Bottlehead Forum
General Category => Tech Tools => Topic started by: rockpassion on August 02, 2013, 05:58:25 PM
-
Hello all,
I am in need of buying a variac to use on my very old IPC AM-1026 amp restoration. What size and make is recommended. I am not looking to spend hundreds of dollars but I also do not want something that is too limited. I guess my budget is $50 to $150.
I look forward to your suggestions.
Thanks
Richard
-
There are always great used ones on eBay. Sometimes the little carbon brush can wear down, becoming bigger and contacting several coils at once. I have an old Power Stat thats rated for 10 amps that I picked up for cheap and I had to disassemble it and file the brush back to a point. I don't have much experience with the newer ones, although they look slick with their output meters and multiple outlets.
-
If you can get to a Ham Fest you will find a number of them there. What you need is one that has meters for voltage and current. That way you can bring up the voltage and watch for a surge in current. A surge indicates a short that is going to mess up the whole works.
Bring it up in several steps. Say start at 40V and leave it sitting for 5 minutes. It forms the capacitors. Then go to 80V, slowly, and let it sit for another 5 minutes. Then slowly to 110V. If it is an old amp it isn't quite designed for 120V or higher that we all have coming into our houses today. That is why I also suggest buying a higher voltage for all the capacitors. We run over 10% higher voltage today, the caps need to be 10-15% higher too.
-
Grainger,
What about current rating? Should it be 5, 10, 15, 20 amp. And is there a make that I should look for. I definitely am sticking with US made such as Powerstat or Staco.
Thanks again for your help.
Richard
-
You need to consider what you are using it for (how many amps do you need). and don't forget to consider you circuit breakers rating (usually 10A).
-
5A is probably all you need, have a look at the fuses on the gear you want to test.
If I found a good deal on a 10A, I would buy it, but that's just me :D...John
-
Look at the fuse on your amplifier. Whatever that is you need that or more. 5A is usually enough.
-
G, I had some of the same questions and appreciate your information. Current AND voltage meters sound to be a much better indicator than current or voltage alone. Also, the ham fest idea is great. I have only been to one in Arizona years back, and was very impressed by these guys and their equipment.
-
The one I have does either current or voltage. So I can measure with my meter how the voltage is coming up and watch with the meter set at current for any sudden increases.
-
Sudden increases are a bummer, except in the stock market.
-
...or one's paycheck...
;D