RCA 9TC240 Alignment...The start of my education (I hope!)

[Chris K]

Different frequency range in this TV but oh that CT100 IF response curve is so beautiful!!!!! If I ever see something like that on my scope I'll send you first class, round trip tickets to Maui!!!!!!

[Penthode]

Originally Posted by Chris K

I'll make the detector. Thank you for the design! There may be issues with the 8601. I don't think I'm getting RF output. Output level doesn't change. I'll need to break into it and see what's going on!

Without the HP8600a, the HP8601a should act as a standard signal generator. If you have a 100MHz scope, simply connect the probe to the RF output and set it to say 10MHz. Switch it to CW mode and you can ignore the sweep mode switches for a moment. Just crank up the output and set the TIME/DIV on the scope to 0.1uS per division and see if you can see a high frequency sinusoid on the scope.

[Penthode]

Here is the setting of my HP8601a generating a 10MHz CW carrier and the scope set to 0.1us per division and scope set to 0.1volts/div with a 10x probe = 1.0 volts per division.

[Chris K]

Yeah I’m not getting the continuous sine wave out of the RF section of the 8601. Something is whacked with the RF generator. I’m going to have to break into this thing and see what’s going on. Thank you for taking the time to setting up the generator and scope and documenting the results for me. The TinySA has a frequency generator in it that gives me a clean CW trace using the same scope. I have an HP and a budget basic Chinese scope and I don’t get the continuous wave. They are both 100MHz scopes

[Chris K]

I’ll be back on it tomorrow night. I’m pretty sure I can fix a balky RF generator section. Thanks for hangin’ in with me.

[Penthode]

Ah! in the test circuit I forgot the most important element: the diode!

Here is the revised drawing.

[Chris K]

I think this is just noise. Output level looks dead. There's a guy on eBay selling these restored/calibrated and certified accurate. Maybe I'll look into those units if I can't get this one working. My ongoing luck with this endeavor and obtaining TVs from this era that require a recap and a few tweaks to get a good picture continues. Kinda ridiculous at this point. I feel cursed!

[Penthode]

Hmm. It may be the output hybrid amplifer. I earlier did research on this and there is a guy who reproduced a better than original amplifier replacement. I was lucky with mine.

He used to manufacture and sell the amplifiers but no more. However he has kindly provided the component list, schematic and PCB layout to build one. That is a project within itself.

Here are the links.

http://www.dasarodesigns.com/product...012-1820-0150/

http://www.dasarodesigns.com/project...012-1820-0150/

[Chris K]

I think I'm just going to buy one that I know is working and keep the one on the bench right now for parts. I'll probably have a go at trying to make it work but at least I'll have an instrument I know I can trust. Are you sure you want to keep your cart hitched to my wayward star!? I seem to be jinxed! It'll be another week before the next one is delivered.

[Chris K]

Here is a second one exactly the same as the one I just bought from the same seller. Apparently he likes these as much as you do!!!

https://www.ebay.com/itm/22616494900...3Avlp_homepage

[bandersen]

Oof, this is getting really expensive.

[Chris K]

Originally Posted by bandersen

Oof, this is getting really expensive.

Always seems to!

[Yamamaya42]

Originally Posted by bandersen

Oof, this is getting really expensive.

my thoughts exactly, I would never be able to put out the kind of $$$ for equipment like this!
If i ever do try to align my FADA, I would just do the MIN/MAX steps laid out in the SAMS with the RF generator and hope it helps it like it did with my Arvin.

[Chris K]

Originally Posted by Yamamaya42

my thoughts exactly, I would never be able to put out the kind of $$$ for equipment like this!
If i ever do try to align my FADA, I would just do the MIN/MAX steps laid out in the SAMS with the RF generator and hope it helps it like it did with my Arvin.

Married for a long time to an understanding, physician wife. Me?...I'm a bum!

[Chris K]

Well...about the only thing I would be capable of fixing might be the issue...the 1/8A 0.75V slow blow fuse on the power board is open. I have a replacement floating around somewhere....