Line 6 Spider Jam strange problem

[guitardad]

Like the header says.

Opened it up and found bad 7293 amp. Customer also reported another odd problem. No reverb, but when you turn the reverb control to max boooooom max volume! So I tested and confirmed that problem (about knocked me back when it cranked and was too loud to detect any reverb) and again tested it unloaded. Turning the reverb control did nothing (no reverb effect at all) til maxed, then nasty oscillation along with the actual guitar sound (signal maxed as if master was dimed). This again blew (destroyed) the 7293.

Line 6 isnt too nice about info/service manuals on these. I wonder if anyone here may know or have an idea or print of the reverb circuit. I am assuming dsp. I measure 0 ohms on two sides of the reverb control. I wonder if a small smd cap is shorted down that line maybe.

Units ribbon cabling to that board also has that old brown glue on it (I hope that stuff isnt like the old kind used on vcr's that became resistive).

I've managed to restore a lot of DSP by just maintenance on these boards and other model amps by resweating the dsp board solder using hot air rework equip..

I don't want to cook another 7293 in the process. Unit is out of warranty. If this thing needs a new board then I'd imagine it's not economical.

Ideas?

Thx

[mozwell]

schematics in this thread
http://music-electronics-forum.com/t31423/
between all of them, you may get what you need......

[olddawg]

Have you tried a hard factory reset? It's the first thing you should do to to any Line 6 that is working with problems. It's in the owner's manual. The procedure is usually unplugging the unit, press several buttons at the same time, plugging it in, and turning the power switch on. You will loose all of the custom presets but it will set it back to the way it was out of the box. I've revived several left for dead with weird problems by doing this.

[guitardad]

Yeah, Did the reset to no avail. Was my first thing to try once the OP IC was replaced initially.

The schematics in the link I looked at those too. Not the same as the Spider Jam. In the event I come across one or a solution, I'll be sure to post it here.

A local auth svc center said to change the main board. Again, that just prices this thing out of any repair. I was hoping to fix it for far less than board replacement costs. Given this is the only thing wrong with it (non working reverb control) I'll try to trace it back. I've seen bad smd caps or diodes on these data lines create havoc for dsp circuits. Could be an open line too. Just nice to have a print to guide me.

Thx

[g1]

Line 6 business model is more like the computer (pc) business model than other music equipment companies. So circuit boards are basically looked upon as components.
Multi-layer (rather than just double-sided) circuit boards are used and bad connections between layers can make the boards unrepairable.
This is why they just do board swaps.
This is just one of the reasons many on this forum do not service line 6 products.
If the pot itself is not defective, I would suggest cutting your losses and returning the unit as is, unless the customer is ok with board replacement costs.

[olddawg]

If the reverb pot does not have an open element or bad wiper (if it even has a pot), I would do the reset a couple of times. Discharge the power supply filter caps first and let it set over night. Also, if it has. 3v battery take it out for the reset then replace it. It may not completely reset until it is stone dead.