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
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
54C Complete Teardown/Rebuild
Hello roy, here is a link to the schematic . Sincerely Richardradiorich — 11:54 PM
54C Complete Teardown/Rebuild
Richard, The Silvertone 2014 also is a transformerless set, so I am incorporating a 1:1 600 ohm audio isolation transfo...glyphmon — 11:37 PM
Preliminary work on wife's Silvertone 2014
Did an alignment today which was interesting.  IF alignment went great, almost all was already spot-on.  Adjusting on th...glyphmon — 11:35 PM
54C Complete Teardown/Rebuild
The main problem with adding a Bluetooth input is that this set lacks a traditional power transformer to isolate it from...radiorich — 11:19 PM
54C Cabinet Refinish
I started stripping this cabinet before it got super chilly out because I knew I wasn't going to be able to work on ...glyphmon — 11:18 PM
54C Complete Teardown/Rebuild
While I'm waiting to wrap up the final steps on my wife's Silvertone 2014, I started disassembly on the next project.  O...glyphmon — 11:07 PM
Preliminary work on wife's Silvertone 2014
Hello roy, that great news glad it worked out for you !! Sincerely Richardradiorich — 10:50 PM

[-]
Who's Online
There are currently 1251 online users. [Complete List]
» 2 Member(s) | 1249 Guest(s)
AvatarAvatar

>