Preferred transformer type

Thread Starter

AirScooter

Joined Mar 23, 2021
2
I had a nice old Fluke 8000A benchtop multimeter until I accidentally bridged the base of the transformer with direct mains current and popped the thermal protection hidden in the primary coil. I was moving a little too fast and popped the thing. I make the same mistake about every 5 years, has something to do with a narrowing distraction quotation.
As a matter of making things right, I feel I owe it to the thing to repair it. After all, it has been in my family since the 70's and was still my main benchtop DMM before I screwed it up. I'm not going to unwind it and replace the Thermal Fuse so I'm in the market for a transformer.
Is there a transformer type that is quieter and smoother than average? I would like to give it the best I can afford, within limits.
The current transformer is: Input 110/120 and output of: +15, -15, +5
Suggestions please.
Dave
 

Hymie

Joined Mar 30, 2018
962
If you are very lucky, by removing the outer layer of the primary coil of the transformer (close to where the wires entre the transformer), you might find the thermal fuse – which you could replace.
You’ve nothing to lose by trying, since the transformer is otherwise shot.
 

sghioto

Joined Dec 31, 2017
2,264
Hymie is correct. I have repaired several transformers this exact way. Many times this "thermal fuse" was just a short length of smaller guage wire.
 

DickCappels

Joined Aug 21, 2008
7,147
But you should feel free to use any old cheap transformer that gives the required voltages. There are regulating transformers but they are large and heavy and have a lot of harmonics in their output. Fluke will handle the ripple. By the way, I remember when that meter was introduced...quite a while ago and it is to your credit that it is still running today!
 

Thread Starter

AirScooter

Joined Mar 23, 2021
2
But you should feel free to use any old cheap transformer that gives the required voltages. There are regulating transformers but they are large and heavy and have a lot of harmonics in their output. Fluke will handle the ripple. By the way, I remember when that meter was introduced...quite a while ago and it is to your credit that it is still running today!
Thanks Dick. The only reason I was under the hood was because the ohm's output wasn't quite as accurate as it had been so I decided a recap was in order. For a 50 year old meter the thing has been absolutely amazing. It belonged to my father and passed down to me 20 years ago.
 
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