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Discussion Starter #1 (Edited)
I have 2 Memory Lane 2 delays, and my older one has started to produce some noise in the delay line. It works well otherwise, but there is a buzz that is present, it gets louder in time with the tap tempo and it is present even when the pedal is bypassed. The other pedal (which is newer) is dead silent.

It is way out of warranty, I contacted Diamond twice with no response. Fair enough, they don't make it or stock the parts anymore.

Anyone know someone who is good with analog delays who might be able to fix this?

These are great pedals, and I'd like to have this one working 100% as a backup.
 

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Discussion Starter #4
Yeah, that’s the same Brian who did the pedal assembly for Scott at aaysr. He might be good.
 

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Discussion Starter #5
Diamond folk are still in the post NAMM catchup mode. I'm sure you'll hear back.
Yes they have been helpful in the past, I had some compander overload issues and Aimish talked me through the fix.

I’ve sent a couple of requests since dec with no response. I can understand, legacy product out of warranty, Troubleshooting, finding parts, it’s a pain in the butt. It would be great if they want to fix it, but I get it if they don’t.
 

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So this has an interesting twist.

Scott brought over a pair of Memory Lane 2s that he owns. One of them was dead quiet, and the other worked great, but after a little while this annoying background whine would come on, like one of those European police/ambulance sirens. The whine was clearly synced to the LFO, and would go up and down faster as the Speed control was advanced. It was also present in bypass mode.

At first I thought that this was merely a case of the clock signal leaking through due to a mis-setting of the balance trimmer. (Bucket brigade chips have two parallel paths internally, and their outputs can have a "clock-bucker" effect if balanced just right to cancel out the clock signal). I wrote to Diamond for some info to identify which trimmer adjusts balance (there are 8 trimmer inside), and repair person Brian Fecteau was very helpful in providing two annotated pics of the inside with trimmers relevant to several functions circled, and adjustment notes provided.

I dickered with the trimmers, to no avail. I wrote back to Brian, indicating lack of success, but this time provided a little more information, I noticed that the chassis indicates 24VDC for the power jack, but the wallwart Scott provided is 18VDC (though he said the adaptor came with the pedal). The pedal uses three voltage regulators to bring the external supply down to 15, 12, and 5 volts, successively, and are visible here as the three objects leaning against the chassis, on the upper left with metal tabs. Such regulators require an input of at least 2V more than they output, so I was wondering if the wallwart might be the source of the problem. It is not uncommon to include diodes to protect the pedal against use of the wrong wallwart, and these could bring the voltage the regulator sees close to, or even below that 2V requirement. But no, when I touched my meter probes to the relevant pins on the 15V regulator, it put out a nice stable 15V. It is normally the case that supplies are "down-regulated". That is, the external supply is regulated to provide one voltage, then additional regulators successively drop that regulated supply voltage to lower ones. I figured if the 15V checked out okay, then the rest would be fine.

BUT, I also mentioned to Brian that the whine didn't really come on for about 5 minutes, which suggested to me a problem with heat or a bad capacitor somewhere. All the discussion of regulators, and the mention of the "warm-up time", triggered a recollection on Brian's part. He mentioned that in an earlier run of Memory Lane pedals they ran into problems with some of the regulators; specifically the ones used for 12 and 5 volts. It seems that the tabs on the batch they received had unusually thin heat-sink tabs. He sent me a photo of what to look for, and sure enough, Scott's pedal had the offending regulators. The ones you see in the pic below have "normal" heat-sink tabs. The ones they had naively installed in the run of pedals that Scott's came from were less than half that thickness.

Anyhow, this weekend I'm going to replace the offending regulators with new ones I have, and hopefully the appropriate heat-sinking capabilities will coax the pedal into blissful quietude.

Many thanks to Brian from Diamond. And also to Scott for trusting me with his pedal and providing the opportunity to learn something about consistency in commercial parts that I would have never suspected.

 

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Discussion Starter #8
Many thanks to Mark for taking this project on. I'm pretty sure that his bench time on this one exceeds the value of the pedal, but I really like ML2's and I appreciate him doing it.

Just a PSA, if you ever get an invite to Mark's place, you need to go. He has more cool pedals, amps and gadgets than anyone I've ever met.
 

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Just a PSA, if you ever get an invite to Mark's place, you need to go. He has more cool pedals, amps and gadgets than anyone I've ever met.
@amagras and I were invited to Mark's home a couple of years ago. A wonderful and extremely special day for me that I will always remember well.
Mark was an exceptional host.
 

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Discussion Starter #10
Additional info, this particular ML2 has a serial number around 270, and is from the batch with the lighter blue lettering if you encounter a similar issue. I bought it used back in Sept. to use on a smaller pedalboard. I did test it, but as Mark mentioned, it takes a few minutes to start happening.

My other one is a navy lettering, SN in the 1000's. I bought it new from L&M in Ottawa a few years back. Its been perfect from day 1.
 

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Thanks guys. You're exceptional guests. Next time you come there will be more interesting stuff. I'm working on a dual delay - admittedly with only 10-bit digital delay chips, so not high-def - that allows for cross feed of feedback signals and individual tone-shaping of the feedback as well as the overall delay signal. So, whatever is in the feedback loop for channel A can be fed to channel B's feedback loop, and vice versa. Normally stereo delay pedals can be patched for "re-processing" (i.e., A's output becomes B's input), which can sound fantastic, but there is only one set of controls for the overall pedal (i.e., the delay time for channel A is the same as that for channel B). My unit under construction has independent delay, mix, and feedback-level controls for each channel, as well as independent tone-shaping. It's been sitting on the pile-of-shame for a few years, and I'm finally getting to it.

And yes, when I wrote back to Brian, I mentioned the colour of the labelling/legending on the pedal, and I suspect that also helped trigger recall of problems that they had experienced early on.
 

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Followup.

To replace the regulators, it required taking the board out to remove solder from both sides of the double-sided board. Taking the board out required removing the retaining nuts on the pots that are soldered to the board and hold it in place. Removing the retaining nuts required removing the control knobs.

And THAT's where the problem happened. Four of the knobs came off easily, using an Allen key to loosen the set screw. However the other two knobs were on so tightly, that when I inserted the Allen key and gave a twist, the set screw didn't budge but the hex socket in the set screw got stripped by the Allen key, such that nothing was going to grip it and turn it.

I drilled a small hole into the set screws, making sure to leave material and not graze the thread in the knob, thinking that I might get the set screw out, pop off to the store and get replacement set screws. I thought that maybe I could find some sort of tool to get in there. Convened an expert panel of four old guys in aprons at Lee Valley Tools, and their best suggestion, after looking at the pedal, was to grind down an oversized Allen key, tap it into place with a hammer, and hope that it would grab the set screw. I did that, but no dice.

Mulling it over, I realized that if I couldn't remove the board if the pots were still attached to the chassis, maybe I could disconnect the pots from the board and leave them attached to the chassis, but liberated from the board. Worked my way through a couple inches of solder wick, because there is a LOT of solder when standard-size pot lugs are soldered to the board. But I was able to wiggle the lugs with my needlenose, giving the thumbs up sign that the board would not be held down by them.

Removed the board, replaced the regulators with new ones that had the proper thick tabs, resoldered the pots, and reassembled the pedal. It has been on for a half hour now, and no sign-o-the-whine. Success! I'm going to bed.
 

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Congrats!

Very impressive perseverance and use of alternate approaches.

And to top it off...the fix is successful!

BTW...Is this what is referred to as "Thinking outside of the chassis"?
 

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Thanks, gents. Richard, I'll put this case in the same pile with that sesame-seed-sized resistor we had to find on my workbench when we brought your Variax back to life. Thank goodness it never fell on the garage floor!
 

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Cool story!

It's amazing to me that you were able to disconnect and then re-attach something so big and heavy from such a complex and delicate circuit board. I think that pedal would be dead if I tried that.

I popped open my Sparkle Drive a year or two back, planning to experiment with some alternate component values to would allow more bass frequencies to pass.

I took a long look at the double-sided PCB with surface mount components, imagined all the damage I was about to do with my mediocre soldering skills, and then put the pedal back together and set it aside to gather dust. Chuckle.

Well done!
 

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So, take a peek here. See that red toggle switch attached to the back of the box? See the phone jack just to the right of that toggle? If you unscrew those two from the back of the enclosure, and move them out of the way (the wire is stiff which will hold them in place and clear), you have a reasonably clear path to the solder lugs of the two pots underneath them. IN fact, once all the things installed along the real skirt of the pedal are moved out of the way, you have a pretty clear path to unsoldering just about all the pots, with the possible exception of the LFO depth pot, that has a switch on the back and is in a "busy" area. As long as one is using a soldering iron with a reasonably slender profile, and slim tip (i.e., not a soldering gun or iron suitable for plumbing), it was not an especially courageous or demanding de-soldering/re-soldering job.

One last point: SOLDER WICK!!! I do confess to use my little handheld solder sucker at some points, but copper braid solder wick is able to absorb excess solder from places that solder-suckers often cannot invade or access. Keep some on your bench. You'll need it. Maybe not today. Maybe not tomorrow. But soon, and for the rest of your life. It's the beginning of a beautiful friendship.;)
 

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Thank me when you get home and it works properly. I slipped on the way to dropping it off and it went flying into a snowbank. I wiped all the snow off quickly, but make sure there is no water in there, first. ;)

But you're most welcome. I enjoyed the challenge and learned a few things along the way.
 
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