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Re: Adding a New Meter to TC Gauge Controlelr

Posted: Sun Feb 19, 2017 8:28 pm
by Richard Hull
This is exactly the scale that is on my meter. You seem to have done such a fine job on testing everything there is in the box previously, so I have little doubt an issue exists there.

The new meter has a polarity just like the old one. Are you sure you got it right? Try swapping the leads. Battery in to proper polarity? Can you adjust the TC tube current at all and see meter deflection. What resistance do you have in parallel.... if this is a 100ua meter? Does your replacement meter really read 100ua or 100ma? It must read 100ua or 200ua if you got an exact replacement.

Was there a resistor in series or parallel with the with the original defective meter?

You really need to check all this out and report fully. I bet the fix is simple either throught error or mis-connection. This controller is abysmally simple.

Richard

Re: Adding a New Meter to TC Gauge Controlelr

Posted: Sun Feb 19, 2017 8:51 pm
by Robert Dwyer
The new meter is a 200ua meter. The battery is in the proper position. There is meter deflection when I adjust the current. Looking back at the old meter I did however find, a small resistor attached in series within the meter. Perhaps I should take the resistor and place it within the new one?

Re: Adding a New Meter to TC Gauge Controlelr

Posted: Sun Feb 19, 2017 11:57 pm
by Richard Hull
You say there was a resistor within the old meter? Was it across the terminals or in series to one of them. Real important.

The classic metering required for all TC gauges was an odd ball 9mv (millivolt meter)!!! The manufacturer of the guage may have had the 200ua meter in the original factor altered to be a 9mv meter of the proper resistance.

Te beat goes on.

Richard Hull

Re: Adding a New Meter to TC Gauge Controlelr

Posted: Mon Feb 20, 2017 12:43 am
by Robert Dwyer
The resistor was in series with on the black wire leading from the terminal to the glavanometer.

Re: Adding a New Meter to TC Gauge Controlelr

Posted: Mon Feb 20, 2017 11:16 am
by Richard Hull
The correct meter for use with a T/C gauge is a 10 or 14 millivolts meter with a 55 ohm impedance. If you don't have this, in the end, you will not have a proper reading. Much of this is covered in the FAQ found in this forum FAQs

viewtopic.php?f=25&t=10098

The Bell Jar article can't be beat for a full explanation to the tubes and metering and how to roll your own T/C gauge for just the price of the tube and a few common electronics junk bin parts. Read it.

It sounds like you need to make that 200ua meter into the above reading meter Without the device and your old and new meters in hand, I can't help you beyond that.

Richard Hull

Re: Adding a New Meter to TC Gauge Controlelr

Posted: Mon Feb 20, 2017 4:06 pm
by Robert Dwyer
Alrighty, thank you very much. I shall set off to do this and give an update on the progress.