Welcome to Australia's only Vintage Radio and Television discussion forums. You are not logged in. Please log in below, apply for an account or retrieve your password.
Australian Vintage Radio Forums
  Home  ·  About Us  ·  Discussion Forums  ·  Glossary  ·  Outside Links  ·  Policies  ·  Services Directory  ·  Safety Warnings  ·  Tutorials

Tech Talk

Forum home - Go back to Tech talk

 Hum and Hiss
« Back · 1 · 2 · Next »
 Return to top of page · Post #: 16 · Written at 11:52:51 AM on 19 May 2019.
Dgnelson's Gravatar
 Location: Perth, WA
 Member since 15 April 2012
 Member #: 1133
 Postcount: 39

Gave the band select switch a good scrub with a toothbrush and all is good, for now at least. Hope that's it.


 
 Return to top of page · Post #: 17 · Written at 12:31:48 PM on 19 May 2019.
Redxm's avatar
 Location: Tamworth, NSW
 Member since 6 April 2012
 Member #: 1126
 Postcount: 436

 
 Return to top of page · Post #: 18 · Written at 1:33:44 PM on 19 May 2019.
Dgnelson's Gravatar
 Location: Perth, WA
 Member since 15 April 2012
 Member #: 1133
 Postcount: 39


 
 Return to top of page · Post #: 19 · Written at 5:23:35 PM on 19 May 2019.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1423

I use the deoxit to flush the brasso from the contacts. It's awesome gear . The reason why I use a old electric toothbrush is because if you can get it to the contacts then there is no back and forth that can disturb other stuff and the constant scrub really works well.


 
 Return to top of page · Post #: 20 · Written at 8:03:43 PM on 19 May 2019.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 3786

According to the 312 data (not the 85) the back bias resistor (R19?) should have around 12.5V (bias of 6v6) across it (chassis to CT: Chassis positive) monitor that it should pass around 75mA. If that drops then one of the valves stopped. 6V6 having the greatest effect. If it rises something is drawing extra current. Do check element voltages before & after it faults. Caps like C20 are prime suspects.

If Mice have been in the pan, they can leave deposits. The only thing I have found to get it off switches is Soda Ash buffering dish washing liquid. That is aggresive towards Bakelite so wash it off quickly. Art brush is an advantage.

Marc


 
« Back · 1 · 2 · Next »
 You need to be a member to post comments on this forum.

Sign In

Username:
Password:
 Keep me logged in.
Do not tick box on a computer with public access.