Project impossible? bringing a magnet-box back from the dead?

[Yamamaya42]

but I do have one of these, but it has no ACG control
https://www.ebay.com/itm/313573344093

[Yamamaya42]

Originally Posted by dieseljeep

I have a tuner and all the controls from a similar Mag set I scrapped.
Unfortunately, I can't get to my warehouse because of health issues.
Be patient, that set don't have to be finished in the next day or so!

exactly
this will be brought up in stages

horz /HV first
then vert
then try to get a raster on the test CRT
then try to get video
I'm just thinking ahead :P

I tend to do that

[zeno]

Chassis number is on a small paper tag. It can be anywhere on the chassis
or large part. usually starts with U, V, or T followed by numbers.
They fell off all the time so see if its in the cabinet.
Maggy model numbers are rarely useful in Sams. The used to sell
the same sets with totally different chassii. Same goes for audio.
Seperate chassis ##'s than the TV.

You can build a tuner subber & get other uses from it.
Get a solid state tuner with antenna isolation OR add isolation.
Needs 9, 12, 18, or 24 volts to run it. Also need a variable bias for AGC 1-3 VDC. Short the AFT to ground. Put it in a box & get a long IF cable with an RCA at the end. You seem like a builder so no big deal making it.


My father had the 27" magy. No UHF so pre march 1964.
Lasted abt 4 yrs & jug went soft. Bought a Zenith color then.
Other than that they were a well built set.

73 Zeno
LFOD !

[Yamamaya42]

https://i.imgur.com/AIQwxRy.jpg

got some tubes in

https://i.imgur.com/E0jx7yD.jpg

horz osc is working,,, but the HOT I got last year on eBay is BAD, works half the time, and I don't think the damper I found laying around is any good also.

can't get stable HV,, can SOMETIMES draw an arc from the HV rect cap, but nothing ever out out of the CRT anode.

Got to get MORE new tubes, and start checking resistors / caps in the sweep circuit.

but this IS progress for a chassis that i picked up from someone's front porch!

an I can't find any ID numbers on it as I mentioned...

[nasadowsk]

Oh, maggie chassis numbers are nuts. The same set might have different numbers based on the tuner used. Best I can tell, that’s the only fiff between the CT-220,221,222. Maybe. I dont think anyone knows.

[Yamamaya42]

Oh HELL yes, I have bad resistors...

https://i.imgur.com/MdXL3cN.jpg
I'm VERY sure that this CAP is bad, cause it's paper, and it's getting hammered by the horz yoke output.

on a lark, i checked the other side.
https://i.imgur.com/zKsZBMN.jpg

R75 checked at 56 ohms :O

I was expecting bad resisters,, but WOW.
no wonder HV was unstable , even with a wonky HOT, it was acting VERY weird, this is why.

[old_coot88]

Originally Posted by Yamamaya42

Oh HELL yes, I have bad resistors...

https://i.imgur.com/MdXL3cN.jpg
I'm VERY sure that this CAP is bad, cause it's paper, and it's getting hammered by the horz yoke output.

on a lark, i checked the other side.
https://i.imgur.com/zKsZBMN.jpg

R75 checked at 56 ohms :O

I was expecting bad resisters,, but WOW.
no wonder HV was unstable , even with a wonky HOT, it was acting VERY weird, this is why.

Dang. That's an interesting way of obtaining the feedbback pulse. What condition is the dual diode in? This is the first time I've ever knowingly seen a series dual diode in use. Most always it's the common cathode version.

[Yamamaya42]

Originally Posted by old_coot88

Dang. That's an interesting way of obtaining the feedbback pulse. What condition is the dual diode in? This is the first time I've ever knowingly seen a series dual diode in use. Most always it's the common cathode version.

hard to tell, not easy to test those silly selenium dual diodes on a DVM, the only one that DID seem to show it as a diode had it as 1.9v one direction, and infinite the other for both junctions, never tested on like this before, so not sure if its good/bad or ugly.

[Yamamaya42]

The phase detector is most likely bad, this is the second Selenium diode type phase detector that I have come across so far, the first being in the one in my CTC-16 which it fine, but not this one, which almost every tester on diode test can't see it as a diode, even the fancy multi tester ( transistor/cap/resistor ) thinks that it is a capacitor.

But now the question is, what type of diode to replace it with, I'm sure there are many to choose from, but what one?

[Yamamaya42]

just randomly searching, came up with the Mouser # 78-SD101A-TAP

no idea if It's right to use as a replacement for it or not. :/

[Yamamaya42]

went over the entire sweep PCB, did not find that many bad resistors, only 3-4 not counting the big 2 watt one I mentioned before, and they are not THAT far off, unlike that big one.

[Yamamaya42]

Ordering a mess of parts now, mostly electrolytic capacitors & that really bad 2w resistor, still unsure if the selenium phase detector is good or bad, seems the only real way to test it is to run it in the correct circuit and see what happens. I saw in a few places, that a BAT86 diode is a workable replacement, so a pair of them is ordered in case it is bad.

I also had to order the audio output tube, even though I'm not ready to get sound working yet, because this thing uses the cathode bias of it to source the 120b+ for the set, though that voltage does not seem to be needed for sweep, it IS needed for IF and video.

[bandersen]

The diode isn't critical. A fast switching diode like a 1N914 or 1N4148 will work or a Schottky type. Use a 1N400X series in a pinch

[Yamamaya42]

That bad 18 ohm resistor is most likely the main reason I could not get stable HV, that and the .047 cap that I suspect was leaky, with that resistor over 3x the rated value, it was like trying to run it with the yoke disconnected, and the HV circuit HATES that! :O

[Yamamaya42]

What I don't get is how can this HOT that got last year ( 6dq6a ) be stronger than the one in my stromberg carlson when it DOES work, but be very intermittent but nit seem to be shorted that I can tell