Rca 8ts30
 

Hi everyone,
I hope I'm not breaking any unwritten rule by posting my question here as well as the Antique Radio Forum. No disrespect intended to the helpful members there. I'm only hoping to have more eyes look at my problem to help me solve it.
Alright, so here goes. The television had a dry rotted power cord, so I only tested the low voltage power supply after getting a new one and having replaced many resistors as well as all capacitors minus the micas. The power resistors in the bleeder network were replaced, but the candohm checked out fine, so I left it. The secondary transformer's center tap voltage measured at pins 4 and 6 of the removed 5U4G tubes was only 196 volts, when it should have been about 320 volts. I don't have proper voltage at the primary winding. Prior to turning the set on, I have 120 volts at the .01 uF safety caps, the terminal strip that connects the safety caps line to the on/off switch line, and the on/off switch. When I turn the set on the safety caps voltage drops to 62 volts, the terminal strip drops to zero along with the on/off switch. I have 62 volts at the primary winding. I've spryed Deoxit in the on/off switch, and exercised it. Its resistance readings are correct (infinite when off and about zero when on). By the way, there are quite a few caps and resistors that I changed in the volume control circuit attached to the on/off switch. That corner of the set is a jungle of components jammed into a very tight space. Could the problem lie in there? I'd appreciate any help you can give.
Thanks,
Mike

http://www.earlytelevision.org/pdf/r...-rider-tv2.pdf

Maybe what I might do is trace from the power to the transformer and if the power branches off to a resistor befor reaching the trans then check it or anything else in between. I would think its the power in to the on- off switch one wire then look for the other power wire where that one goes. Unless maybe you are using an outlet that has a dimmer on it maybe. :scratch2: either way the primary should be 115 or 120 volts unless the transformer is bad. Ok I looked at the schematic, did you check for any output on the secondary? And those caps at the transformer c 183 and c184 don't have anything to do with the power going into the trans, if they were holding back in some way they would explode so that's out. Check the secondary for output. The 62 volts you speak of sounds like half the line voltage.

Any chance you're using a dim bulb tester with too low of wattage bulb, or a Variac set too low? Definitely seems like something is dropping line voltage before it enters your set. Caps and resistors in the set could not do that, unless you've inadvertently wired a component in series with one of the AC lines before the transformers primary.

Are you measuring safety cap voltage and winding voltages to the chassis, perhaps. :scratch2:

jr

As I posted on the ARF, the chances are that it is a bad cord/chassis connector based on the information provided. I would also reflow all associated solder joints.
Best way to get down to the bottom of it is to take a line cord, strip the ends and connect it directly to the power transformer. If that works then connect it across where the safety caps connect to prove the switch. Process of elimination would leave the line cord/connector as the last possibly bad item.

There is nothing to powering this transformer up.
https://i.imgur.com/SCv0nwX.jpg

I'm with Kevin Something is miswired and "added" to the circuit. I wouldn't force ac mains power across the primary leads quite yet. The circuit is too simple. Carefully trace it out and verify the primary leads to the transformer.

With the power switched on and set unplugged, measure across the AC plug. should be 0.6 ohms.

Good News
 

I'm happy to report that the fault was not with the television, but rather my dim bulb tester. All voltages are present and accounted for. Thanks for patiently working with me to find the solution. I'll be back with more problems as they arise. I'm so glad the initial tests are good. I was starting to think I had wasted a lot of time and money on something that would never work. By the way, does anyone have any experience with a company called Amptech Systems, and the work they do repairing detent assemblies for the tuning shafts of early model RCA televisions? Mine doesn't click correctly when channels are changed. It seems like $80 is a reasonable price to pay to have it repaired.

I'm not real familiar with your sets specific tuner, but I'd suggest before going to all the bother and expense of removal and shipping, that you post some close up pictures of the mech which may help us better diagnose what the problem could be. It's possible someone had it apart and left a part out. By removal you're inviting more potential for damage and wiring errors.

Here's some info I found on the web:

http://evilfurnaceman.tripod.com/tvs...del-8ts30.html

"THE TUNER DETENT ASSEMBLY IS EASILY BROKEN. REPLACEMENTS ARE IMPOSSIBLE TO FIND. WHEN CLEANING THE TUNER IN ONE OF THESE, DO NOT USE CONTACT CLEANER WITH ANY KIND OF LUBRICANT. IT WILL SEND THE SOUND CARRIER INTO OUTER SPACE. I USE COTTON SWABS DIPPED IN ALCOHOL, OR A NON-LUBRICATING CLEANER. ALSO, THIS SET HAS CHANNEL 1."

http://antiqueradios.com/forums/view...hp?f=3&t=10886

"Some old tuners have a springy strip anchored to the tuner shaft. This has a cutout for a ball bearing which clicks into little depressions in the front plate of the tuner. If the spring breaks, the ball falls out and you have no detent - the switch will just glide from channel to channel. If anyone has ever found a repair for this, I'd like to hear about it;"

"I have a fix for the tuner detent problem. I ran into the same problem on a 630TS which I recently restored, which of course uses the same tuner. Luckily, it is fairly easy to dis-assemble the shaft from this particular tuner; I don't have it in front of me at the moment but there are just a few screws accessible from the front around the shaft, which when removed allow the shaft and detent mechanism to be slid out the front. Be careful not to disturb the positions of switch sections when you slide it out!

As was mentioned, the problem is usually caused by a broken spring clip and a missing ball-bearing. I drilled out the rivet holding the old spring clip and fashioned a replacement from a piece of scrap plastic with 3 drilled holes: one for the shaft, one for the rivet (replaced with a small nut and bolt) and one for the ball bearing. I replaced the missing ball bearing with an ordinary brass BB. It works great, though probably not as "crisp" as the original since the plastic is more flexible than the spring steel. Luckily there's plenty of extra room in this tuner to make these mods.<P>I agree that this is an excellent chassis design and well worth the restoration effort - I also have a restored RCA 9PC41 projection TV which as mentioned uses the same circuitry. The picture is amazingly sharp and clear, despite being blown up from a 5" CRT to a 25" diagonal screen. This chassis also has all of the required adjacent-channel traps to get a good picture direcly off of cable."

Hello again,
I've made some progress since my last posting. I'm able to get a distorted image, which makes me very happy believe it or not. I don't have any sound though, and the fine tuning shaft seems to need some attention. I've attached pictures that show that I'm able to pull it out and spin it freely. I'm not sure if this is to be expected, or something to be concerned about. It doesn't seem to do anything. Also, I mentioned in a previous post that the channel selector needs work on the detent assembly. It's missing the ball bearing. I appreciate the advice given so far, but I'm still not sure of a plan of attack. Any other thoughts on how you would take this on?
Thanks,
Mike

The fine tuning shaft connected to the actual fine tuning control via a belt. Your belt probably rotted off..Time for a new belt.

I didn't know there was a belt. Thanks for letting me know. Any idea what I can use for a replacement? I'd love to see a picture of what it looks like. That would probably go a long way in improving my lack of audio.

Use a string and make a belt install it then take it off and get a rubber O ring but it has to be smaller then the diameter of the string you just made so that you can stretch it on.

The 8TS doesn't use a belt, if I recall right it has the friction drive.