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levelhead86

JTV-69: Intermittent Battery functionality

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So, I inheited a non-functional JTV-69 a few months ago. All I knew at the time was that the unit would not power on under battery and wouldn't be recognized by the Workbench adapter (likely because it wasn't powering on).

 

When it arrived, the first thing I did was charge up the battery and plugged it in to see what it was doing. Sure as advertised, the guitar wouldn't power on and the battery LED shows nothing. I checked the battery with a multimeter and I was getting 8.4v, so appeared to be charged and alive. For the heck of it, I checked the charger and I'm getting 12v at the adaptor and about 8.7v across the prongs on the charger. All seemed in line.

 

Based on this, I ended up ordering a replacement main PCB (from Full Compass). Three weeks later, that came in and I installed it. On first try after installing it, I got full LED appearance and finally got the guitar to power on. Played it for maybe 5 minutes, unplugged it. Came back later, tried it again and it worked again. Came back later and nope, stone dead and no battery LED again.

 

At this point I was a little freaked out because I thought the first PCB got fried and the new one was fine until some time plugged in and this one fried too. After I calmed down, I got a hold of someone with an HD500 to try seeing I'd it'd power on with the data cable. Tried it and it worked reliably for several days. So, confirmed the PCB is fine.

 

I started suspecting the battery was the issue. I've had Li-Ion batteries for drills and whatnot that show full charge right after a charge but die instantly on use.

 

So that in mind, I ordered a new battery from Sweetwater. Two days later, it arrived, I inserted it into the guitar just to test and I got LED readout, albeit one blinking light. I assume that they ship discharged. So, I put it in the charger, solid red light for about the prescribed 8 hours then blinking red light, so full.

 

Installeded into the guitar, shows full LED and guitar powers up. Works great and reliably on and off all day. I only check it for maybe 5 minutes at a time and a few times today, so no more than 30 minutes of playtime. I was also removing the battery between uses. Came back to use it this evening and uh oh, back to no LEDs and guitar is stone dead.

 

I plugged the battery in and it's reading full (blinking red light).

 

Pulling my hair out over here.... My last remaining cause I can think of is the battery holder itself. I pulled the batter holder out and used the multimeter on the back to make sure the battery is making full contact with the prongs and I'm showing full voltage. But there's a small PCB on the back, so I'm guessing it's possible the problem is there?

 

Just wondering if anyone has had this experience or has any ideas. I'm starting to miss my ol' 6 double-A Variax 300 haha

 

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Quick update to this.

 

Tried the new battery this morning five different times and it worked every time. Put battery in, full LED indicators, powered it on and played, unplugged, came back later and tried again and it worked every time. Also tried the OLD battery twice and that's ALSO working every time I plug it in.

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Intermittent problems don't get solved until they become constant problems. If I were you, I'd just run with it as long as it's working. If and when it craps the bed again, you can try to diagnose it further... but till then you'd just be beating your head against the wall. 

 

I'd also give it a real test drive, and see if it functions normally for any length of time, with real use.  Switch models, tunings, etc... Plugging it in periodically and fiddling with it for a few seconds at a time really isn't telling you much. Play it for a couple of hours and see what it does. These guitars are notoriously weird...

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You make a lot of very good points!

 

So, I took a break on this thing and decided to revisit it as recommended above. Here's what I found.

 

The guitar eventually stopped responding to a battery being installed entirely, despite being at least 99% charged. HOWEVER, a battery fresh off the charger gets the guitar to power on just fine... for about 3 - 5 minutes and then it dies again. THIS I've been able to repeat predictably a few dozen times now, so no more reading tea leaves, no longer "intermittent".

 

My assessment: the guitar refuses to power on unless the battery source is essentially 'overcharged'. When the battery was brand brand new out of the box and on a fresh charge, it was outputting enough voltage to satisfy whatever issue the guitar is having for a few minutes before it dropped to what would be considered 'normal' operating voltage and the guitar would shut off. After a few weeks/months of battery degradation, the battery no longer has AS much power on the top end, so the guitar goes from lasting several minutes with a fresh battery to only a couple before shutting off... that's also why the new battery was getting the guitar to power up at first and the old battery wasn't, despite both being within acceptable range.

 

So the current assessment is the battery holder, considering I already replaced the main PCB. I'm not the worlds biggest fan of Full Compass, so I spoke to Sweetwater about seeing if they can source one through their parts department; they took two weeks just to answer me back and after that, they want list price ($49) plus shipping and it's special order, so I'd still have another couple weeks. Bit the bullet and got it through Full Compass instead for $42 and free shipping, I'll give an update when it arrives.


Thanks again!

 

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One way to test your battery pack would be to rig a simple DVM (volt meter) connection in order to view/measure voltage sag when the battery pack is powering the Variax.  I suspect very high IR (internal resistance) of the lithium battery pack so that when even a small/light load is applied the voltage drops below required circuit specifications.  

 

Search youtube for lithium battery IR testing/measurement - although normally associated with RC models the technique can be applied to practically any battery chemistry and configuration.  Any battery much above 100 mOhm (that's mili Ohm, btw) will sag significantly under even mild load.

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On 6/8/2018 at 7:59 AM, jerseyboy said:

One way to test your battery pack would be to rig a simple DVM (volt meter) connection in order to view/measure voltage sag when the battery pack is powering the Variax.  I suspect very high IR (internal resistance) of the lithium battery pack so that when even a small/light load is applied the voltage drops below required circuit specifications.  

 

Search youtube for lithium battery IR testing/measurement - although normally associated with RC models the technique can be applied to practically any battery chemistry and configuration.  Any battery much above 100 mOhm (that's mili Ohm, btw) will sag significantly under even mild load.

Thanks for the advice!

 

So, I'd say the issue is finally resolved. Unfortunately I never got a chance to do as thorough a diagnostic as listed above but I did narrow things down to the battery power and seeing as I replaced the battery already, the battery holder was next and did the trick.

 

Not much to add to what was mentioned in my previous posts. The new one came in, I swapped it and since then, I've used the guitar a combined 4 - 5 hours and everything works. The guitar showed some sign of abuse and maybe having beer spilled on it, so my guess was that the battery holder issue was the result of damage rather than any kind of factory defect.

 

Worth mentioning, Full Compass listed the battery holder as 'in stock' but I waited over a month and a half for it. After getting frustrated, I called to find out what was going on, the sales rep was nice and said they'd look into it. The next day they called and said the Line 6 shipment was incoming, and two days later I got notification it was in route to me. Maybe I had really lucky timing or maybe they forgot it but regardless of the reason, it did take a long time and that's the second Line 6 product I bought through Full Compass that took over a month to arrive.

 

Anyway, thanks guys! Appreciate the advice throughout and loving having this working.

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I did a gig in 100 plus degree heat outside yesterday and both my charged batteries went into protect and would not function.As soon as it cooled off they both showed 100 per cent.No big deal as the rest of the guitar is great for all styles but I had never used it out in the heat.Now I know lol!

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Suffice to say, the battery system is especially finicky. To be honest, if it weren't for not being Workbench HD compatible, I'd prefer my old 300 for the AA batteries.

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I am often surprised lately at how killer the tones of my Variax 500 are and how the little battery pack works with rechargeable AAs

such a great little utility guitar!The JTV on the other hand has big boy playability and features along with the modeling tones.Just not in any kind of extreme weather lol!

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On 8/12/2018 at 10:38 PM, levelhead86 said:

Suffice to say, the battery system is especially finicky. To be honest, if it weren't for not being Workbench HD compatible, I'd prefer my old 300 for the AA batteries.

 

Yeah, it would’ve made much better sense IMO to widen JTV operating voltage and a mounting system/sled to allow the “option” of either AA or 18650 lithium rechargeable packs.  Particularly since there's no "charging" taking place inside the guitar.  

 

RC model industry did it with computerized radios as lithium packs became more prevalent and better understood.  

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On 8/12/2018 at 11:16 PM, JTSC777 said:

I am often surprised lately at how killer the tones of my Variax 500 are and how the little battery pack works with rechargeable AAs

such a great little utility guitar!The JTV on the other hand has big boy playability and features along with the modeling tones.Just not in any kind of extreme weather lol!

 

I'm a fan of 500 models too.  JTV59 magnetics make it my goto Axe but if I had the 500 models in a magnetic 3 pickup Tele body the JTV would collect some dust.  

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I came here with a very similar problem and see this post at the top of the list...wow.

 

Helping my father in law with his Variaxe.  His will not power on with a battery.  Ordered new battery and charged it, still not powering on or indicating LED status.  Tried the battery from my Variaxe, same results.  Plugged the guitar into HD500X with data cable, and it does work.  So it is something to do with the battery not getting power to the unit.

 

Do you think it would be the battery holder as it was with yours?  How hard was it to swap?

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27 minutes ago, toobhed said:

I came here with a very similar problem and see this post at the top of the list...wow.

 

Helping my father in law with his Variaxe.  His will not power on with a battery.  Ordered new battery and charged it, still not powering on or indicating LED status.  Tried the battery from my Variaxe, same results.  Plugged the guitar into HD500X with data cable, and it does work.  So it is something to do with the battery not getting power to the unit.

 

Do you think it would be the battery holder as it was with yours?  How hard was it to swap?

 

Yeah that sounds a whole lot like my issue. Clearly some of the guys on here are a lot better suited to explain what's going on inside of one of these from an electrical standpoint but to the extent I did troubleshooting on mine, I was very surprised when I took the battery holder out the first time. I just assumed the battery ran straight to the brain with maybe something off to the side for the LED indicator but the battery runs to a PCB mounted on the back of the battery holder itself (this all comes as one unit if you replace it) and lord knows what it does in there but it exits somewhere else on the board and out to the brain. No way of knowing if one of the traces is damaged or a component burned out, as mine showed no visible damage. That was a big part of my confusion/frustration.

 

For my 2 cents, the last thing I'd check before buying a new holder are prongs themselves. They were kinda flimsy and sometimes mine would tend to fold down under the battery rather than insert into the openings on the battery. It would take a couple tries to thread them in right (don't get me started on the charger) and I knew I was replacing the holder anyway, so I actually unscrewed the holder (inspected it thoroughly while I had it apart) and broke the prongs free of the older and plugged them into the battery directly just to rule out contact problems from how it was seating. Didn't make a difference in my case. Not that I'm recommending you do that but yeah, double and triple check the prongs and any connection from battery to pcb on holder and from pcb to brain.

 

As far as replacing it, it was cake. 4 screws, removed the cavity cover for the brain, unplug and replace with new. Everything snapped together. No soldering, no snaking cables through narrow passages, etc. The opening in the body are ample space to feed the wire and connector through. The only pain was just how long it too Full Compass to send it.

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36 minutes ago, toobhed said:

I came here with a very similar problem and see this post at the top of the list...wow.

 

Helping my father in law with his Variaxe.  His will not power on with a battery.  Ordered new battery and charged it, still not powering on or indicating LED status.  Tried the battery from my Variaxe, same results.  Plugged the guitar into HD500X with data cable, and it does work.  So it is something to do with the battery not getting power to the unit.

 

Do you think it would be the battery holder as it was with yours?  How hard was it to swap?

 

It appears you've ruled out the battery pack itself.  Likely open connection someplace between the battery terminal connection point and DC input to the logic board.  

 

Official response will most likely be to open a ticket and seek authorized repair.  Certainly not a "bad" option although time consuming.  

 

Could be something further down into the PCB however, an experienced solder jockey can probably trace/track things well enough to do no further harm while exploring where the fault might be found and perhaps correct it without any need to seek outside assistance.  

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1 minute ago, jerseyboy said:

Official response will most likely be to open a ticket and seek authorized repair.  Certainly not a "bad" option although time consuming.  

 

That's a good point and one I forgot to mention. Mine was several years old, I'm the third owner and it's had a hard life, so warranty coverage wasn't an option and L6 shop price was rich for my blood but if you're even remotely covered under warranty, it's worth a try.

 

The replacement holder on mine was ~$45 and just took a philips screwdriver to replace it. The brain I wasted my money on was ~$165 if I'm remembering right, so that gives you an idea of the cost involved with buying your way to a diagnosis. Not sure how those match up with bench fees.

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jerseyboy,.... right.

 

Could be as simple as a loose connection. 

Or as bad as the battery box, main board and jack plate circuit damage because of too much current

being pulled because of trying to run both 1/4" and VDI together, or not using a TRS end guitar cable.

 

Won't know for certain until it's on the repair bench and properly gone through and evaluated.

 

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3 hours ago, jerseyboy said:

 

I'm a fan of 500 models too.  JTV59 magnetics make it my goto Axe but if I had the 500 models in a magnetic 3 pickup Tele body the JTV would collect some dust.  

 

I hear you there. I was very much surprised at how much I liked the magnetic pickups in this, to the point that I'm planning on carrying them over IF I should happen to make a replacement body.

 

I'll make sure to post pics if/when that say comes.

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I have the new battery holder, looking to install it, but I can't tell if this is a connector that can be removed or if I have to snake the cable through the cavity.  Check out this post.

 

 

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