Electric Mistress debugging: Please help!

[cathexis]

Hi!

Well, I got bit by the flanger bug upon finishing my A/DA Flanger last month. It's the best pedal I've built.
I made my own vero layout for it, and thought I learned a lot in the building process, especially about calibrating such a beast.
So I decided to tackle the EH Deluxe Electric mistress first, then move on to the Ibanez and the DOD flangers...
For me it's just the challenge. I don't really need flangers, I just find them fun to build, at least until now.

I finished my vero layout about a week ago (see pic at the end of this post). I used this schematic from GGG:

http://www.generalguitargadgets.com/diagrams/dmistsc.gif

I made an on-board diode bridge with filter caps so I can use it with an 18vAC PSU.

I noted the error on the schem, where pin 1 and 4 of the LM311 are tied to ground instead of pin 7, so I fixed that on my vero layout.
Other than that, I followed the schem, no part substitutions.

Since completing the build, I've been twiddling trimpots like crazy, checking things with a scope,
but I can not get this thing to work in any way. At some settings It passes the original sound, albeit at a low level,
some settings are just noise, sometimes modulated with the speed changing according to how I set the Rate control.
The clock and LFO seems erratic, but at some point I could get a square wave of 35kHz at pin5 of the 4013 with Range maxed in
Filter Matrix mode, as per the alignment instructions posted elsewhere on this forum. Other than that, I've had no luck at all with this.

Of course, the first thing you suspect is a faulty SAD1024 - mainly because that would plainly suck .
Then again, nothing else seems to work right either.

The Rate and Range controls seem to work, in Flanger mode I can see the sweep doing the right things when I probe
pin 5 of the 4013 with a scope. The Mode switch works, in that is halts the sweep in Matrix mode.
The Color control I'm not sure of, I can't detect any changes from turning that.

I've checked this layout more than I've ever checked anything. I've checked and reflowed my soldering.
I even carefully breadboarded the whole circuit once, and it sounded just as bad...

I'm at a total lack of understanding here - any help would be greatly appreciated!



Here are some readings:

Controls: Rate min, Color min, Range max, Matrix mode. All trimpots set to mid point.

Power: 14.7VDC from pin 3 of 7815.

IC1: 741
1:   0
2:   12.45
3:   12.57
4:   0
5:   0
6:   12.65
7:   13.61
8:   0

IC2: 4558
1:   3.45
2:   3.46
3:   3.43
4:   0
5:   0.71
6:   8.04
7:   12.75
8:   13.60

IC3: SAD1024
1:   0
2:   3.45
3:   6.31
4:   0
5:   13.12
6:   0.60
7:   13.12
8:   0
9:   13.12
10:   0
11:   13.12
12:   0.66
13:   0
14:   6.31
15:   3.44
16:   0

IC4: 324
1:   12.29
2:   6.24
3:   var from 3-8V
4:   13.60
5:   1.58
6:   1.58
7:   8.30
8:   var from 4-8V
9:   6.24
10:   6.24
11:   0
12:   1.58
13:   1.58
14:   1.58

IC5: LM311
1:   0
2:   8.28
3:   6.53
4:   0
5:   13.59
6:   13.59
7:   14.20
8:   13.59

IC6: 4013
1:   0
2:   6.31
3:   14.20
4:   0
5:   6.31
6:   0
7:   0
8:   0
9:   0
10:   0
11:   0
12:   0
13:   13.60
14:   13.60

Q1: 2N5087
C:   var from 1-6v
B:   12.50
E:   13.15

Regulator: 7815
1:   25.24
2:   0
3:   14.7

Diode 1N914 between pin 3 & 7 of LM311:
A:   var 1-6V
C:   var 14-17v

Trimpots:

Feedback 100K:
1:   12.70
2:   12.70
3:   12.70

Bias 10K:
1:   0
2:   3.53
3:   7.23

Balance 1K:
1:   0.65
2:   0.59
3:   0.59

Gain 10K:

1:   0
2:   0
3:   0.59

Clock 100K:
1:   13.58
2:   13.58
3:   13.22





Direct link to pic in my gallery: http://www.aronnelson.com/gallery/main.php/v/cathexis/Temporary+files/DEM.jpg.html

LARS

[Scruffie]

Hey there, well i dunno if it'll help but on the 'other' forum as im led to beleive its called the free one if you don't know what i mean on this topic .org/viewtopic.php?f=13&t=4482 (I'm led to beleive if i post the actual link it wont work) There is the original factory schematic for the Electric Mistress with instructions on trim settings, hope this helps.

Thanks, (keep your layouts and samples coming there amazing!, another lover of veroboard i see)
Scruffie.

[WLS]

I thought I seen this post once before when I was deciding on building this one for myself.

Anyways I started my build using the same schematic and GGG's PCB layout. I added a charge pump and planned on bringing the clock pot out to be external. Before my build I investigated the changes you stated about where pin 1 and 4 of the LM311 are tied to ground instead of pin 7 and only found 1 out of 4 schematics that made this change.

The 9 volt version at MG's site does not incorporate this change and I believe this is where your problem lies. I will know more later this week when my enclosure arrives with my batter snap and I try to fire this thing up.


Bill

[d@vide]

there's some problems on IC1... look for short or bad route or fault IC...

[cathexis]

Hi!

Thanks for replying to my most unpopular thread ever on this forum! 

I got so frustrated with this that I put it away for many weeks, and went on with my flanger quest:



A/DA, DOD FX75B, Ultra Flanger (twice), EH DEM, Morley Sapphire, Guyatone FL3. Some of them actually works!
I've had lots of fun, and there will be working vero layouts of some of these eventually.

Then, last night I actually got the DEM out again and started scoping it some more. I have successfully breadboarded a 9v Mistress, so I know my SAD1024 is working.

Anyways I started my build using the same schematic and GGG's PCB layout. I added a charge pump and planned on bringing the clock pot out to be external. Before my build I investigated the changes you stated about where pin 1 and 4 of the LM311 are tied to ground instead of pin 7 and only found 1 out of 4 schematics that made this change.

The 9 volt version at MG's site does not incorporate this change and I believe this is where your problem lies. I will know more later this week when my enclosure arrives with my batter snap and I try to fire this thing up.

Thanks, Bill! I'd appreciate if you'd post some voltages for reference when you get it working. As far as I can see from the GGG PCB layout, pins 1&4 ARE tied to ground, contrary to the GGG schem. Hmm... As far as I can see on my scope, the clock signal going into the BBD looks good. I measured the frequency sweep, and that seems fine too.

there's some problems on IC1... look for short or bad route or fault IC...

d@vide, I think you're right... On my scope I get something like this, sine wave going in:



Doesn't look very good. I swapped the IC:s, tried a 071/072 combo, no luck there. If I pull out the 741 I get a clean sine wave on pin 2 of the socket. The signal seems to pass through the circuit fine if I pull out the op-amps and check point to point. I cannot find any shorts or other boo-boos. I have suspected a bad cap somewhere, but that might be desperation only.

I'll keep trying with this - any input is appreciated! I know there are some guys on this forum with serious flanger knowledge - a fellow psychologist springs to mind... 
Does anyone see any mistakes on the layout? I know the input is wrong, It should come in two rows down, to meet the south end of the .027 cap, of course.

Scruffie, thanks for the feedback and the link! There are a few other alignment instructions floating around on this forum as well, minor variants. I think Stephen Giles posted them.

LARS

[WLS]

I will be more than happpy to post the voltages for you once I recieve all my parts. Stupid me I forgot to order the 100k pot and just did that today. Mousers is usually pretty quick in filling thier orders so it should arrive in a few day's.

I am sure that like most builds that mine will not be flawless and I my need some input on your end to resolve issues also. At least they both shouldn't have the same problem.

I hope not!

Bill

[WLS]

The pedal has not been tested but by looking at it, it appears to be solid. All trim pots and adjustable items have been set to mimic yours prior to readings being taken.

Anyways ...


Here are the voltages you asked for.

DEM Voltages

TC-1044S

Pin 1     9.3          Pin 5     0
Pin 2     4.8          Pin 6     4.4
Pin 3     0             Pin 7     5.9
Pin 4     0             Pin 8     9.27


TL-071

Pin 1     0            Pin 5     0
Pin 2     4.1         Pin 6     4.4
Pin 3     4.1         Pin 7     14.22
Pin 4     0            Pin 8     0


RC-4558

Pin 1     1.8
Pin 2     1.8
Pin 3     1.8
Pin 4     0
Pin 5     4.3
Pin 6     4.3
Pin 7     4.3
Pin 8     14.22

SAD1024A

Pin 1     0             Pin 9      13.6
Pin 2     1.8          Pin 10     6.9
Pin 3     7             Pin 11     13.6
Pin 4     0             Pin 12     4.9
Pin 5     13.6        Pin 13     0
Pin 6      4.8         Pin 14     7
Pin 7     13.6        Pin 15     1.8
Pin 8     6.9          Pin 16     0


LM-324

Pin 1     6.6              Pin 8       6.3 Var
Pin 2     6.4              Pin 9       6.41
Pin 3    6.3 Var         Pin 10     6.4
Pin 4    14.22           Pin 11     0
Pin 5     1.7              Pin 12     1.6
Pin 6     1.7              Pin 13     1.6
Pin 7     7.2              Pin 14     1.6

LM-311

Pin 1     0
Pin 2     7.2
Pin 3     5.3
Pin 4     0
Pin 5     14.2
Pin 6     14.2
Pin 7     14.1
Pin 8     14.23


CD-4013B

Pin 1     7          Pin 8       0
Pin 2     7          Pin 9       0
Pin 3     14        Pin 10     0
Pin 4     0          Pin 11     0
Pin 5     7          Pin 12     0
Pin 6     0          Pin 13     14.2
Pin 7     0          Pin 14     14.23

Regulater

Input     19.76
Ground  0
Output  14.63

2N5087

Emitter  13.59
Base      13.08
Collector 4.3

1N914

14.08 - Cath. Side
4.31


Trim Pots

Feedback

Pin 1     4.1
Pin 2     4.1
Pin 3     4.2


Bias

Pin 1     0
Pin 2     1.78
Pin 3     7.55


Balance

Pin 1     4.8
Pin 2     4.3
Pin 3     4.3


Gain

Pin 1     4.3
Pin 2     0
Pin 3     0


Clock 

Pin 1     4.1
Pin 2     4.1
Pin 3     4.1



Bill

[cathexis]

Thanks Bill! I haven't really compared the readings fully, but at a glance there are some obvious differences to start working with. I have straightened out the problems with the 741 and the 448 so the signal to the input of the SAD1024 now looks ok. I think it was a bad cap, actually.

I have begun to worry again that my SAD chip is busted, but I'll give it another try now that I've got some readings to compare with.

Let me know how your Mistress sounds when you get it up and running!

LARS

[WLS]

When you breadboarded the 9v circuit I thought you said that your SAD1024A was ok!

I hope it's not your SAD1024A, it's a hard one to find not a lone poney up for twice.

I am in the process of boxing it up, just glued in my board supports and waiting for them to dry.

I made the box able to use five pots. I am bringing the clock out and for now the other is the volume of only the effect. I was thinking of changing that out to the balance but I'll wait to see witch other trim pots change the signal the most before making any changes.

I have recently picked up a scope, but I am still figuring the thing out. I think that I am setup right on the trim pots, I have read the posts on the trim pot setup. But I am not quite getting it in relation too the scope.

Well at least I can't hurt anything playing with the trim pots.

I will let you know how it goes in a day or so...

Keep me posted on your progress and I am glade the voltages are helping.


Bill

[cathexis]

When you breadboarded the 9v circuit I thought you said that your SAD1024A was ok!

Yeah, At least one of the sides of the chip passed signal, but I was impatient and tore down my breadboard before I could really confirm it. And these damn super-rare expensive chips tend to make me think the worst right away. Please let me know when you confirm that your build works! Right now I'm tweaking some of my other flanger builds - the Morley Sapphire sounds very, very good.

LARS

[WLS]

So far, I think mine is working right. On the scope it turns a sine wave into an upside down double stacked V with curveatures in the middle. Pretty Wild! Changes in the pots are being reflected in the wave.


I'll let you know when I can confirm it's operation though.

Good Luck With Your Other Builds!


Bill

[WLS]

cathexis,

I still did not box the DEM up yet because I am changing boards out , I accidentally cut a trace and I don't want the soldered bridge in it for ever. Anyways I made a mistake that may have effected the voltages that I posted for you earlier... The diode between pin 3 & 7 I had in backwards 

Anyways the pedal works great and sounds sweet, my best pedal so far...


Voltages are as follows:

TC-1044S

Pin 1     9.28       Pin 5     0
Pin 2     4.78       Pin 6     4.43
Pin 3     0            Pin 7     5.78
Pin 4     0            Pin 8     9.27



TL-071   


Pin 1     0         Pin 5     0
Pin 2     3.96    Pin 6     5.09
Pin 3     3.96    Pin 7     14.34
Pin 4     0         Pin 8     7.43



RC-4558


Pin 1     5.31     Pin 5     4.80
Pin 2     5.36     Pin 6     4.83
Pin 3     5.29     Pin 7     4.76
Pin 4     0          Pin 8     14.46



SAD1024A


Pin 1     0           Pin 9     13.78
Pin 2     5.32      Pin 10    7.22
Pin 3     7.22      Pin 11    13.78
Pin 4     5.0        Pin 12    5.70
Pin 5     13.78    Pin 13    5.10
Pin 6     5.59      Pin 14    7.22
Pin 7     13.78    Pin 15    5.32
Pin 8     7.22      Pin 16    0


LM-324



Pin 1     0.13 VAR Pin 8     4-8 VAR
Pin 2     6.56        Pin 9     6.57
Pin 3     4-8 VAR   Pin 10    6.57
Pin 4     14.47      Pin 11    0
Pin 5     3-5 VAR   Pin 12    1.75
Pin 6     4.35        Pin 13    1.75
Pin 7     13.51      Pin 14    1.75


LM-311


Pin 1     0.18      Pin 5     14.83
Pin 2     13.06    Pin 6     14.48
Pin 3     7.98      Pin 7     14.40
Pin 4     0           Pin 8     14.48


CD-4013B


Pin 1     7.18      Pin 8      0
Pin 2     7.23      Pin 9      0
Pin 3     14.41    Pin 10    0
Pin 4     0           Pin 11    0
Pin 5     7.09      Pin 12    0
Pin 6     0           Pin 13    14.47
Pin 7     0           Pin 14    14.47


Regulator                 2N5087

Input       22.60          Emitter     14.40
Ground     0                Base        14.40
Output     14.87         Collector   6.41



1N914 Diode Between Pin 3 & 7 of LM-311

14.40 Cathside

7.9


Feedback 100K      Bias 10K            Balance 1K

Pin 1   3.42           Pin 1   7.57        Pin 1   5.61
Pin 2   3.42           Pin 2   5.36        Pin 2   4.83
Pin 3   3.24           Pin 3   0             Pin 3   5.72



Gain 10K           Clock 100K

Pin 1   0          Pin 1   14.48
Pin 2   0          Pin 2   14.48
Pin 3   4.82     Pin 3   13.95




Sorry for the wait.


Bill

[cathexis]

Thanks a lot Bill! I guess I'll give this one another chance then. Debugging is always easier when you have readings from a working build. I really appreciate the work you put into this!

LARS

[WLS]

You're more than welcome I am glad I could be of some help.

Let us know how everything works out.


Bill