Rca CTC-25 overview and help

[ZenithNut]

Originally Posted by Electronic M

Look at the what?

Do"h

I want to look at the overall ac current draw the set is using. I checked my fluke meter and it tops out at 320ma so an analog dc milliamp meter is on its way.

[Electronic M]

Originally Posted by ZenithNut

Do"h

I want to look at the overall ac current draw the set is using. I checked my fluke meter and it tops out at 320ma so an analog dc milliamp meter is on its way.

On tube sets that test is much less informational than solid state. A meter that can't measure 5-10A AC can't directly measure the line current the set draws. (also some DMMs that can do 10A only do DC and some only do AC so knowing which the meter can do is important)....

All that said there is a way to indirectly measure the AC that set uses with your present meter (assuming it has an AC volts range) get a 5W or higher, 1 OHM power resistor place that resistor in series with one leg of the cord (can hack up an extension cord to do this (and make a universal adapter) ) then with the meter in AC volts range measure the voltage across that resistor...You can then compute the approximate current using ohms law: I=E/R= measured voltage/resistance...Given resistance should be 1 OHM that means measured voltage should be approximately equal to the current flowing. The accuracy of the resistor, the accuracy of the meter, where you connect the meter along the wire will all introduce some error to the measurement, but it should give a decent approximation.

[ZenithNut]

Originally Posted by Electronic M

On tube sets that test is much less informational than solid state. A meter that can't measure 5-10A AC can't directly measure the line current the set draws. (also some DMMs that can do 10A only do DC and some only do AC so knowing which the meter can do is important)....

All that said there is a way to indirectly measure the AC that set uses with your present meter (assuming it has an AC volts range) get a 5W or higher, 1 OHM power resistor place that resistor in series with one leg of the cord (can hack up an extension cord to do this (and make a universal adapter) ) then with the meter in AC volts range measure the voltage across that resistor...You can then compute the approximate current using ohms law: I=E/R= measured voltage/resistance...Given resistance should be 1 OHM that means measured voltage should be approximately equal to the current flowing. The accuracy of the resistor, the accuracy of the meter, where you connect the meter along the wire will all introduce some error to the measurement, but it should give a decent approximation.

My fluke meter can go up to 10 amps ac/dc
Youve been really helpful so far. Cleaning out the hv cage and all the leads. I swore this hissing noise came from the back side if the cage. It will be a while till I get that dc milliamp meter in the mail.

One thing i forgot to mention is that one of the power resistors has been replaced on the chroma board. Also Ive been told theres a trace along that board that tends to fail. Fortunately mines in good shape. All ive done to it to add on is replace a few e caps and reflow the ground stags. Some have mentioned hard wiring the ground with a wire.

To touch up on your earlier post the ctc 25 does use a cup ontop of the flyback where the plate cap of the hv rectifier sits inside. I will wrangle up a few and see if it helps next time i power it up with a ammeter telling me what the cathode current.

If any of the wire insulation is at fault from breaking down (and this IS a high hour set) what would be a good replacement? I imagine regular old heat shrink tubing wouldnt be good enough for the 24kv..