AC hum Fender Cyber twin

[Lastnote]

I purchased my Fender Cyber Twin in 2004. Last week it got a loud AC hum, no guitar plugged in, all pots completed off, vol or master vol pot does not have an effect on the hum. Tried other outlets in the house, hum stayed the same. Any ideas?

[Chuck H]

If it's been awhile since you used the amp it's possible there is an oxidized contact somewhere. Tube socket pin holes, switches, switching jacks or even a pot CT. Otherwise you may just be overdue for new filters. They go bad with age and sitting unused is actually worse than regular use for these parts. It's also possible that a tube is bad. If an output tube failed (or even just failing) that could imbalance the hum cancellation in the power amp and maybe even damage any sort of hum balance circuit.

[Enzo]

Or one of the large main filter caps has cracked its solder.

The Cyber Twin is a stereo solid state amp. There are two little 12AX7s over in the corner of the preamp, just 'cause.

You might also look at the speaker cones and see if either one moves one direction and stays there when power is turned on. That would mean a blown channel and DC on the speaker. TURN IT OFF immediately then.

[Chuck H]

I probably should have guessed by the name Cyber Twin, but I didn't know that amp had a SS power amp. So, yeah, like Enzo said. Look for DC on the output. A speaker jutting forward and staying that way would indicate that.

[J M Fahey]

Stay tuned for the SS version of JTM45, Custom Hiwatt 100, and Ampeg V4B .

No need to wait for SS AC30 , SVT or Dual Showman versions though.

I bet no Psychologist, not even hardened ones, can get into the mind of somebosy who pays lots of $$$ for a Fender Twin label glued to an SS, digital amp.

Not far from people (I know a couple ) who dare to brag about "the hot woman they met last night" and "all the naughty things they did together" , while actually referring to:


After all, a similar falsification

[Enzo]

The Cyber Twin came out maybe 15-16 years ago, and was to be the start of the next generation of amps. It never really went anywhere. But it had digital outs in a SPDIF as well as MIDI controls. it was fancy. COMPLICATED. It was a twin 12, but not really meant to be a Twin Reverb. It was the last big huge service book, before they switched to the CD-ROM service materials.

[52 Bill]

The Cyber Twin came out maybe 15-16 years ago, and was to be the start of the next generation of amps. It never really went anywhere. But it had digital outs in a SPDIF as well as MIDI controls. it was fancy. COMPLICATED. It was a twin 12, but not really meant to be a Twin Reverb. It was the last big huge service book, before they switched to the CD-ROM service materials.

Yeah but the real cool thing was the motorized pots that would spin to the different preset sounds.

[Enzo]

yeah, it had tons of capabilities.

[Lastnote]

Thank your for the response.

I use the amp every day. Tubes tested good (with my Max-Preamp 2 tester), however, put two new pre-amp tubes, hum is still there. Checked the speakers and they do not move when power on. I am thinking it is a bad filer cap.

[Enzo]

So wiggle the large main ones while it is running, does the hum come and go? For that matter, without even disassembling it, just whack the thing on the top, does that do anything to the hum, even for a moment? A bad cap is possible, but cracked solder is WAY more likely.

[Lastnote]

Enzo,

thank you for the replay. Will give it a try and let you know how it went. I have worked and I am very familiar with the Fender Hot Rod Deluxe. The Cyber twin seems to be a much better built amp, however the layout is very different.

LastNote

[Enzo]

Totally different, there is very little the two have in common other than the brand name.

[Lastnote]

AC Hum on Fender Cyber Twin SE

Thank you Enzo,
How you worked much on this amp? If so, are there any inside track ideals/tips you can give on working on this amp? I don't understand why there might be a cracked solder joint. This amp never been gigged and seats in my studio, is it poor quality like on the Hot Rod?

Lastnote

[52 Bill]

I don't understand why there might be a cracked solder joint. This amp never been gigged and seats in my studio, is it poor quality like on the Hot Rod?

Do you play the amp with the internal speakers? Every time the amp vibrates from the music played through it, it can start to cause small fractures in the solder joints of the larger components like the filter caps.

Your amp is maybe 10 or more years old? I don't think that you can be critical of the build quality after that amount of time.

And in any case, the broken solder joint is just a possibility. You have not proven it one way or another. It may just be a bad filter cap or some other component. It can be hard to diagnose an electrical problem from thousands of miles away, with only a written description of the sound.

[Enzo]

I have worked on a few, I was a Fender warranty center for years. But this model is constructed just like a zillion other Fender solid state amps of the era. No special insight, just looking at the sort of things that go wrong in amps. Loud hum in an amp is almost always either a blown output making DC on the speakers, or a loss of filtration in the power supply. And cracked solder is far more common than actual bad caps.

And even if it is a one in a thousand thing, someone got that thousandth amp. Might be you.