Hi,
I have 2 ML 336 amps. One of them is blowing the 20 Amp fuses in my home when switching from off to standby. I found that there are 3 wire wound resistors inside, that I guess are used to slowly load the huge caps in this amp. These wire wound caps are defective. Anyone knows where to get them and what would be the specs of these resistors ? Thanks.
I have 2 ML 336 amps. One of them is blowing the 20 Amp fuses in my home when switching from off to standby. I found that there are 3 wire wound resistors inside, that I guess are used to slowly load the huge caps in this amp. These wire wound caps are defective. Anyone knows where to get them and what would be the specs of these resistors ? Thanks.
Thanks for your reply. I am in Belgium (220 V, 50 Hz) and since I have 2 ML 336 amps it should not be related to wiring in my home. Attached a picture of the wire wound resistors where it can clearly be seen that the wire is interrupted. Any chance to repair the wire with resistance wire. I found that the resistors are 10 ohm.
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At least 2 of the wire wounds are open circuit, so could be touching another track, causing the breaker to trip.
I would buy the largest wattage 10 ohm resistors you can fit in the space and not use resistance wire.
I presume the main reservoir caps have been replaced looking at the screw heads?
I would replace the resistors and then take it from there, but they may blow again if a fault exists.
I would buy the largest wattage 10 ohm resistors you can fit in the space and not use resistance wire.
I presume the main reservoir caps have been replaced looking at the screw heads?
I would replace the resistors and then take it from there, but they may blow again if a fault exists.
The correct spec for the 331,332 and 333 is Nichrome 0.024 wire with 10 Ohms Resistance.
However, I'm not 100% sure on the 336.
It heats up temporarily to about 1000 Deg C and is designed to break at 1400 Deg C to avoid damage to the amp, so if you wish to use a resistor, you will have to go high wattage and if it breaks, go higher again.
Nichrome wire is more like your lightbulb principle than a simple resistor.
However, I'm not 100% sure on the 336.
It heats up temporarily to about 1000 Deg C and is designed to break at 1400 Deg C to avoid damage to the amp, so if you wish to use a resistor, you will have to go high wattage and if it breaks, go higher again.
Nichrome wire is more like your lightbulb principle than a simple resistor.
It heats up temporarily to about 1000 Deg C and is designed to break at 1400 Deg C to avoid damage to the amp, so if you wish to use a resistor, you will have to go high wattage and if it breaks, go higher again.
Is this not like fitting a bigger fuse because it keeps blowing?
The FIRST thing to do is find out why they were overloaded.
No, I said use the correct nichrome wire, which is acting as a heating element and not like a fuse. It is not overloaded.
There is no fault with the amp, its just over time with constant powering on and off the nichrome wire degrades, just like a lightbulb filament.
An overspecced resistor will work, but will offer little or no protection if the amp develops a fault.
I would say a 22W wire wound resistor should work. When I recapped one of my Krell KSA250 amplifiers I replaced the four power supply caps with 100K uF units (original was 40K). There are four 7.5 ohm 20 watt sand resistors as part of the soft start circuit which promptly blew. Granted the amp was in use for approximately 20 years before recap so I am sure they were weakened. I replaced them with 22 watt wire wound resistors and the amp has been functioning fine for the last four years. The resistors only need to conduct the high inrush current for a very short period of time before they are switched out by the soft start circuit.
I measured and found that the 3 resistors were in parallel. Bridged them by 4 1 ohm 100 W resistors in series, which I connected outside the amp and the amp is now switching on perfectly. The resistors don't even get warm and they fit nicely under the amp. Thanks for all your comments.
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You cannot use any surge resistors for Mark Levinson 331/332/333/334/335/336/33H. ML uses special surge resistors that have to meet High voltage rating Joules about 290 Working voltage at 1090V. Nichrome wire wounded to get 10 Ohms either 10 watt or 15 watt. I send the new Levinson resistors to Reidon to make a better one, They made the SP-1976 10 Ohms 15 watts. and coated with Silicone. Redon eng recommended It. In case the wire breaks it will not fly around and hit any board. The surge resistors are there to protect the amp. THIS PART IS SPECIAL ORDERED AND MADE IN USA.
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Pff, over engineered audiophile nonsense from ML. They could just as well have used ordinary wirewound resistors with a thermal fuse sandwiched between them for protection.
Wirewounds will also blow open if they overheat, the ceramic body will probably crack but they certainly wont fail as a short
Wirewounds will also blow open if they overheat, the ceramic body will probably crack but they certainly wont fail as a short
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