Anyone have this happen to them with the MTS series?

[yigba]

I was playing my Lynchbox combo at very low volume last night and the amp stopped making sound. On both modules.

I checked everything - replaced the preamp tubes, made sure the bias levels were right for the 6L6's I have in there, used a different cable, used a different guitar, even checked all the fuses on the amp and nothing.

I then thought to take out the first module (Tweed) and reinsert it. Voila - the amp fired right back up.

I assume the connectors were either out of place or dirty? Is this normal for these amps, as I am concerned that this happened and I didn't move the amp or even played loudly (thus no strange vibrations should have caused this)?

 

[lolthrash]

Yeah just make sure you jam them in pretty tight so there's really solid connection, that's definitely caused problems for people.

 

[Aaronharmon]

They make a cleaner that you can buy at radioshack or the like. It's very inexpensive. You spray the contacts and wipe the grime off. That's what I do.

 

[yigba]

I have tuner cleaner that I've used on all of my amps. Thanks for the info.

 

[yigba]

Now the same d@mn thing happens when my furnace kicks on.

Is this possible? I mean to have some sort of surge or static electricity that kills the sound in the amp but doeasn't seem to be blowing anyhting on it? Once again I popped out the module then put it back in and it worked. I have had it on a surge protector all this time.

 

[m0jo]

Ground lift on or off? I'd try the other option

 

[crankyrayhanky]

there's something real wrong here; this doesn't sound like a module connection issue- that wouldn't effect both modules simoultaneously

 

[SimonSezz]

Something happened with my RM100 today, the Blackface module in the first channel spot had no output, the other channels worked fine. It was screwed in all the way so I don't know how there could be a contact problem. But I turned off the amp, removed the module and reinstalled it and when I restarted the amp everything was working fine again. Hopefully it's just a one time thing <crosses fingers>.

 

[yigba]

Is there some sort of circuit breaker/protection built into the amp?

This is very weird. No smoke, no smells of anything burning, just no sound, but all the tubes glowing, the bias circuit working, etc.

 

[JKD]

Possible there's a fault in the switching circuit....there have been a few reports of late where the opto-isolator has been failing but I wouldn't expect them to work intermittently.

Do the channels still 'switch' when it's in this state?

Can you plug into the Series FX return with your guitar and get sound when this has happened?

 

[RD/Steve]

also check the v1 preamp tube...

 

[yigba]

I already swapped the V1 tube, so that's not it. I'll check the switching and the Series return loop the next time it happens.

 

[yigba]

So last night it happened again. This time it happened as soon as I fired the amp up. no sound at all. And the channels switched - there was no sound out of either one.

Unplugged the cord and put it into the serial return and I had sound. When I replugged in the guitar to the amp's regular input it was suddenly working again.

I am completely stumped. Some sort of static electricity????

I am dying to use this at a gig but am hesitant to do so.

 

[Mesa Triple]

You have two choices here. Either send it back to Randall and demand a new one or sell it as defective.

 

[JKD]

So last night it happened again. This time it happened as soon as I fired the amp up. no sound at all. And the channels switched - there was no sound out of either one.

Unplugged the cord and put it into the serial return and I had sound. When I replugged in the guitar to the amp's regular input it was suddenly working again.

I am completely stumped. Some sort of static electricity????

I am dying to use this at a gig but am hesitant to do so.

Might be a dirty Series Send or Return jack....can you make it go away by plugging a regular pedal cable between the series send and return? If so, the culprit is the 'normalizing contact' on the jack....it might be broken or it may be fixable using a little de-oxit/contact cleaner.

 

[yigba]

I'll check out the jacks.

I called US Sound - Stacy said to either ship it and pay the postage (which I think sucks as I just bought the amp 3 months ago) or bring it to a Service Center.

Being that this only happens sporadically I can foresee it not happening for the amp tech when he goes to check it out. ARRRRRGHHH!!!!

I've worked on amps before - ripped apart and installed a Hoffman PTP board on a RI Tweed Bassman, but nothing as complex as this. I'm trying to figure out how to even trace the signal thru the preamp.

 

[Julia]

I feel for you with intemittent problems. Unfortunately you'll have to go through the motions. Here's my history:

* take it to an amp tech. They will tell you the problem is tubes, and will replace the tubes and charge you for a retube and bias.

* the amp will work for a couple weeks.

* then it will start acting up again

* then you'll take it back to the tech and they'll say there's something weird going on that they can't find. This won't cost you anything.

* then you'll take the amp back to the store where you bought it and they will... send it back to Randall.

Problem with all this is that you've ended up paying for shipping already. So send it back to Randall and get it over with. If it's a new amp you don't want to f*** with it. You could void your warranty by attempting any repair, and right now that warranty is the most important thing you have.

 

[guitarcomet]

It's Gremlins.

 

[Julia]

Yep. Gremlins. My ex-Marshall JVM had 'em. Sent it back to NY to Korg. People at Korg said...."there's definitely something wrong, but we can't find it, because as soon as we start isolating the problem it fixes itself. Do you want a new amp?"

However, knowing that the gremlins were in proximity to the one they were going to send me, I opted for the Randall.

The gremlins in the meantime invaded my home. Next was my XBox 360. Then they got into my Randall. They destroyed the JJ E34Ls, popped a quad of Sovteks, but I think they over stretched themselves on the 6L6GEs from Groove Tubes. And the Russian =c= 6550s seemed to take care of them or at least set back their breeding program

 

[kc2eeb]

If you look straight at them, they disappear.
In the '80s, I repaired electronics for a local music store.
I had one customer with a Tapco (later became Mackie) 200 watt power amp. The amp was a dead short. Replaced 16 power transistors, 2 drive
transistors, set the bias, ran it for 1/2 an hour, out it goes.
Comes back after the weekend, blown again.
Usual questions to the customer, cables shorted, bad spkr. etc.
Fix it again, check against the service manual, all O.K.
Out it goes.
Next week, back again.
This time, checked EVERY component, besides the 18 blown transistors, all
O.K.
Call the company. Tell them everything, including, setting the bias.
Pause on the phone.
Then, "Err, yeah. Ahh, there's a design problem, just turn the bias pot all
the way cw, (thus making it a 50 watt amp), and it should be fine.
And it was.