a real challange?

[old_tv_nut]

A note on the use of a fixed AGC/gain voltage:

Changing the bias of the RF and IF amplifier tubes to adjust signal gain can affect the tuning of the stages. In the earliest sets, it is likely that the designers tried to minimize this or just lived with it - hence, the best procedure in alignment was to use a specified bias instead of a specified input signal level.

When designers later got this effect understood and under control, they designed IF amplifiers for black and white sets that deliberately changed response at low signal conditions to roll off the high video frequencies (low IF frequencies), thereby reducing noise ("snow") in the picture. In these sets it is even more important to use known bias and hence strong signal conditions that do not produce the roll-off when aligning the IF.

Finally, when color came along, designers had to minimize any response shift, which could have attenuated the color signal. Still, it was good practice to align the IF under specific fixed bias conditions, so any undesired variations would occur from there and not some random conditions that the technician happened to use.

[Yamamaya42]

here is how SAMs says to do it
https://imgur.com/HpMK2wJ

[old_tv_nut]

Looks like they're depending on IF frequencies getting through the tuner. If that doesn't work, they send you to connect at the mixer grid. This means that everything from the mixer output to the video detector cannot accidentally be loaded/detuned by your signal connection. It also probably means you will need greater signal level than I mentioned above, because I thought you were inputting a channel 9 RF sweep.

[Yamamaya42]

On a unrelated note, I have secured the Stromberg Carlson X-21 M4B, for restoration project 2021, I don't HAVE it yet, but it's paid for, and I just have to go get it once I'm able to drive again.

This does bring up an odd question, what does one DO WITH all these old sets when done? You tend to run out of places to display them all when done! :p

And, it seems that restoring stuff is like a drug addiction, heroin or crack cocaine, the more you do, the more you want!

[Electronic M]

I wish Photobucket would let me navigate to the picture of my wall of color sets from the years when I was stuck in a small apartment room.

I've learned to stack and or shelve stuff. I literally have walls of sets that I can turn on and watch...I've been known to watch the same show on 3 sets at once, or 3+ different shows at once. It's sort of like the old intros to robot chicken.
Once I buy my own home and am not limited to the basement, my bedroom and display room I'll probably be set up like Walter Matheaus character in Grumpy Old Men where I can walk half way across the house and not have my eyes off the program on some TV.

I do actually sell off stuff. I reevaluate my collection and sell off the bottom 10% of things on the likeability scale and or things that don't fit themes or categories I want to collect. The ETF is my primary selling ground, though the radio clubs within 3 hours drive of me sometimes result in TV sales...I collect radios too and bringing TVs to radio meets sometimes gets leads on TVs and other stuff.
I'm at the point where with ~100 sets I'm happy with what I have and have almost stopped buying new stuff/gotten pickey.

[Yamamaya42]

The stromberg carlson x-21 seems to be an interesting set, (been looking at the SAMS)

It's clearly more power efficient than the RCA 630ts, needing only 1 5u4g vs 2, the set has 2 speakers, 1 in front, 1 side, it uses 1 of those compact resistor / capacitor modules, and it has an option for phonograph input ( ceramic ), the dual switch changes audio to ext input, and kills HOT output via cathode, and thus vertical scan through boost.
https://imgur.com/Iv55YPT

[Yamamaya42]

my surgery went OK, and now my arm is hanging off me like a dead fish, due to the nerve block. So now i wait for it to wear off and the horrid post op pain to start, and the 2 weeks of aggressive PT to follow.

[Electronic M]

Originally Posted by Yamamaya42

my surgery went OK, and now my arm is hanging off me like a dead fish, due to the nerve block. So now i wait for it to wear off and the horrid post op pain to start, and the 2 weeks of aggressive PT to follow.

Ouch. Hope your recovery goes fast and well.

[Yamamaya42]

Sitting around waiting for PT later today, I was watching some Trek fan episodes, and in ep#2 of "Space Command,The Greatest Star Trek Series You're Not Watching "

I spotted something VERY familiar !


https://imgur.com/8SJBu3V

[Yamamaya42]

alignment question...
In the sams, it says that if you are doing an IF alignment with CRT removed, to remove V22( horz osc ) to disable HV, but in the many videos I have seen, (mostly shango066 stuff ) , that this is bad, as it can cause the HOT to over bias and melt down w/o being fed an osc source.

this chassis has S2 ( fuse 2) which is easy access under side, that cuts power from the damper cathode to the FBT primary, would not pulling that be a safer easier way to disable HV than to remove the horz osc tube?

[Yamamaya42]

Tuner cleaning was unsuccessful, after using RS contact / tuner cleaner on it, and aggressive changing channels for several minutes, there is no change in how well channel 7 is working, I am still having to rotate quite a bit far away from the "click " for that channel for it to come in correctly and there is something wrong with the contacts in the tuner in that area, and 2 cleaning attempts have not helped, this is also probably having an impact on channel 9, and preventing me from doing a proper IF alignment, so rather then trying to figure out what is going on with the tuner, I think the best way to go ahead is to do direct A/V input.

Sent from my VS501 using Tapatalk

[Kevin Kuehn]

If that's a Standard brand tuner it seems there may be a slot in the clunk roller mounting bracket so you can fine tune the contact alignment?

[bandersen]

Could be it has the same multi-deck wafer rotary switch as the RCA 630. Not sure why that would affect the IF alignment ?

[Yamamaya42]

Originally Posted by bandersen

Could be it has the same multi-deck wafer rotary switch as the RCA 630. Not sure why that would affect the IF alignment ?

it has the exact same multi-deck wafer rotary switch as the RCA 630.

and where as I did not see the problem on channel 3-4, I only became aware of it after I got a BT modu which is set to channel 7,
and as mentioned, I can only get chan 7 to come in if I turn the turner off the indent and into between 7-8 .

I'm highly suspecting this is contact problems that 2 cleanings did not help, and did not seem to effect chan 3-4.
the reason it may be affecting IF alignment is, the way is is said to do it on this set is to turn to channel 9 and feed in a signal from a RF generator, I have tried this 2 times with a old analog generator (Eico 324) and have not been able to complete the process, signal input had no effect on meter, I had thought this may because the Eico 324 was not exact enough, or something, but I now suspect hat chan 9 may also be flaky, and without any way to test it, I have no way to know if it works correctly to even try using it for IF alignment.
if there was a way to do IF alignment that did NOT feed a signal trough the tuner on chan 9 with this set, I'd try it, but there does not seem to be one...

and so I'm now direct input.
https://www.youtube.com/watch?v=pTZ2pWFNQCE
camera still sux :/

I really found no way to adjust the clunk roller mounting bracket ,

what it would take is something along the lines Phil Nelson did in his GE 810 TV Restoration, https://antiqueradio.org/GE810Television.htm - Tuner Cleaning Redux
same sort of problems, but at this point, its not worth it for me to pull it out to get to it all to clean it.

[Notimetolooz]

The contacts for channel 7 may be damaged and no amount of cleaning will fix it. I don't see why you couldn't use another channel for alignment but I don't know this set.
From the video it looks like you might have a noise or interference problem in the video signal.