GE M935AWL roundie restoration part 1
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- Опубліковано 26 вер 2024
- Let's get going with the 1964 GE by doing a controlled power up. Also, was in for a surprise when I tested all the tubes!
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Just wanted to say that I enjoy watching these videos. I learn a lot from them. Im honestly amazed and the amount of work you get done. You must never sleep.
Slide the chassis back a few inches and jump the breaker, Then try bringing it up again. Rectifer diodes don't go open, they short And you will see that immediately On your meter
Even as a teen doing side jobs for a guy in a seamy part of town, I was always a little more cautious and connected something like another breaker in, or maybe a fuse. If something went kablooie I didn't want it to be my careless fault (though I still had things like that happen sometimes). And if anything, the more so now, given that a few things are made of unobtanium.
But again Bob's style is more careful anyhow. His whole bench is set up to baby these sets for he knows the issues, the generalities if not every single specific. At worst, a variac is cranked up while watching current flow and actual set signs of life. A jumped breaker probably won't be a disaster with that much care.
Whatever you've done, Shango, I don't remember babying sets as being included, and I used to watch till things got so rough and ready it started looking silly to me. I appreciate Bob's respect, even though I'll sometimes argue with Bob about details that in the end Bob will work out anyhow.
I have been waiting ten years for you ton work on one of these color sets! :)
Me too :) This was my first favorite electronics channel alongside joernone and shango066.
It was great chatting with you at VCF. Looking forward to this series!
The thick neck of color roundies is the most beautiful of consumer electronics artifacts. Artful and electrical. Three highly refined cathode ray generators, an invisible event.
Yes, chunky and as in-your-face as anything could reasonably get. Of course the newer rectangular tubes operate the same way too, but everything's, well, little. (Cf. "Little Girls" from "Little Orphan Annie")
Well this video confirms the answers to my questions in a previous video. Top notch restoration process so far Bob.
That set brings back memories. The RCA also. I don't remember how many 21FJP22 CRT's I replaced back then. If you need some of the HOT tubes let me know. I likely still have a box of tested used ones and maybe a few NOS left.
One hazard of touching the filter caps is some were isolated from the chassis on phenolic plates. Sometimes touching a couple of of the cans at the same time gave you a really rude shock. I still have a lot of NOS circuit breakers and many chemical fuses if you need any.
Thanks for the insights. I thought about that hazard as well, but it seems the three visible caps are all grounded to the chassis. Perhaps there are others lurking below the chassis? It seems 6JS6 tube have come a bit down in price since I last looked. Maybe the illegal high powered CB craze has faded?
@@bandersentv With a voltage doubler circuit there will be one cap that is floating. That is C1 located to the right of the audio board behind the video amplifier board. It has a black cardboard wrapper.
Circuit breakers were always issues in this vintage of sets along with the varistors that were used in the degaussing circuit. Seeing a set of this vintage brings back memories of people giving me sets like this in the early 1980's in the days where I barely had a clue of what I was doing.
Hey Bob when I got my 62 Admiral set the circuit breaker was messed up on mine too. So I figured it was already broken I couldn't break it more. I was able to flip the chassis over and spray contact cleaner, then contact cleaner with lube and keep jiggling the button and eventually it popped free and it has been working ever since you may want to give that a shot
yes, that blue wire on the lat magnet does go to the ground, an easy check fro bias will be to check for voltage at R204, the big resistor near the CRT inside the set, should be close to 400v on one side, 280v on the other, it;s tricky, but can be reached w/o pulling the chassis those parts are chassis clips, it has been out before.
6GH8 tubes would often develop shorts after four or five years.
Bob, this GE chassis is a carbon copy of the RCA design. As you discovered, there are no plugs to disconnect the tuners and front panel controls. On the RCA chassis, there is a mounting location for the tuner assembly on the rear of the chassis by the power transformer. I didn't see any type of chassis mounting on that GE. Yeah unfortunately, any kind of bottom chassis access means you have to pull the chassis, no bottom chassis access is built into the cabinet.
The probable lack of B+ could also be caused by the degaussing thermistor opening up. Also, depending upon the degaussing circuit used, if the thermistor opens, it will route all the power supply current through the degaussing coil and simultaneously burn up the VDR (Voltage Dependant Resistor). It is obvious when the thermistor opens; there will be a visible separation between one of the component leads and the thermistor body. Also check to see if the degausser is plugged in.
Those circuit breakers had a high failure rate. They are a simple, super cheap thermal breaker. These power supplies with the voltage doubler have really high 60 Hz peak currents. About 5 years later RCA went with a bridge rectifier.
So, when you fix the B+, you will need to repeat the slow power-up. While doing the initial power-up, it wouldn't hurt to have a several hundred watt bulb in series with the set just in case something decides to hard short.
The Horizontal Output cathode current monitor is a great idea! I don't really see the need to do the initial power-up with the Horizontal Output Tube removed, just watch your cathode current.
When powering up the set again, make sure the deflection yoke is connected (it wasn't connected in the video). I haven't proven this but, the deflection yoke provides a necessary load to the Horizontal and Vertical outputs, damage may occur with the yoke disconnected.
Your first video of this set, told me the back had probably never been off before. The first thing most TV Techs would do when servicing a set, was to toss all but 2 back screws.
That wire from the Blue Lateral Magnet needs to be connected to chassis ground to dissipate static electricity buildup.
Thanks for all the info, but the deflection coil is connected as far as I know?
@@bandersentv That type yoke uses 4 Faston wire terminals that individually plug into the backside of the yoke. I only saw 2 of the wires connected in the video.
many color sets with an octal yoke plug had B+ looped through the connector. The deflection circuits/HV would be unpowered if the yoke was disconnected.
You could probably monitor B+ at the horizontal output tube plate cap since you have the tube out of circuit. Otherwise that's one location we are told to never measure voltage at due to the high pulse peak voltage.
You could probably flip the set and pull the metal cover underneath to get at most of the chassis before you pull the whole chassis but everyone did what they wanted. I remember most of the the tube sets I had, especially the Zeniths, had a cover underneath. I worked on hybrid and solid state as things progressed. I did play with a few radios and some earlier b/w sets when I could find them.
Unfortunately, there is no removable cover underneath.
Well it figures. Just makes it harder but not impossible. 🤬
The term for those phone stabilizer thingies to throw at your favorite bay or jungle site is "gimbal" btw. The DJI osmo line is very common, but apparently those break pretty easily
That certainly sounds like something GE would do, with the hardwiring of the controls to the chassis. The bean counters' agenda apparently won over quality and serviceability.
Is the yoke disconnected? red and blue would be horiz. and yellow and green or black would be vertical. Looks like the red wire is laying loose to the right of the blue convergence coil.
Yes, one wire is out
Is X1 diode drawn backwards? If not I don't understand how voltage doubler works which may be the case.
Good eye. I think it is drawn backwards. SAMS makes mistakes like this from time to time.
Looks that way. Apparently the same thing ( diodes drawn in reverse) is common with SAMs as I have found at
least 8 of their phonograph schematics drawn with wrong direction diodes in my collection of very small
component count drawings. So I was just a matter of poor proofreading before publishing!
The dog is saying "turn it up to 11" Hey Shango is here , god is he annoying
Good Morning Bob and Shango. check the ckt bkr often bad. Good your checking Horiz current very important. Love this new adventure I will be standing by for the next video super thanks for making video
The Invaders!