Help: is this power supply going bad?

[Wire Dawg]

I purchased a new Astron RS 70M about 5 months ago, and have been using it on weekends exclusively to power an RCI 2970n2 (at 10W dk). Three months after I bought the PS, it dropped voltage enough to shut the radio. The PS returned to 13.79V after switching it off and then on again, and the radio continued to work without any problems. Just today, it happened again, and I noticed that the PS built-in meter was reading 5V. I disconnected the radio, shut off the PS, and turned it on again. A digital multimeter read 13.79V across the terminals (the built-in meter was @ 13.5V). The local power company is reliable, and I'm not aware of any recent AC power outages or major fluctuations. The only variable this second time was a drop in temperature to 22 degrees F (last night). My equipment is installed in an outside shack (no heat or AC). Could such low temps trigger the drop in voltage (the drop occurred about 10 minutes after powering up), or may I consider the two independent events (voltage drops) as a sign of the PS going bad? This is my first experience with Astron PS's.

 

[W5LZ]

I think that temperature isn't the problem. It sounds like the power supply is loosing regulation. That would be an 'internal' problem, usually not an 'external' problem unless there's a very large AC fluctuation, or the load on the power supply is huge. From what you've said, I doubt if the 'load' or 'fluctuation' is a problem. I think I would contact the dealer or the factory about it, see what they think.
- 'Doc

 

[Shockwave]

If the power supply is under warranty, send it back because it's defective. If it's not under warranty, the good news is this repair is easy, the part is cheap and you don't even need to heat up a soldering iron to change it. Astron is notorious for having the LM723 IC regulator go bad on the PC board. So much so that they mount the chip in a socket on the PC board to make changing it easy. Radio Shack use to sell this part but I think they only offer it online now. Make sure you install the new chip with the keyway notch on one end identifying pin 1, facing the same way as the old chip. When working on power supplies, never connect expensive equipment to them until after you have confirmed an acceptable output voltage is present.

 

[TonyV225]

I agree that its a regulation problem and would look at the voltage regulator they are usually nowdays Chips that fail in the regulation.

 

[Wire Dawg]

I called, and were authorized to return. It was a no-hassle process, so must give kudos to Astron. I am now weighing the option of finding the part on the RS's catalog (thanks Shockwave) because, while repair or replacement is at no cost, the shipping of this 60 lbs rock is not free. If weight was an indicator of quality, this PS would definitely be a STAR. Thanks to all of you for these tips.