Magnavox Roundie Problem

[Kalamazoo-DJ]

I found the thremistor and resistor totally burned as the repairman suspected. The thermistor on this was located under the chasis below the transformer I couldnt see it because of the cabinet. resistor just hanging as well. Now is to find out why it burned I guess.

[DaveWM]

most likey is a shorted cap in the filter or doubler cans.

with power off and everything unpluged check the can caps terminals to the chassis iwith a ohm meter should read in the thousands (after a few seconds, the cap will read very low ohms at 1st until it charges from the meter.

I am guessing the circuit breaker did not kick off? thats odd.

[Kalamazoo-DJ]

they are doing as described and no it didnt kick the breaker out, the material on the thermistor is very brittle the tab gets a varying reading and on both sides of it , resistor is fried in half 3.5 ohms on one side 2.1670 on the other hmmm

[DaveWM]

something caused the resistor to pull too much current.

You can replace it, but you will need to put a meter on the B+ and monitor it as you bring up the power, this is where a variac is very helpful.

if the B+ load is in the thousands, the it should not have burned anything up.

You need to check all the doubler caps as well as the filter. since a resistor is burned I would guess it is in the filter circuit. the filter cap will be after the doubler, prob after a big choke. I would put the current meter between the output from the choke. just a WAG but prob around 300 to 500ma, this is where you need the schematic to try and figure what is going on (what resistor burned, trace it back to the PS etc..).

Or you could take the approach that all can caps just need to be replaced. I dont like doing that until I have a pretty good idea that one or more is shorted or open.

[freakaftr8]

I remember on a CTC-16 I had a thermistor make bad connections and caused a resistor to burn.

[Kalamazoo-DJ]

I was able to be really lucky to have a vintageTV repair shop locally I never knew it even existed until today. They said they would me help in total restoration if I wanted to go that far seeings how this is my first time. I was flabbergasted when I walked in there, I did get a few pictures of the place and some old tv's too. I will be shiping it out there this week and hope to get my hands dirty and learn even more, I certainly appreaciate all the help so far I have gotten in here though

[DaveWM]

Wow that is great news! that is really a find to get someone that can work on it.

[Kalamazoo-DJ]

yes,I was becoming overwhelmed with some of the upcoming procedures I was being told about, I enjoy this stuff tho, and to actually see someone actually doing it helps and having the test equipment and parts available really makes it good for learning.

[DaveWM]

smart move, Not a good 1st set for sure.