1981 V6 EH Electric Mistress.
http://www.metzgerralf.de/elekt/stom...tress-v6.shtml
I dug this pedal out this week, having last used it a few months ago. It's my spare.
I have done nothing to it since last using it, but inexplicably it's decided to stop flanging.
I have no idea why.
Bypass works fine.
The "filter" mode works (or whatever that other effect is, the metallic kind of effect).
Switch to flange and it stays in the same mode, so which ever position the switch is in, I only get that filter effect.
There are no strange noises in bypass or active mode.
I have tried using 9V battery as well as without battery and with direct power instead, and in isolation of other pedals.
Nothing makes any difference.
I have opened it up and checked for any broken solder / wire connections and can't find any.
Has anyone had a similar problem and / or have any ideas how I can solve this?
Thanks!
http://www.imagebam.com/image/c00f97439299378
http://www.imagebam.com/image/49fc11439299406
http://www.imagebam.com/image/11d14c439299443
just watched your video. wish i had seen it before my post. thats pretty amazing. i modified my phase 45 90 and small stone for univibe ha ha. i have a question if i wanted to mod my univibe for phase . What would be a good cap value(range) to start with? i pure
y guessing 47n?. i think the LDrs are so lish and warm i want to hear them phase ha ha. you guys are upto some serious stuff here. I love it. i wish i would have gotten into this years ago but i got the fever now. please explain a little about whats going on in the video. it sounded nice and chewy extra. warbled and to be honest like a univibe on steroids. the androvibe steroidvibe ha ha. killer vibe
Quote from: strassercaster on October 05, 2015, 02:56:36 AM
just watched your video. wish i had seen it before my post. thats pretty amazing. i modified my phase 45 90 and small stone for univibe ha ha. i have a question if i wanted to mod my univibe for phase . What would be a good cap value(range) to start with? i pure
y guessing 47n?. i think the LDrs are so lish and warm i want to hear them phase ha ha. you guys are upto some serious stuff here. I love it. i wish i would have gotten into this years ago but i got the fever now. please explain a little about whats going on in the video. it sounded nice and chewy extra. warbled and to be honest like a univibe on steroids. the androvibe steroidvibe ha ha. killer vibe
Woah dude, I don't know how you managed it but you sure as heck haven't written a reply to *my* thread.... damn, got all excited thinking it was a solution! Please don't reply to this, as I'll only get another notification making me think someone has actually replied to my post.... thanks in advance.
Hi Tj,
I was going to mod my airplane into a helicopter when I saw your post which reminded me the crazy jet flanger effect....
lol
jocking... :icon_mrgreen:
check the filter matrix switch first, otherwise focus on LFO (ic4a or ic4c).
Quote from: Fender3D on October 05, 2015, 06:32:23 AM
check the filter matrix switch first, otherwise focus on LFO (ic4a or ic4c).
Ok, but check how...?
Quote from: tj7 on October 05, 2015, 01:46:14 AM
The "filter" mode works (or whatever that other effect is, the metallic kind of effect).
Switch to flange and it stays in the same mode, so which ever position the switch is in, I only get that filter effect.
You say Filter Matrix mode works but didn't clarify if that mode fully works.
When in FM mode, does the Range pot affect the sound?
You also say when you put it in Sweep mode, it sounds the same as FM mode.
So same question for that case. Does range pot have an effect on the sound?
If it does that suggests it is stuck in a fully working FM mode, and that points to a bad switch.
If you find that range pot only has an effect in FM mode, but not in Sweep mode then that suggests non-functioning LFO.
The switch has 6 connections in this pattern...
X O X
X O X
Put the Range pot at maximum and the Rate pot to give slowest sweep, and then measure the voltages on the 4 X pins.
One of those pins will be connected to the LFO output and so have a voltage that varies in time.
When in "Sweep" mode, that pin with put its varying voltage onto one of the central O pins.
So if you don't see a varying voltage on any of the X pins, then then the LFO is not working.
If you find a varying voltage on one of the X pins but not the O pin, then the switch internals are bad, and switch-cleaning spray could fix it.
Quote from: tj7 on October 05, 2015, 04:51:59 PM
Ok, but check how...?
Take an Ohm meter and make sure when you trip the switch it actually switches output contacts (remember, the contacts come in groups of 3 depending on if it's a single or double pole etc - the middle is in, and the other 2 are the out depending on switch position). That's an old switch; they can go (especially if you used it a lot). Check for continuity between middle and both sides (only one should work); throw the switch the other way and check again; the other putput should work. If either both outs work or if the working out does not change with switch position then the problem is the switch.
... yeah what DrAlx said.
Quote from: DrAlx on October 05, 2015, 06:11:36 PM
Quote from: tj7 on October 05, 2015, 01:46:14 AM
The "filter" mode works (or whatever that other effect is, the metallic kind of effect).
Switch to flange and it stays in the same mode, so which ever position the switch is in, I only get that filter effect.
You say Filter Matrix mode works but didn't clarify if that mode fully works.
When in FM mode, does the Range pot affect the sound?
You also say when you put it in Sweep mode, it sounds the same as FM mode.
So same question for that case. Does range pot have an effect on the sound?
If it does that suggests it is stuck in a fully working FM mode, and that points to a bad switch.
If you find that range pot only has an effect in FM mode, but not in Sweep mode then that suggests non-functioning LFO.
The switch has 6 connections in this pattern...
X O X
X O X
Put the Range pot at maximum and the Rate pot to give slowest sweep, and then measure the voltages on the 4 X pins.
One of those pins will be connected to the LFO output and so have a voltage that varies in time.
When in "Sweep" mode, that pin with put its varying voltage onto one of the central O pins.
So if you don't see a varying voltage on any of the X pins, then then the LFO is not working.
If you find a varying voltage on one of the X pins but not the O pin, then the switch internals are bad, and switch-cleaning spray could fix it.
Thanks for all this info everyone.
I have never done more than basic soldering, so I am going to have to buy a meter and learn how to do these measurements!
However - I have more info.
In *either switch* position, neither RATE nor RANGE pots make any difference. They do absolutely nothing.
The COLOR pot *does* affect the sound - the Filter sound is made deeper with a higher knob position. This is the same in either switch position. It's evidently stuck in filter mode, but given this new info, does this also mean the LFO has died?
If so, would it just make more sense for me to buy a replacement part and solder it in?
Range pot doing nothing means filter matrix mode is not actually working either.
At this point I'm not even sure you have a working BBD.
You say the color pot does something to the sound. Can you actually get "bell-like" sounds in FM mode when Color is set high ?
If so then the BBD may be OK, but for some reason is only ever being clocked at one clock rate.
If you can, record some sound samples and upload them to soundcloud or some other file sharing site so we can have a listen.
If the sounds are bell-like then the BBD is probably OK, and the problem is that it is only ever getting clocked at one rate.
No bell like sounds suggests broken BBD.
If the filter/matrix switch is broken ic4b can't work properly...
If you happen to have a dpdt switch, you might swap it just to see if it works.
Just remember you're dealing with an extremely rare and expensive SAD1024 here.
Before you make any further damages, consider referring to an authorized or capable technician
Quote from: Fender3D on October 06, 2015, 02:19:17 PM
If the filter/matrix switch is broken ic4b can't work properly...
If you happen to have a dpdt switch, you might swap it just to see if it works.
Just remember you're dealing with an extremely rare and expensive SAD1024 here.
Before you make any further damages, consider referring to an authorized or capable technician
I'm in Australia. Not gonna happen. I'll record some samples tonight.
This is really inexplicable. This pedal has been sitting in a box for two months after perfectly functioning at last use.... and suddenly this has happened. Bugger!
That's why I think it's the switch. Similar thing happenned to me with a vintage bass' output jack the other month - I was worried because it has complex electronics (a large Moog circuitboard) and some irreplaceable parts, but I just needed to replace the extra long bushing Switchcraft jack and it's all good. Hadn't played it for a year or 3 and it was fine the last time I unplugged it; been in it's case ever since.
Quote from: DrAlx on October 05, 2015, 06:11:36 PM
Quote from: tj7 on October 05, 2015, 01:46:14 AM
The "filter" mode works (or whatever that other effect is, the metallic kind of effect).
Switch to flange and it stays in the same mode, so which ever position the switch is in, I only get that filter effect.
You say Filter Matrix mode works but didn't clarify if that mode fully works.
When in FM mode, does the Range pot affect the sound?
Ok, here's a sound file:
https://soundcloud.com/matthew-h-slaughter/9v-ehx-em-color
This is EXACTLY what I get in either switch mode. The variation in sound you hear is me changing the position of the COLOR pot. The other pots do nothing....
It sounds like the BBD is fine, and the VCO (i.e. clock generator) is most probably OK too. That's good news.
The problem must be that the control voltage for the VCO is never changing.
A bad switch (mentioned above) is the most likely culprit.
The switch pins look like this
1 2 3
4 5 6
One switch position will connect (1 to 2) and (4 to 5) like this:
1--2 3
4--5 6
Other switch position will connect (2 to 3) and (5 to 6) like this:
1 2--3
4 5--6
Slide the switch to sweep mode, and then take of couple of flat screwdriver blades (or knife blades) and make those connections manually.
e.g. if the switch is slid over to the left, then connect the 2 sets of pins to the left using the two blades
Otherwise the two right sets of pins.
There should be enough hiss on the pedal to hear any sort of sweeping, so you don't need to play the guitar with your feet while your holding the blades in place :)
Quote from: DrAlx on October 09, 2015, 11:58:07 AM
Slide the switch to sweep mode, and then take of couple of flat screwdriver blades (or knife blades) and make those connections manually.
e.g. if the switch is slid over to the left, then connect the 2 sets of pins to the left using the two blades
Otherwise the two right sets of pins.
There should be enough hiss on the pedal to hear any sort of sweeping, so you don't need to play the guitar with your feet while your holding the blades in place :)
Ok. Here's a photo of exactly what I did:
http://www.imagebam.com/image/ede8c0440055109
The audio file is a recording of me manually making the connection between the pins as pictured, also just 2 at a time eventually covering all permutations with the effect switch flipped left AND right. As you can hear, it makes no difference which mode I have the pedal in.
I have sat there gingerly manually connecting pins with this piece of metal for quite a while and at no point can I get any evidence of a sweeping sound or the flange effect that I am all too familiar with. I have also found that adjusting the RANGE and RATE knobs makes no difference to this process. Sometimes, as you will hear, when I held the place between pins in a certain way the effect was bypassed altogether.
Thoughts?
https://soundcloud.com/matthew-h-slaughter/ehx-em-9v-switch
I believe your link to the project page was mangled in the copy/paste.
Page: http://www.metzgerralf.de/elekt/stomp/mistress/electric-mistress-v6.shtml
Schematic: http://www.metzgerralf.de/elekt/stomp/mistress/images/1981-electric-mistress-v6-schematic.gif
> does this also mean the LFO has died? ...make more sense for me to buy a replacement part...
LFO is at least 9 parts and 20 connections. Which one wants replacing?
DrAlx seems to know this circuit and his advice seems excellent. While there still could be some question about switch (AND connections), soon you need to meter voltages around the LFO, IC4a IC4C and associated parts. As a dumb-guess, IC4 pin 8 should be wobbling from +2V to +7V at a tremolo-like rate. (Many meters can't display this properly, but a "wobbly" reading suggests LFO action; a dead-steady reading is not good but a good clue.)
Thanks. I have ordered a multimeter so I can do these tests....
Trying all sorts of different permutations will confuse things. You should only connect the two pairs of pins on the switch. e.g. if the switch is slid over to the left, then its the 4 left-most pins of the switch. Also you need to be using use TWO blades, one for the top pair of pins and a separate blade for the bottom set of pins. Did you do that? I'm not sure from your reply or photo.
I have a 9V EM clone, and I've put it in SWEEP mode. I put the COLOR to maximum so I can hear the BBD clock noise as much as possible, and I can here the periodic change in noise as it is sweeping (I have Rate pot around 50% to 75%). I don't play the guitar through, I just listen to the output noise of the circuit. When I go in with a blade and short out the relevant pins I get no change at all in the noise. In other words, you couldn't tell I was messing about with the circuit at all ('cos my switch is fine).
In other words, if the switch was doing its job and connecting Pins 1 to Pin2 (for example) then sticking a blade between pins 1 and 2 would not have any effect.
Now from the sample it sounds like sticking the blade in there WAS doing something. See where I put a comment on the soundcloud clip. There are "record scratching" type sounds. That's due to the control voltage for the BBD changing (going from high to low very quickly when it "scratches up").
Unfortunately because you haven't said exactly what pins you were shorting out, and that you tried all sorts of combinations, I can't tell if these sounds occurred for the pins of interest, or for some other combination that is not relevant.
Do the test in SWEEP mode only, RANGE and COLOR at maximum, RATE over 75%. Connect ONLY the two pairs of pins I described. Try with one blade connecting the top pair only, then with one blade connecting the bottom pair only, then with two blades together (one for each pair). If you hear a change in the output noise then the switch is not good. If you find that the noise does not change at all, then the switch may be OK, and the problem could be with the LFO section.
A meter will help greatly.
Quote from: DrAlx on October 10, 2015, 07:05:04 AM
Trying all sorts of different permutations will confuse things. You should only connect the two pairs of pins on the switch. e.g. if the switch is slid over to the left, then its the 4 left-most pins of the switch. Also you need to be using use TWO blades, one for the top pair of pins and a separate blade for the bottom set of pins. Did you do that? I'm not sure from your reply or photo.
Thanks for all your help here.
https://soundcloud.com/matthew-h-slaughter/ehx-em-9v-switch-2
I had the box in "sweep" mode, and used two metal conductors (a bread knife and the back end of a scalpel) to connect the pins as you suggested, i.e. the 4 pins on the same side as the switch position, top two and bottom two each connected). FYI I found exactly the same response when I tried the other two pins on the opposite side of the switch position, but didn't record this.
I would have thought that if I managed to get a stable connection, I'd hear a proper flange effect, even momentarily?
Very strange. The blades are doing something 'cos I can hear the BBD clock noise disappear, but it is not flanging. So there's more going on here than a bad switch. We'll have to wait for you to post meter readings.
We'll need the voltage on all pins of the LM324. Pin 8 should have a voltage that varies over a range of a few volts, and you should see this voltage going up and down when you put the RATE to low.
After going through the switch (in FLANGE mode) that varying voltage gets scaled and appears at Pin1 of the LM324. So if the RANGE put to maximum, then you'll see a varying voltage at Pin1 of the LM324 also.
That voltage then gets passed to Pin2 of the LM311 IC (which controls the speed of the BBD clock). So if you don't get flanging, then its likely that one of the voltages described above is not changing.
Quote from: DrAlx on October 11, 2015, 09:22:09 AM
Very strange. The blades are doing something 'cos I can hear the BBD clock noise disappear, but it is not flanging. So there's more going on here than a bad switch. We'll have to wait for you to post meter readings.
We'll need the voltage on all pins of the LM324. Pin 8 should have a voltage that varies over a range of a few volts, and you should see this voltage going up and down when you put the RATE to low.
After going through the switch (in FLANGE mode)...
Ok. I should get my multimeter this week. I am guessing you use the terms "SWEEP" and "FLANGE" mode interchangeably? In any case, I am getting the same results no matter which position I have the switch in...
Ok, I have my multimeter. I am about to do some googling to learn exactly how to measure voltages. Any idiot proof would be really appreciated. How do I identify specific number pins? I presume I'll need to remove the entire casing to access both sides of the circuit board...
I don't remember if you did it already - did you check the switch? If not start there; easy and most likely problem. Instructions above IIRC.
IC pin 1 is on the top left if the divet is facing up or the corner marked with a circle if no divet (ignore any circles not in a corner):
(http://cdselectronics.com/components/chip/ic_legs1.jpg)
Connect one MM lead to circuit/chassis ground and touch each pin with the other lead to take a reading. Sometimes you have to fiddle with the test lead to get good contact. Same as when using an audio probe really.
Ok. Because I have no idea even which settings to set my multimeter to (the thing has a million dials), I decided to simply buy a new switch and replace the old one. I have just done this -not a bad soldering job if I say so myself - and the pedal functioning is *exactly the same*. No change whatsoever.
(http://s15.postimg.org/6eo4goakn/unnamed.jpg) (http://postimg.org/image/6eo4goakn/)
Is the likely problem an irreplaceable SAD 1024 chip?
Should I use my multimeter for checking something else? Pic attached. If someone could tell me how to se the thing up, I'd be much obliged.... I am a complete noob with this. Literally.
Bump!
Quote from: tj7 on November 25, 2015, 12:48:06 AM
Ok. Because I have no idea even which settings to set my multimeter to (the thing has a million dials), I decided to simply buy a new switch and replace the old one.
That'll keep the switch-maker company shareholders happy! ;) Anyway, I think you'll find your multimeter only has the
one dial. ;D Granny was asking for voltages at each of the IC pins. If you have a (black) meter lead with a croc clip, put it in the COM socket and clamp the other end to a ground point - the pedal chassis or (better) a jack socket screen tab will do. (If not a croc clip, then you'll just have to multi-task and hold that one still with one hand while...) ...you take your red lead and plug one end into the second socket up (VΩmA) and poke the other end at each of the IC pins in turn, having previously turned your single dial to the DCV 20 position (about ten o'clock).
> If you have a (black) meter lead... ... ... . .... . . . ... dial to the DCV 20 position
Picture:
(http://oi65.tinypic.com/2m7xheb.jpg)
Wow, it's been months.... I've not been terribly motivated here!
Ok, I finally hooked up my multimeter as instructed.
As I have never done this before, and just could not be bothered trying to learn the basics, I tried all permutations of:
Battery connected
Battery not connected
In Flange mode
In Filter mode
Guitar leads in
Guitar leads not in
Switch engaged
Switch not engaged
I also changed the settings of the rate etc knobs and this was the result in ALL permutations:
NO VOLTAGE READ. At all. The multimeter read -0.00 at all times. On ALL pins.
I touched ALL of the pins on every chip with the black lead grounded to the chassis and ZERO read on anything.
Any ideas as to what this means and how to rectify....?
Thanks again to everyone for helping me out!
Quote from: Granny Gremlin on October 18, 2015, 09:19:33 AM
I don't remember if you did it already - did you check the switch? If not start there; easy and most likely problem. Instructions above IIRC.
IC pin 1 is on the top left if the divet is facing up or the corner marked with a circle if no divet (ignore any circles not in a corner):
(http://cdselectronics.com/components/chip/ic_legs1.jpg)
Connect one MM lead to circuit/chassis ground and touch each pin with the other lead to take a reading. Sometimes you have to fiddle with the test lead to get good contact. Same as when using an audio probe really.
Just a headsup that I've finally tried this out! Any advice re my latest post?
Quote from: bluebunny on November 29, 2015, 11:04:34 AM
Quote from: tj7 on November 25, 2015, 12:48:06 AM
Ok. Because I have no idea even which settings to set my multimeter to (the thing has a million dials), I decided to simply buy a new switch and replace the old one.
That'll keep the switch-maker company shareholders happy! ;) Anyway, I think you'll find your multimeter only has the one dial. ;D Granny was asking for voltages at each of the IC pins. If you have a (black) meter lead with a croc clip, put it in the COM socket and clamp the other end to a ground point - the pedal chassis or (better) a jack socket screen tab will do. (If not a croc clip, then you'll just have to multi-task and hold that one still with one hand while...) ...you take your red lead and plug one end into the second socket up (VΩmA) and poke the other end at each of the IC pins in turn, having previously turned your single dial to the DCV 20 position (about ten o'clock).
Measure your battery.
Follow the battery wires and go along.
Thanks. Definitive proof of my noobness.
Ok, I have some results - see attached image. Flange mode. Rate set fairly low.
(http://i63.tinypic.com/20z8djo.jpg)
Quote from: PRR on March 31, 2016, 11:29:26 PM
Measure your battery.
Follow the battery wires and go along.
The voltages are mostly OK. 3 voltages seem suspect but that may not be the ICs fault. It could be the wiring. The suspect voltages are the ones near the top right (1.01, 0, 7.6).
Now when you are in flange mode, the pin where you measured 1.01 should actually be showing a voltage that varies from roughly 1.01 to 1.85. So the first thing to do is double check that pin voltage and see if it varies at all or is really stuck at 1.01.
The zero voltage at the pin next to it looks wrong because it should vary too (from about 1.01 to 1.85 also).
I think the cause of your problem is a bad connection to the Range pot. The pin with the bad voltage of 0 should have a connection to one end of the Range pot and the pin the bad voltage of 7.6 should have a connection to the other end of the Range pot.
Using the exact same set up, measure the voltages at the 2 pins used on the Range pot and post them here.
EDIT: Also let us know how the Range pot was configured , i.e. was it at maximum range or minimum.
Thanks.
I carefully did the test again, with the range pot at min and again at max. This made no difference at all.
The three pins at top right (as far as the diagram I drew goes) gave me the *exact same results* as in my first test.
FYI I did this with the rate knob at min and max also, and this again made no difference.
That 7.6 is actually 7.59, and also this particular pin will sometimes revert to 0 depending on exactly where on the pin I touch with the multimeter needle.
Quote from: DrAlx on April 01, 2016, 10:29:07 PM
The voltages are mostly OK. 3 voltages seem suspect but that may not be the ICs fault. It could be the wiring. The suspect voltages are the ones near the top right (1.01, 0, 7.6).
What voltages did you measure on the terminals of the Range pot?
I asked you to measure at those terminals (i.e. directly on the pot) in order to see if they agree or disagree with the bad pin voltages. If they disagree then you have a wiring problem.
Sorry, my bad - Ok -
Range @ Min
Left pin: 7.53 - 7.54
Right pin: 7.53 - 7.54
Range @ Max
Left pin: 6.85 - 6.86
Right pin: 7.53 - 7.54
Quote from: DrAlx on April 01, 2016, 11:03:52 PM
What voltages did you measure on the terminals of the Range pot?
I asked you to measure at those terminals to see if they agree or disagree with the bad pin voltages. If they disagree then you have a wiring problem.
Bingo. So there is a missing connection from the left terminal to the pin with a bad voltage of zero. It might be a broken wire or bad solder joint or bad track on the PCB. Probably a bad solder join.
Hopefully this means a solution!
Here's what I can see when I flip the board - can you advise me exactly what I need to solder?
(http://i64.tinypic.com/2nbu07n.jpg)
(http://i65.tinypic.com/2djxo9z.jpg)
Quote from: DrAlx on April 01, 2016, 11:30:48 PM
Bingo. So there is a missing connection from the left terminal to the pin with a bad voltage of zero. It might be a broken wire or bad solder joint or bad track on the PCB. Probably a bad solder join.
You have marked the correct points. They are already connected by a short green trace on the PCB so in theory should measure the same voltage.
Now the problem is that applying heat to the IC risks damaging it.
So before soldering anything, double check that the two points do indeed read different voltages. Do that on the side of the board shown in your photo measuring directly on the solder blobs that you circled in red. I only mention this because I am not sure which side of the board you took your measurements on. For example, the lower solder joint could be bad in different ways. The solders job is to connect the pot to the trace on the PCB. If it is a bad joint, then the solder might be connected to the trace but not to the pot, or it might be connected to the pot but not the trace, or it might not be connected to either.
Before soldering anything, get a piece of scrap wire and use it to manually connect the solder blobs in the two red circles. i.e. with range at max, manually hold the wire onto those two solder spots and see if you get flanging. If that works then it shows a fix is possible by using the short piece of wire, but you might find that just remelting the lower solder blob used to attach the pot could do the trick. Definitely do not solder anything before doing the manual test.
Edit: just noticed something else that is a bit poor quality. The top ted circle has a pad to the left of it and someone soldered a grey wire there directly on an IC pin which is a dodgy thing to do as it risks damaging the IC with heat. The PCB has a pad for that grey wire immediately to the left of the lower ted circle (you can see the trace). That's what they should have used. I am not suggesting you change that, only pointing it out.
I would just add, sometimes a 0 reading is the result of a bad contact with your meter probe. It looks like you're touching it solidly, but some flux or oxidation or something is preventing good contact. Might help to lightly scratch at the solder with the tip of the probe. Could still be a bad trace, though, just sayin'.
Can't be sure, but in the pictures, the range pot pin on the right looks like a cold solder joint, with corrosion on the pin. I would recommend desoldering that pot, hitting the pins with a bit of sandpaper, and soldering it back in.
Edit: Just noticed (duh) that the pin in question is connected to the wiper, so probably not related to your problem.
Agree that the pot soldering is dubious.
Pot legs need cleaning and pre-tinning. When soldering, heat the fat pot leg more than the thin PCB trace. Your solder is not "blobby" (good!) but could be thinner so you KNOW the solder "wet" both the leg and the PCB. Sheer blouse, not a Maine parka.
Thanks everyone!
I did the wire connection test that DrAlx suggested, and I believe the evidence is that he was right. I can hear intermittent spurts of flanging when I hold the wire there with one hand as I attempt to strum with my other.
The signal also intermittently cuts out altogether and makes other noises - I presume because of how clumsily maintained the hand-holding-wire process was.
Here's audio in case anyone hears something I need to be warned about...listen to the whole thing as the clearest moments of flanging are towards the end.
https://soundcloud.com/matthew-h-slaughter/ehx-em-flange-test
Quote from: DrAlx on April 02, 2016, 12:57:31 AM
You have marked the correct points. They are already connected by a short green trace on the PCB so in theory should measure the same voltage.
Now the problem is that applying heat to the IC risks damaging it.
Doesn't sound right to me. I cant here any sweeping but then I dont know how the pots are set. Set both range and rate pots to maximum and if possible see if you can feed the pedal with a noisy guitar signal (from a distortion pedal) rather than a clean signal. If you pluck a single string rather than strum then you should hear a wobbly pitch effect when the wire is in place.
You may have other problems apart from that bad connection.
When you do the wire manual test, try and measure what the voltage on the wire goes to. When the wire is not there the two solder pads would have had different voltages. Adding the wire should give them a common voltage. Tell us what that voltage is using the original pot settings that you used for the IC pin measuremnts. You don't need to play the guitar to take the measurements.
I just need to clarify -
Am I touching the multimeter needle to the actual wire that I am holding in place to measure "what the voltage on the wire goes (UP) to"? See photo of what I was doing.
Range Min and Max - wire reading was 1.01
However I managed to *once* get a moving reading cycling up and down from around 0 back up to 1 at each setting, but only after moving the wire around the solder points and reading - rereading about 20-30 times.
(http://i65.tinypic.com/n5ofw4.jpg)
(apologies for the orientation, tiny pic did that)
Here's a new recording:
https://soundcloud.com/matthew-h-slaughter/ehx-2
Quote from: DrAlx on April 02, 2016, 05:16:47 AM
When you do the wire manual test, try and measure what the voltage on the wire goes to. When the wire is not there the two solder pads would have had different voltages. Adding the wire should give them a common voltage. Tell us what that voltage is using the original pot settings that you used for the IC pin measuremnts. You don't need to play the guitar to take the measurements.
Yes that's correct measurement and correct voltage but that does not sound like flanging. Let me explain the three problem voltages on the IC pins...
You had this:
Pin1: 7.6
Pin2: 0
Pin3: 1.01
The job of that bit of the IC is to take whatever voltage is input on pin3 and then scale it up and output it on pin1. The scale factor is set by the Range pot, and when all wired properly, pin2 will read the same voltage as pin3. If pin2 shows a lower voltage than pin3 then the output voltage on pin1 will max out. That is what is happening in your case, and the output voltage is going as high as it possibly can regardless of the voltage input on pin3. Fixing the bad connection to the range pot causes Pin2 to show correct voltage. Good. So why no flanging?
Well this bit of the IC is just setting the size of the control voltage that determines location in the flanger sweep. In this case, the 1.01 volts input at pin3 gets scaled and output on pin1 where it will be between 1.01 (when range pot is at minimum) and some larger number (when range pot is max).
If the voltage input to pin3 does not change then there is no way that the output voltage on pin1 will change either. Therefore no sweep. So that fixed voltage on pin3 is the next thing to investigate.
Now the switch that toggles between filter matrix mode and flanging (I.e. sweeping) determines the voltage passed into pin3. In filter matrix mode, it gives pin3 a fixed voltage of around 1.01. In sweep mode, it will give pin3 a varying voltage between 1.01 and 1.85. That varying voltage produces the sweep. So I am wondering if you are not using filter matrix mode by mistake, or have the switch wired wrong? Toggle that switch to the other position and then see if that gives you a varying voltage on pin3. You don't need to have the manual wire in place for that measurement. If you don't get a varying voltage on pin3 then we have to investigate the switch and how it is wired. That will involve taking voltage measurements on the 6 terminals of the switch.
Yep, I think you nailed it!
I was referring to my "No. 1" EHX EM as a reference unit, and *that* one has the switch wired the opposite way!!
That 3rd pin now does vary in a cycle from around 1 to 1.78. Up and down.
Here's audio of my manual wire and strum job: https://soundcloud.com/matthew-h-slaughter/ehx-3
The thing flanges definitely now. So I guess the next thing for me to do is follow the advice I've been given about resoldering the range pot pin etc. Man, I hope I don't mess this up. Any further advice on this delicate operation based on my pics?
Also, re: "The top ted circle has a pad to the left of it and someone soldered a grey wire there directly on an IC pin which is a dodgy thing to do as it risks damaging the IC with heat. The PCB has a pad for that grey wire immediately to the left of the lower ted circle (you can see the trace). That's what they should have used. I am not suggesting you change that, only pointing it out." - I should not touch this, correct?
Quote from: DrAlx on April 03, 2016, 04:28:49 AM
So I am wondering if you are not using filter matrix mode by mistake, or have the switch wired wrong? Toggle that switch to the other position and then see if that gives you a varying voltage on pin3. You don't need to have the manual wire in place for that measurement. If you don't get a varying voltage on pin3 then we have to investigate the switch and how it is wired. That will involve taking voltage measurements on the 6 terminals of the switch.
The two most likely causes of the problem are the lower solder joint on the pot, or a break in the track close to that joint. The solder on the IC pin is probably OK. I would leave it. Regarding the grey wire soldered to pin 3, I would leave it alone. No point risking damage to the IC.
Note that you might not see a break in the track because the copper track is underneath the light green paint.
The problem with having the pot mounted directly on the board is that it puts mechanical stress on the track near the mount point, which is why a track break is more likely to occur there than on the IC end of the track.
If it was me I would just remelt the solder on the lower solder blob, and see if that fixes things. If that does not work then I would get a solder sucker and remove that lower solder blob and then resolder it with fresh solder. If that still doesn't work then I would scratch away a small portion of the green paint covering the track close to the pot in order to expose the copper track and lay solder onto that track. Basically I would avoid putting a wire directly on the IC pin. My prefered option would always be to use the track that is already on the board.
Edit: Note that there is also a third solder blob on that track (north of the lower blob in the picture) for a resistor leg. You can solder there instead of the IC pin. So I probably would not expose the track. I would run a small wire fron the pot to that resistor leg.
Hopefully just redoing the solder on the pot pin will be enough to fix things.
How did that picture turn into an RPG?
I had the similar problem and it was the BDD chip (very unfortunate). When it burns down the old Mistress will pass the clean signal.
EDIT: oh i overlooked the Filter mode works, the BDD should be fine then.
Lo and behold, IT FLANGES!
Remelting the solder didn't work, so I had to remove it with my solder sucker (so THAT's what that thing was for, that came with my solder kit) and did a reasonably neat job of scraping away a tiny section of the green track to expose the copper, then resoldered the pin in place.
Here's how it looks now:
(http://i65.tinypic.com/e9i04x.jpg)
I resoldered the pin that is right in the centre of the pic - i.e. the left side range pot pin.
THANKYOU for all of the help - everyone!
Quote from: DrAlx on April 03, 2016, 08:41:49 PM
Hopefully just redoing the solder on the pot pin will be enough to fix things.