Smallbox Died - Help Needed

[SavageRiffer]

So I bought a Smallbox and it came in a few days ago. Everything was working perfectly fine. Then today, after playing about 30 minutes, it just stop making any sound at all. The power lights are all on, the tubes are all glowing evenly, there was not a single hiss or microphonic noise whatsoever. It just literally stopped making any sound all of the sudden. There was no pop or anything, just silence.

I unplugged my effects and plugged straight into the amp, still nothing. I replaced the fuse with an exact match, still the same. At this point, I'm not going to poke around the amp or anything as I'm inclined to send it back to the buyer. If it's not the power tubes, then what could be the problem? Is it something serious or will it be an expensive repair?

 

[Deleted member 21375]

Swap in a known good speaker cable between the head and cab.

 

[Deleted member 21375]

So I bought a Smallbox and it came in a few days ago. Everything was working perfectly fine. Then today, after playing about 30 minutes, it just stop making any sound at all. The power lights are all on, the tubes are all glowing evenly, there was not a single hiss or microphonic noise whatsoever. It just literally stopped making any sound all of the sudden. There was no pop or anything, just silence.

I unplugged my effects and plugged straight into the amp, still nothing. I replaced the fuse with an exact match, still the same. At this point, I'm not going to poke around the amp or anything as I'm inclined to send it back to the buyer. If it's not the power tubes, then what could be the problem? Is it something serious or will it be an expensive repair?

Theres also a T3A fuse inside the compartment just under the IEC plug connection.

 

[steve_k]

The fuse inside the IEC is good if lights are on. You changed the B+ fuse.

Plug your guitar into the FX return and turn the volume up. Makes sound? You have a bad preamp tube, either V1 or the PI tube.

 

[scottosan]

So I bought a Smallbox and it came in a few days ago. Everything was working perfectly fine. Then today, after playing about 30 minutes, it just stop making any sound at all. The power lights are all on, the tubes are all glowing evenly, there was not a single hiss or microphonic noise whatsoever. It just literally stopped making any sound all of the sudden. There was no pop or anything, just silence.

I unplugged my effects and plugged straight into the amp, still nothing. I replaced the fuse with an exact match, still the same. At this point, I'm not going to poke around the amp or anything as I'm inclined to send it back to the buyer. If it's not the power tubes, then what could be the problem? Is it something serious or will it be an expensive repair?

Did you change the mains or the B+ fuse? Everything will still light up with a good mains fuse

 

[PBGas]

Did you test the tubes? Strangely enough, this happened when I picked up a new BE-100 back in June. Mine died after 4 days. Volume suddenly went up, dropped and poof.
The store could not figure out what was wrong with it and sent it back to Friedman. It showed up 4 months later for sale again on their site. I picked up something else that they had instead.

These things can happen with anything these days.

 

[scottosan]

https://ibb.co/ko4euF



I just remembered the small box fuse has the center tap going to ground instead of a more common B+ fuse. If you have a bias probe, check to se if you are getting any high voltage

 

[motorboy1]

You can't return it. It was working when you got it. Get it fixed....

 

[SavageRiffer]

OK, here's what I've done so far. I swapped the main fuse for a new one, still the same. Then I swapped all preamp and power tubes with brand new ones, still the same. Channel 1 does nothing. Channel 2 has a faint signal if I turn it all the way up - with some crackling. I tried a different speaker cable and different cab. So, it's not any of the tubes, it's not the fuse, and it's not the speaker or cables. I plugged my guitar straight into the return jack and got sound on both channels. So if it works from the return jack, that would mean that the preamp is fine and that there is an issue in the power section? If that's the case, then since I put new power tubes in then it's something really bad right?

 

[Deleted member 21375]

OK, here's what I've done so far. I swapped the main fuse for a new one, still the same. Then I swapped all preamp and power tubes with brand new ones, still the same. Channel 1 does nothing. Channel 2 has a faint signal if I turn it all the way up - with some crackling. I tried a different speaker cable and different cab. So, it's not any of the tubes, it's not the fuse, and it's not the speaker or cables. I plugged my guitar straight into the return jack and got sound on both channels. So if it works from the return jack, that would mean that the preamp is fine and that there is an issue in the power section? If that's the case, then since I put new power tubes in then it's something really bad right?

No, the return is right before the power amp so it seems the power amp is not the problem.

 

[SavageRiffer]

OK, here's what I've done so far. I swapped the main fuse for a new one, still the same. Then I swapped all preamp and power tubes with brand new ones, still the same. Channel 1 does nothing. Channel 2 has a faint signal if I turn it all the way up - with some crackling. I tried a different speaker cable and different cab. So, it's not any of the tubes, it's not the fuse, and it's not the speaker or cables. I plugged my guitar straight into the return jack and got sound on both channels. So if it works from the return jack, that would mean that the preamp is fine and that there is an issue in the power section? If that's the case, then since I put new power tubes in then it's something really bad right?

No, the return is right before the power amp so it seems the power amp is not the problem.

Ah, right. So if I put new preamp tubes, then what could be the problem? Bad amp?

 

[glip22]

OK, here's what I've done so far. I swapped the main fuse for a new one, still the same. Then I swapped all preamp and power tubes with brand new ones, still the same. Channel 1 does nothing. Channel 2 has a faint signal if I turn it all the way up - with some crackling. I tried a different speaker cable and different cab. So, it's not any of the tubes, it's not the fuse, and it's not the speaker or cables. I plugged my guitar straight into the return jack and got sound on both channels. So if it works from the return jack, that would mean that the preamp is fine and that there is an issue in the power section? If that's the case, then since I put new power tubes in then it's something really bad right?

Sounds like you opened a primary winding on the output transformer. That crackling sound is key to a blown OT. Thats sucks.

 

[steve_k]

OK, here's what I've done so far. I swapped the main fuse for a new one, still the same. Then I swapped all preamp and power tubes with brand new ones, still the same. Channel 1 does nothing. Channel 2 has a faint signal if I turn it all the way up - with some crackling. I tried a different speaker cable and different cab. So, it's not any of the tubes, it's not the fuse, and it's not the speaker or cables. I plugged my guitar straight into the return jack and got sound on both channels. So if it works from the return jack, that would mean that the preamp is fine and that there is an issue in the power section? If that's the case, then since I put new power tubes in then it's something really bad right?

yeah, it needs to go back. if you felt inclined, you could pull the chassis, pull all the power tubes, turn it on in run, use your DMM and measure all the voltages to ground from one of the power tube sockets. i bet you aren't getting bias supply voltage. but, you need to inform the seller and tell him it is coming back.

 

[Deleted member 21375]

OK, here's what I've done so far. I swapped the main fuse for a new one, still the same. Then I swapped all preamp and power tubes with brand new ones, still the same. Channel 1 does nothing. Channel 2 has a faint signal if I turn it all the way up - with some crackling. I tried a different speaker cable and different cab. So, it's not any of the tubes, it's not the fuse, and it's not the speaker or cables. I plugged my guitar straight into the return jack and got sound on both channels. So if it works from the return jack, that would mean that the preamp is fine and that there is an issue in the power section? If that's the case, then since I put new power tubes in then it's something really bad right?

Sounds like you opened a primary winding on the output transformer. That crackling sound is key to a blown OT. Thats sucks.

Yeah,certainly a possibility but he plugged into the return jack and is getting sound in both channels.

 

[SavageRiffer]

OK, here's what I've done so far. I swapped the main fuse for a new one, still the same. Then I swapped all preamp and power tubes with brand new ones, still the same. Channel 1 does nothing. Channel 2 has a faint signal if I turn it all the way up - with some crackling. I tried a different speaker cable and different cab. So, it's not any of the tubes, it's not the fuse, and it's not the speaker or cables. I plugged my guitar straight into the return jack and got sound on both channels. So if it works from the return jack, that would mean that the preamp is fine and that there is an issue in the power section? If that's the case, then since I put new power tubes in then it's something really bad right?

yeah, it needs to go back. if you felt inclined, you could pull the chassis, pull all the power tubes, turn it on in run, use your DMM and measure all the voltages to ground from one of the power tube sockets. i bet you aren't getting bias supply voltage. but, you need to inform the seller and tell him it is coming back.

I'm not going to tamper with it. The guy must have known something because why else would (since it appears to be the problem) a transformer go out suddenly? Fuck I'm so sick and tired of getting ripped off. I knew I shouldn't have bought anything used.

 

[glip22]

OK, here's what I've done so far. I swapped the main fuse for a new one, still the same. Then I swapped all preamp and power tubes with brand new ones, still the same. Channel 1 does nothing. Channel 2 has a faint signal if I turn it all the way up - with some crackling. I tried a different speaker cable and different cab. So, it's not any of the tubes, it's not the fuse, and it's not the speaker or cables. I plugged my guitar straight into the return jack and got sound on both channels. So if it works from the return jack, that would mean that the preamp is fine and that there is an issue in the power section? If that's the case, then since I put new power tubes in then it's something really bad right?

yeah, it needs to go back. if you felt inclined, you could pull the chassis, pull all the power tubes, turn it on in run, use your DMM and measure all the voltages to ground from one of the power tube sockets. i bet you aren't getting bias supply voltage. but, you need to inform the seller and tell him it is coming back.

I'm not going to tamper with it. The guy must have known something because why else would (since it appears to be the problem) a transformer go out suddenly? Fuck I'm so sick and tired of getting ripped off. I knew I shouldn't have bought anything used.

Transformers can go easily sometimes. Usually if it's a bad tube the fuse will blow. If there's no pop or blown fuse it usually points toward an OT that was stressed from poor connection to the load. Over time this can cause the transformer's windings to weaken. Then one day it just goes south. Maybe your seller ran it with no load or had a loose jack at his speaker cab or something along these lines. I wouldn't blame him as it worked perfect before he shipped it but I would still return it.

 

[SavageRiffer]

OK, so if I dime the gain on channel 1, it also makes a faint sound when it dime the volume. One thing I didn't notice before that I notice now, is that if I dime the volume one one of the channels and get that faint sound, the presence knob makes a static sound if i turn it. None of the other knobs make that sound. Would that indicate anything?

 

[SavageRiffer]

OK, here's what I've done so far. I swapped the main fuse for a new one, still the same. Then I swapped all preamp and power tubes with brand new ones, still the same. Channel 1 does nothing. Channel 2 has a faint signal if I turn it all the way up - with some crackling. I tried a different speaker cable and different cab. So, it's not any of the tubes, it's not the fuse, and it's not the speaker or cables. I plugged my guitar straight into the return jack and got sound on both channels. So if it works from the return jack, that would mean that the preamp is fine and that there is an issue in the power section? If that's the case, then since I put new power tubes in then it's something really bad right?

yeah, it needs to go back. if you felt inclined, you could pull the chassis, pull all the power tubes, turn it on in run, use your DMM and measure all the voltages to ground from one of the power tube sockets. i bet you aren't getting bias supply voltage. but, you need to inform the seller and tell him it is coming back.

I'm not going to tamper with it. The guy must have known something because why else would (since it appears to be the problem) a transformer go out suddenly? Fuck I'm so sick and tired of getting ripped off. I knew I shouldn't have bought anything used.

Transformers can go easily sometimes. Usually if it's a bad tube the fuse will blow. If there's no pop or blown fuse it usually points toward an OT that was stressed from poor connection to the load. Over time this can cause the transformer's windings to weaken. Then one day it just goes south. Maybe your seller ran it with no load or had a loose jack at his speaker cab or something along these lines. I wouldn't blame him as it worked perfect before he shipped it but I would still return it.

Oh man, I hope I don't get stuck with another broken amp. That would be the 2nd time this year I get fucked over. I just sent Reverb a message to let them know that I intend to return it. Maybe the guy didn't know, but it's not right to stick me with it. I sure as hell don't want to have to ship it to Friedman and wait weeks to get a repair or whatever. If I somehow get stuck with it, is it going to screw me pretty bad financially? Is it an expensive repair?

 

[raiken]

If you hear high volume sound when you plug into the fx loop return jack, all the expensive stuff, like output and power transformers, is okay.

You will likely need to use a boost pedal or drive it with a preamp or something that can generate a line-level signal into the return back to get enough drive to hear a loud signal. A guitar output will probably not drive it hard enough.

If this is the case, and changing preamp tubes doesn't fix it, and all the preamp tubes filaments light up, the problem is likely the effects loop board itself, which would be a simple fix, likely a bad solder joint or dead transistor (I believe that amp uses LND150 mosfets on the effects board).

If you have any effects that have a level indicator, like a rack-mount multi-effects unit, you can see if anything is coming out of the send jack by hitting a few chords and looking for a level indication. Alternately, if you have a power amp, you can drive it with the effects send and see if you get sound.

 

[milkchickenbomb]

if The amp was working for a couple of days since you got it, why do you think the seller is at fault?

I seem to remember a thread about someone who sold an amp thru reverb and the buyer claimed it wasn’t functioning properly and returned the amp. And it was a big fucking fiasco with loads of butthurt, threats, and reverb and PayPal are the devil.

Now the shoe is on the other foot and obviously it’s the sellers fault and he gets to clean up the mess. Even though in this situation, the buyer received a functional amp.

I wonder if it worked for a week would you still think it’s the seller’s responsibility? A year? Is there an implied warranty? How does a buyer qualify for this warranty? Because clearly some buyers are just scammers.