| Author | Message | ||
| Ray D. |
I have a MM 110-RD Fifty combo that has a strange, sort of metallic "buzz" going on. It is present on both the Clean and Limiter channels. I have already ruled out a speaker problem by trying it through a different speaker (still there). The noise even appears when shutting the amp off (w/o an input signal):"...zzzziiipp!" Any suggestions or ideas about where to start looking for the cause? Thanks. | ||
| Steve Kennedy |
Is this a mechanical "buzz" or is it electrical (coming out of the speaker) or both? If you shut off the power switch and it is STILL continuously occuring, it would have to be either the switch or another component between the AC line and switch which is always seeing power regardless of the power switch's position. Also, which model do you have? The schematic shows 4 different AC Mains primary configurations. You could have a bad thermal breaker (a device similar to a turn-signal flasher that can be built into the AC transformer), a bad switch, a pinched wire, a "leaky or damaged courtesy outlet or an arcing noise (grounding) cap. If it is the cap, the buzzing would only occur when the grounding switch was in one position (assuming the switch is not ALSO bad!). If a thermal breaker were at fault, it would only buzz when power is applied (unless you were vibrating the amp and it was sympathetic vibration or other mechanical problem). This is assuming your amp is wired properly and not modified (which would double or triple the amount of potential suspects)! Steve | ||
| Ray D. |
Steve, First, it's model 110-RD-50, with chassis 1650-RD serial # ENO1218. The "buzz" sounds like an electrical one (definitely comes from the speaker). The noise is present while playing through the amp AND can also be heard (easier to hear) when shutting the amp down (zzziipp). It stops after the amp is shut off. The amp doesn't appear to be modified. I'll start by checking your suggestions.The courtesy outlet and grounding cap sound like good ideas... Thanks, Ray | ||
| Steve Kennedy |
OK... that is another valuable clue. Check this... take an audio ouput from the reverb SEND connection (audio TO the reverb tank, use a standard RCA phono cable) and plug it into the audio input of a stereo or headphone amp. Listen for the buzz at this point. If the signal is clean here, then the problem is NOT being generated by the preamp and resides solely in the power amp or high-voltage/AC power supply sections. If it only happens at speaker output your problem could very well be a high-voltage rectifier diode that is breaking down OR filter caps or it could also be an arcing output transformer (I hope not!). It could even be an arcing output tube! Is the Buzz audible in the Line Out signal too? I suspect it will be. Most anything else I can think of requires that the amp chassis be removed and the amp benched with some audio test gear to find the source. Steve | ||
| brenno |
i?m nothing speaking english very well......i?m brazilian men.......... i have the solution for your noise problem....... turn the button bright in the off position........ and the noises terminated....!!!!! |
Tue, 03/25/2014 - 09:58
#1