deluxe electric mistress problem

[fatfoot51]

Hey! Fatty here continuing the long line of electro harmonix questions... Thanks to TELEFUNKON for that wonderful holiday wish on my last post! So good! My question involves our lovable legendary effect called the electro harmonix deluxe electric mistress... You can hear a bit of whooshing in the background but for the most part it seems like the flange is another ring modulator.. The guy that had it before me said he changed the pot but it seems to be the right resistance... Please don't tell me my SAD1024 is dead... If you have to, I guess you have to break the news eventually... Well here goes...I appreciate any and all ideas! Thanks!  ;DThe readings are:
            741                                   4558                            311                                    324                                      4013
1.   0            5.   0            1.   5.20        5.   6.23         1.   0         5.   14.68          1.   varies       8.    4-8            1.   7.29           8.   0
2.   6.32       6.   6.32        2.   5.60        6.   6.30         2.   varies  6.   14.68          2.   6.54         9.   5.55            2.   7.34           9.   0
3.   6.28       7.   14.68      3.   5.17        7.   6.30         3.   varies  7.   10-13          3.   4-8         10.   5.55            3.   10-13       10.   0
4.   0           8.   0             4.   0            8.   14.7         4.   0         8.   14.68          4. 14.68        11.   0                 4.   0             11.   0
                                                                                                                       5. 1-3           12.   1.6              5.   7.34         12.   0
                                                                                                                       6. 1-3           13.   1.6              6.   0              13.   14.68
                                                                                                                       7. varies       14.   1.6              7.   0               14.   14.68

SAD
1.   0                     9.    14.13
2.   5.20               10.      7.33
3.   7.34               11.    14.13
4.   0                   12.     6.66
5.   14.13             13.    0
6.   6.43               14.    7.33
7.   14.13              15.   5.21
8.   7.33                16.   0

[oldschoolanalog]

Did you first try to re-calibrate it?

[fatfoot51]

The trim pots don't really affect anything noticeable in a good way.. By that I mean the flange doesn't move in and out when I turn them one way or the other... Its almost like it just sits there...not that I have a real idea of what the parameters should be in order for the flange to oscillate correctly..  There's a slight vibrato effect when I turn the rate knob all the way to the right but that's about it, not your typical interesting flange sound... For now that's what I'm dealing with..

[oldschoolanalog]

Go here:
http://www.metzgerralf.de/elekt/stomp/mistress/index.shtml
Figure out which version is yours and copy the schematic. Then audio probe it.
I will look over the V's you posted later today. Is the Filter matrix switch in the correct position/working properly?
Also check for any damage the previous owner may have done when he worked on it. Which pot did he change and why?
More later.

[Govmnt_Lacky]

The fact that you list an LM741 IC is questionable 

All of the DEM models DID NOT have a 741 chip in them. 

Furthermore, ALL of the standard electric mistress models had a 741 chip but DID NOT have an LM324 chip. 

So what gives?? 

[oldschoolanalog]

>So what gives??
I have a feeling this pedal was modded (aka; mutilated) by the previous owner. More than just changing a pot.
It "swooshes", so there is some hope the BBD is still good.
How about posting/linking some clear pix of both sides of the board?

[fatfoot51]

Thanks old school and Govmnt!  The schematic does list a 741 and a 324 ic...That website you sent me to old school was very interesting.. I wish I had a generator to go with my scope that I'm still learning about... Since I can't really tell you about which complex concepts I understand in terms of troubleshooting, I can at least tell you that the version I own is from 1979 with the 5150c board, though it doesn't look like it... Until I get my camera up and running I can tell you that it resembles the green and black version since there are only four trim pots.. Where the gain trim pot should be
(near the sad1024) there is a 7.5k resistor(brown green red)... On one side of it is a 47k resistor( yellow violet and orange) and on the other side is a 100k(brown black yellow) .. Not sure if that means anything... Those are just merely factual observations... Thanks much! 

[Lurco]

The fact that you list an LM741 IC is questionable 

All of the DEM models DID NOT have a 741 chip in them. 

Furthermore, ALL of the standard electric mistress models had a 741 chip but DID NOT have an LM324 chip. 

So what gives?? 

Nelson says https://sites.google.com/site/electroconducive/EHXDlxElectricMistressEH-5150.jpg

[Govmnt_Lacky]

VERY GOOD SIR!! 

I agree with your findings and now see what you have there 

After looking over your voltages, the only thing that I see somewhat odd is your 4013 Pin 13 voltage. I am not sure whether or not you should have the same volatge there as your V+ voltage. Could you have a short between 13 and 14?

Your best bet is to wait for oldschoolanalog to post some good voltages! He is a wiz at the new old fandagled flanger type thingies!! 

[oldschoolanalog]

Did you try audio probing it yet? You really don't need a function generator for this. A guitar will do.
You don't need a full featured function generator for most testing/troubleshooting. Although it is nice to have one.
For the time being why not just make a "Quick and Dirty" oscillator for testing...
@ Greg: The only EM's I have left are DIY. And not an EM like this one. I have to compare the schematic ff51 posted and cross reference with what I have to get an idea.
Maybe Thomeeque (he's an EM encyclopedia!) or F3D will see this and chime in.
I would really like to see picture of the board. Very curious about that pot change...

[Govmnt_Lacky]

Maybe Thomeeque (he's an EM encyclopedia!) or F3D will see this and chime in.

Definitely!! 

I would really like to see picture of the board. Very curious about that pot change...

Pot or trimmer? He indicates that the pot "seems to be the right resistance" so if this is true... and depending on which POT was changed... it should still function.

The only other thing that I see "could" be an issue is that the 741 and 4558 op amps appear to be a bit low when compared to the V+ input. If the V+ is ~14.7VDC then the other voltages should be ~7.3VDC 

[Govmnt_Lacky]

Where the gain trim pot should be (near the sad1024) there is a 7.5k resistor(brown green red)...

Are you saying that the 10K Gain trimpot was removed from the PCB and it is currently replaced with a 7.5K resistor?

If this is the case, you may consider replacing that resistor with another 10K trim pot. Just to rule out anything that is not a "stock" value.

[oldschoolanalog]

Since somebody other than the OP hacked into this pedal before he got it I will refrain from making any additional comments until more info is posted.
I do have some thoughts about this. However without any more info/pix we are just in an "Easter egg hunt" phase.
@ff51: It's in your hands my friend. Pictures, more info about the pot change, and audio probe it. Folks want to help you.

[Fender3D]

Is it a PCB like the described here? http://www.diystompboxes.com/smfforum/index.php?topic=92295.msg789667#msg789667

[oldschoolanalog]

>After looking over your voltages, the only thing that I see somewhat odd is your 4013 Pin 13 voltage. I am not sure whether or not you should have the same volatge there as your V+ voltage. Could you have a short between 13 and 14?
Good call Greg. Check this first, ff51.
> The only other thing that I see "could" be an issue is that the 741 and 4558 op amps appear to be a bit low when compared to the V+ input. If the V+ is ~14.7VDC then the other voltages should be ~7.3VDC.
Can this just be due to the way the audio sections and BBD are all biased from one point?  Not just a "local/isolated" bias of the BBD as seen in other designs?

Is it a PCB like the described here? http://www.diystompboxes.com/smfforum/index.php?topic=92295.msg789667#msg789667

I just read that old post and find it strangely similar to what's going on here in certain ways. Trimpots replaced w/fixed R's. Hmmm...

Quick edit: If you take a close look at those photos in the link above it looks like pin 13 of the 4013 is not connected to anything. Or I am seeing things; which is always a possibility. 

[Fender3D]

4013 is a dual D flip-flop.
Here just one flip flop is used (pins 1 to 6) to obtain a 50-50% duty cycle 2 phases square wave, halving the clock frequency from LM311.

If pin 12 (Q out) is 0 Pin 13 (Q out)will always be 1 and vice-versa.
BTW, everything from pin 8 to pin 13 doesn't really matter, since that flip-flop is not used...

fatty,
I guess it's time for o-scope readings: clock and audio signals...