9V to +-14v

willwaush · February 04, 2018, 04:17:03 PM

Hey guys, while you are still troubleshooting the issue I went on by myself and draw a schematic & board layout for a 1590BB CE-1.
I have used a DC/DC converter that takes from 9 to 18V and gives +-15V. It has 100mA output per rail. The thing is that on its own it gives me some nice +14.8 and -14.8 but as soon as I hook it up to the circuit something takes the input voltage down around 11V and it starts to smell bad..
The effect doesn't work, I only have clean signal in every configuration. The peak level led and the speed led don't light up.. I am assuming that something is drawing too much around the 1458 area since it seems that it isn't doing its job. Could you please help me to troubleshoot this if I post maybe the schematic and PCB layout?

(Just to be clear, I am not getting any output from the MN3002 by probe testing)

njkmonty · February 04, 2018, 07:05:30 PM

do you have a real mn3002? or one of those da converter eBay things?

DFX-PCBS · February 04, 2018, 08:05:33 PM

What's these da converter eBay things you mention?

njkmonty · February 04, 2018, 08:25:15 PM

MN3002 Package:DIP-14,High-Accuracy 8-Bit D/A Converters

willwaush · February 04, 2018, 08:29:55 PM

Quote from: njkmonty on February 04, 2018, 08:25:15 PM
MN3002 Package:DIP-14,High-Accuracy 8-Bit D/A Converters

I know what you mean, I have the real ones... I got those from a guy who works for Malekko, so they should be good. I could still try to sub one into my original CE-1, but I am afraid of socketing the original MN3002 inside of it.

Anyway, I measured the draw and it seems like 65mA on the negative rail, and 10-20 on the positive. Looks like the 1458 isn't generating the LFO though, otherwise the modulation LED would blink no matter the MN3002

DFX-PCBS · February 04, 2018, 08:32:54 PM

Oh right, never knew of these things, same part number as the bbd.

These..

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F273047649965

willwaush · February 04, 2018, 09:12:02 PM

Quote from: DFX-PCBS on February 04, 2018, 08:32:54 PM
Oh right, never knew of these things, same part number as the bbd.

These..

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F273047649965

Yes I have those even if I didn't get them through eBay. They seem legit. But there is something strange around the circuit... I have tried as well with the LT1054 charge pump on a breadboard and I have the same results. It seems to draw too much no matter what I do. I still don't get why the 1458 isn't generating the LFO wave..

njkmonty · February 04, 2018, 10:45:40 PM

my version draws that amount and sounds great

willwaush · February 05, 2018, 11:26:24 AM

What's your Z impedance seen if you hook up your DMM on +14 and -14 (without supplying it) seen by the meter?
And what about +14 to 0 and -14 to 0?
I have
-14 - 0 = 8.90K
+14 - 0 = 15.13K
+14 -14 = 6.73K

I was thinking... are there any resistors which need to have a strict wattage? Like the ones linked directly to 14V... could a lower wattage resistor cause draw issues and voltage drop to my DC/DC?

willwaush · February 06, 2018, 09:01:13 PM

Okay guys, I've troubleshooted my build and now it powers up nicely with no issues. It draws aprox -25mA on the negative rail now that I fixed it.

Although I still have two issues:

no peak & rate LEDs light up

Vibrato is amazing, but switching to chorus provides no effect.

Any suggestions on what to look at?

njkmonty · February 07, 2018, 01:39:18 AM

check led voltages and try different orientation aswell as q14

check around ic4a measure volatge at d5/r35 are their any voltages when switching to chorus? if not trace back through switch to ic 4

willwaush · February 08, 2018, 05:58:47 PM

Okay guys, made it work. Thank you for your support.
In the end it only draws maximum -30/35mA and +15/20mA. I have tested the LT1054 pump and it powers it up without issues, although I prefer using a DC converter which saves much more space and it's much more reliable (even if it costs about 15€).
One thing that I don't get it's the trimpot... what does that adjust?

armdnrdy · February 09, 2018, 05:40:54 AM

Quote from: willwaush on February 08, 2018, 05:58:47 PM
One thing that I don't get it's the trimpot... what does that adjust?

The balance between the two outputs of the BBD.
It is also called a clock null trimpot for cancelling the clock signal noise.
This can be adjusted by ear but...for best results...an oscilloscope should be used.
With a scope connected to the trimmer's output...while adjusting the trimmer...you can visually see one BBD output superimpose over the other.

nickbungus · February 09, 2018, 08:01:21 AM

Great, well done Willaush!! Glad you got it going. I nearly have a working board too and was wondering about the trim pot. Havent touched it yet and I dont have an Anuscope .

By the way, this is how I got my power section working:

---> Variable Voltage Regulator (LM317) ----> +14v
/
18v Wallwart
\
---> LT1054 -----> -14v

When biasing both the LT1054 and the LM317, after doing the maths, I used trim pots in place of the biasing resistors. Under load, both rails dropped a little bit so I was able to re-adjust. I know this thread is entitled '9V to +-14v' and I've used an 18v supply. This is just a temp measure until I am satisfied my board is 100%

willwaush · February 09, 2018, 12:15:53 PM

Quote from: nickbungus on February 09, 2018, 08:01:21 AM
Great, well done Willaush!! Glad you got it going. I nearly have a working board too and was wondering about the trim pot. Havent touched it yet and I dont have an Anuscope .

By the way, this is how I got my power section working:

---> Variable Voltage Regulator (LM317) ----> +14v
/
18v Wallwart
\
---> LT1054 -----> -14v

When biasing both the LT1054 and the LM317, after doing the maths, I used trim pots in place of the biasing resistors. Under load, both rails dropped a little bit so I was able to re-adjust. I know this thread is entitled '9V to +-14v' and I've used an 18v supply. This is just a temp measure until I am satisfied my board is 100%

That's not an issue since you can always double your 9V to 18V when you get your board working! I simply used diodes instead since, like you say, the voltage drops down a little bit on his own anyway.. so with usually 2-3 diodes you get exactly the +-14V.
I don't have an oscilloscope as well, I need to figure out how to set it by ear.. I am noticing a tiny little volume drop when I engage the effect, I am wondering if it's caused from this trimpot (?). anyway, it's barely hearable as drop, not a big deal. I was thinking as well of lowering R46 and R90 to get more signal pass through, but I'm not sure if the tone of the chorus remains the same.
Anyway, it's really clear how if you design a good board with the right links you can use any kind of supply, even a double LT1054 isn't an issue at all. You guys should go on with it... it's clear how that etched board is probably having some issue that makes it draw more than expected

DFX-PCBS · February 09, 2018, 03:45:16 PM

Quote from: willwaush on February 06, 2018, 09:01:13 PM
Okay guys, I've troubleshooted my build and now it powers up nicely with no issues. It draws aprox -25mA on the negative rail now that I fixed it.

Although I still have two issues:

no peak & rate LEDs light up

Vibrato is amazing, but switching to chorus provides no effect.

Any suggestions on what to look at?

What solved your issue?

willwaush · February 09, 2018, 06:01:31 PM

I had an extra link onto the PCB design so I simply needed to remove that.
Leds didn't work because they were wired reverse
Chorus didn't work because since mine is a double PCB design looks like the pin didn't bring the chorus stage voltage to the MN3002... I had to run it with an extra wire to where it needed to go

Anyway, they were all issues related to my board design, nothing special!

willwaush · February 11, 2018, 05:06:04 PM

Hey guys, does any of you know why on the "stereo" channel I have plenty of wet volume but on the "mono", where it blends automatically wet and dry, when I engage the effect I get a slight volume drop ? What should I look at?

nickbungus · February 12, 2018, 05:57:56 PM

Sorry, I don't but I was having an issue where my output 1 (the effect out) sounded horrible muddy and bassy. I had 2n5457s for the fets. I swapped one of them out for a j113 and it instantly sounded better.

I'm going to try the other 2 tomorrow to see if that makes a difference, but I remember buying some J201s and 2n5457s from China ebay when I first started and I've never been convinced they aren't dodgey.

nickbungus · February 13, 2018, 10:58:28 AM

Just another note on the powering of the CE-1. Heres the schematic

With my test rig as it is with pots controlling the output voltage on both rails:

---> Variable Voltage Regulator (LM317) ----> +14v
/
18v Wallwart
\
---> LT1054 -----> -14v

I can control the voltage on both rails. By playing with the pots, I can really fine tune the lfo to give me the most swing.

This has led me to question whether I have a mistake on my board as there are no trimpots or other methods for fine tuning the lfo on the schematic.

Could it be so sensitive or if I have made a mistake where would be the place to look.

p.s. Could subbing the transistors make a difference. I cant remember what I used as I'm at work at the moment but I will post them tonight with my voltages.

News:

9V to +-14v