Transformer buzz?

[twiiii]

All they can do is replace the transformer with a new one. You wanted a new MC 1502 or two MC 2301's or MC 3500 MK II's anyway. Now is the time to go shoping. ONe of my MC 60's had a noisy transformer, but the transformers were still available in the early 60's. And it gave Davie O'Brien something to do replacing it for me at a MAC amplifier clinic. Those were the good old days when only Mcintosh as is and a few Marantz units could meet Mcintosh specs with new tubes. Most of the time Mcintosh far exceeded factory specs by a large margin.

 

[cspyon]

All they can do is replace the transformer with a new one. You wanted a new MC 1502 or two MC 2301's or MC 3500 MK II's anyway. Now is the time to go shoping. ONe of my MC 60's had a noisy transformer, but the transformers were still available in the early 60's. And it gave Davie O'Brien something to do replacing it for me at a MAC amplifier clinic. Those were the good old days when only Mcintosh as is and a few Marantz units could meet Mcintosh specs with new tubes. Most of the time Mcintosh far exceeded factory specs by a large margin.View attachment 2999121View attachment 2999122View attachment 2999123

My MA230 (with big audible buzz from the transformer) is in the shop at the moment. Four big caps on the chassis need to be replaced, according to the technician. My 225 is slightly audible.

 

[SaturationPt]

I see. I don't hear anything like hum or buzz from the speakers. Thanks for your informative feedback. I'm not sure if the filter or double caps are leaky (I don't know how to check them anyway), but given its vintage status, I think it's time to have it overhauled sooner or later.

Agreed, probably time.

 

[cspyon]

My MA230 (with big audible buzz from the transformer) is in the shop at the moment. Four big caps on the chassis need to be replaced, according to the technician. My 225 is slightly audible.

The technician replaced all the big can caps on the chassis, which he said were the source of the buzzing. I picked up the serviced unit the other day. All good now. The buzzing was gone, but when I put my ears close to the unit, I hear something like a very slight hum (not buzz) from the unit itself. I guess it's normal, given its vintage status.

 

[SaturationPt]

You will probably notice that unplugging all of the tubes so there is very little load on the power supply, that final hum will get much quieter.

 

[cspyon]

You will probably notice that unplugging all of the tubes so there is very little load on the power supply, that final hum will get much quieter.

Is it okay to power on the tube amp without the tubes? Just double checking before doing it according to your suggestion.

 

[SaturationPt]

Yes, and no. The only risk is the higher voltages that will be present without the loads, and whether that is too high for components installed. It has been suggested to my by Terry in the past (I didn’t know it was an option when doing my first restoration).

When I’m restoring, I always power up on a DBT without tubes before installing tubes, of course the DBT will reduce supply voltage somewhat.

 

[cspyon]

Yes, and no. The only risk is the higher voltages that will be present without the loads, and whether that is too high for components installed. It has been suggested to my by Terry in the past (I didn’t know it was an option when doing my first restoration).

When I’m restoring, I always power up on a DBT without tubes before installing tubes, of course the DBT will reduce supply voltage somewhat.

Just checked it without the tubes on, but I heard the same very slight hum from the unit itself when I put my ears close to it. The veteran technician, who specializes in vintage McIntosh tube gear, thoroughly checked the problems of this unit, and changed all the necessary caps and resistors. So, I think that very little hum is inherent in the unit itself. Thanks for your kind reply, as always.