Thread: LS27 randomly shuts down

Have a minor problem in my now 10-year old LS27. While plugged into my ARC S20BLK UPS, this preamp randomly just "blinked off" and then back on twice now in the past 7 days.

It's like there was a momentary loss of power so I checked the batteries in the APC. All is well there.

Cruising forums, I found that other systems in this vintage had an issue with the remote trigger input. While this is unused in my gear, I just wondered has anyone heard of what the "cure" was for in these other units?

And/Or, has anyone experienced a similar issue and found the real source of this problem?

Frustrated in Florida

Originally Posted by 2fastdriving

Are you sure the UPS can supply the required wattage for the LS27? Tube gear draws quite a bit of wattage, and some UPS are very light duty.

Good point. Yes; I confirmed this. The S20 is rated at a full 15A@120V and I know for certain that it will deliver this. The total peak the load on this UPS is only about 60% of its rating.

BTW, my system runs off grid. I have a dedicated 20A line running from our 4KW photovoltaic system.

Greg Christensen at ARC gave me a tip after contacting their support email. He said that a different model with a similar display was sent in for this same issue. What they found was the power cable from the main PC board to the front panel "micro board" used a crimped connection on the plug and one of the crimps had failed. They recommended changing the crimped to soldered connections plus re-soldering the PC board connections at both ends of this cable.

VERY long story short, this was indeed the problem. The crimped connections on this 4-pin cable were subject to an intermittent thermal failure.

To properly repair this issue, the main PC board and the micro board had to be removed. This was by no means a simple task but it's been running perfectly now for three days.