Recently Acquired 1969 Motorola Color Tube Tv

[Lain94]

Originally Posted by AlanInSitges

That ceramic across the line looks fine. It should be replaced regardless.

Most likely what happened was one of those filters was leaky and overheated while it was powered on. It was coincidental that it finally vented right when you turned it off. You really need to replace the electrolytics in the power supply, the fuses, and that across the line cap, then power up again slowly. I'd probably check the diodes in the power supply first too. None of that is particularly difficult to do, so you might want to try that yourself and see how far it gets you.

Yeah that makes sense to me I figured it was a capacitor issue. I traced down the likely origin of the problem as being somewhere in the power supply circuit.

Diodes going bad? I did not ever think to suspect diodes could fail, were early diodes more prone to failure back then?

Also what are your thoughts on there being performance issues caused by all those old carbon comp. resistors? I know they are notorious for drifting upwards in value as they age. They are also noisy usually. The issue though is that carbon film resistors will introduced inductance into the circuit which I heard apparently may cause issues in a vacuum tube circuit. Is it worth messing with replacing all the carbon comps and if so what should I replace them with?

[old_tv_nut]

Originally Posted by Lain94

Yeah that makes sense to me I figured it was a capacitor issue. I traced down the likely origin of the problem as being somewhere in the power supply circuit.

Diodes going bad? I did not ever think to suspect diodes could fail, were early diodes more prone to failure back then?

Also what are your thoughts on there being performance issues caused by all those old carbon comp. resistors? I know they are notorious for drifting upwards in value as they age. They are also noisy usually. The issue though is that carbon film resistors will introduced inductance into the circuit which I heard apparently may cause issues in a vacuum tube circuit. Is it worth messing with replacing all the carbon comps and if so what should I replace them with?

Shorting of electrolytics in the power supply could kill the diodes.

My approach to resistors would be to first see what circuits have problems and then test the resistors, rather than a blanket replacement. The small inductance of a spiral resistor is not likely to cause trouble unless it is actually carrying high frequency signals (IF or RF). In the typical case, resistors in these circuits are bypassed by small capacitors anyway. In tube circuits, stray capacitance can be an issue, so component placement and lead length can have an effect, again, mostly in the IF and tuner. So, I wouldn't worry about the resistor type in video and sweep circuits, but have a bit of caution when working in the IF and especially the tuner.

[Notimetolooz]

The most likely parts in electronics of that era is the electrolytic capacitors.
That is why the best thing to do is assume they are bad before applying power.
Semiconductors are easily damaged by excessive current or voltage. A tube can withstand an overload for a few seconds but semiconductors will die in an instant, often without making a sound or without any smoke.
Of course any part can go bad. Many times TVs or radios are retired because something went bad and the owner doesn't want to bother getting it fixed.

Yes, stay away from the IF and Tuner since you don't have the test equipment for readjusting them. An exception might be carefully cleaning the contacts in the tuner.