uedat125

Hi BoggianoSoy, Excuse me for writing off of my memory but I seem to remember those are near the DSP on the other side of the board. Good luck, and if you get it fixed, please post how you did it!

Hi BoggianoSoy, Yes, L4P is the package label for BAT54 series schottky diodes. FYI, I've attached a datasheet for them. As to the problem of no sound with M5, I have a unit that has a similar issue where there's a faint sound when the effect is switched on, and at the time of finding the issue I was suspecting one of the op amps but will have to look again when I have time, as I stowed it away and haven't gotten around to fixing it. In the meantime, once again I'd suggest you go through all the test points, marked TP and see for any failure in order to narrow down which part of the circuit is causing the issue. Good luck! https://datasheetspdf.com/datasheet/BAT54C.html uedat125

Hi eenymason, I know the post was from more than 5 years ago but I'm wondering if you still have any of those. I have a body assembly of Variax 300 which is missing the bridge (I have a Tyler bridge but it's incompatible). I could probably use the bridge and the neck.

Hi PedroHesse, Copy/Pasting my previous comment here, knowing that your problem sounds similar to what I had: I would try to separate issues. First check the connectors between PCBs. They can come loose over time and quite often the problem. Also there may be corrosion in the contacts. If the sound is there but no display, make sure the display driver has the right voltage. If there’s no sound, check the input/output for potential disconnect, or any indication of small piece of metal/solder bridging input and the ground. Check all test points for correct voltage. Check any indication of dead IC/transistors. It could be resistors or caps, by the way. If there’s a faint sound coming from the output, check the op amps and power amps. All these things will require patience, but remember that the circuit once worked well and there’s probably one disconnect in the path of the guitar signal. Good luck!

Congratulations on your excellent job finding the right part and the schematics, edgibbs! You just proved that my sharing of the repair experience made a bit of contribution to Line 6 users, which is the whole purpose of the post. BTW, where did you find the schematics? I'd very much like to take a close look!

Hi Wtfusay I would try to separate issues. First check the connectors between PCBs.They can come loose over time and quite often the problem. If the sound is there but no display, make sure the display driver has the right voltage. If there’s no sound, check the input/output for potential disconnect, or any indication of small piece of metal/solder bridging input and the ground. Chances are that the IC/transistor you’ve replaced had fault in itself or not in good contact. Check all test points for correct voltage. Check any indication of dead IC/transistors. It could be resistors or caps, by the way. If there’s a faint sound coming from the output, check the op amps and power amps. All these things will require patience, but remember that the circuit once worked well and there’s probably one disconnect in the path of the guitar signal. Good luck!

Okay, one of my 9V AC adapters for M9 had gone funky and I first thought the transformer was the issue, and went ahead with getting cheap replacement transformer. It turned out to be a broken cable inside the bushing at the secondary, and I got it taken care of, being left with an idle 9VAC 400mA (3.6VA) trans on hand. As a matter of fact, I had ended up buying a lower capacity trans (3.6VA) by mistake, which overheated during use and failed to deliver constant output, leaving M9's display blank with colored back-light, nothing legible, while the sound coming out fine. So I bought another power adapter of same make, cracked the case and took out the transformers, and wired them in parallel to produce 800mA (7.2VA), and found them working all day. The transformers would heat up to a modest temperature but not to the point of failure. Then I wondered what to do with the case, and after looking around I found a cool looking soap box at a dollar shop, and after some thinking I came up with an easy solution involving double sided cushion tape for mounting the transformers and narrow double sided tape for fixing the top and the bottom of the box. (I had bought the tape previously at dollar shop too) Cables were put through the drain holes at the bottom so I didn't have the trouble of drilling holes. Done cheap and easy.

Just to share my experience, I was able to run M9 with a 9VAC 400mA (3.6VA) power adapter for about 10 min, then the transformer in the power adapter would heat up and fail to deliver required current, rendering the LCD screen fade into blank with no legible letters but the colored light. I took the transformer out of the adapter, and did the same with another power adapter, and wired them in parallel to produce 800mA, then M9 continued to wok all day. The transformers heated to a modest temperature but not up to the point of failure. So, I'd assume the unit requires more than 800mA power supply. I hope this helps.

Hi pepethebull, Congrats on successfully repairing your M9. I have an M13 which is a working unit, I haven't gone far as to opening it up, but I'd examine voltage around the audio section by checking out all the test points, as the circuit design may vary. While you have the power on, check the test points, then if all check out okay, check the semi-conductors visually for any indication of burnout. Also make sure that the tru bypass is working to eliminate possibility of relay or coil burnout. I've had a faulty inductor in a Tonecore, FWIW. Best of luck!

I thought I’d share my experience with a non-working M9 which I successfully repaired myself. I auctioned off a M9 described as faulty, no sound,. The owner used it for a long time and when he powered it on for the first time in about a year, it failed to produce any sound. Uppn receiving I pluged in and confirmed the condition where the LCD and switch indicators light up normally and function as expected but no sound. However the sound would come through when the effect was bypassed via tru-bypass, but not a humming noise when it’s on, so I figured the input/output and their relays are okay, and on an assumption that the trouble was somewhere around the DSP, I began probing the test points for voltage. I found +12V power was not there in the analog amp section and spotted the DC regulator “2SC1623-L4” (D23) was faulty. However it’s an old transistor rather hard to find. Eventually it was found at a Chinese parts shop Aitendo in Akihabara where I’d been a few times, but they only had “2SC1623-L6.” Crossing my fingers that the circuit design wasn’t so strict I bought a strip of them and managed to replace the faulty one with a new one which is smaller than a grain of rice. Having seen the correct voltage at the test point, I connected the guitar and amp to hear colorful sound fly out of the box. It was worth the perseverance in the research and craft.