Tetsujin Posted January 22, 2015 Share Posted January 22, 2015 This came on quite suddenly, initially I thought it was software-based, then PSU or footswitch. After using the just fine guitar for about half an hour, the volume started to fade in and out, like a very slow tremolo. Doing the usual relaunch of software, jiggling plugs in sockets etc it came back, but only for a while. I then noticed the power light on the footswitch was fading in & out with the same frequency; so that got my attention for the next hour or so, trying to figure out whether the PSU or switch was dying. Long story short… after a while it got so the power light would show up green for just a few seconds after plugging in, & for those few seconds I'd get sound, then it would fade out again. I tried it on battery power - same thing, short period of sound, then quickly fades to silence.. rinse & repeat each time I unplug & replug. So… it's the guitar itself, I'm guessing. Does this sound like a capacitor is dying, or is it more serious? Is it repairable, or do I need to start buying up what old bits of 500s I can from eBay & start stockpiling spares? Quote Link to comment Share on other sites More sharing options...
allanboe Posted April 13, 2015 Share Posted April 13, 2015 Hi Just this morning I experienced the same thing with my variax 500. Lost my XPS power supply a month ago, ordered a new one and used batteries while waiting for new power supply. Received new power supply today, but experience the same problem as you describes. Still works well with batteries though. Have you gotten any helpful answers or found a solution yourself? Regards Allan Quote Link to comment Share on other sites More sharing options...
cz-milan Posted May 21, 2015 Share Posted May 21, 2015 Hi, I had the same problem after upgrading my Vax to higher version. I solved it buying and using the XPS-DI box (power supply for Variax Bass). It has more power and a little higher voltage. No problem has appeared after that fix. Quote Link to comment Share on other sites More sharing options...
leesteel Posted May 21, 2015 Share Posted May 21, 2015 Just for reference. Full Compass can get any parts you might need. If you don't see it on their site, they can still get it. 1 Quote Link to comment Share on other sites More sharing options...
Charlie_Watt Posted May 21, 2015 Share Posted May 21, 2015 The Variax electronics stop working if the supply goes below about 7V. Make sure your TRS cable isn't suffering a problem since the power is sent on the ring of that cable. If it runs on batteries, the other thing to check is the connection from the TRS jack on the Variax to the board. It has to be a power issue. The Variax board regulates the voltage down to the 5V it needs to run it's circuits but it needs almost 7V for the regulator to work properly. 1 Quote Link to comment Share on other sites More sharing options...
Tetsujin Posted May 23, 2015 Author Share Posted May 23, 2015 Ach - serves me right for thinking that testing with a PP9V was going to be an accurate 'second opinion'. If I put a meter on the PSU itself, it shows the voltage quickly drops to zero, over a few seconds. Do you know how resilient the guitar input is to over-voltage? I have a stack of 12v 4000mA PSUs I use for work. I'm loathe to buy a new specific PSU for the Variax if I can get away with one of those for free. Also - is the Variax PSU definitely centre pin + [looks to be on the meter, but it's gone so fast I'd rather be sure] If it wouldn't stand it long-term but would be OK for a 5 min test, that would at least be sufficient to then get my hand in my pocket for a new PSU, after checking the guitar isn't as dead as rumour would have me believe :unsure: Quote Link to comment Share on other sites More sharing options...
Charlie_Watt Posted May 23, 2015 Share Posted May 23, 2015 The power supply that came with My Variax is AC. (the wall wart piece) The XPS box converts it to DC. The Variax uses about 700mA at about 7V when running on batteries. You could rig a 7-9 VDC supply for it if you know what you are doing. (Using the TRS cable) The guitar regulates the voltage down to 5V anyway. Don't ever give it the wrong polarity or you will smoke the diode protection circuit. Lots of folks have done that by accidentally hooking the 9V battery pack up backwards. I always make very sure that I match up the connector before hooking up the battery. I use NiMh rechargeable batteries in mine and I always have a spare one ready to go. I now use my JTV most of the time but I have used my 500 since they came out. I don't even remember what year that was...... 1 Quote Link to comment Share on other sites More sharing options...
Tetsujin Posted May 23, 2015 Author Share Posted May 23, 2015 AC? Ahhh… that changes things, I guess. I wasn't really aware of what the XPS box was doing. Meter on the unloaded PSU shows 11.7V AC - but plugging it to the XPS box lights the ¼" green, but the red Power light only stays lit for a few seconds then dims. Push-pulling the power plug generates blips on the red light but nothing more Trying to get the meter on the TRS jack gives a brief DC voltage, probably not long enough for an accurate measurement, then drops back to zero. As I don't know how to actually measure the voltage from the PSU when under load, I'm now unsure whether that would point the finger at PSU or XPS as being at fault. Is there any way I can eliminate one or the other as being possible source, with limited resources- i.e., a multi-meter & little prowess with it - short of finding a spare of each? Quote Link to comment Share on other sites More sharing options...
Charlie_Watt Posted May 23, 2015 Share Posted May 23, 2015 Are you sure your TRS cable isn't shorted? Try without the TRS cable plugged into the XPS and see if the power stays on. Quote Link to comment Share on other sites More sharing options...
Tetsujin Posted May 23, 2015 Author Share Posted May 23, 2015 TRS looks fine. Tested end to end, no short, no open circuit. I cleaned all contacts again, right the way through - now I'm back to something closer to my initial symptom... I get a green light on Power when the guitar's plugged in - but it's fading in & out [quickly through red to off & back] at about once a second, sound comes & goes with it, more off than on, just a pulse. I've sprung for a new PSU. If it turns out to be the XPS, that's going to be less easy to get hold of a spare... Quote Link to comment Share on other sites More sharing options...
Charlie_Watt Posted May 23, 2015 Share Posted May 23, 2015 I would bet that it's in the XPS and not in the PS. Quote Link to comment Share on other sites More sharing options...
Tetsujin Posted May 23, 2015 Author Share Posted May 23, 2015 I managed to find an XPS too - here's hoping... Quote Link to comment Share on other sites More sharing options...
Tetsujin Posted May 28, 2015 Author Share Posted May 28, 2015 So far you would appear to be correct - new PSU, no difference. XPS, of course, is a special order item & may take a month :( Quote Link to comment Share on other sites More sharing options...
Charlie_Watt Posted May 28, 2015 Share Posted May 28, 2015 For what it's worth, I always use rechargeable batteries in my 500. I have two sets. I use 2100 mAH NiMh batteries. I have the XPS but I never use it. I also have a JTV and I use that on the VDI or on batteries. Quote Link to comment Share on other sites More sharing options...
Tetsujin Posted July 14, 2015 Author Share Posted July 14, 2015 So - 6 months almost to the day on this miserable saga... My new XPS box eventually arrives... .. & is not the fix either. Identical symptom to before, light goes red/green/red… sound comes & goes in time with the light. Quote Link to comment Share on other sites More sharing options...
brue58ski Posted July 21, 2015 Share Posted July 21, 2015 The power supply that came with My Variax is AC. (the wall wart piece) The XPS box converts it to DC. The Variax uses about 700mA at about 7V when running on batteries. You could rig a 7-9 VDC supply for it if you know what you are doing. (Using the TRS cable) The guitar regulates the voltage down to 5V anyway. Don't ever give it the wrong polarity or you will smoke the diode protection circuit. Lots of folks have done that by accidentally hooking the 9V battery pack up backwards. I always make very sure that I match up the connector before hooking up the battery. I use NiMh rechargeable batteries in mine and I always have a spare one ready to go. I now use my JTV most of the time but I have used my 500 since they came out. I don't even remember what year that was...... It's my understanding that when matching power supplies the voltage always has to be the same and the current's amperage can be the same or higher. Never lower (I have seen this. Lower is bad) Quote Link to comment Share on other sites More sharing options...
Tetsujin Posted July 21, 2015 Author Share Posted July 21, 2015 More sago to add the saga - I've found an entire 500 electronics structure in a failed DIY project for sale on eBay - will see if swapping components in the guitar itself improves things... … otherwise I guess it's time to go for a new JTV - with all the added effort of setting it all up just how I like it, rather than the existing 500 which I got right 10 years ago. I have to admit I didn't really like the 500 to play when I first got it - I grew up on Strats of various qualities/ages - but I did manage to set it just right with not too much work. Quote Link to comment Share on other sites More sharing options...
briannolan_99 Posted July 26, 2015 Share Posted July 26, 2015 Same problem here - volume fading in-and-out behaviour has been happening on-and-off for a few months now with my Variax 500, but today I only get a couple of seconds of sound out of the guitar before it disappears :-( @ Tetsujin - keep us up-to-date if you make any progress with your investigations... I'm quite fond of my 500 too! Cheers! Quote Link to comment Share on other sites More sharing options...
eltonhilburn Posted January 4, 2016 Share Posted January 4, 2016 I am having the same problem with my Variax (it is from the first generation, circa 2004, as I recall). Using the XPS box, power light turns from green to red. What is the solution?! Quote Link to comment Share on other sites More sharing options...
Tetsujin Posted January 4, 2016 Author Share Posted January 4, 2016 My eventual solution was swapping out the main logic board, from the bag of bits I bought on eBay. I've had no issues since. I now have a spare everything - except another logic board, of course - the bag of bits was a complete set of electronics from a Variax 500. Quote Link to comment Share on other sites More sharing options...
moonsai98 Posted March 15, 2020 Share Posted March 15, 2020 Not sure whether it’s too late for you guys as I just saw this thread. I owned a 500 and a 600. With the 500, same sound faded out and sometimes in-and-out, especially using the XPS. Eventually I fixed the problem by spraying WD40 over the entire circuit board and all switches (you need to spray a lot like soaking it with WD40). It’s been over a year and still working good no matter with battery or the XPS. With the 600, no sound with battery or XPS. I did the same trick by spraying WD40 on the mode selector (soaking with WD40) and the same miracle happened. If the faulty 500 still with you guys, it’s worth to give it a try as i worked for me. Quote Link to comment Share on other sites More sharing options...
Tetsujin Posted June 3, 2022 Author Share Posted June 3, 2022 I GOT IT… I think. Well, to put at least a temporary close on this... 6 years later, I'd found someone with the necessary chops to have a look at this. In preparation for shipping it off I cleaned it down & thought I'd give it one last shot. Put a battery in, mono jack - it worked. I spent the rest of the day trying to track down just what power supply issue this hinted at - something on the switching between battery & mains... I cleaned it all to within an inch of its life, half a can of contact cleaner later. IT WORKS AGAIN. Been playing it all day, no fails so far. Let's see how it goes. Quote Link to comment Share on other sites More sharing options...
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