Ibanez ES2 Echo Shifter

1 second analog delay with modulation, an oscillation switch and tap-temp from Ibanez. I really like this delay. Opinion tends to be split on these, they sound great and and have a very nice feature set but are very prone to dying. Online reviews are split between gushing praise and reports of the things crapping out:
http://www.musiciansfriend.com/amplifiers-effects/ibanez-echo-shifter-analog-delay-with-modulation-guitar-effects-pedal#reviews

https://www.amazon.com/Ibanez-ES2-Shifter-Analog-Guitar/dp/B00BFWIZGI/ref=sr_1_1?ie=UTF8&qid=1473597444&sr=8-1&keywords=ibanez+es2#customerReviews

I wanted to look at these to figure out why, I ended up with two with different faults. These seem to match the most common complaints.

Broken Sliders

This first unit was sent to me already repaired and modded. The previous owner had had someone swap out the footswitches for nicer soft-touch switches. The originals are actuators that press microswitches on the PCB. The new switches worked, but tap-tempo and bypass had been swapped functions. The slider for delay time had also been sheared off and the battery snap had been cut off.

 

The backside has some opamps (TL072) and some 74HC4040 ripple counters. I don't know what the counters are doing. The toggle switches are wired to the PCB and mounted through the PCB in rectangular cut-outs - I like this, it prevents form turning when the nut is tightened and they are strain-relieved from the rest of the board. J6 has two pins soldered together. The trimpot on the right hand side looks like a mod but may be done at the factory, it looks pretty clean.

 

The other side has two Coolaudio V3205 4096 stage BBDs, and 2 BL3102 clock drivers. The clock frequencies for the BBDs goes as low as ~3.5 kHz, which is ~500 ms for a 4096 stage delay, so if both BBDs are cascaded then a 1 second analog delay is achieved with a bandwidth in the region of 1-1.5 kHz. This is dark but still sounds very nice for long delays for guitar.

U9 is an Analog Devices ADAU1701 DSP. This device has 2 ADCs and 4 DACs but very little memory, so it seems very unlikely that it is providing any digital delay. I am guessing that this is only handling tap-tempo, bypass, generating the modulation signal and maybe doing filtering and/or compression of the delay signal before and after it hits the BBDs. U13 is 24AA128 EEPROM for the program code.Analog Devices make a visual drag-and-drop programming environment for these DSPs (SigmaStudio) but unfortunately it will not load binary ROM dumps so I can't see what exactly what this chip is doing. I can probably dump this if anyone needs it.

 

These sliders are a standard 45mm footprint.

 The delay slider is a 10K linear 45mm potentiometer, I used a Bourns part (PTA4543-2015DPB103) as a replacement.

Added a connector to footswitch wiring so I could take the board in and out of the case.

I also re-did some wiring to swap the footswitches back.

Power Failures

This seems to be the most common problem. I came across a second unit that refused to power up at all. This one had a piece of foam between the battery bracket and the back of the board, and had the original switch PCB and actuators. There was no trimpot with hot-glue this time, but otherwise identical.

L1 looking worse for wear.

 I started measuring for power at the 9V jack. No current was drawn, and L1 looked a bit dodgy. This looks like a common-mode choke on the power input, filtering noise along with C7 and C70. The top of the ceramic broke off when touched with a tweezers. I guess this part wasn't rated for the current draw of the pedal, or doesn't handle vibration or shock well.

L1 bridged.

 As this is just a choke, we can jumper straight across it and restore power to the rest of the pedal. I lifted it off with hot-air and used some bus bar to bridge the pads.

Working again, and sounds just like the other one.

Current draw is less than 60 mA on these, which is surprisingly low.

I haven't seen any problems with noise or interference since removing this choke, so I will probably go back to the first pedal and do the same as a preventative measure. It is likely that this filter is need for EMC compliance to stop power cabling radiating the ADAU clock signal. This is a simple enough repair, and only needs the back casing taken off, the board can stay in place inside the pedal.