Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12, 2025) x

Thread Closed

Bad Transformer?
#2

First off, be VERY careful checking your a.c. transformer!, high voltage from the secondary to the plates of the #84 rectifier is lethal ! To check to see if your a.c. trans is still good, you will need to use a variac to "slow up" line voltage from 0 up to full 120 v very slowly. You will also need a ammeter set to low scale to read the current being pulled by the transformer. The ammeter needs to be connected in series on one side of your a.c. line cord that powers the transformer with ac switch on (primary side of trans).
Remove your # 84 rectifier tube from the socket. With variac set at 0 volts, slowly up the voltage to about 25 volts ac, watch the ammeter, if it starts climbing beyond 1 amps... going on up as you slowly increase the ac voltage up higher, you have a bad transformer. On the other hand, if the ammeter doesn't climb as you up the the a.c. voltage from the variac up to full line voltage (120 v), your transformer is most likely still good. In that case, look for mistakes or other problems by carefully reading the schematic. Most radios pull around 1 amp max +/- a little current on the primary side when everything is working properly. If your trans is bad, you can lookup each individual tube and add up the total amperes (filament current) of all tubes combined in the set. Same with the 84 rectifier tube filament and plate currents. You can then determine what kind of replacement to purchase. Be careful working around the a.c. trans!!


Messages In This Thread
Bad Transformer? - by Dark High - 10-28-2011, 09:19 AM
Re: Bad Transformer? - by Texasrocker - 10-28-2011, 03:15 PM
Re: Bad Transformer? - by Dark High - 10-28-2011, 08:00 PM
Re: Bad Transformer? - by Arran - 10-28-2011, 09:19 PM
Re: Bad Transformer? - by gvel - 10-29-2011, 10:28 AM
Re: Bad Transformer? - by Dark High - 11-14-2011, 09:32 PM
Re: Bad Transformer? - by 7estatdef - 11-15-2011, 12:30 AM
Re: Bad Transformer? - by morzh - 11-15-2011, 12:10 PM
Re: Bad Transformer? - by Chuck Schwark - 11-15-2011, 12:36 PM
Re: Bad Transformer? - by codefox1 - 11-15-2011, 02:28 PM
Re: Bad Transformer? - by Dark High - 11-15-2011, 03:45 PM
Re: Bad Transformer? - by Ron Ramirez - 11-15-2011, 05:13 PM
Re: Bad Transformer? - by Dark High - 11-16-2011, 05:56 PM
Re: Bad Transformer? - by 7estatdef - 11-16-2011, 07:05 PM
Re: Bad Transformer? - by james1095 - 11-17-2011, 02:43 AM
Re: Bad Transformer? - by Dark High - 11-17-2011, 09:17 PM
Re: Bad Transformer? - by 7estatdef - 11-17-2011, 11:44 PM
Re: Bad Transformer? - by Dark High - 11-18-2011, 10:33 AM
Re: Bad Transformer? - by Dark High - 11-18-2011, 04:04 PM
Re: Bad Transformer? - by morzh - 11-18-2011, 10:24 PM
Re: Bad Transformer? - by Dark High - 11-21-2011, 01:14 PM
Re: Bad Transformer? - by 7estatdef - 11-21-2011, 02:03 PM
Re: Bad Transformer? - by james1095 - 11-22-2011, 01:33 AM
Re: Bad Transformer? - by Dark High - 11-22-2011, 10:53 AM
Re: Bad Transformer? - by codefox1 - 11-22-2011, 04:47 PM
Re: Bad Transformer? - by 7estatdef - 11-23-2011, 12:28 AM
Re: Bad Transformer? - by Texasrocker - 11-23-2011, 10:41 PM
Re: Bad Transformer? - by james1095 - 11-25-2011, 03:20 AM
Re: Bad Transformer? - by Dark High - 11-28-2011, 01:00 PM
Re: Bad Transformer? - by Dark High - 11-28-2011, 01:01 PM
Re: Bad Transformer? - by Dark High - 11-28-2011, 04:19 PM
Re: Bad Transformer? - by morzh - 11-28-2011, 06:25 PM
Re: Bad Transformer? - by Dark High - 11-29-2011, 11:54 AM
Re: Bad Transformer? - by morzh - 11-29-2011, 05:52 PM
Re: Bad Transformer? - by TA Forbes - 11-29-2011, 08:27 PM
Re: Bad Transformer? - by 7estatdef - 11-29-2011, 09:28 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
under chassis parts locator diagram for 1938 Zenith 9s262
Has anyone gone to the trouble of creating an under chassis parts locator image?  Yes, I can identify components by foll...bobloney — 08:57 PM
Plug Voltages Needed For A 1943 CRV-20130 Power Supply
Try looking at this site the book mark is for a old generator that I was given. David    https://radionerds.com/index.ph...David — 08:36 PM
Plug Voltages Needed For A 1943 CRV-20130 Power Supply
Hello Everyone, I am looking for voltage identification for all the pin positions on the socket of a CRV-20130 power su...Tonym4704 — 08:16 PM
Philco P45-6365 Universal Transformer Instruction Manual
Can anyone guide me to where this may be found?GRG — 03:00 PM
54C Complete Teardown/Rebuild
I don't think that I have encountered a 12Z3 before, curious how it uses one of those but includes a #43, which is a 25 ...Arran — 02:17 PM
HiFi (Chifi) tube amp build - but my own design.
It's the other forum. I'm also in DIY, but mostly read there. Honestly, I kinda jumped into this without much thought to...TV MAN — 10:43 AM
Philco 71 Code 125
Hello,  I am in need of a schematic for this radio. Mine has the three separate circular tube shields and a shadow me...dconant — 08:06 AM
Stromberg Carlson 1500 Squeal
And life just keeps getting more complicated.dconant — 07:57 AM
54C Complete Teardown/Rebuild
Hello Roy, here is this one sincerely Richardradiorich — 12:45 AM
54C Complete Teardown/Rebuild
Richard, Had grabbed it already but thank you just the same.  I find myself wanting to find some way to block out the...glyphmon — 12:03 AM

[-]
Who's Online
There are currently no members online.

>