Posts: 553
Threads: 89
Joined: Jun 2022
City: Marion
State, Province, Country: NY
Hello, I just finished splicing in new wire to a power transformer (Philco 45). The transformer is still out of the chassis. I did a continuity test on all leads to the core and got no readings. All AC reading are as expected but higher as expected being no load with power on the AC leads. Then I went and did something I have not done before having one meter lead on the 6 volt lead I then touched the other lead to the core and got about 40 volts using a DMM. I then did the same to all other leads except the primary ones. I get any where 40 to 150 volts. Since I never tried this before I don't know what to think. The core is in nice shape with no wax leaking. I checked my splices and found no shorts to the core. My leakage meter shows no leakage at all on the core with power applied. The transformer is plugged into and isolation transformer. Is this normal, if so where is this voltage coming from? I'm wondering if this is some kind of phantom voltage reading. Using a VTVM the most I get is 15 volts.
Dan
Posts: 18,427
Threads: 622
Joined: Oct 2011
City: Jackson
State, Province, Country: NJ
Put a ... 100K resistor between the core and the lead and see if the voltage goes down and how much.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
Posts: 5,652
Threads: 56
Joined: Sep 2008
City: Sandwick, BC, CA
I don't think that I have had a power transformer that had leakage to the iron core but I have found a few that had shorted turns in the H.V secondary and typically the transformer will start getting hot within 10 minutes, and almost immediately if it's really bad.
Regards
Arran
Posts: 553
Threads: 89
Joined: Jun 2022
City: Marion
State, Province, Country: NY
The voltage does not change one bit. After leaving connected for 15 minutes transformer is still room temperature.
Posts: 1,135
Threads: 54
Joined: Feb 2013
City: Shenandoah,
State, Province, Country: Pennsylvania
Dan, possibly that is stray voltage induced into the core, something you don’t see when the transformer is physically mounted to and grounded to the chassis, just a thought!
Ron
Bendix 0626. RCA T64 Philco 20B
Philco 41-250. Philco49-500
GE 201. Philco 39-25
Motorola 61X13. Philco 46-420 Crosley 52TQ
Philco 37-116. Philco 70
AK 35 Philco 46-350
Philco 620B. Zenith Transoceanic B-600
Philco 60B. Majestic 50
Philco 52-944. AK 84
Posts: 553
Threads: 89
Joined: Jun 2022
City: Marion
State, Province, Country: NY
That is what I am thinking too. I tested another transformer out of chassis and get the same thing.
Dan
Posts: 1,797
Threads: 55
Joined: Feb 2015
City: Roseville, MN
Stray voltage, isn't that called lightning? You guys are playing with the wrong power supply.
Posts: 18,427
Threads: 622
Joined: Oct 2011
City: Jackson
State, Province, Country: NJ
The voltages could be:
Stray
Feral
Wild
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
