Mojave input jack issue?

[GuitarBrent]

My Mojave Sidewinder is doing something kinda funky. The high input channel sounds fine. When I plug into the Low input channel though the volume tends to kick up and down while I play. Could this be a loose or faulty input jack? This thing is so well built, I'm perplexed as to what the issue is. I don't think it's the tubes going down, as it's only on the Low input channel. ANY HELP?

[Blue Strat]

It does sound like the low input jack from your description. Possibly an intermittent solder connection? If the amp is PC board based that would be a very real possibility.

[dankayaker]

I have this exact issue with my Divided by Thirteen.

[John Phillips]

It's most likely the shorting contact in the High input jack. It's this that provides the ground end of the voltage divider when you use the Low jack, so if it's not making proper contact, the Low input volume will go up and down by 6dB (quite a lot).

Try a little contact cleaner in the jacks (both of them, to be on the safe side). If that doesn't cure it you may need to get inside and clean or retension the switch contacts manually.

[phsyconoodler]

Those amps use a cliffjack type unit that is far inferior to the REAL cliffjack.I have used them on occasion but they are a real pain when stuff like this happens.I have even had that issue with some switchcraft jacks on a 2204 build.The quality of these parts are in question these days,as the older switchcrafts have often been in service for 50 years and more without issues.
There is also another problem I'd like to share.Planet Waves cables.They have those gold sleeves to supposedly make the contact better?Well I don't use them anymore becuse they have expanded the jacks on a few vintage pieces and cause problems when other cables are used.Haven't had those issues with George L's.So there may be a couple of things going on here;poor quality jacks and cable sizing.

[GuitarBrent]

Ok, the Mojave is handwired on a turret board much like the old Hiwatts. It uses the highest quality parts throughout. My cables are Klotz la Grange with Neutrik straight ends. My guess is maybe a loose soldering connection on one or both of the input jacks, but the high sensativity jack works fine.

[phsyconoodler]

Hiwatts never used turret boards,they were strictly point to point with terminal strips.
Mojave's definitely use high quality stuff,I was not disputing that fact,it's just information about my experiences with some stuff that I was trying to share here.Even the best quality stuff can sometimes fail.If it is indeed solder joints then it's not the part.

[GuitarBrent]

Hiwatts never used turret boards,they were strictly point to point with terminal strips.
Mojave's definitely use high quality stuff,I was not disputing that fact,it's just information about my experiences with some stuff that I was trying to share here.Even the best quality stuff can sometimes fail.If it is indeed solder joints then it's not the part.


I simply meant that these amps have a nice and clean circuit layout on the board, like an old Hiwatt. You're right though, it could be a failed part or solder joint, no matter how nice. John Phillips has good info too. I'll try cleaning both jacks first and see what happens.:)

[Dai H.]

Hiwatt did use turret boards:

http://mhuss.com/php/pix.php?pic=HiwattTurret

As far as any jack(s) that are problematic, if cleaning doesn't work (Deoxit, etc.) I would replace since they are typically not expensive. Some metal parts like jacks, and tube socket contacts just wear out with use.

[ogradyboy]

You might want to contact Victor Mason directly. Since he builds each one he's the go-to guy. Super friendly and helpful.

www.mojaveampworks.com (http://www.mojaveampworks.com)

[carlygtr56]

I had a Hiwatt and a Germino do the same thing and both times it pissed me off to no end.

[fullerplast]

It's most likely the shorting contact in the High input jack. It's this that provides the ground end of the voltage divider when you use the Low jack, so if it's not making proper contact, the Low input volume will go up and down by 6dB (quite a lot).

Try a little contact cleaner in the jacks (both of them, to be on the safe side). If that doesn't cure it you may need to get inside and clean or retension the switch contacts manually.

A big +1 on this being the likely source of the problem. Try running a piece of paper saturated with contact cleaner between the shorting contact points. It's usually just a raised nub on one side against a flat surface on the other and it can get dirty or loose tension.

[GuitarBrent]

Thanks guys. Great responses and ideas. I'll try them out this weekend and also shoot Victor an email.

[GuitarBrent]

Ok, so tonight I sprayed some contct cleaner into both jacks and then sprayed it on my cable end and slid it in and out of each jack a few times. I played the amp on the low input for about an hour, and had no issues with any volume drop! I hope this isn't just a temporary fix. Time will tell I guess. Thanks to everyone for their suggestions. :AOK