Ok. Let’s try this again…RCA 9TC240 Alignment

[bandersen]

Originally Posted by Zenith26kc20

Bob
On the old WO33A you show, is the probe you are using a WG-349A probe?
No demod in it, but is it a form of 10-1 modern day scope probe?

It's whatever it came with it. I got the scope NiB

Originally Posted by Yamamaya42

Seen them before, not sure what you call those old type RF jacks :O

Amphenol mic jacks is one term

[Penthode]

Let's get back to the discriminator response. The results you are getting are poor. The noise with lack of the S- curve means something is wrong.

It is difficult to diagnose via this forum. However the noise and the lack of an S- curve suggests the 6AL5 may not be conducting. Check to see if the tube is lit.

A common fault with this chassis is the 5.1ohm series filament resistor which goes open. Can you check this first?

[Yamamaya42]

OK. I'm a bit confused here. I have been following this closely, as I also have sets that can do with alignment. But will NEVER have the money to throw at stuff like the HP 8600 marker/HP 8601 combo mentioned. However, I saw mentioned later in the thread a EICO Model 369 which is a bit confusing, cause I had thought the HP setup was being used :O.

These are also a bit pricey and hard to find, HOWEVER, I do see some EICO Model 368s out there that ARE in my price range that can be updated to a Model 369 w/o too much effort, so, can this be used for alignment of my sets?

[Penthode]

There is something fundamentally wrong here because the alignment process should be pretty straight forward. It is however extremely important to try and understand what is happening here.

The HP equipment was not expensive. As I said I shopped around and the total price for the pair I bought was well under $100. As for sets not needing alignment after more than 70 years? Let's put it this way: a proper alignment transforms the quality of the picture and sound. These RCA sets featured full Luma bandwidth. My sets after proper alignment can resolve the resolution wedge of the Indian head test pattern right to the center. Not many sets can do that.

So let's not disparage the process and find out what is wrong. As I said, the discriminator alignment is not working. The noise and the odd response suggests the 6AL5 is not conducting. Can you check the 5.1 ohm resistor to the 6AL5 filament and check the tube is actually lit?

[Chris K]

Thanks everyone. I will take all suggestions and report back. Tuesdays and Wednesdays I teach in the evenings so I can’t be in front of the bench. Wish I was. Public school system is producing freshman college students who cannot write or speak!

[Yamamaya42]

As i said I ave been looking and to get the same HP combo it would take $400-$500 or more, on evil bay. NOT gonna happen! but can an EICO Model 368 do the job?

[Penthode]

Originally Posted by Yamamaya42

As i said I ave been looking and to get the same HP combo it would take $400-$500 or more, on evil bay. NOT gonna happen! but can an EICO Model 368 do the job?

I saw the same on eBay. All I can suggest is be patient. I waited. Both my units were from eBay.

[bandersen]

Eico 368 does not do post parker injection and only supports one marker. It's also an entry level device and will require TLC to use. Meaning routine calibration and good understanding how it works and how it should be used.

[Yamamaya42]

Originally Posted by bandersen

Eico 368 does not do post parker injection and only supports one marker. It's also an entry level device and will require TLC to use. Meaning routine calibration and good understanding how it works and how it should be used.

but I was referring to this

https://bama.edebris.com/download/ei...L-combined.pdf

the upgrade 368 - > 369 .

Will the 369 do? or is it also limited?

[Penthode]

Originally Posted by Yamamaya42

but I was referring to this

https://bama.edebris.com/download/ei...L-combined.pdf

the upgrade 368 - > 369 .

Will the 369 do? or is it also limited?

It will work. But the job becomes more complicated because it does not have an accurate marker. You would need some means of calibrating the marker or use a separate marker generator.

The Eico is okay for later cheaper intercarrier sets which only have a couple of traps. The late 40's RCA receivers are as complicated to align as you can get with 6 video if traps and the split sound tuning constraints which means absolute marker accuracy is necessary if you wish to have decent results. The RCA and Dumont were the best and most expensive sets available due to their design.

[Chris K]

I did everything I could to get my Eico 369 working correctly including having custom RF out and demod in made and I couldn’t get it to work right but, then again, I can’t get this setup to work right so maybe I’m not the best judge. I’m going to convert the Eico leads to terminate in male BNC connectors so I can use them for this ongoing project. The RF probe has a built in 47ohm resistor.

[bandersen]

Aw don't do that. It's only original once. I doubt it's the source of your problem anyway.

Don't use the 1,000pF cap and turn up the RF out. Forget about what level the alignment says to use. I've also asked several times what volts/div you have the vertical at?

What I'm trying to determine is do you have a very weak signal and it's getting swamped by noise. Or are you just not feeding a strong enough signal into the set

[Yamamaya42]

Well, I have an offer to get an EICO Model 368 at a rather good price, which will need to be rebuilt anyway, so if I do jump on it, might as well do the 369 update to it at the same time, there is calibration instructions for it as well.
I have till this weekend to decide, (offer expires) :O

[Chris K]

They aren't original probes for the unit. There's a seller on eBay who makes custom probes for all kinds of old equipment since for many of them, the accessories have long since separated and have been lost. He made custom DC voltage and resistance probes for my Heathkit VTVM. I think there must be something of a demand for the Eico 369 probes since he offers them as part of his standard "for sale" stock.

[Chris K]

Originally Posted by bandersen

Aw don't do that. It's only original once. I doubt it's the source of your problem anyway.

Don't use the 1,000pF cap and turn up the RF out. Forget about what level the alignment says to use. I've also asked several times what volts/div you have the vertical at?

What I'm trying to determine is do you have a very weak signal and it's getting swamped by noise. Or are you just not feeding a strong enough signal into the set

Again, I'm not sitting with the unit at the moment so I'm not 100% sure but deleting the cap, 10X on the scope probe and 250mV of signal strength I still have these results. When I get my new old stock Tektronix setup tonight, I'll get you a spot on read for the vertical V/Div. Previously, I had blasted a 1.0V RF into the TV and was instructed that was a huge signal strength so I started using the reduced recommended voltage.

I did swap out the 6AL5 for 2 other replacement tubes with no change. If it is a filament voltage issue, that wouldn't make a difference so I need to check that out as well and check the filament resistor as Penthode recommended.

.