NotTaR of Television Sets : Old TV requires warmup period           
 Copyright © 1994-2007, Samuel M. Goldwasser. All Rights Reserved. Reproduction of this document in whole or in part is permitted if both of the following conditions are satisfied: 1. This notice is included in its entirety at the beginning. 2. There is no charge except to cover the costs of copying. I may be contacted via the Sci.Electronics.Repair FAQ (www.repairfaq.org) Email Links Page.

     << TV doesn't power up immed.. |  Index  | TV shuts down with bright.. >>

Old TV requires warmup period

So, what else is new? In the old days, a TV was expected to take a few minutes (at least) to warm up. We are all spoiled today. Of course, you usually maintained a full time technician or engineer to fiddle with the convergence adjustments!

A TV (from around 1983) needs at least 5 min. to warm up (lighting up the screen and making sound if I give it a cold start. Once warmed up, you can it off and on again from the front panel and it will work immediately. Another thing this TV has a sub-power switch in the rear.

1983 sounds a bit late, but sets in the late '70 during the transition from tubes to all solid state chassis often had the 'sub-power' switch providing some power to the filaments of the CRT and other tubes - usually in the deflection and high voltage circuits since these would take a while to heat up and stabilize. The idea was to leave this switch on all the time (except when going on vacation - it was sometimes labeled 'vacation') so that you would have nearly instant warm up. Supposedly, this led to an increased risk of fire as well (see the section: About instant-on TVs).

If it is a totally solid state chassis, then there is some component - probably a capacitor in the power supply since it affects both picture and sound - that is drifting with temperature and needs to be located with cold spray or a heat gun.