Nick Danger's Yamaha M80 Amplifier Repair/ Restoration

[laatsch55]

I have a low frequency hum also but I can't do anything about it since this is my main amp. I only hear it when a source is not playing and it does not get any louder with volume increase. I only hear it in the speakers, not the chassis. I am wondering if the fault is in the nest of wires in back of my stand so I can't fault the amp yet

So your's is audible through the speakers?

 

[Northwinds]

Yes

EDIT: Months ago I eliminated the eq and dbx unit, just preamp, amp, cd player and TT hooked up

 

[laatsch55]

Yep, lotta if's there..

 

[Northwinds]

I will start pulling everything apart and see if I can figure out what's causing it, I doubt the SA3 preamp but there is so many wires hanging down in back, speaker wires mixed with power cords, RCA cables everywhere not to mention I use two power strips because there is other gear just waiting to be hooked up by swapping cables around. I am listening to the system now and it sounds as good as ever but if I stop the source, that low hum is prevalent

I may go ahead and hook the Peavey CS800 up and see if I still hear the hum. I also wonder if it's because I have the WOPL sitting right on the preamp and wonder if the PL tranny is causing havoc since it's sitting right on the preamp

 

[laatsch55]

Could be Ron, the pre should be a couple feet away from the amp and not on top or bottom of it. The PL throws a pretty good sized electromagnetic field..

 

[Northwinds]

Could be Ron, the pre should be a couple feet away from the amp and not on top or bottom of it. The PL throws a pretty good sized electromagnetic field..

I will see what I can do separating them Lee. It's tough because the WOPL and the Perreaux will not fit in the rack so they sit on the top. My Pioneer PL-550 sits to the right on the same stand since it can't go anywhere else. I wonder how come I don't get feedback through the cart then??? I crank the shit out of records and never get that dreaded feedback but the cart is probably 2ft away from the amp and on the opposite side of the WOPL's tranny so that may be the reason

 

[jbeckva]

Hey Ron,

Although it may also be due to the fabled (dratted) "Grado Hum", I had the same issue here while spinning LP's the other night. The xformers do put a good strong field out.

 

[Northwinds]

See the mess, again the eq and dbx unit are not hooked up at all

 

[Northwinds]

Hey Ron,

Although it may also be due to the fabled (dratted) "Grado Hum", I had the same issue here while spinning LP's the other night. The xformers do put a good strong field out.

I have no Grado's, only Shure V15's (types II, III and IV) Jer. I will try to figure out how to separate the preamp and WOPL but I only started to notice this hum about 2-3 weeks ago. It makes that noise when the turntable is not being used also

 

[laatsch55]

Bad place for that pre....

 

[Northwinds]

I just had Deb come over and listen for me. I lifted the WOPL away a good 3 ft and the hum is still there. I did notice that when I turned the rotary switch to off position for the ceiling fan control, the hum got really faint so I wonder if I am getting interference from the wall switches behind the amp that control the outside lights and livingroom ceiling fan. Never noticed this before though, just in the last few weeks. All the switches are off now and I still hear that very faint hum in the speakers

 

[laatsch55]

With all the moisture you've had in the walls anything could be possible. Do you have dimmer switches?

 

[Northwinds]

The fan control acts as a dimmer Lee

I am going to get a heavy long extension cord and move everything to another outlet in another room and see if the hum is still present. Good point about the moisture in the walls. I took a reading on the back wall and it's normal

 

[laatsch55]

Ah....

 

[Northwinds]

I will try all this later on. My granddaughter has a singing solo at a highschool concert at 3pm so I have to go get ready

 

[brutal]

Is it common on this board to jack a thread like this?

 

[laatsch55]

One of our specialities....

 

[brutal]

Thank you. I will figure out how to check it later today and will post my findings.

It was an 18pf 500VDC mica cap and I had to order replacements.

 

[Northwinds]

Hum seems to be gone. Moved the amp down into the area where a TV would sit. Put the preamp, amp and walwart fan into their own surge protector and it seems to have done the trick. Just have to get used to the look but I hope to replace the stand with something I build or find at a tagsale this year

 

[laatsch55]

Good deal..