Not to worry! It won't take that long...

The service is called 'UPS Mail Innovations' and my package ETA is 9/17. If I had gone with FedEx ground it, would have arrived a week sooner at about the same cost.

Do a web search on 'UPS Mail Innovations review' and you'll find plenty of nasty feedback.

After the Predicta is assembled, can you get access to align the IF transformers?

Carl

Not very easily, but the cables are long enough that you can slide the chassis out a bit to make adjustments easier.
I'll probably align it while it's out of the cabinet entirely though.

While waiting for parts to arrive, I took care of some other items.

The rebuilt electrolytics have been installed.
http://farm9.staticflickr.com/8317/7...44c62cd6_c.jpg

Also, the germanium power rectifier module has been replaced with a terminal strip and two 1N4007 silicon rectifiers.
http://farm9.staticflickr.com/8038/7...014abc51_c.jpg

These things were not that accurate when they were manufactured back in the day. The resistance may have increased some over they years, but it's hard to figure out how the capacitance went up (unless leakage is fooling your test equipment, but that equipment likely also has a leakage test). Replacing them with modern parts certainly won't hurt, and may fix a problem if one of these modules did get too far out of spec.

Bob,

thought you might be interested that diode package you removed is a Germanium diode(like you suspected) the max forward voltage is 380V and current is 0.4A.

I think it looks rather cool.

Matt

I've finished creating replica K2, K5 and K6 networks and should be ready to try firing it up soon :)

http://farm9.staticflickr.com/8436/8...948b69e3_c.jpg

that turned out nice and neat .

Hi Bob,

I noticed one of the caps on your networks looks to be 600VDC. For some reason, I thought that all the caps on these things needed to be 2KV. What are the voltages on the brown caps?

Very neat job, by the way!

Cheers,

Adam

That's actually 800VDC. I don't know what the voltage rating is on the original caps in the K networks. I'm going with the experience of other restorers and common sense.

For example the K4 network connects to a cap on the main board rated for 1KV so it's been recommended to use a 1KV cap in the replica network. I used 2KV caps because that's what I had on hand.

As for the other networks, they don't connect to any circuit nodes running at more than a few 100 volts so I figure 500 volt mica and 630+ VDC ceramic and film caps should be more than sufficient.

Dang these old eyes! It IS an 800V cap! Thanks for the info, I can't remember where I thought I read about the caps being 2KV, but I remember thinking at the time that seemed really high compared to everything else in the circuit.

I have a 17in Princess giving me woes, and I suspect it's the couplate feeding the grid of the HOT. The voltage is too high (approaching zero instead of -45V) and I'm getting red plates. Your solutions really do look top notch, very tidy.

Cheers,

Adam :)

Here's what I came up with for the K3 network. Two 47K plus two 1200 and a 1600 to replace the 90K + 4000pF sandwich in the original.
I would have liked to use a small ceramic 5100pF cap, but the closest I had on hand was a big 2,000V 5100pF film cap.

http://farm9.staticflickr.com/8457/8...671a18f3_c.jpg

It's tempting to coat these networks in epoxy or silicone, but I'm afraid I may need to tinker with them to get the set running properly.
http://farm9.staticflickr.com/8180/8...bd471f25_c.jpg

that turned out nice ,i wouldnt dip them in nothing you never know when you might have to replace something, or get at it for a test.

Looking good. You could use heat shrink over those little boards. Can even do that after they're installed and tested. But who's going to see them after the hoods on.

It's finally time to reinstall the main board. Hopefully, I won't need to pull it out again anytime soon.
http://farm9.staticflickr.com/8040/8...fe58d23d_c.jpg

I popped the HV cage off to get a closer look at the flyback. Some chunks of insulation have fallen off, but the resistances match the schematic.
I picked up some RTV133 silicone to patch it up.
http://farm9.staticflickr.com/8318/8...40a2cf26_c.jpg

I wonder why the 15 ohm resistor has been shorted out :scratch2:
http://farm9.staticflickr.com/8437/8...8c127eed_c.jpg


It's R72 on the schematic.
http://farm9.staticflickr.com/8301/8...2f420fa5_c.jpg

I've been going through the tubes and found a 12CU5 in the 12CA5 socket.
They have similar specs, but I don't see 12CU5 listed as a valid sub only the 12EH5 :scratch2:

I'm SO waiting to see this beauty lit up!

It's an AWESOME meticulous restore you are doing here....I hope you are KEEPING it so it runs another 20-30 years or so.

Yeah predictas are cool :)

Just saw one in a garage of a friend of mine over the weekend. He had the last tv shop here in town, closed months ago. Was doing my impression of american pickers in his garage.. Told him about AK and VK here, Hope to see alot of his gear for sale on here soon... Wont get rid of the predicta as of yet, (was his dads) Hope he'll fix it one day :)

SR

I just hit a minor roadblock. The push on/off power switch is bad. Perhaps it got fried along with the fusistor and thermistor. Probably when some knucklehead tried to turn the set on.

I'll try working it for a while and hopefully the contacts will work themselves clean. Otherwise, I'll just jumper it for now.

I hope you are still planning to variac this to life!

:dammit: I new this was a common point of failure and even bought some replacement sockets. Unfortunately, the break didn't reveal itself until after I wired the PCB back in :tears:

http://farm9.staticflickr.com/8461/8...607f2a95_c.jpg

I globbed a little solder on the break and it's restored continuity through the PCB (for now). If I ever need to pull the PCB for some reason, I'll replace the socket.
I still don't have continuity through to the AC plug though.
There seems to be another break somewhere between the CRT and tuner tubes.

I fixed a loose tube in the tuner and finally have filament continuity :) Here it is powered up with the fusistor pulled out so there's no B+.
I'll try a full power up after I get some sleep.
http://farm9.staticflickr.com/8310/8...fa2db835_c.jpg

Startup filament current
 

I checked the filament current when the set is turned on and found it peaked at about 1 amp then settled down to 600mA after 10 seconds. That's with a single CL-90 (120 ohms cold) in place of the original thermistor (400 ohms cold).

I then tried it with two CL-90s in series and got a peak or around 850mA before settling down to 580mA.

I checked in my RCA tube manual but couldn't find any data about permissible cold filament startup currents.

Does anyone know if it's OK to have 1A (or more) running through a 600mA tube for a few seconds every time a set is turned on ?

If not, I could go with three CL-90s in series to really keep that current surge down.

I did some searching on the web and discovered Ametherm has a nice line of thermistors including these with a cold resistance of 220 ohms.

1 Amp max, 2.2 ohm hot
http://www.digikey.com/product-detai...873490?cur=USD

2 Amp max, 0.9 ohm hot
http://www.digikey.com/product-detai...873476?cur=USD

I hooked up a test speaker, popped in a fusistor and slowly bright it up on a variac until I achieved full B+.
Only the tubes weren't lit up until I wiggled that tube in the broken socket again. I'm definitely going to have to replace it!

After fiddling a bit with the tuner, I heard our LPTV channel 6 coming through the speaker :music:
http://farm9.staticflickr.com/8036/8...8805eb4c_c.jpg

I removed the screw locking down the CRT and popped it off the chassis.
I'll lay down some padding on my workbench so it doesn't get damaged and hook it up next.
http://farm9.staticflickr.com/8029/8...3d05ff3d_c.jpg

I hooked up the CRT and powered it up again. That got me a nice bright horizontal line :)
I quickly turn the brightness down to avoid a burn. Wiggling the 10DE7 vertical osc. and output tube produced some vertical deflection so I'll start checking there.
http://farm9.staticflickr.com/8322/8...d57e2eec_c.jpg

Ugh, another broken socket pin.
http://farm9.staticflickr.com/8037/8...0d9f3d9a_c.jpg

I globbed some solder on that break too and achieved vertical deflection :)
After a bit of tweaking, I got a watchable picture.
The hor. linearity is off, vertical hold touchy, channel oscillator slugs are off and it needs an alignment, but it's progress :yes:
http://farm9.staticflickr.com/8039/8...fedc4d2a_c.jpg


http://farm9.staticflickr.com/8175/8...538046c8_c.jpg

After all that.... ALIVE is GOOOOOOD!!!! and a picture too??? BONUS ROUND!! :thmbsp:

SR

Wow! That looks great so far!

And what's the first thing we see? Mr Death! :D

Maybe you should have gone ahead and replaced all the sockets! :scratch2:

LOL - I hadn't noticed that when I snapped the pic.

I swear all these 9-pin sockets looked fine when I inspected them. I'll be pulling the PCB back out and replacing them. Better order up some more for my other sets too :yes:

That's funny, as I read this post, that episode of TZ is on right now.

its alive ! you sure took that tv a long way back to the living .

Hey Bob, I'm collecting knowledge on these old Predicta's
because they seem to catch my eye. Can you post a
picture of a new tube socket and tell who can supply them?
If I find a Predicta, might as well replace all the tube sockets
with the recapping.

Thanks

Carl

Bravo!! It looks like all your excellent work replacing the "K" networks really paid off. Congrats!

-Clark

They're identical to the originals.

Check out these two earlier posts in this thread.
http://www.videokarma.org/showpost.p...3&postcount=28

http://www.videokarma.org/showpost.p...1&postcount=32


There are also some white ceramic ones available like these guys that might hold up better: http://www.ebay.com/itm/10-ceramic-9...-/320962006659

The central ground post doesn't go through to the PCB though. Not sure if that matters.

Thanks! Now I'll be forever curious if these networks are working as well as the originals would have :scratch2:

I've not done anything with the couplates in my Predicta but I sure like how yours turned out. I could imagine my luck could change at some point....

Once you know everything's fine I do like the heatshrink method to protect/cover 'em with.

Great work with this set! It has been a great thread to follow. Cant wait to see it all done!

Congratulations Bob!

The replacement couplates that you designed seem to be a valid replacement after all. Nice work! I am suspecting bad couplates in my Eico 369 Sweep Generator which may be bad/out of tolerance as well. Maybe that is why your Eico 369 is a little out of whack also.

Good luck with the final tweaks in the Predicta!
Take Care,
Tom