Northeast Electronics Corp. Model TTS-28 - Testing

See the previous post, Phone Meter Repair, where I did some minor repairs to this meter.

I wrote some more information about this process on the EEVBlog, and you can find that post here: https://www.eevblog.com/forum/repair/northeast-electronics-tts-28-telephone-multimeter-repair-testing-pictures/

Briefly, an old meter like this uses different internal components to test different inputs. So 140 volts would be tested by one set of components, but 5 volts would be tested by another. Here in this post, I’m going through some of the primary ranges to assess there general accuracy.

As you read the meter screen, pay attention to which scale. Red is DC voltage, black is AC, green is ohms, etc.

Testing a 1K resistor in the x1 range. Meter reads dead on

Testing a 1K resistor in the x100 range. Still very good accuracy. A 100K resistor also tested dead on in this range.

30 volts in the 150 volt range

Testing 15 volts in the 30 volt range

30 volts in the 30 volt range

7.3 AC volts in the 15 VAC range. pretty accurate, but reading a little low

15.39 volts in the 15 VAC range. pretty accurate, but reading a little low

50 V in the 150 VAC range. still reasonable accurate but low

54 mA in the 150 mA range. Seems spot on

14.92 mA in the 30 mA range. Meter is reading a bit high