Anyone a Line6 service center?

[defaced]

I have a dead XT Live and wanted to pick someones brain about the problem.

[cjlectronics]

I'm not a Line 6 service center but I am a Roland Authorized Service center. Tell us what the problem is in detail and maybe one of us can help.

CJ

[Enzo]

Dead - as in no sign of life - is usually one of the simplest things to repair. Generally is power related.

If by dead you just mean generically in the shop, well it could be anything.

I am not a Line 6 shop, but I have yet to encounter one I couldn;t fix, and there is no support from Line 6 for sure.

[defaced]

It's a Line6 XT Live that's about 2.5 years old. I flipped it on a couple of weeks ago and the screen lit up but was blank. Resetting and safe mode did nothing. In searching the Line6 site, this seems to be a common problem and is a symptom of an SRAM failure. I've got a thread started on their forum, and rumor has it this particular problem is covered out of warranty - does anyone know if this is true?

I don't expect to get much support from them regarding a DIY solution. How much of a pain these things are to work on and get parts for? Assuming something happens and I can't get it fixed at a service center, I'd like to have some idea if a DIY solution is feasible. I can't imagine this being more than a board swap, but getting the board could be a challenge.

[jrfrond]

We are a Line 6 service center. Many times, but not ALL the time, reloading the OS can solve these type of issues, but you won't know it until you try and see if it works.....or fails. You will NOT be able to obtain PC Boards from Line 6, but you CAN download OS updates at their website. Updates DO require a MIDI interface and a piece of proprietary freeware called "Line 6 Monkey".

[defaced]

Monkey does not detect the device over a USB connection. The computer prompts to reinstall the drivers when I connect the device, so something is living, but Monkey is a no-go. Is it pertinent that the connection be made with MIDI cables?

[Enzo]

Have you checked internally for missing power supply voltage?

[defaced]

I've not opened the unit - yet. I wanted to see what Line6 had to say, which amounts to I'm on my own for this one.

The unit gets power and the screen flashes. I'm going to open it and see if I can find a smoking gun.

[Enzo]

In a digital/analog system like this you will find +/- high voltage for the power amp, then +/-15 (or maybe 12 or 17) for the analog circuits. There will be typically +5 for the digital stuff and sometimes +3.3 for the processors. SOmetimes there are separate +5v rails for the digital and the A/D stuff. I don't know what the screen uses to light up, but some are back lit by LEDs, some are electroluminscent panels or even mini-flourescent. Those wopuld also have sepearate power supplies. John would know which parts of this are correct for your model.

SO a loss of +5 digital would leave the computer dead, but the screen could still light up.

[defaced]

R121 is the smoking gun and R123 looks like a possible casualty. Geographically, this looks to be something that links the USB circuit to the main computer. There are seperate ground planes for each broad category of device. Does anyone know what values these two resistors are?

[defaced]

R123 appears to be ok, it was just covered in junk. I cleaned it up and it's a 22.1 ohm resistor. I found two other fried parts, C25 and L4. In checking voltages, all of them are low, but the 3.3v one is reading .21 volts and get very hot within seconds of powering on, so it looks like there's a short somewhere.

John, would you mind looking up the values for the following parts if you have a schematic?
R123
C25
L4
My main board is Rev B, dated 06.25.2004.

[Steve Conner]

I'm going to guess that someone plugged the USB into a grounded PC, then stuck the output cord into an old Fender with a bad death cap, and the resulting short between 120V line and ground cremated the USB circuit.

If you're lucky, it just blew out some transient suppressor or buffer chip on the USB lines, and this is shorting the 3.3V supply and preventing the DSP from booting. (Everything digital runs off 3.3 now, 5V went out with the original Gameboy.)

If you're unlucky, it went right up the USB lines and blew out the DSP itself. Ominously, 22 ohms is the standard value for series resistors in USB lines, and you have two fried 22 ohm resistors in there.

In situations like this, when all else fails, I like to hook up a heavier 3.3V current limited supply to ram several amps of current through the shorted supply rail. Whatever component is dragging the rail down will let you know by getting hot. And you don't have to worry about wrecking the offending part, since it's already blown. Just don't overcook it and start burning up PCB traces.

[defaced]

That sounds about like what happened: I plugged my amp into the pod and things went south. I don't think my amp has a death cap, so possible there's a mains wiring issue I need to sort out. Would a coupling cap on the input of the first gain stage have prevented this, or is this an AC mains issue?

I'll dig around tonight when I get home and see if I can find the offending USB device. Transient suppressors and buffer chips, are those larger multi leg chips or smaller 3 legged chips?

Do you have a standard higher current 3.3 device you like to use?

[defaced]

Plugged it in and started touching things. Two chips get hot: CS8420-CS, which is a digital audio sample rate converter, and a removable CMOS chip. I lifted the power legs of the D/A converter (which resolved it's heating symptom) and removed the CMOS chip but the 3.3v rail is still low.

[Steve Conner]

Hi Mike

The fact that the USB interface burnt up so violently suggests to me that either your amp or your computer has 120V on its chassis. So yes, I'd say you have an AC mains issue that you should resolve quickly, before you personally follow your Pod to the grave. And no, I doubt a coupling cap would have helped.

I'm kind of a USB newbie, I've laid out PCBs for a few USB products. The only USB protection chip I know of is TI's SN75240PW, but it doesn't connect to the supply rail at all, so that kind of ruins my theory.

About the 3.3 thing, I always have a few different power supplies lying around. Bench power supplies are really useful to have, and standard equipment in most electronics labs. We use them every day at work. However, if you just tinker with stuff occasionally at home, or mainly do repairs, they might not be worth the expense. You could buy another Pod for the price of a good one. (Enzo, do you use power supplies in your repair shop?)