Help Diagnosing Amp noise

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Shizzeldizzel

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I've had my Traynor YCS50 for about 3 or so years, never given me a hiccup. Now all the sudden its deleveloped a hum. Could be 60 cycle but I'm not sure. Anyway, the hum is there on the gain channel and gets louder as the gain is increased as well as the master voume. The hum is also effected by the mid and treble controls mostly....the bass control doesnt do a whole lot. If I roll the volume down on the guitar, the hum goes away (same with three different guitars so it isnt a guitar issue). I've replaced all three preamp tubes and two power amp tubes with no improvement. Something else which is a little strange is depending on where I stand with the guitar, I can manipulate the hum's volume. At certain angles, the hum gets louder and other angles I can nearly make it disappear. This is true at home and at a gig so it isnt environmental in nature.

Ideas, thoughts?
 
any florescent lights or neon signs plugged into the same circuit that the amp is plugged into? or a dimmer switch.. all these things can cause the type of noise you are describing. Does it happen in any outlet?
 
Like i said, it happens at entirely different rooms and locations.
 
Does the hum disappear as soon as you put it on stand-by?
 
Yes, or turn the lead channel gain or master volume down. Clean channel doesn't seem affected.
 
If you cannot hear the hum fade-away with the signal when you put it on standby, then the problem is likely in the HV end of the amp. You really should take it to a qualified technician. Your Traynor amplifier has no user-servicable parts other than valves and fuses. Whatever you do, do not 'lift' the ground of the amp.

Here's a quote form Ray at RAGE Electronics:
"The most important thing with hum is - what is the pitch of the hum? If it's 60 Hz hum (roughly the open low E on the guitar - is that correct?) and sounds really smooth and pure, it's most probably related to the parts of the amp's circuitry that uses 60 Hz - the heaters and the heater center-tap ground, the power transformer primary, (and the field it throws - ever see an amp hum on standby, with the output tubes out?), AC-operated relays, and GROUND-LOOP HUM FROM OTHER EQUIPMENT. If it's 120 Hz hum, it's probably something to do with the DC power supplies in the amp, starting from the power transformer hi-voltage secondary center-tap ground (if used), and moving on to every filter cap and its ground, and also (sometimes I tend to forget this, and it's especially important in the 2205/2210) any other DC voltage derived from the power transformer. In the 2205/2210, the input jack serves to ground out the rectified DC used for the channel-switching circuitry - this is why the red gain-channel LED goes out when you unplug your guitar. There's some real potential for hum bleed here, and in fact everywhere where the channel-switching circuit's tentacles reach (and they reach a fair number of places). If the low-voltage DC to the switching circuitry in this amp develops a hum, it will inject it all over the place, and unless you know where to look, the amp will seem to be humming from multiple, unrelated sources."
 
Interesting. I guess I'll have someone check it out. Thanks for the info!
 
does anybody have samples of what 60 cycle and 120 cycle amp hum sound like?
 
:)
Shizzeldizzel":3en8omrs said:
Interesting. I guess I'll have someone check it out. Thanks for the info!
Click to expand...

I had the same issue with a Soldano HR Plus, and it ended-up being the filter capacitors. I hope it's nothing too costly... Rock on! :)
 
Thanks. Got an old tube repair guy down the street. Taking a look at it tomorrow.
 
Somebody already mentioned it but it could very well be just a tired filter cap if it's a new noise. It happens. If you have a way to record you can record the noise and then bring it up in one of the tools/plugins to look at the waveform to try to find the frequency.
 
Two things to check:

1) Chassis ground. Make sure the ground wire form the power cable is securely attached to the metal chassis. It may have become corroded. And make sure they outlet you're plugging into is grounded.

2) Input ground. Check the ground on the input jack and ground connection(s) at the first gain stage. If the cathode cap on that gain stage fails, it can cause hum that changes depending on the guitar volume control setting.
 
The tech I'm working with seems to think its a ground near the input. The hum goes away when he shorts the input. He said if it was filter cap, the hum would still be there. I'm going from memory so don't take me word for word.

So Bruce sounds like he's on it. Cathode cap eh? I'll look it up on the schematics from the traynor site. I'll update this thread if we find the problem. Thanks everyone!
 
I love this amp. I've played others of this model and they didn't quite sound the same. I know you were joking but I'm not selling anyway!
 
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