Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Sep Wed 20, 2017 6:28 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 5 posts ] 
Author Message
 Post subject: Starting up a Webster 80-1 restoration
PostPosted: Jan Fri 06, 2017 4:01 pm 
New Member

Joined: Jan Fri 06, 2017 3:17 pm
Posts: 3
Hi guys

Ive been given an old Webster 80-1 which i thought would make a decent restoration project but the test meter has already checked out a short and continuity across the mains input pins with a resistance of around 10ohm.

I have the basic online circuit for the 80-1 which shows the primary of the transformer and i see that there are two 0.05uf capacitors (number 9 on the circuit) to down to earth.

Not having the precise specifications details of the circuit I do not know the resistances of the primary and secondary transformer windings, but im wondering if the resistance of these two capacitors is so bad, whether that would account for the discover of a short so soon?

Could somebody please advice?

John


Top
 Profile  
 
 Post subject: Re: Starting up a Webster 80-1 restoration
PostPosted: Jan Fri 06, 2017 4:58 pm 
Moderator

Joined: Jul Tue 18, 2006 5:23 am
Posts: 10763
Location: Roseville,Ca
Transformer primary resistance will be low,you could cut the caps loose to be sure,they are probably bad anyway.
Phil

_________________
I've been doing so much for so long with so little I can now do anything with nothing!


Top
 Profile  
 
 Post subject: Re: Starting up a Webster 80-1 restoration
PostPosted: Jan Fri 06, 2017 5:44 pm 
New Member

Joined: Jan Fri 06, 2017 3:17 pm
Posts: 3
They sure were Phil...every single one already taken out was rated bad at around 370nf

I just wanted to be certain that the meter alarm is firing off because it is registering the 10ohm resistance to the primary and not a more direct short elsewhere.

Does anybody have the resistance specifications on here that they can post to help me along until the SAMS arrives here by mail?


Top
 Profile  
 
 Post subject: Re: Starting up a Webster 80-1 restoration
PostPosted: Jan Fri 06, 2017 6:02 pm 
Member

Joined: Feb Sat 12, 2011 2:29 pm
Posts: 407
Location: Fayette County, Pa
10 ohms for the primary sounds Ok but use caution. You can leave those two caps out for testing if you use an isolation transformer and variac to slowly bring up the line voltage while monitoring the output. Also be aware that any electroyltics also could be shorted so use care and if the current increases beyond what is called for STOP IMMEDIATELY and troubleshoot the problem.

Such testing before replacing filters is risky, but I often do it since it might find a defective piece of unobtainium that might render going on with the project not worth the effort. Do not leave it run for any extended period until caps are changed and never leave it running unattended since you may have to shut it down should something fail.


Top
 Profile  
 
 Post subject: Re: Starting up a Webster 80-1 restoration
PostPosted: Jan Fri 06, 2017 6:15 pm 
New Member

Joined: Jan Fri 06, 2017 3:17 pm
Posts: 3
Im not even going to risk running this up even on a variac as its been off and in storage since 1959 to certain knowledge.

So far, every cap bench tested has gone way past reforming so they are gonna need replacing anyhow and i see that there are quite a few resistors which will need replacing as well so this really is a full strip down job.

I guess there is only so long any of these components are going to prove to be reliable now even though the set has sat idle for the past fifty seven years.


Top
 Profile  
 
Post New Topic Post Reply  [ 5 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 11 guests



Search for:
Jump to:  
-->






















Privacy Policy :: Powered by phpBB