 3 on bbd 1 then you are bound to have an even more distorted signal on pin 3 of the secon bbd. So let's get he first one right first.

If you have a clean signal going in bbd 1 then you shpuld be able to bias it with a reasonable clean signal at pin3 of bbd 1 when the clock is working ok.
If you have to dial the clock ccw to get signal then there should be someting wrong there.


What clock chip are you using? It should be the mn3101 when on 15 volt.
I would check all the components around the clock and my soldering there. What are your voltages on the clock Ic?

Maybe it helps for a start.

Marc

[Scruffie]

Oh lordy. I'm not sure this is really a tech help thread or an opportunity to laugh at me ...

1. Modulation isn't modulating -- the LFO isn't functioning. Somehow I have 15v on pins 1 and 5 .... even though pins 2, 3, etc don't have voltages that high. The chip is socketted and I tried another. No weird continuity or anything.

2. Delay is extremely distorted at pin 3 of the BBD and extremely low level. The bias range where I get any sound at all is very, very tiny. That part might be normal I guess ...

3. Signal is further attenuated at pin 3 of IC 4, and even more distorted.

4. My clock has to be dialed almost all the way CCW to get any signal on pin 3. Hallway is very loud clock noise and no audio. Since the biasing instructions have the clock STARTING at halfway, I'm assuming this isn't normal.

5. I have good signal from the compander going into pin 2 of the BBD, and I have the distorted repeats with almost no delay going into the post-bbd buffers, and I have signal when it hits the compander -- but then the signal completely disappears at pins 10 and 11. 100% dead on those pins.

Using 3005s tested by Gtr2 as genuine ... And the accompanying parts.

This is so many problems I don't even know which to start with.

Right... i'm assuming this is the DX project?

A full list of voltages is going to help here as always.

A few things gitaar0 has already covered here so forgive for the repeating.

1) While gitaar0 is right about it being a separate issue, let's look at it anyway. Pins 1 & 5, what is connected to them in any way, R45-47 & C34 & 35 and the Rate Pot, assuming you have 7.5Vish on Pin 3, the LFO V.Ref is working so we can ignore R43&44 and one of those components I mentioned is probably shorted or has a solder hair connecting it to a 15V point, a re-flow of the area might be all that's needed.
(I'd look closely at R43, the voltage input to the V.Ref is at the top of it and it's right next to R45, 46 & Pin 1)

2) Bias range should be... a rough estimate 1/8th to 1/10th of the entire rotation of the trim should provide some delay. You say the output is distorted and quiet, what's the signal like on Pin 7, clean and present like you'd expect? As gitaar0 mentioned again, the next BBD is working with a crappy signal so it's gunna put out an even worse one, focus on getting the first BBD to delay properly first. Voltages for this BBD might make an issue clear. A poor clock signal will result in a poor BBD output, the other option is something is wrong with the source follower.

3) See above.

4) It does sound like your clock isn't working right, it shouldn't need to be dialled to long delay times just to hear delay, seems it's not putting out a proper pulse. Voltages! Also where was it sourced from and did you take ESD precautions when handling it (CMOS so it's static sensitive). It's not a sure check but you should expect to see half supplyish on pins 2 & 4 and they should both be the same voltage.

5) Get output from the BBDs first before you trace further down the line.

[midwayfair]

Thanks guys. I'll go over it this weekend and give it a reflow as well and then take voltages.

Clock is 3101 and the compander is a 570, both from smallbear.

EDIT: Since there's no signal at pins 10 and 11 of the compander (and correspondingly on the mix and feedback pots), am I likely to need a new compander as well? I mean, I should still have the same signal that went in at pins 15 and 16, right? 

[juansolo]

It's REALLY easy to pop the compander when messing around with this circuit. I think I've killed at least 3.

[madbean]

Try lowering or removing R37, Jon. See if that fixes the output on pins 10/11.

[midwayfair]

It's REALLY easy to pop the compander when messing around with this circuit. I think I've killed at least 3.

fuuuuuuuuuuuuuuuuuuuuu

Blowing $5 chips is not my idea of fun.

Brian, thanks for the tip, I'll try that, too.

[gtr2]

If you need a compander, I believe I have a one that I'm not using anytime soon.  You know where to find me..

[midwayfair]

If you need a compander, I believe I have a one that I'm not using anytime soon.  You know where to find me..

Thanks, Josh, but I need other stuff from Smallbear, and you already did me a big solid testing the BBD chips to put my mind at rest about THAT particular question.

[midwayfair]

Updated the first post with voltages and a top-side picture.

The LFO still has me mystified. Everything checks out according to the multimeter; it's just not functioning.

[midwayfair]

Doh. I just saw that I need to omit R55 and R27. Will report back in a moment.

Edit: no meaningful changes.

[gitaar0]

Hi Jon,

I am not at home so i can not compare all voltages. Just a few things for now:

D3 should be left out if you are using mn3005's at 15 volt.

Your power supply voltage at ic 3 and 4 is too low. (i forgot which pin) It should be around 15 volt.

Check my thread on the compander voltages that should be half the powersupply to get the best signal. Yours are off too.
Scruffie pointed that out to me.

[midwayfair]

Hi Jon,

I am not at home so i can not compare all voltages. Just a few things for now:

D3 should be left out if you are using mn3005's at 15 volt.

Your power supply voltage at ic 3 and 4 is too low. (i forgot which pin) It should be around 15 volt.

Check my thread on the compander voltages that should be half the powersupply to get the best signal. Yours are off too.
Scruffie pointed that out to me.

This is partly my carelessness for sure. I made a note about your thread weeks ago and completely forgot. I'll make a few more changes, pull D3, etc.

[midwayfair]

Well, if the compander wasn't dead before, it is now ...
I pulled D3, changed R13 & 14 (sockets), and removed R37 (also sockets). The clock chip still whines above about a 1/4 turn, and now there's no signal after the input at the cmpander. I'm going to get new chips before I give up on this.

I've tried everything I can think of on the modulation circuit, too. I'm baffled and I've built this sort of modulator a dozen times and never had it not fire.

[gitaar0]

Do not give up on this. It is a great build when it works.
Considering what I have seen of your builds you should be able to ge this working.
Sorry that I can not be f help from where I am now. Maybe later.

Do not give up!