JVT-89F Model LED Colors

[StanPenn1]

I have a JTV-89F purchased new a few years ago, plus a spare I picked up used a few months ago. The 1st one is quite solid on functionality (knock on veneer). Sadly, the 2nd one is being flaky on engaging modeling. I've ruled out the typical knob/switch issue.
 

It appears to be a power-on initialization problem. If it boots up properly, the model LED is white when engaged, and it's good for days if not unplugged. But if bootup doesn't go well (frequency of this happening varies wildly), behavior with battery+1/4", XPS with 1/4", and VDI run the gamut:

1. No light at all, and mags only with 1/4" (nothing for VDI - kind of expected if DSP -> AES path isn't up).

2. Blue, green, or purple (!) model light and mags only with 1/4". Seen most often with XPS.

3. About 1/2 second red flash and mags only only with 1/4" . Every once in a while on trying this, if I wait a while, the normal white modeling light/functionality does come on when pushed.

4. Red alt tuning light and same outcome.

5. Strangely, sometimes the white model light is on right after plugging in via VDI. My #1 unit doesn't do this.

 

Here's where I disclose I've been an electrical engineer for 40 years, so you can all roll your eyes now. Plus a hack musician from earlier than that. I've designed analog instrumentation, digital boards, mixed signal very low EMI boards, lots of embedded systems, some PC peripherals, and worked in firmware and software. There are lots of questions I could ask that likely wouldn't be acceptable in this forum.

 

I did remove the main board and inspected it under magnification, along with all connectors. I blew off the board (with an antistatic-rigged air source). No difference. I do have a spare UI PCB assembly I could try, but I doubt that's going to matter unless something about the model/tuning switch states are intermittently wigging out the processor on startup.

 

Anything else to try other than a service ticket? I've been building a rough idea of a schematic from lots of continuity testing, but that could go on for quite a while ;)

[StanPenn1]

Er, for any English majors, I didn't proofread enough after some editing. Should be: behavior ... runs, and something ... is. 

 

[brue58ski]

The only time I've seen these colors mentioned in this forum, it needed a service ticket. I think one or two of them are a "danger Will Robinson" sign.

[psarkissian]

A lot going on there, a great exercise in circuitry. Sounds like more than one issue.

Time for a trip to a Line 6 authorized service center, so that each one can be dealt with.

 

[JAYSTER-X]

Hello StanPenn1 - I have the same issue with my L6 Shuriken 250 scale modeling guitar.  Sounds like the same exact problem, Have you found the root of the trouble yet ?   I have had my board out under a scope and extracted as much schematic info as I could.  My problem is associated with the  Main relay  (NEC EA2-5NU) that is when it clicks or engages the white led is lit and guitar functions. The problem is that this does not always happen at initial power up and I find I have to cycle the power afew times to get it to respond.  It has always finally worked, sometimes with 1 or 2 attempts or many more it's not predictable.  I also have the variety of lights at the modeling switches and have not found any reference or pattern in there appearance.   I have found the early schematic for the Variax pcb mk1 but not much of it translates over to the latest version, but there are many good points of reference. I don't believe I have a bad relay I think it is in some circuit that drives the relay that is in question. Any thoughts that might be helpful would be appreciated. The problem still exists but I seem to cycle my way around it eventually. I run/power through a Helix rack and love the system when it works.  Would love to get my hands on the main board schematic if anyone has access to it.  Pictures attached is front and back of mainboard, backlit to show via pathways.    Cheers, Jack K.