Another Ibanez ES2 Echo Shifter repair

I took another look at an Ibanez Echo Shifter that I had previously repaired, but had come back to me. This time it wouldn't light up, but did pass a clean signal. I suspected a bad power supply for the digital section.

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.

Before

Desoldering was straight-forward, I used hot air and kapton for protecting parts I didn't want to overheat.

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.

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.

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.

Ibanez DDL10 Delay II

This is another early digital delay pedal, I am guessing it was built in 1986 from some of the IC date codes. I don't know if the 10 series included the first Ibanez/Maxon digital delay. Obviously this is the "Delay II", but the DDL Delay I and Delay III were also released in the same series of pedals,  each with different delay times. The max delay time of 900ms of the Delay II put it in a similar league to the Boss DD-2.

Inside, there is a two PCB construction with a hard-wired ribbon cable. The top board has unpopulated parts, I would guess that a DML10 (modulated delay) could be built on this same board by populating an opamp LFO and adding the two extra pots.

DDL10 internals

The bottom PCB has two 4164 DRAMs, an NE571 compoundor, LM311 comparator (most likely used as part of an ADC as in the DD-2 and PDS delays) and a bunch of opamps. The SIL (single in-line) package chips are M5218L low-noise preamplifiers, used in lots of Japanese pedals. There are only 2 4164 64kb DRAMs, the DD-2 has 3. Either the DD-3 has higher sampling rates, or the Ibanez uses 8-bit samples instead of 12-bit. This is still more than the single 64k seen in Digitech PDS 1 second delays.

Main PCB, component side

The back side of the lower board just has a main controller MC4101F IC. I can't find any info on this, it's almost certainly a custom controller for digital delays (like the Boss/Roland RDD63H101).

Main PCB, back-side.

This unit looked mostly dead, it passed no effected signal and LED didn't respond to the footswitch. I thought the back of the larger board looked a bit crusty so I clean it with 99% IPA, afterwards I saw the LED blink with the footswitch. Still no signal.

I couldn't find any schematics for this model online, but someone has scanned and uploaded an Ibanez factory schematic for the DFL10 flanger from the same series, which uses the same controller IC. There is a full pinout.

DFL10 schematic page 1.

DFL10 schematic page 2.

From the schematic, the clock signal for the controller looked like it was coming from a VCO to pin 26 ("2F"). I probed my board and found that I did have a clock signal, it could be varied by turning the Delay knob, and I also had what looked like communication between the controller and the RAM chips.

At this point I got really lucky. There was a 100uF electrolytic capacitor near the LM311 comparator that was a little discoloured. While taking measurements I noticed it was getting warm. I pulled it from the circuit, and the pedal started passing a delayed signal. This cap is connected from 5V to ground right next to the comparator input, if the cap was leaky then it would effectively mute the comparator. Everything worked without this capacitor, I replaced it anyway with a new low profile 100uF for peace of mind.

Faulty capacitor pulled.

The LED turned out to be a bad solder joint - it would light sometimes if it was held in a certain position. Reflowing the joints fixed it.

Ibanez FL9

A quick one. I got this original 80's 9-series flanger that didn't seem to be "flange-ing".

Ibanez Fl9

When plugged in it gave out that tell-tale "whirr" sound when power was applied that some kind of delay was happening. It sounded like the signal was delayed correctly and mixed in with the clean signal, but nothing was happening with the LFO, so there was no "movement". First thing to check is if the Speed pot is wired up or broken.

Back of speed pot

Hey, are those two lugs of the speed pot shorting together? I removed the pot and separated them with some needle nose pliers. The speed pot now varies the speed of the LFO and everything works as expected.

PCB topside

A quick shot of the board while I have this open. The BBD and clock generator ICs are MN3207 and MN3102, manufactured by Mitsubishi. Build quality is pretty high for what was standard at the time. All the electrolytic capacitors are Nichicon brands, some have "8138" datecodes so I think this is 1981 vintage.

The flanger sounds great, but is much more subtle than the MXR I looked at recently. This does chorus-style sounds much better rather than screaming airplane sounds. 9V operation is a bonus.

Revisiting the Ibanez Echo Shifter

After repairing the second Echo Shifter, the PCB sat on the bench for a few days before I re-assembled it. When I did, I found that it had stopped working again. It would light up, but there was no signal in either effected or bypass modes. When I played with the controls I found I could still get it to oscillate by changing delay times with the oscillation switch on, so I knew the delay and output circuits were good.

I opened it up, connected a signal to the input jack and started tracing to see where it died. It wasn't getting past the input jack. Measuring continuity, I found that the jack tip and sleeve were shorted together. I desoldered the jack and it tested fine out of circuit. There is another choke/filter at the input jack, presumably to keep any high-frequency digital noise out of guitar cables, and it looks just like the failed one on the power input. I took it off, and the jack was no longer shorted, but no signal was getting through. Shorting across the pads as before and everything works again. I measured the part out of circuit and the pins were shorted together in a way that doesn't make sense to me at all. It seems like they fail both as open circuits and as shorts.

L6 removed and pads shorted

This is probably totally fine as a fix, and I couldn't see any clock noise or similar on the input jack. I decided to replace the jumpers with some ferrite beads to help cut any high frequency crap. 0805 parts will just about fit, the ones I had are 1 kOhm at 100 MHz.

L6 populated with ferrites

There is another one of these filters at the output jack, I replaced this part at the same time.

L7 replaced wit ferrites as well

Technically these parts have a 500 mA rating but I decided not to add them to the power supply input, as I worried about reliability.

After re-assembling and punishing the switches and jacks for a little while all seems good. This should make the ES-2 closer to bulletproof. Hopefully some more dead units can be revived as well.

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.