How to repair and refurbish vintage tube amps? - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 10th April 2011, 12:25 PM   #1
diyAudio Member
 
Join Date: Jan 2011
Location: Mumbai, India
Default How to repair and refurbish vintage tube amps?

Hallo everybody,


I have a few vintage amps that need repair and refurbishment. I am a novice as far as valve circuitry is concerned, although I have been dabbling in DIY electronics since childhood. I shall be doing this myself as there are no professional experts in valve/tube technology available here. The old timers have closed shop, retired and gone away.


I am now preparing “how to go about this job” notes to guide me and request experienced members to help fill the gaps in my knowledge and provide answers. The equipment I have consists of hand tools, soldering guns, DMM and bulb tester with 15, 40 and 100 watt bulbs.


I am aware of the extreme caution to be taken while working on such equipment, because of the high ac and dc voltages in the equipment.


The procedure:-
1) Clean the amp chassis of accumulated dust, cobwebs, dead insects etc.
2) Clean all pots, switches, valve sockets, RCA terminals and speaker terminals with electronic grade contact cleaner (“safe with most plastics” type)
3) Connect speakers and slowly power up through the bulb variac.
4) If the high wattage bulb does not light up, or is dim, then connect directly to mains and check if the chassis is live. This check shall be done with one probe of the DMM on the chassis and the other connected to the earth on the wall outlet.
5) Replace the capacitors and resistors. Here, I seek advice on what types of caps and resistors are best.
6) Check voltages on valve pins and bias. I know heater should have ac current only, but what about the anode? I checked anode voltages for the first time last week and found both ac and dc current. Is this correct? Also, how to check bias? Any other method than this? Bias FAQ
7) Hopefully, the amp should work properly after this and is ready for minor upgrades such as replacement pilot lamp with LED (How do I do this?), in-rush current limiter, delayed start (something like this http://www.nervenet.info/HT_delay/ax_aug-2001.pdf ), individual bias pots on each tube (How is this done?)


There must be some dumb methods that I have contemplated, and have probably asked some dumber questions. Also I am asking for this advice on other forums too. I hope members here do not mind that and thank in advance for the valuable advice received from them.


With Best Regards,


analogadikt
  Reply With Quote
Old 10th April 2011, 12:51 PM   #2
diyAudio Member
 
Join Date: Aug 2008
Hi !

You can find a complete walk-through of restoration process in my blog:

Pioneer SM-83 Vacuum Tube Amplifier Restoration | MacGuru HQ
Fisher 400 Vacuum Tube/Valve Tuner/Amplifier Restoration | MacGuru HQ
  Reply With Quote
Old 13th April 2011, 02:39 PM   #3
diyAudio Member
 
Join Date: Jan 2011
Location: Mumbai, India
Quote:
Originally Posted by LinuksGuru View Post
That is very helpful.

Thanks and Regards
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
vintage amplifier repair/upgrade manual east electronics Solid State 25 31st May 2014 08:42 PM
How to repair and refurbish vintage tube amps? analogadikt Tubes / Valves 0 10th April 2011 12:17 PM
Tube amps from vintage RTR's? Brisso57 Tubes / Valves 5 19th February 2009 07:08 PM
vintage tube amp repair help adason Tubes / Valves 25 10th December 2006 09:48 PM
Vintage Repair in UK EchoWars Solid State 3 6th July 2003 08:24 PM


New To Site? Need Help?

All times are GMT. The time now is 11:40 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2