Hello, all. My name is Tim, and I have a problem. It's a lack of confidence in myself and my abilities that some friends around me can't understand. Because of that, I've been "burdened" with the task of repairing a pile of vintage EHX pedals. Among them are some not so vintage and not so rare items; a BassBalls and MX-3M were in and out with very little fuss. There's a Rhythm-12 I'm waiting on parts for and might get stuck on, once they arrive. Not a lot of readily available info for repair of those beat-boxes.
Then, there are the "Big Three." These are all big-box, 2-prong AC powered units made in the late '70s or early 80's.
The first I tackled was the PolyChorus, the value and visibility of which has skyrocketed due to it's use by Kurt Cobain and Adrian Belew years before Nirvana. As it sits, I'm waiting on new knobs from EHX for that one. I had to fly-wire two new pots, as I couldn't source the stand-off legged CTS pots to replace the ones that had the D-shaft sheared off. I contacted Ron at Ronsound, but he didn't have any D-shafts available. The original pots work, and will go back to the owner should the proper d-shaft plastics be located.
Next up was a Bass Micro Synth that didn't need much work. A new "trig" fader was sourced from Small Bear, as the original had the slider-shaft broken off. The gain-trim pot doesn't line up with the hole on the back, and I suspect a previous owner inadvertently turned the squelch trim after opening up the back of the pedal, making the pedal "dead." (I have short videos of these two now-working pedals up on facebook; Later today, I'll take the time to figure out how to do pic and vid uploads that won't burden the server here.)
That brings me to the topic of this thread, a pedal I had no prior knowledge of, and therefore had put on the back burner while I attended to the others, the gen-u-ine, O.G., vintage EHX Attack Decay pedal! This board is marked as EH2500A, making me believe it's either a test-bed or the earliest rev. The only other pics I've found for a OG PCB is for a EH2500B, and there are some notable differences, specifically in the power section. They weren't made for very long, so I'm not sure what to make of those differences. I have copies of the original schematics, re-drawn schematics, and RustBucket schematics, but I'm stuck because of how rare this pedal is. There's not a lot of direct info that I can find, mostly just references to re-issues and clones. The designer, Howard "Mick" Davis, has been the go-to guy for these for quite some time, but has recently gone incomunicado. I hope he's just busy with other new projects.
As it sits, direct sound is fine, and un-effected sound comes through, but when I start to crank the blend in, it hums. I presume that's because no one taught it the words. ::)
I haven't measured the frequency, but I'd guess it's 60 or 120Hz. Since this is one of the "holy-grails" of EHX pedal collecting, I'd like to try to keep it as original as possible. Obviously for a collector, an all-original working pedal will have more value than a non-working, pre-bodged pedal. Someone has definitely been in this one before. One of the x-istors was replaced with a MPSA56, and there's a few newer looking e-caps, along with some messed up traces. I'm trying to find the balance between "working" and original, as I have no other options, at this point. So for starters, I'll ask a few general questions:
1. What ICs lend most to the "sound" of this pedal? Or to put it another way, which of the IC's would it be best to source "original" parts for, as opposed to re-pops? For example, Xvive makes MN3007 chips, but Panasonic MN3007s are also available. There are 9 different ICs in this pedal I have the same questions for.
2. Is it worth my time to build the appropriate test-jigs to individually test the ICs? Some of the chips are socketed, some are not. It would make my work easier to put sockets in all the positions, but would that negatively effect the value of this pedal?
3. Should I try to make this as close to the OG schematic as possible? It's currently got 2N5087 and 88 x-istors in it, where the OG schem shows BC309 and BC239s. In a few posts floating around the internet, HMD states that some of the original EHX schematics are not "Correct." Might this just be his way of saying "Send it to me. I'll make it "Right."?"
I'll take some time to figure out how to link pics/vids properly, as I'm new to the forum. I've taken some voltages, and some are certainly out of whack. I'll figure out how to post that as well, as I know that'll be asked of me. I'll post one pic of the big three, just to let you all know I'm not B.S.-ing you.
Any info or direction you could provide would be greatly appreciated.
Tim C.
Valley of the Sunburn, AZ, USA
One more question, for now. Are pictures or PDFs of schematics preferred on this forum?
Thanks,
Tim C.
First things first, post a full set of voltages for every chip, you either need to trace it and correspond the IC numbers to the rust bucket or photo it and annotate the image.
Second, the 2N5088 & 5087 are probably original, they were interchanged with BC239 & 309 @ EHX regularly.
Third, don't assume it's been worked on, EHX did a lot of in house modifications for when particular parts were out of stock or circuit updates/modifications etc. and their soldering could be... less than desirable.
Fourth, pictures suit me best.
If you wish to go the shotgun route, replace all the CD chips in sockets i.e. 4047, 4066 etc. (the MN3007 will almost certainly be fine) as those are likely culprits and have no bearing on the 'sound' of the effect.
Oh and I don't know which attack decay schematic you have, but the main 'original' one on the internet is very wrong.
Any specific knob settings or signal inputs for the voltage readings, Scruffie?
Stick all controls CW, no need for an input signal.
I'm getting a comfy chair and getting a ring side seat for this. I just love to see Scruff in his natural environment.
Thanks for stopping in, gordo. I've got a bunch of other stuff to work on, as well as trying to maintain a healthy home environment. I won't be able to get back to this until Sunday, at the earliest.
I'm not exactly forlorn about tomorrow's day-trip to a former mining mountain-town; it's "inside season" in the Valley of the Sunburn and I think cabin-fever is setting in. In one sense, I'm putting off the AD to complete some easier tasks in order to get my head together. I "de-noised" a 90's JoeMeek SC2 earlier today, and I'm deep into shielding and re-wiring a '85/'86 MIJ Jazzmaster that's been autographed by Dick Dale for it's owner. It's been a good day and I'm in a much better head-space than I was at this time yesterday.
I'm pretty frustrated with myself that I've had to resort to asking for help with this pedal. I feel it warrants it, though. It's not like there are many of these around, so it should be done right. To soothe those interested, here's a few more pics of the AD. Sorry to whomever maintains the server here. I haven't gotten around to learning the ropes as far as linking from hosting sites.
The first three pics show how the unit arrived to me. Please note, in the "pots lifted" pic, I had switched two x-istors around, as I had inadvertently opened the wrong PDF, but caught it and and reverted them to their original config before re-applying power.
Also, here are FB links to the short videos I made after fixing the PolyChorus and BMS.
https://www.facebook.com/100074733483188/videos/1210476163033816/
https://www.facebook.com/100074733483188/videos/991333494877419/
I hope you all have a great weekend and I look forward to getting back to this repair. I've got some work to do. :D
Tim C in AZ
Well, you were definitely right about it having been worked on before, several new chips there.
I wonder if the same section might have failed again, if it has, an electrolytic/tantalum re-cap will be in order. There's not a lot of point keeping them original, their value has usually drifted horrendously over the years (some EHX I've repaired they've all been at 100% off tolerance) and all that'll happen is they'll eventually fail even if they haven't already so you're giving it a much longer potential life.
Scruffie, I suppose I should re-cap it before bothering with new voltage checks? Haven't quite woken up yet, but my quick check is 8 electrolytics and 4 tantalums. I'm wondering about two others, though. There's a fat, light-brown chiclet-looking cap near the mica at the end of the CD4047 and a thick looking disk cap near the 741 IC. They don't appear to be tants, but sometimes packaging change. Would it be worth while to upgrade the electros in the power supply to appropriate film caps, given all the extra space on that end of the power supply? Any reason to suspect the mica cap, as well? Any suggestions regarding "upgrades" to parts that must be changed before continuing would be greatly appreciated.
Those other caps are ceramic, wouldn't ever suspect a mica cap and any way, easy to test, if it had an issue the 4047 clock wouldn't work.
I'd just leave the power caps as electrolytic personally, another 40 years of service life and keeps it fairly original.
Just replacing the electro and tantalum is all I'd worry about.
I've pulled all the tantalum and electrolytic caps. At first, I thought my cheap meter's capacitance measuring circuit was dead, as all the 'lytics were reading in the nF range, but after the tants all read much closer to their specs, it seems all but two of the 'lytics are essentially dead or nearly 50% out of tolerance.
In looking at the axial 3.3uF IC cap and seeing that the different schematics variously list that as a 2.2 or 3.3 uF part, it dawned on me that I should probably clarify which schematic I should be working from. More on this cap later.
I've got the "original" schematic, hand drawn, with no notation of who drew it when, and known to be incorrect. A schematic drawn by Larry Leon, drawn in Dec of 2011. The Madbean Rustbucket docs dated 2015. Also, I have a layout drawing from Kaputepalla drawn in 2010, which seems to reflect the original schematic. This is only based on a cursory glance which shows a 4558 as the input IC. I've got to lean on the "original" schematic, just a bit, as it seems the closest representation of the power supply layout on this board.
Is it safe to assume that the madbean docs will be used going forward?
After pulling parts from the board, I found 2ea of the 1uF tants, one of which is in a position that I believe is noted as C15 in the madbean docs and C18 on the Leon schematic. I suspect it should be replaced with a 2.2uF tant, correct?
Regarding the axial cap, it appears to be non-polar. Should it be replaced with a 2.2uf or 3.3 non-polar axial electrolytic? I guess the answer will likely depend on the answer of which schematic I should be using.
While waiting for the new parts to arrive, should I pull the xistors and test them with my Atlas DCA55?
Thanks again.
Yup, that sounds like old EHX electrolytics :)
Replace like for like, don't try and adjust values for the schematics, your unit is as intended. The schematic is purely for reference.
No, testing the resistors would be overkill, some unit component drift is part of its original sound, but a 5% drifted resistor isn't going to kill a unit (unless it's visibly black from burning out) unlike a dead capacitor. Very-very rarely they had a carbon composite resistor which can go brittle, that's about the only time I'd ever consider testing or replacing a resistor but I can't see any there.
My apologies. I meant "should I test the transistors?" If caps were bad and the unit powered on for a while, couldn't that kill some of them?
Additionally, the 33uf tantalum capacitor that was in here is rated at 6V. It's connected to the -15V rail. On my meter it reads 36.3 uF, so it's not dead. I ended up selecting a 16V cap for that replacement, just to be safe.
Transistors are pretty hardy unless they're reverse biased, I don't think any will have been harmed.
Yeah, upping that to 16V was a safe bet :) Higher voltage caps would have both been more expensive and physically larger back then, probably why it was as low as could be gotten away with.
Thanks, Scruffie. I ordered parts from Mouser yesterday. Aside from upping the voltage of that one tantalum, the only other changes on the new parts is that the axial non-polar cap will be radial. Supply chain issues, I figure. It'll be a few days before the parts arrive. In the meantime, I'm gonna take a look at the EHX Rhythm-12 and other projects I need to build some momentum on. Thanks again, for your for your help.
New caps came in! I verified my order and proceeded to plop the new caps right back where the old ones were, based on the pics I posted previously. As I clicked off my soldering iron for the day, it dawned on me that I should probably verify that the ones that were in it were installed polarity-correct. I think I got lucky and it appears as if they all were. I'll double-check tomorrow before firing it up to verify the voltages.
IIRC, in another thread, Brian(madbean) had specified a procedure for the order in which to put the ICs on the board, checking voltages for each as you go. That was for a Rustbucket, which I suspect most people are building with sockets in each position. I don't have that luxury, so is that procedure relevant for diagnosing this pedal? Should I just keep them all in, fire it up slowly with the variac, and start taking and recording the V data?
I'm looking forward to getting back to this, but I've also got a mid-80 MIJ Jazzmaster with some custom pick-ups and wiring to finish setting up and a Wilson 707-3 "widow-maker" to sound-test at wall voltage before each of them go back to their owners. This little amp is a real champ-killer with the input voltage dialed back a bit. I sure hope the owner bites Re: my insistence that he have me put in an isolation transformer on this amp. Anyways, these seem like better jobs to finish the day with.
Quote from: Scruffie on July 29, 2022, 04:47:17 PM
First things first, post a full set of voltages for every chip, you either need to trace it and correspond the IC numbers to the rust bucket or photo it and annotate the image.
Your next step :) no order to worry about.
I don't feel like my head is in this today, but I've pushed myself and fumbled through it.
In tracing through the circuit, I found that Q3 and Q4 HAD been reversed when it arrived. They've been changed back and forth a few times now. I tested the components and put them right before taking these measurements.
The voltage chart has columns labeled RB V. These are the voltages from the Rustbucket docs, for reference. I did my best to match component labels to those docs, as well. Attached are the two documents I've created.
I forgot to add it to the chart, but my voltages out of the W02G regulator are -17.29V and +18.29V.
IC4 is dead, looks like IC11 probably is too with that output pin voltage.
I've got a replacement for IC4, I'll have to hunt down a 3080 for IC11. Do you figure the other voltages will come back to where they should be with these two fixes, or is this just step two?
I haven't thoroughly checked it, but most of the other voltages looked just fine to me.
New parts arrived today! As usual, the place I ordered the hard-to-get part put on a 22% sale the day AFTER I put in the order. Oh well.
New IC4(4558D) and IC11(CA3080AE) parts added to the board. I took voltages from these, but not the rest.
Should I re-check ALL the voltages or get brave and run a guitar through it?
A guitar ain't gonna hurt it, time to find out if I missed anything!
Well, the hum is gone, but so is any signal related to the effect. As before, raw signal passes with the effect off and on, and less so as the blend is rotated clockwise. I'll pull it apart, looking for any obvious mistakes. If I don't find anything, I'll take a full-panel voltages again, and start signal tracing.
I found the grounded leg of the Sens Pot had broken, likely due to being flexed back and forth while troubleshooting. Mending that did not fix the issue, so here's a new set of voltages I've just taken. I've highlighted sections that seem to have reversed polarity voltage readings, and others that just seem fishy. These lead me to believe I've installed something incorrectly, or that some other part has failed.
I'm starting to think that building fresh is much more fun that repairing, even when it's something vintage like this thing.
Those are differences in the mV... I wouldn't worry about them.
Have you got an audio probe? If not, build one and it's time to start tracing through the circuit to find where the signal is getting lost.
Follow this path for the wet signal.
IC1 Pin 1 > IC1 Pin 7 > IC4 Pin 7 > R28/29/30 Junction > IC11 Pin 6 > IC12 Pin 7
I've got a scope and sig gen. I'll dig into it tomorrow. Thanks again, Scruffie.
I started tracing this out this morning. It's noisy, but I've got signal up to pin 3 of the MN3007.
I had to back-track as there's nothing on the R28/29/30 junction. I also tracked further down-stream to verify any wonkiness; the 4.7Uf cap is oriented properly. Signal off of pin 7 of the MN3007 is all kinds of crappy, but I'm not certain what I'm supposed to be seeing. The following three images are from pin 7 of the 3007 with the bias at one extreme, centered, and the other extreme.
I thought I was dead in the water until I got another 3007, but then remembered I DID have another one of those, and a CD4047, to boot. I'm not really certain of their operational relationship, but figuring all that out likely won't benefit getting this pedal fixed. I've got the 2 new chips in, but found I had accidentally shut off my scope. I'm letting that warm back up now. ...and now having to run out for the GF.
Does anyone know where to get replacement CTS pots with the appropriate stand-offs for this and other EHX pedals from the same era?
P.S. I'm hoping to figure out, this weekend, how to format my posts and pics how'd I like them to show. Many works in progress. :/
Noisy signal on pin 3 is to be expected, it's being fed by a compressor and depending on where your harmonics pot is set, that'll add some distortion to proceedings.
The 4047 is a clock that tells the MN3007 BBD to work, pins 10 & 11 of the 4047 should have opposing square waves at some frequency in the ~10-100kHz region (too hot to calculate closer).
The bias trim will have a range of about 10-20% somewhere around the middle where it passes signal, you need to adjust it while scoping that junction until that happens and find the spot with the least amount of clipping.
Both chips have appropriate looking voltages and I don't think I have ever seen a broken MN3007 from natural causes... check the bias trim is actually adjusting the voltage on pin 3.
CTS pots you're probably out of luck, the best you can usually do is scour ebay for similar old CTS pots and hack together new ones from the bits you have.
I'm going to take a break from this project for the rest of the day. There's got to be an obvious problem that I'm missing and it's making me so frustrated that I doubt spending more time on it will be fruitful. I did swap out both the MN3007 and CD4047.
Bias adjustment is changing voltage on pin 3, from near zero to -15.5-ish V. This appears correct based on the RB schematic. I checked the 4047 for the square wave signal from 10 and 11, which it has with a frequency near 36kHz, IIRC, but I couldn't find another probe to see both at the same time. With my cheap digital o-scope, the trigger function alters the phase, so it appears as if they are IN phase, as opposed to out of phase. There's probably a setting that will help me figure that out, but the broken English that the help-guide is written in is equally frustrating, as it often contradicts itself.
None of the signals to or from the 3007 look any different than with the original IC. Attached is the "cleanest" signal I can get from pin 7 of the NEW 3007. This is at one extreme of the bias adjustment. It's more or less the same through 30% of the travel. From there, the waveform gets considerably more deformed. With the bias set somewhere in the middle, regardless of waveform, I can get the tiniest signal at the 28/29/30 junction, but it's totally swamped in noise that's an order of magnitude greater.
I'm kinda wishing I had a part-time plumbing job. I could go for some pre-construction demolition right about now.
The signal is heavily divided at that junction hence the weak signal, you need to adjust your scope, but sounds like that stage is actually working.
So, once biased, on to IC11 pin 6 which is the VCA (voltage controlled amplifier) controlled by all that 4013/4066 business, so attack & decay will impact it.
Any suggestions as to where I should have the various pots set at this point?
Sens, Decay & Attack about 1/3rd the way up.
I had to go back to square one. It seems I have at least one bad cap upstream. I get solid signal at the input, pin 3 and pin 1 of the first 4558, and can see it shorting to ground on the wiper of the sense pot when turned to that extreme.
Pin 5 of the 4558 has NO signal on it. But I do get a signal at the output pin 7. It seems the coupling cap is DEAD.(C2 on the RB schem) I verified the crappy new DMM with some other known good caps which read in spec. I guess more parts need to be ordered. I really miss having old-school RadioShack and Fry's Electronics stores to go to.
What signal am I seeing downstream from the 4558? Amplified noise? An OOP signal from the differential amplifier?
Have you checked for broken/intermittent traces? The board mounted pots do lead to failure and sometimes need a jumper or re-flowing. Also check for broken leads on the cap, not saying a dead film cap isn't possible, but it's rare, but if you're going that route, the 39k biasing resistor being dead would also cause issues.
But IC1 pin 1 is your input signal at twice gain, IC1 pin 7 is a compressed output with a little tone shaping.
Scopes are great, but I do still suggest you build an audio probe, can't beat being able to actually hear what is happening and they only take 15-30 minutes to whip together.
Edit: Sorry, I misread your post, see you've taken the cap out and tested it to verify your hypothesis. Hopefully that's all that's wrong now.
Little by little, I seem to be eliminating unexpected problems. Scruffie was right in regards to changing my scope settings. Previously, I was trying to bias the 3007 from what I think is the timer noise from the 4047. I had thought that the low output from pin 7 of the 4885 was just a quirk of a circuit I still don't fully understand. Now that the coupling cap between the A/B sides of the 4558 has been replaced, I'm seeing that timer noise riding something that more resembles the waveform going into the 3007.
It seems my signal at the 28/29/30 junction is low, or I've killed another 3080. Pics show the signal on pin 3 of the MN3007, junction of 28/29/30, (input)pin2 of the 3080, and (output) pin6 of the 3080. Obviously, the signal isn't coning out of IC11. I probed pin 3, seeing as this is a differential input, but there was nothing there. R55, R56, and C17 measure appropriately.
After lunch, I'll try a different 3080 in the IC11 position.
Any input on what sort of signal strength I should be seeing at various parts of the circuit would be appreciated.
The signal at the 28/29/30 junction is meant to be very low, OTA's can only accept 25mV (IIRC, low anyway) signals before distorting and you'll get nothing on the output of the OTA @ pin 6 if it's not turned on via current at pin 5 from the attack/decay circuitry.
Have you tried playing through the pedal again?
I'm not sure if it's fixed just yet, but it is doing SOMETHING! I wonder how much of the way this is working is part-and-parcel of the triggering circuit and how much of it is other things that have yet to be repaired. Is it possible that "hot" pickups would mess up the triggering? Sloppy playing messing up the trigger? Is it just a matter of setting all the knobs correctly?
Around the 35sec mark of this first video, you can hear there is still quite a bit of hum in the background of the effect that is not at all present on the "clean side" of the blend pot.
https://www.facebook.com/100074733483188/videos/pcb.185448067289642/1071094436871915
The second video is essentially more of the same string slapping and knob twirling.
https://www.facebook.com/100074733483188/videos/pcb.185448067289642/765317831370852
I feel like there's more to do, but my expectations may be greater than the reality of what this pedal does. What do you think?
It was designed at a time of low output single coils, it is monophonic so playing is important and it's not the quietest circuit, plus the transformer adds hum.
Operating Instructions:
Plug the unit into an AC-outlet and turn it ON. Connect your
instrument to the input jack, amplifier to the output. Unmodified
signal is available at the DIRECT output and at the effect output
alternating with the processed signal when the footswitch is
thrown. Operation is most reliable when only the rhythm pick-up
is used and the guitar volume is at or near maximum.
Set SENSITIVITY about 1/3 of the way up, HARMONICS all the way
down, BLEND fully clockwise (proceeded signal only), and ATTACK
and DECAY about 1/3 up. Play a single note and if no effect is
heard, throw the footswitch. The attack-decay should be heard,
and the infinite variety of effects possible by varying the
controls can be explored.
The best setting for the SENSITIVITY control is where it triggers
Reliably for notes on the high strings but doesn't multiple-trigger
When playing the lowest string. Once found this setting should
not be changed. This unit works best for single notes and some
basic two-string chords; complex or discordant chords will cause
multiple triggering. The EDGE switch adds bite to the effect of the HARMONICS control.
EFFECT CONTROL SETTINGS
Attack Decay Harmonics Blend
Tape medium or minimum as desired processed signal
reverse long only
Slap echo minimum short or med as desired midway
Modulated short or med min to med as desired as desired
envelope
Sustain* minimum maximum as desired processed sig only
Chops min or short short or min as desired processed sig only
Violin, medium med or long as desired processed sig only
Cello
Acoustic min or short medium as desired as desired
bass
Bowed bass medium medium as desired processed sig only
Toy Piano minimum short med or high processed sig only
Piano minimum medium medium processed sig only
Banjo minimum short maximum processed sig only
Horns min or short maximum med or high processed sig only
(EDGE on)
* Set SENSITIVITY at or near maximum
I guess I'll have to box it back up and see if I can get to a point where it feels like it's "done."
Thank you so much, Scruffie. I would've NEVER suspected that coupling cap was bad and I would never have gotten to the point of suspecting it had you not talked me through the rest of the stuff.
A kind person in Japan sent me a private link of their working Attack Decay and it confirms that this one still needs some work. I think I'm going to have to build an audio probe to figure the rest of it out. I suspect it'll be easiest to just hack an old multimeter probe with an appropriate capacitor, but if anyone knows of some tricks for the "ultimate audio probe", I'm all ears. I'm considering building a +1000V probe as I've recently been given an AIMS VT-100 all tube PA amp, and I think voltages are over 600V in that beast.
Possibly something to do with Q2 emitter, was okay on your first set of voltages but not on your second.
Thank you, Scruffie. Plans for today changed when my GF said she won tickets to the first band she saw live, so I'm working on making that happen as smoothly as possible. I'll look at the AD tomorrow, hopefully for the last time.
Yeah, I'm still struggling with this. The hass-alfed audio probe I made is far too noisy just from handling to be any good to me. It doesn't help that the amp itself is noisy and frequency limited. Regardless, I took new voltages with sense, blend, and attack around 30%, everything else at zero, and a 1k signal of .25v p-p on the input. I can't seem to do much with the info today. Too many superglue fumes, maybe? Q2 emitter V is way low. I pulled the part and tested it as good; replaced it with another with similar results. Hopefully tomorrow I'll be able to look at these voltages and my brain will do stuff.
Noisy audio probe sounds like a ground issue.
So what exactly is wrong with it now that makes you sure it needs work?
Same as before, when it was "fixed" on the 15th. There's noise within only the effected portion of the signal. Bypassed sound and blended clean sound is completely free of the noise; the more effect is blended in, the more the noise is present. It's like a background low hum/rumble and a higher frequency buzz that's independent of the input signal frequency. The noise gets gated with the effect. Additionally, in comparison to another OG Attack Decay, this one sounds like it's always distorted. Edge and harmonics only make the distortion "messier." Unfortunately, I've found it hard to get a decent recording of the sound, though I tried to make it more prominent in the video from the 15th by futzing with the tone controls on my amp. I'll send you a link to the private video in PM so you can hear the stark difference between mine the the other persons AD.
What's the possibility that a socket "goes bad", or isn't making good connection with all the pins on the IC? Is there a way to re-tension socket pins, like there is for tube sockets? Could it be a lead-dress issue in the pedal?
Also, I just realized I had forgotten about the possible grounding issue, so I'll pull and re-set the in/out jacks in hopes that it makes a difference. I really think I'm just going to have to futz with it until I figure out where the issue is.
I finally got around to this, again. :-\ I've got some NEW wonky voltages. IC7, IC9, Q2, and Q5 are my main focus. I've swapped in a new IC7, as I've got some bad voltages there. I don't have any 1458s for IC9, but they're on order. I'm not certain if Q5 is causing problems at IC9, or the other way around. I think I'll swap both Q2 and Q5 transistors when I put in the new 1458. I'm determined to get this pedal done this week. The owner has been extremely patient with me on this one, and I want to see what it can really do.
I couldn't come up with any resolutions for the problems I had been experiencing, so I've convinced myself that I'm chasing snipe. The noise I was chasing is most noticeable with the sens turned ALL the way up, and the gate triggered, but nothing being played. I thinks it might be noise associated with the compression in the circuit, as had been previously stated. I'm calling this one done and taking it back to the owner. Thanks again, Scruffie. I really appreciate all your efforts.
Tim C in AZ