CraigGT

The Normal channel of a Deluxe Reverb uses two triodes before the PI and the Vibrato channel uses three. Every triode stage causes phase inversion and that is why the channels are out of phase and they don't jump well.

Mine's still in bits I'm afraid, I ended up buying a new one with three years warranty. Craig

Yes everything else works fine.

Thanks for your effort and it pretty much confirms my thought that it's the processor board and there's not much that's replicable on there. I was quoted around £400 for a repair, I ended up buying a new one wit three years warranty. Craig

On a second look you are correct and I do get that 220 Ohm and continuity of the other usb pins too, apart from the screen.

I traced it out and found similar except I see the ground to pin 5 and shield not connected to the header. Shield and ground have continuity through the MCU board if the header is plugged in. The capacitor you said was grounded both sides and is missing on mine goes between ground and shield so that explains your measurements. I can't find any continuity for the other side of L22. Craig

Here is the equivalent area from my Helix floor. R349 is 220R, C38 and C316 are 220pF I'm not sure if C8 is my problem or just not populated. One side of C8 is USB ground.

I have a Helix in a similar state and I've not seen any TVS diodes. There are some passives on the IO board then it's cabled to the CPU board where I can find no continuity so I believe it's connected straight to the BGA processor chip. Craig

At least he's using the search function :-)

You can go straight to 3.6

Also there were Grammatico's before 3.6, It just added an extra one.

Good advice @mmccain, I think the bigger issue is if it was out of warranty, an authorised service centre would charge for a replacement footswitch pcb. I have the same issue with a DSP board that won't communicate over USB.

There is a very short cable between the processor board and the screen which powers the backlight, it's possible that it could have become dislodged.

Good point, I guess it landed at a more convenient time here in the UK.

I'm not sure what went wrong but the cabs are in the firmware not your backup. That only contains your presets and settings.

I can't believe that no one is talking about the new Grammatico amp. While I appreciate that it's not to everybody's taste it really is a fantastic sounding amp.

There is also a lamp test in the test menu, I forgot about that.

The switch and LED are seperate parts and changing the LED is not for the faint hearted. There's four solder pads on that! Also there are two LEDs per switch so it's unlikely that both have failed. Craig

Are you sure there's a tonal change and not just a volume change? The FX loop should absolutely be set at 100% that's not debatable so there's something else going on. Do you have the FX loop and B unit in and outs all set to the same Line/Instrument?

If the FX Loop Mix is set to 100% then latency won't be an issue, it sounds like you've got a parallel path somewhere. Unplug the output from B and you should lose all signal, if not then it proves the parallel path.

The PSU is a board on it's own and wouldn't be too difficult to change. That said, I've not heard of one failing before.

I just edited my post but not before you replied.

There isn't a fan in a Helix. If you're hearing a noise I'd suggest that the PSU board is making it which isn't a good sign.

Something like these https://uk.rs-online.com/web/p/leds/8154332 Craig

I can't remember where I bought mine but they're a generic RGB Led, it measures 3.1 x 2.1 mm if that helps. Craig