I opened it up, and I could see ~8.5V volts powering the opamps but no voltage at any of the digital parts, where I would expect 3.3V.
Way back in July 2017 a commenter asked if I knew what the part number for U14 was, likely to be a buck-converter, and that they suspected it was a Texas Instruments TPS62056. The package, function and chips marking all looked like a perfect match so I ordered a few this week to see if it was right.
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| Before |
Desoldering was straight-forward, I used hot air and kapton for protecting parts I didn't want to overheat.
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| During |
The new chip has near identical markings to the old one. Re-soldering was a little harder as there isn't a lot of space, I ended up removing C73 temporarily to get better access. The bridged pins are fine, all those pins are connected together at the PCB.
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| After |
Everything works again with the new chip. Thanks to Shane Bussiere for doing the research and sharing the part number, sorry I didn't help out.
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| All working again. |
Looking at the TPS62056 datasheet, I can guess why this failed. The buck converter chip has a maximum Vin of 10V, the Echo Shifter runs the power jack through a series Schottky diode for polarity protection and then to the TPS. If you use a 9V power supply the chip gets around 8.6V, which is fine, but using a 12V power supply or higher will probably kill it. I couldn't find a compatible chip from TI with the same footprint and pinout but higher maximum input voltage, let me know if one exists.
I would really like to modify this to add a modulation rate control. I hunted around for modulation signals and unfortunately there doesn't seem to be a LFO onboard, it looks like the modulation is done in software in the ADAU1701 DSP. A modulated square wave is run out of the first audio DAC on pin 46.
While I had this open I desoldered the 24AA128 serial EEPROM and dumped the contents, it can be downloaded here. Afaik the ADAU1701 instruction set is not publicly documented, so I don't think the firmware can be easily modified.
Thanks for sharing. Great post very Informative, also checkout Excel Electronics
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ReplyDeleteThe article is much informative which i was searching for.Nice intro good explanation thanks for sharing.
ReplyDeleteEnrgtech
Hello!
ReplyDeleteI fix pedals and amps as a hobby and just discovered your website... you can probably imagine how excited I am to take the time to read all of it, I even might get popcorn to eat while I do :)
I'm working on a very strange ES2. It's already been fixed (mainly the ferrite/ jumpers usual suspects), but the symptoms are quite surprising to me.
All the chips get proper voltage, no problem with that.
When I plug it in without any jack it looks like it's turning on normally (tempo blinks regularly, the speed changes with the slider or I tap it, the bypass switch turns on and off, etc) but when I plug the jacks I can only hear the dry signal, no delay or else.
The strange part is when I plug the power supply while the jacks are already in : then the two lights (bypass and tempo) turn on continuously and nothing changes that. I can only hear the guitar signal the moment I plug the power supply, but just for about 1/4 of a second and then it fades away real fast.
I suppose the unit is using the standard ibanez/boss flipflop jfet switching, I'm going to check that first, but if you have any other clues in mind that'd be really nice.
Thanks a lot and congrats again on the website!
Mat
Hi Mat,
DeleteThanks for the kind words. That is some strange behaviour you're seeing. I don't think the ES2 uses traditional style switching, I believe the footswitches are wired to the ADAU1701, so I would guess it mutes the wet signal. It's been a long time since I looked at these pedals though. It does sound like the digital side is working (or mostly working) and usually that's the hardest part to diagnose.
Some ideas for missing wet signal:
Bad mix pot? (I don't remember if the mixing is analog or done digitally)
Blown opamp somewhere on the wet path?
Bad DAC?
Most of these could be ruled out by looking for a delayed signal with an oscilloscope or audio probe.
The issue with inserted cables is really strange. There is a transistor (Q1) near the input jack - maybe this is for detecting when a cable is inserted, and it's having trouble?
Thanks a lot !
DeleteI'll try and test with your tips in mind when I have the time. I'll report the results here in case someone find them useful some day !
Hi, did you fixed it?, I have problems with another ES2.
DeleteHi, did you fixed it?, I have problems with another ES2.
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