FOUND! ARVIN 9219-cm-uhf television.

[Yamamaya42]

tuner is in pretty crappy shape, it works, but not very well. It may not be worth trying to get IF working up to snuff on this with such a poor tuner.

[Yamamaya42]

Kind of at a dilemma at this point of what to do next, the tuner is working, but very poorly, judging by the amount of resistors I have had to replace so far, (90%) , many of which were way out of tolerance, some by more than 2x, but now, after going over most of the chassis, except for the tuner area, IF is now working in FAIR condition, there still may be a few more bad resistors here and there that I have not found yet, but it over all seems to be working in a stable manor.
It can definitely benefit from an IF alignment attempt, but with the tuner in such poor condition, is it even worth it?
There will be no doubt bad resistors in the tuner, just like there was in the chassis, but it can't be touched for fear of making it worse/ destroying it. It is highly evident just by looking at it, that it has suffered years of abuse from solvents and chemicals, there was oils and varnish all over it which I carefully tried to clean, but I noticed that the visible wires in it had degraded to the point to where the insolation on them was like chalk and was coming off to the slightest touch.
Just WAY too many years with caustic chemicals eating away at things, so I have to wonder, with the tuner in such a poor state do I attempt to adjust IF, or go for direct A/V. :O

[Yamamaya42]

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

why I will most likely go with direct A/V input on this set.

pretty bad shape.

[old_tv_nut]

How much of it is damaged? If it's just the fat wires like the ones on the right, you should be able to replace them without disturbing the alignment; but if it's all those enamel wire coils, I would probably forget it. The coils will be individually spiked (turns spaced to reduce inductance) for alignment, so you would have to make new ones with the right number of turns and diameters and then figure out how to adjust (spike) them.

[Yamamaya42]

It does look like the coils are degraded, I have no idea what was sprayed on there, BUT , I just found something unbelievable on eBay...
https://www.ebay.com/itm/33393078910...UAAOSwwgxgWUtm

for THAT price, its worth a try.

I still may end up going direct input, building the amp now for it cause 1v ptp is not enough.

[Yamamaya42]

slowly getting better

https://www.youtube.com/watch?v=b2Ic8Z_SC1g

gonna try IF alignment

[Yamamaya42]

About Attempting the IF alignment :O

the SAMs says what Freq to use with the generator, but not what not what amplitude :O

my fancy generator can go from 0v - 5v, what do i set it to?

[bandersen]

The lowest level possible that results in a good meter deflection on the most sensitive scale. Or scope if that's what you're using.

[Yamamaya42]

WOW,, with no aunt hooked up, I'm pulling in my transmitter from downstairs Chan 7 with this thing

[Yamamaya42]

https://www.youtube.com/watch?v=RxfXPKdu1oc

latest video test, after IF alignment attempt

[Yamamaya42]

:O

https://imgur.com/TUl1wO8

I had an interesting “WTF” scare over the weekend, the chassis that was working so well after the IF alignment, suddenly stopped working, no video, poor sound, only a raster with herringbone pattern.
Putting scope on point B ( output to CRT) showed strong 60 hz wave, but input on V9 grid was normal, WTF happened here?
Then noticed no bias on plate, huh? Where did the 140v go?!
Then saw that R124 was smoking... did something short?
Shut down and checked, yup, 140v, hard short to gnd, what happened? Did the replacement for C4 die? Nope, it was fine, solder fault someplace? Nope, whats going on here... wait a sec, V10! Pulled it out, short GONE! :O
The damn thing took a dump and went H-K short on me in a hard way, never saw one go this bad before, but this once again proves the rule that you should not run these un-watched :/
Who knows what could have happened, now running on another 6AU6, it seems they are pushing it to the limit in this set, some specs say cathode 100v others say 200v in relation to the heater, I know that before everything heats up it goes above 200v there, so its stressing that spec, if I saw it right.

Gotta keep an eye on that.

[Yamamaya42]

ran it for about 90 min tonight w/o any smoke.

the 400 ohm 5w resistor is now 10w and is no longer black and too hot looking.

fixed the error in the Vert hold that had it at the far extreme of the control.

https://i.imgur.com/EOFc6d2.jpg

NO IDEA why some dweeb put in a 1.5 meg in for r91, works much better with a 1.3.

EDIT---
I may go over the IF setup one more time,, this time with a analog meter.

[Yamamaya42]

I have managed to beat my father's old "rat-shack" micronta 22-220a multimeter into submission, which I shall attempt to use for the 2nd IF alignment pass on this chassis, I understand now why these older types are preferred over the digital, because the numbers on the digital jump all over the place.

The setup for this IF alignment in the SAMs says to remove the AGC keying tube, set local-distance-suburban switch to “suburban” and apply -2.5 to AGC control point junction of R59-60, which I did, but the clip lead fell off at some point when I was doing the alignment and did not notice, but still got a great improvement when done.
It seemed that the traps were more detuned ( adjust for min deflection ), than the passive transfomers were, (adjust for max ).

I don't know if doing it a 2nd time will yeild any improvement, but it will only cost the better part of an eveing to try!

[bandersen]

Unfortunately, uou need to use a VTVM. They typically have a 10 Meg input impedance. That multimeter will load the circuit down and is not sensitive enough.

[Yamamaya42]

Originally Posted by bandersen

Unfortunately, uou need to use a VTVM. They typically have a 10 Meg input impedance. That multimeter will load the circuit down and is not sensitive enough.

quote "the micronta 22-220A analog multimeter is a FET Analog multitester for highly accurate results, it has 10 megaohms input impedance and performs like a VTVM "


It wont be good enough? :O