Hotone Ampero II Stomp - Review

[laxu]

I'd be interested in seeing how you fix this.

The plan:

• Carefully disconnect the flat cables. There's usually a clamp you need to pop open with a spudger.
• Remove the potentiometer hats and their nuts.
• Remove the 4 screws holding the PCB seen in the top pic.
• Desolder the center potentiometer, its connections are near the footswitch board connector.
• Replace with the matching potentiometer. Finding the exact right part is probably the biggest challenge.
• Assemble back together.

 

[wgowwgo]

The plan:

• Carefully disconnect the flat cables. There's usually a clamp you need to pop open with a spudger.
• Remove the potentiometer hats and their nuts.
• Remove the 4 screws holding the PCB seen in the top pic.
• Desolder the center potentiometer, its connections are near the footswitch board connector.
• Replace with the matching potentiometer. Finding the exact right part is probably the biggest challenge.
• Assemble back together.

Good luck mate.
Hope it's an easy fix.

 

[laxu]

So, faulty encoder desoldered. It was a huge pain in the ass.

Disassembling the unit is actually very easy. Desoldering the encoder is very tedious.

Tools disassembly:

• Screwdriver to remove the boards.
• Allen key to open the chassis.
• Nut socket wrench to remove nuts on knobs without damaging the pedal surface.
• Spudger to open flat cable connectors.
• Small tweezers, preferably plastic.
• Small pliers to get out the PCB connectors.

Good to know disassembling:

• The Volume knob hat can be stuck harder than the rest. The others you can just pull by hand but you want to carefully wiggle the Volume knob out as that knob is its own separate little PCB so don't pull too hard.
• The flat cable between the two halves can be a bit tricky to get out and back in since it's right against a footswitch. Use a spudger.
• The touchscreen cables are also a bit finicky, just work carefully and slip them under the PCB they are connected on.
• Remove the processor/memory board (small board with a metal backplate).
  • It's good to remove this so you have more room with your soldering iron and don't risk scorching the brains.
  • I thought the backplate was a heatsink but it's just a cover, under it you can find a Winbond chip of 256 GB DDR3 or DDR4 I think.

Then on to actually desoldering the encoder.

Tools for desoldering:

• You absolutely need a proper soldering station! Even with one, I had a helluva time getting enough heat going to get the solder out of the larger tabs holding the encoder.
• A PCB holder is a very useful tool to help you.
• Solder wick.
• Desoldering pump.
• Good solder, duh!
• Good lighting is essential.
• A magnifying glass and a small flashlight are great for actually seeing if you got the solder out.

Good to know desoldering:

• Be very careful around a few places:
  1. The multi-pin connector for the "brain" PCB. I slightly scorched mine because I tilted my soldering iron a bit too much, but thankfully no real damage was done and I could get the PCB back on just fine.
  2. There is a surface mount resistor very close to the center encoder's 3rd leg, and there are others close to the other encoders.
  3. The pins of the encoder are close to the footswitch PCB jack, so avoid melting that.
• The actual encoder is held by 3 pins, and 2 legs.
  • I recommend you treat the encoder as a goner because I broke one of its pins getting it out and mangled it a good bit too.
  • It's best to desolder the legs first, then you can bend it out so it's hanging by the pins and desolder them. The encoder should then just drop.
• Finally clean up any stray solder, metal bits etc. I use a bit of isopropyl alcohol to clean it up with a small brush, and finally use a bit of canned air to dust it off.

Finally just assemble it back together in reverse order. It will work fine without the encoder, you can use the param/value knob as a replacement until then or operate the middle button with the touchscreen. It's great that Hotone has fallback options like these!

So what about replacement parts? I contacted Hotone, and they said then can ship me spare encoders! Will probably take a few weeks to arrive.

 

[KingsXJJ]

So, faulty encoder desoldered. It was a huge pain in the ass.

Disassembling the unit is actually very easy. Desoldering the encoder is very tedious.

Tools disassembly:

• Screwdriver to remove the boards.
• Allen key to open the chassis.
• Nut socket wrench to remove nuts on knobs without damaging the pedal surface.
• Spudger to open flat cable connectors.
• Small tweezers, preferably plastic.
• Small pliers to get out the PCB connectors.

Good to know disassembling:

• The Volume knob hat can be stuck harder than the rest. The others you can just pull by hand but you want to carefully wiggle the Volume knob out as that knob is its own separate little PCB so don't pull too hard.
• The flat cable between the two halves can be a bit tricky to get out and back in since it's right against a footswitch. Use a spudger.
• The touchscreen cables are also a bit finicky, just work carefully and slip them under the PCB they are connected on.
• Remove the processor/memory board (small board with a metal backplate).
  • It's good to remove this so you have more room with your soldering iron and don't risk scorching the brains.
  • I thought the backplate was a heatsink but it's just a cover, under it you can find a Winbond chip of 256 GB DDR3 or DDR4 I think.

Then on to actually desoldering the encoder.

Tools for desoldering:

• You absolutely need a proper soldering station! Even with one, I had a helluva time getting enough heat going to get the solder out of the larger tabs holding the encoder.
• A PCB holder is a very useful tool to help you.
• Solder wick.
• Desoldering pump.
• Good solder, duh!
• Good lighting is essential.
• A magnifying glass and a small flashlight are great for actually seeing if you got the solder out.

Good to know desoldering:

• Be very careful around a few places:
  1. The multi-pin connector for the "brain" PCB. I slightly scorched mine because I tilted my soldering iron a bit too much, but thankfully no real damage was done and I could get the PCB back on just fine.
  2. There is a surface mount resistor very close to the center encoder's 3rd leg, and there are others close to the other encoders.
  3. The pins of the encoder are close to the footswitch PCB jack, so avoid melting that.
• The actual encoder is held by 3 pins, and 2 legs.
  • I recommend you treat the encoder as a goner because I broke one of its pins getting it out and mangled it a good bit too.
  • It's best to desolder the legs first, then you can bend it out so it's hanging by the pins and desolder them. The encoder should then just drop.
• Finally clean up any stray solder, metal bits etc. I use a bit of isopropyl alcohol to clean it up with a small brush, and finally use a bit of canned air to dust it off.

Finally just assemble it back together in reverse order. It will work fine without the encoder, you can use the param/value knob as a replacement until then or operate the middle button with the touchscreen. It's great that Hotone has fallback options like these!

So what about replacement parts? I contacted Hotone, and they said then can ship me spare encoders! Will probably take a few weeks to arrive.

I don’t think this will end well but I wish you luck.

 

[laxu]

More pictures of the insides. Sorry for a bit crap quality here, just quick snaps.

Main PCB. Backplate from processor removed. You can see here I've desoldered the encoder right near the white connector up top.

Main PCB with processor removed. It's stuck pretty hard so you have to carefully wiggle it out from the sides to lift it.

Back of touchscreen. There's a bit of tape to hold the cables flat against it when it's assembled, and the cables go through the slot in the main PCB.

Back of processor board. You can see the Winbond 256 Mbit memory module here.

Other side of the PCB. You can see the ADSP-21573 DSP chip, and interestingly a separate MIMXRT1052 ARM core most likely used for UI etc.
There's a Winbond 25Q128JV 128 Mbit flash memory module.
Then there's a Micron D9PSL memory module. It's afaik a SDRAM DDR3 module but no idea about the size, couldn't find much with those .

 

[laxu]

Encoders from the other side of the main PCB. The one in the bottom center is the one that was stuck. The hardest to replace would be the bottom left encoder because it's close to a few capacitors. I'd probably try to clip its legs instead of trying to desolder the whole part.

Closeup of the faulty encoder. After removing it (and breaking one of its legs in the process) I took it apart completely but still could not figure out what exactly makes it stuck. My guess is some tiny metal shaving has lodged in it somewhere.

No pics of the disassembled encoder, but it's a couple of contacts on each side, a greased wheel that clicks and pushes the contacts together, a plastic shaft inside a metal one that connects to the wheel. Pretty simple design so it's no wonder these probably cost very little in China.

New encoder. There's no markings for value or anything on these. Hotone says they are customized somehow from the OEM.

 

[laxu]

Then I'm proving @KingsXJJ wrong.

I replaced the faulty encoder, and now the A2 Stomp works like brand new!

Good to know:

• As I said in my earlier desolder post, a proper solder station is a must for this repair. No cheap ass 15W soldering irons!
• The 3 pins on the encoder are quite easy to bend by accident, so make sure you clear the PCB holes for these very well.

The installation of the new encoder is easy, desoldering the old one was much harder.

1. Clean the board first with some isopropyl alcohol. Let it evaporate for a minute or two.
2. Carefully push the 3 pins of the encoder in first, then push the two legs in and make sure the encoder rests firmly against the board similar to the other encoders.
3. Then just carefully solder the 3 pins and the two legs and you are done.
   1. With this encoder's position, the parts to watch out for are the white footswitch connector (easy to melt plastic), the surface mount resistor right next to one of the pins, and the processor board socket. So don't tilt your iron too much.
4. Clean the area again with isopropyl alcohol. Let it evaporate for a minute or two.
5. Use canned air to clear the board of any solder flakes, hair or dirt that might've landed on it.
6. Reassemble the device.

It cost me $32 to get 3 encoders shipped from Hotone to Finland. The parts were free but the shipping was not, or you can consider it parts + shipping cost. While that's a somewhat sizeable chunk of the cost of the unit, I still commend Hotone for being willing to send spare parts like this to some random owner. They didn't ask for receipts, serial numbers or anything like that.

I consider the encoder fault to be a fluke. These are just some OEM parts that probably don't cost a lot and there's always a chance that one of them fails along the line. I bought this Ampero 2 Stomp used, and the seller had used it for over a year so we are not talking about a brand new unit here. Otherwise I would have just had it replaced under warranty.

I have to give them props for the Ampero 2 Stomp design. It's very modular and pretty easy to disassemble, and if you can get the parts all boards would be easy to swap.

My least favorite part of it is the power supply. It's cheap, and it sucks. It doesn't use a standard IEC connector but a 3 prong fitted version so you can't just use a longer cable on it. The included cable is annoyingly short. I've got a CIOKS doubler cable coming from Thomann and I'll see if I can power the A2 Stomp with my CIOKS DC7 or CIOKS Expander 4 instead.

 

[KingsXJJ]

Glad that you proved me wrong and that it worked out!

 

[wgowwgo]

Thought I'd give an update on my experiences with the Ampero 2 Stomp.

TLR It's great.

I've used it for five shows since I bought one second hand in February. I've not experienced an major problems. I'm a weekend warrior who plays in a Royal Blood style two piece, but with a guitar instead of a bass.

This means the Stomp is providing the bass and guitar tones, so if anything goes wrong, the show is over.

I have the Stomp set up for one guitar output with an IR to go to the front desk, one guitar output to run into the fx return of a stage amp, and an octave down "bass" output to run to the bass amp.

It does everything I could ask of it. Sometimes I run into DSP limitations, but I expected that. It does require me to prepare everything before the show though, so there is a bit of homework in regards to setting up my patches and scenes.

I would recommend the Stomp to anyone looking for an affordable entry into going digital. It's made my life a lot easier at shows.

Thanks again to all the people who answered my questions about this unit.