My Marantz receiver has never had this problem before. I have installed a new replacement MVH heater with 3 output settings: low, med and high (just like original). Suddenly when this is on and set to Med the Marantz has a loud buzz. By adding two ferrite beads at the power cord plug end it cut this in half. The plug is attached to an APC filtered strip. I've added eight more ferrites and even slid them to the back of the heater where cord comes out. No difference. Any ideas? Thanks.
Asked
Active
Viewed 84 times
0
-
Do you have any on the Marantz power cord? Might help there too. – rdtsc Jul 29 '21 at 19:19
4 Answers
2
The heater probably has triad phase control to control the output.
In the medium position the heater is being switched on half way through the AC power cycle that results in a very fast voltage change across the heater element.
In the high position the heater is on 100% of the time so there are no rapid voltage transients. In the low position phase control is probably still being used but the point in the cycle where it is turned on is at a lower voltage so causes less interference.
This fast edge is being conducted through the power cord into the amplifier. That is why filtering the AC improves the situation.
Lamp dimmers common use this method of control and it is very common for them to cause interference.
The heater is at fault as it shouldn't be causing this problem although it may be a design issue rather than something specifically with that heater.
Ferrite beads at the heater may help or a small inductor internal to the heater.
Kevin White
- 33,153
- 1
- 48
- 78
0
If it were me I would take it back and ask for one that operates properly. It sounds like the emissions are much higher then allowed. I think most of the EMI you are seeing is conducted but there also has to be some radiated.
Gil
- 5,113
- 2
- 13
- 14
0
If the buzz comes from the amp transformer, suspect the "mid" setting in the heater is implemented with a diode in series with the heater which injects DC on mains.
If the buzz is coming from the speakers, suspect a triac dimmer in the heater, without proper filtering.
In both cases, the heater is faulty.
bobflux
- 77,207
- 3
- 91
- 222
0
My son sent a link from another forum where it was suggested in these events to make sure offending appliance and amplifier are on two different circuits, in a motor home there are only two! So I put this heater on the same circuit its predecessor was on and all fixed. Thanks folks.
-
Interesting, today on the same circuit as the original model of this heater (now replaced and gone) that change only worked for one day and the rumbling sound from inside the Marantz is back only on Med output of the heater setting. Low works fine, I do not use High. – Doug Kerr Jul 31 '21 at 13:10