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A Warning for Owners of Furman IT Refernence 20i

A Warning to anyone who owns a Furman IT Reference 20i for power filtering-
Do Not Leave the unit unattended while powered on. A few weeks ago, I smelled the very acrid smell of melting plastic and circuit board coming from my stereo. Long story short, my Furman IT Reference was the source and one of the circuit boards that was designed to prevent ‘current inrush’ self destructed. 
Thankfully, I was close by and was able to quickly unplug the unit or there was a very serious chance of fire! Since then I have tried, without any success, to have the unit repaired, but have gotten nowhere with Furman (now part of Nortek). I have tried sending in multiple requests for service. I’ve tried calling, only to end up in ‘press 1 for, press 2, purgatory..‘. When I have managed to get someone on the line, they referred me to their ‘dealer network’ for repairs. I contacted one of the dealers and they told me that only Furman is allowed to perform their own repairs. Call back Nortek and they won’t sell parts and they only use their dealers for repairs. Lather, Rinse, repeat. For $5k I’d expected better. The only good news is that I’m a very experienced service person for research instrumentation and I was able to identify the electrical component that failed (Ametek Thermistor SL22). Furman undersized the thermistor in their inrush circuit and thereby started the board to self destruct. The part is very cheap and I’m hoping I can still salvage the circuit board. But BEWARE! Had I not been nearby, it could have been much much worse!!!

mbachemist

Showing 2 responses by mbachemist

mbachemist OP
3 posts
 

I recommend not leaving your stereo equipment plugged in and turned on and unattended for any length of time. I take it even further and unplug my stereo when I’m not home. Not for reasons of safety, but it’s more that I’ve known owners who lost their entire system due to a nearby lightening strike during a thunderstorm. As for Furman, I had hoped that they’d stand behind their product. 

mbachemist OP
3 posts
 

Thanks so much for the information. I really do appreciate it! 
For whatever it’s worth (and after 40 some years of working with research instrumentation , I know this part is boring), their toroidal transformer is one of the largest I’ve yet seen in high end audio, bigger than what I’ve seen inside of big Krells or even the big Boulder amps. While toroidal transformers are well recognized for their low stray fields, it comes with a cost- serious ‘inrush current’ till the AC field is stabile. A very common approach to handling inrush is to place a thermistor in front of the transformer. Upon startup, the thermistor (dependent on type) appears as a high resistive load. That load is then dissipated as heat. Unfortunately, in this case, the heavy gauge wires carrying the AC load were run over the top of the thermistor. As the thermistor was overheating the circuit board traces, it was also melting through the load wires and would have eventually fused the wires together likely creating a ‘dead short’ to the metal chassis. The unit has a circuit breaker, as does the main panel to my house. But, after decades of working inside of instrumentation, I believe it’s always best not to ‘tempt the gods’. Never turning off the unit would definitely reduce the amount of ‘thermal cycling’ that the thermistor sees and extends its MTBF (Mean Time Before Failure- old term). I strongly recommend Not leaving electrical equipment powered on. 

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