A friend picked up this set last fall and I'm going to take a whack at restoring it. It's a 1958 Philco Predicta Holiday with 9L37 chassis. The cabinet has seen better days plus the channel knob and antenna are missing, but otherwise it looks OK.
Hopefully, the gunk on the screen will buff out.
http://farm8.staticflickr.com/7148/6427703995_e0c669c874_z.jpg (http://www.flickr.com/photos/70039806@N00/6427703995/) http://farm9.staticflickr.com/8447/7818153748_1a74b5b62d_z.jpg (http://www.flickr.com/photos/70039806@N00/7818153748/)


http://farm8.staticflickr.com/7139/7818043522_460c937918_z.jpg (http://www.flickr.com/photos/70039806@N00/7818043522/) http://farm9.staticflickr.com/8290/7818119206_ba32fc9fdc_z.jpg (http://www.flickr.com/photos/70039806@N00/7818119206/)

A few months ago I found a channel knob on ebay :)
The CRT has been replaced with a 6 volt version and it tests good. Not great, but good.
http://farm8.staticflickr.com/7008/6815172575_de63b03f6a_z.jpg (http://www.flickr.com/photos/70039806@N00/6815172575/) http://farm8.staticflickr.com/7144/6421144971_f1ecc616a9_z.jpg (http://www.flickr.com/photos/70039806@N00/6421144971/)

As for the chassis, the fuse resistor had exploded and the thermistor vaporized!
I think all of the components are original.
http://farm9.staticflickr.com/8430/7818048064_72e9ed37b1_z.jpg (http://www.flickr.com/photos/70039806@N00/7818048064/) http://farm9.staticflickr.com/8443/7818046610_db633e389c_z.jpg (http://www.flickr.com/photos/70039806@N00/7818046610/)

http://farm9.staticflickr.com/8437/7818039716_de0ab6267c_z.jpg (http://www.flickr.com/photos/70039806@N00/7818039716/)

I dove right in last night and pulled the main board. About half the wire wrap connections had been soldered which made it all the more fun to remove them.

One of the 7-pin sockets is damaged. Anyone know of a suitable replacement ?
http://farm9.staticflickr.com/8447/7818038126_e096b1bb8a_z.jpg (http://www.flickr.com/photos/70039806@N00/7818038126/) http://farm9.staticflickr.com/8425/7818049606_be39a90a0c_z.jpg (http://www.flickr.com/photos/70039806@N00/7818049606/)

I certainly will be tuning in for this resto.

:lurk:

Yeah me too, Bob you're a brave man for tackling one of these! :yes: At least with the Philco T&C you've been slightly seasoned to Philco's chassis design and layout!:D
Cheers Glen

Hey Bob! Can you snap a close up of the bad socket for me? I might be able to get an exact replacement for you.

Hi Mark. Does this help ? I'm sure it used to look like the one on the left before it broke apart.
http://farm8.staticflickr.com/7250/7819456090_39c095a7c7_c.jpg (http://www.flickr.com/photos/70039806@N00/7819456090/)

Yeah me too, Bob you're a brave man for tackling one of these! :yes: At least with the Philco T&C you've been slightly seasoned to Philco's chassis design and layout!:D
Cheers Glen

Yeah, the T&C was great practice. Those wirewrap posts are no longer intimidating. Good thing too - I have four more Predictas after this one :D

Yep, that helps a lot! I'll let you know asap if I find one, if I do it's NOS, not a used one.

Cool, thanks.
It turns out this set has had a few more repairs than I first realized. There's an extra electrolytic can under the chassis and a few other replacement parts scattered around.

I also found that in addition to the fusistor and thermistor all 3 sections of the filament dropping resistor as well as the pilot light are open. What the heck happened to this set ?!?
I figure one tap of this resistor was cut when the 6.3v CRT was installed.
http://farm9.staticflickr.com/8431/7818045108_1b20cb2e58_z.jpg (http://www.flickr.com/photos/70039806@N00/7818045108/)

That was the chassis that helped bankrupt Philco. Long time dealers dropped their products. They were such dogs.
IIRC, that was the only Philco that used the Zenith type gated beam audio detector.

I finished recapping the main board without any problems :)
Pulled the K4 network too as I've heard they are often faulty. The components to make a new one are in the foreground.
Maybe I should pull the K3 network too ?
http://farm9.staticflickr.com/8292/7841084234_8b6650af09_c.jpg (http://www.flickr.com/photos/70039806@N00/7841084234/)

Has anyone tried to make these networks plugable ? I'm thinking maybe reuse some PC board mount tube or transistor socket pins :scratch2:
http://farm9.staticflickr.com/8441/7841084822_f7b526ed6d_z.jpg (http://www.flickr.com/photos/70039806@N00/7841084822/)

While I ponder the K networks and search for a tube socket, I'm moving onto the chassis underside. One electrolytic and a bunch of power resistors were replaced at some point.
http://farm9.staticflickr.com/8445/7841086178_27b386e466_c.jpg (http://www.flickr.com/photos/70039806@N00/7841086178/)

One corner is finished so far. I've been using over spec resistors e.g. 2W for 1W and 3W for 2W.
http://farm8.staticflickr.com/7257/7841890236_8dd3a20d08_c.jpg (http://www.flickr.com/photos/70039806@N00/7841890236/)

I found one cap held in place by this nifty strap and was able to reuse it.
Very handy :yes: Anyone know where I can get more ?
http://farm8.staticflickr.com/7120/7841890818_ec483c3563_z.jpg (http://www.flickr.com/photos/70039806@N00/7841890818/) http://farm8.staticflickr.com/7258/7841891508_90c06efa67_z.jpg (http://www.flickr.com/photos/70039806@N00/7841891508/)

How about these?
http://www.ebay.com/itm/20-8-CABLE-WIRE-ZIP-TIES-W-SCREW-DOWN-HOLE-MOUNTING-RING-/140832817950?pt=US_Car_Audio_Video_Connectors_Term inals&hash=item20ca4a431e#ht_481wt_1185

OR

http://www.ebay.com/itm/100-Count-White-4-Mountable-Head-Nylon-Cable-Zip-Ties-GUARANTEED-IN-STOCK-/230838702365?pt=LH_DefaultDomain_0&hash=item35bf0f111d

Looks like a clean non-smoker chassis at least. The wires on my Predicta are a sticky, fragile mess that I contend with. That filament resistor is just horrible as mine was opened up/burnt at one spot as well as the leads being all covered with that green corrosion....

Those 12CA5 audio output tubes like to run hot and ruin sockets as you know!

Has anyone tried to make these networks plugable?Plugability seems low priority to me. If you build a new network, it may outlive everyone reading this post.

Phil Nelson

I was thinking it would be a nice way to test them before bothering to rebuild them.

I found one cap held in place by this nifty strap and was able to reuse it.
Very handy :yes: Anyone know where I can get more ?


We order them by the 100s at work. Let me know if you'd like some and I can ship em your way.

The only reliable test for those is how well they perform in the set, 'specially in regard to thermal stability during the heating/cooling cycle.

Home depot sells those straps. Called "Screw Mount Cable Ties". Look in the electrical aisle. You can get them in White or Black (UV Resistant).

We have those straps at work too, very handy but "Unauthentic" in a vintage TV. :D

Plugability seems low priority to me. If you build a new network, it may outlive everyone reading this post.

Phil Nelson

Those modern Micas and Metal Film? caps are probably good for a hundred years or so. :yes: Of course, that's what they thought about Sprague Bumblebees too.

We have those straps at work too, very handy but "Unauthentic" in a vintage TV. :D

True, but the original can cap is gone. Hmm, that reminds me I have a scrap Motorola TS-23 chassis with a very similar cap. Maybe I'll restuff that one for this set :scratch2:

Those modern Micas and Metal Film? caps are probably good for a hundred years or so. :yes: Of course, that's what they thought about Sprague Bumblebees too.

Sure, but I'm hoping I won't have to replace all of them. I have five Predictas to restore each with a few networks on the PCB. So I was thinking if I put some socket pins in on of the sets, I could test all the networks before bothering to replace them. Also gives me a way to test the reproduction networks easily.

Looks like a clean non-smoker chassis at least. The wires on my Predicta are a sticky, fragile mess that I contend with. That filament resistor is just horrible as mine was opened up/burnt at one spot as well as the leads being all covered with that green corrosion....

Those 12CA5 audio output tubes like to run hot and ruin sockets as you know!

The wires in this set were pretty sticky too. I cleaned them off with lacquer thinner as best I could. I wonder why they used a mix of cloth and plastic insulated wires :scratch2:

The nasty old filament resistor has been replaced :) These silicone coated Dale power resistors should hold up for a long time.
http://farm9.staticflickr.com/8425/7852882846_3a65248914_z.jpg (http://www.flickr.com/photos/70039806@N00/7852882846/)

I wonder why they used a mix of cloth and plastic insulated wires :scratch2:


Philco parts buyers probably found a deal on some NOS, or it was left over from an older model run. I really doubt they were worried about authenticity at the time. :D

Vendor components usually have plastic insulation. Philco parts and chassis wiring is usually cloth covered wire. Manufacturing Engineering called out the colors and sizes according to Philco practices.

Production wiring was cut and tinned weeks in advance by machine and placed on the line at the position where it was to be used. No one would have wasted time separating wires hoping to find some unused lengths for use on another product. Even tubes and parts that dropped on the floor were not salvaged. They were continuously swept up and discarded.

At the end of a production run, unused material was discarded by the ton.

Don

Thanks, Don. Pretty interesting to hear it from someone that experienced how it all played out. Sort of like having our own Philco time machine here on VK. :thmbsp:

Yes, thanks for the info Don. I see now that the main chassis wiring like for the AC line is cloth while the wiring harness for the tuner and control cluster is plastic.

I finished with replacing the paper caps and moved on to restuffing the electrolytics.
http://farm9.staticflickr.com/8308/7882341510_07a0f46f93_c.jpg (http://www.flickr.com/photos/70039806@N00/7882341510/)

If you still need the tube socket, Surplus Sales of Nebraska has some very similar to the originals.

http://www.surplussales.com/Tube-Sockets/TubeSkts-2.html

Thanks. I'll pick some up.

I managed to arrange the new caps so they'll just fit in the old cans.
http://farm9.staticflickr.com/8439/7895877988_0853cefde7_c.jpg (http://www.flickr.com/photos/70039806@N00/7895877988/)

Nice work Bob,

i see some Low ESR caps in that lot, i am assuming all of the caps are 105 degree caps.

Looking forward to another progress video for this set.

Matt

Thanks. Yes, they are all 105C rated caps :)

The replacements tube sockets from Surplus Sales of Nebraska have arrived and are identical to the originals :)
http://farm9.staticflickr.com/8316/7947113638_78f3c5bd8c_z.jpg (http://www.flickr.com/photos/70039806@N00/7947113638/)

The replacements tube sockets from Surplus Sales of Nebraska have arrived and are identical to the originals :)


Cool, are you replacing them all?

Oh no. Just the 7-pin socket that broke in the upper left obscured by my hand. I have four more Predicta sets to restore though and they have some damaged sockets too so I stocked up.

How long has the restoration took?

The first post is dated Aug. 19th so it's been about 3 weeks so far.

I popped out the K6 network to do a little testing. It's tough to do because of the internal parallel and series combinations, but I here's what I found.

There's a 47K and 4.7K in series between pins one and 2 for a total of 51.7K. I measured 70.7K.
http://farm9.staticflickr.com/8037/7961018144_786280e91a_z.jpg (http://www.flickr.com/photos/70039806@N00/7961018144/)

Between pins 2 and 7 I should have 3300pF but measured around 4300pF.
http://farm9.staticflickr.com/8301/7961018634_e35541c18f_z.jpg (http://www.flickr.com/photos/70039806@N00/7961018634/)

Seems to me those are pretty far off and I should replace this network. I'll pop out K2 next and see how it measures up.

The other networks showed similar results so I decided to just replace them all. I was curious about the internal construction and dissected a couple. The resistors are just carbon powder and the caps look like ceramic cylinders.

I rebuilt the K4 network using plastic caps and metal film resistors on a little perf board. The 0.0015 uF cap is rated for 2,000 volts like the one next to it on the main board.

Parts for the other neworks will arrive in a couple days.
http://farm9.staticflickr.com/8437/7978028160_f6afc5a696_c.jpg (http://www.flickr.com/photos/70039806@N00/7978028160/)

That's looking great Bob,
You are making me want to eventually try a predicta but I will need to work up to it with some easier sets first, that I have in the wings.
I like how the networks are looking on the board.
I have my eye on one that is within driving distance if I win the auction, but I would never have one shipped.
If I win it will have to be on display for a little while until I get up the nerve to give it a go.
Tom

I like the solution to the networks, since you could not do what you did on the T&C. Looking forward to more updates as always!

I ordered my parts from Mouser as usual, but made a mistake when choosing shipping options. I usually choose FedEx Ground if I'm in a hurry (2 days) or US Post Office (3-4 days) if I can wait a bit.

This time I choose a new option - a rather generic "Standard Shipping". When I received a shipping confirmation, it turned out to be UPS. I later did a package track with UPS and discovered they had farmed it out to the Post Office with an ETA of 10-14 days!?!

If I had just chosen the Post Office in the first place, I probably would have received my parts by now. Instead, I'll be lucky to get them next week :(

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/8317/7984819119_1d44c62cd6_c.jpg (http://www.flickr.com/photos/70039806@N00/7984819119/)

Also, the germanium power rectifier module has been replaced with a terminal strip and two 1N4007 silicon rectifiers.
http://farm9.staticflickr.com/8038/7984815219_55014abc51_c.jpg (http://www.flickr.com/photos/70039806@N00/7984815219/)

There's a 47K and 4.7K in series between pins one and 2 for a total of 51.7K. I measured 70.7K.

Between pins 2 and 7 I should have 3300pF but measured around 4300pF.

Seems to me those are pretty far off and I should replace this network. I'll pop out K2 next and see how it measures up.

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/8436/8005554306_bf948b69e3_c.jpg (http://www.flickr.com/photos/70039806@N00/8005554306/)

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/8457/8008455553_b0671a18f3_c.jpg (http://www.flickr.com/photos/70039806@N00/8008455553/)

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/8180/8008460942_3fbd471f25_c.jpg (http://www.flickr.com/photos/70039806@N00/8008460942/)

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/8040/8014644717_f5fe58d23d_c.jpg (http://www.flickr.com/photos/70039806@N00/8014644717/)

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/8318/8014644447_f140a2cf26_c.jpg (http://www.flickr.com/photos/70039806@N00/8014644447/)

I wonder why the 15 ohm resistor has been shorted out :scratch2:
http://farm9.staticflickr.com/8437/8014645920_678c127eed_c.jpg (http://www.flickr.com/photos/70039806@N00/8014645920/)


It's R72 on the schematic.
http://farm9.staticflickr.com/8301/8014646724_002f420fa5_c.jpg (http://www.flickr.com/photos/70039806@N00/8014646724/)

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/8461/8022460552_9c607f2a95_c.jpg (http://www.flickr.com/photos/70039806@N00/8022460552/)

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/8310/8022560342_e6fa2db835_c.jpg (http://www.flickr.com/photos/70039806@N00/8022560342/)

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 (http://www.ametherm.com/) 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-detail/en/SL03%2022101/570-1087-ND/1873490?cur=USD

2 Amp max, 0.9 ohm hot
http://www.digikey.com/product-detail/en/SL15%2022102/570-1073-ND/1873476?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/8036/8024698699_b78805eb4c_c.jpg (http://www.flickr.com/photos/70039806@N00/8024698699/)

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/8029/8024699125_9a3d05ff3d_c.jpg (http://www.flickr.com/photos/70039806@N00/8024699125/)

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/8322/8024952042_00d57e2eec_c.jpg (http://www.flickr.com/photos/70039806@N00/8024952042/)

Ugh, another broken socket pin.
http://farm9.staticflickr.com/8037/8025447386_360d9f3d9a_c.jpg (http://www.flickr.com/photos/70039806@N00/8025447386/)

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/8039/8025445707_d0fedc4d2a_c.jpg (http://www.flickr.com/photos/70039806@N00/8025445707/)


http://farm9.staticflickr.com/8175/8025458618_3b538046c8_c.jpg (http://www.flickr.com/photos/70039806@N00/8025458618/)

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:

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 .

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:

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

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

They're identical to the originals.

Check out these two earlier posts in this thread.
http://www.videokarma.org/showpost.php?p=3046263&postcount=28

http://www.videokarma.org/showpost.php?p=3047121&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-9pin-B9A-PCB-MOUNT-vacuum-tube-socket-FOR-12AX7-12AT7-12AU7-ECC83-6DJ-/320962006659

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

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

-Clark

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

Thanks. I do have vertical jitters so my K networks may need a little tweaking. That or something else is not quite right. I'm in the process of checking all the voltages and waveforms.

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.


They do kind of look like they're built out of Saltine Crackers. :yes:

Hi Bob,

I'm reading your post with interest, as I have a Holiday that I'll start working on as time permits. I'm also working on a Debutante and Princess just to punish myself!

With regards to those tube sockets, where does the break occur exactly? It's a bit hard to see, even on your close ups. The boards are out of my 17in TVs at the moment, so I'd like to know what I'm looking for in terms of broken sockets BEFORE I solder the boards back in.

Of course I'll be testing the boards first, but if any of my sockets look suss, I'll replace them.

I'd LOVE to get a Tandem, but I have to be welll cashed up to get one of these. They go for a lot, and then I have to add around $700.00 freight just to get it to Australia!
:(

But thanks for your continued posts, I always find them interesting!

Checkout this post: http://www.antiqueradios.com/forums/viewtopic.php?f=3&t=176131

I just happen to have two Tandem sets and will likely sell one off. I'd like to get them both working before I make a decision though.

I'll also be restoring a Princess and Siesta model along with the Tandems.

I pulled the main PCB again which actually wasn't bad to do now that I've got the hang of it.
Getting the old sockets out isn't quite so easy though. I ended up cracking the old brittle plastic and removing the pins one at a time.

I had thought the replacements were identical to the originals, but I was wrong. The replacements are made from heavier gauge metal and are twice as wide where the old ones broke. They should hold up very well :)
http://farm9.staticflickr.com/8177/8033036228_88fed0d6e0_c.jpg (http://www.flickr.com/photos/70039806@N00/8033036228/)

Moving on to the cabinet. Structurally it's fine, but the photo finish is badly flaking off around the CRT base.
http://farm9.staticflickr.com/8317/8031817379_97d1a764c3_c.jpg (http://www.flickr.com/photos/70039806@N00/8031817379/)

Perhaps some real veneer is the easiest way to go :scratch2:
http://farm9.staticflickr.com/8037/8031815332_c5e1f98e67_c.jpg (http://www.flickr.com/photos/70039806@N00/8031815332/)

I really need to get on here more! First time I've logged in for months and I see this great restoration. First time I did one of these sets I absolutely hated it, several more later it's not so bad.

I think the wood veneer (teak?) will look really good. Just be prepared to spend a lot of time cutting around all those lines!

That's real mahogany veneer. I might just veneer that bad center section to avoid having to cut out all the pieces. On the other hand it might stand out if I do that.

I'll also be restoring a Princess and Siesta model along with the Tandems.

A real glutton for punishment, I love it!

I love the tandems, especially the mahogany ones.

Thanks for that link to ARF, I can see where the sockets fail now. Looks like a job for my magnifier lamp!

Now that I've experienced the heat put out by the 3-section filament dropping resistor, I've been thinking how it could be eliminated.

I crunched the numbers and came up with about 97 volts consumed by the tubes including a 6.3 VAC replacement picture tube. If I assume 125 VAC at the plug, a 20uF AC capacitor would do the trick.

However, those two taps are there for light bulbs that illuminate the VHF and optional UHF channel knobs. I did a little research and found there are 130 VAC white LEDs available in a BA9S base.
They're a bit harsh compared to the yellowy incandescent blub, but work fine.

I figure I'll give it a try and if I don't like the results it's easily reversible.

http://farm9.staticflickr.com/8032/8045108001_b6d43713c6_c.jpg (http://www.flickr.com/photos/70039806@N00/8045108001/)

Hi Bob,

those LEDs are a great find. If you're concerned about the bluish colour, you could perhaps try some transparent paint. Craft and hobby shops usually sell this stuff designed for glass to achieve the fake leadlight look.

Too much paint and the thing will go yellow, but a few carefully and evenly placed stripes on the LED with an artists brush should do the trick, especially if there is a light diffuser in front. If not, you could always paint the back of the channel selector knob with a frosted paint, but I'm sure there are better options.

That should give you that nice, warm look.

Cheers,

Adam

I like the LED and dropping cap solution. The less heat we have radiating on the inside of these beasts the better!

No more 'saltine cracker' K networks :)

First some epoxy.
http://farm9.staticflickr.com/8461/8051394893_6e44e49253_z.jpg (http://www.flickr.com/photos/70039806@N00/8051394893/)

Then some paint.
http://farm9.staticflickr.com/8171/8052615200_b96a86bbe5_z.jpg (http://www.flickr.com/photos/70039806@N00/8052615200/)

The satin was a bit too shiny so I switched to Rusty metal Primer. Much better :yes:
http://farm9.staticflickr.com/8036/8055341155_8de6054ccb_z.jpg (http://www.flickr.com/photos/70039806@N00/8055341155/)

OOOOOOOhhh caramels :)

SR

Great work!

Very nice. Those will blend in much better than the bareback kind I have made before.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Thanks! I was half expecting you guys to say I was wasting my time on details no one would ever see ;)

Bob, that's what made the difference! That is a great idea. Now, you need to ink-stamp them with some numbers etc. ;). Seriously, that did make the difference. Just like cleaning wires so that the original color jumps out at you!

NAAAHHH

Invent you own logo and stamp those works of ART :D

SR

LOL - maybe I will

My earlier dissection showed the resistors in the original networks were carbon comp, but what about the capacitors?

Here's a closeup of a network without the opaque coating.

This side shows the values.
http://farm9.staticflickr.com/8454/8057590443_c9f15fec79_z.jpg (http://www.flickr.com/photos/70039806@N00/8057590443/)

While this side shows the components. I looks to me like the caps are made from ceramic cylinders dipped in a conductive coating. The more coating it has, the larger the value.

That's what led me to try using NP0/C0G ceramic caps which seem to work just fine :)
http://farm9.staticflickr.com/8178/8057590216_783dbba9e3_z.jpg (http://www.flickr.com/photos/70039806@N00/8057590216/)

I coated the flyback with some RTV133. It comes out of the tube as a thin paste and is easy to spread on.

Not exactly a thing of beauty, but should do the trick.
http://farm9.staticflickr.com/8453/8063964674_e0e92c7abb_c.jpg (http://www.flickr.com/photos/70039806@N00/8063964674/)

Nice job on the networks. Thoughts on flybacks

a member here did an interesting video on boiling out a flyback in molten wax, with a vacuum pulled to get all the air out. Based on the video it would seem that moisture is part of the problem, getting into the insulting strips of paper in the HV doughnut. My concern would be if there was excessive humidity and then the RTV seals it in.

I have often though of boiling in hot medium (oil or wax) under a vacuum, then building a dam around the flyback and sealing in a compatible potting compound.

this would of course require removing the fly from the mount, removing the core, blocking the core hole to prevent the compound from fouling that.

A lot of work for sure, but seems like the ultimate fix.

Based on the video it would seem that moisture is part of the problem, getting into the insulting strips of paper in the HV doughnut.


Who is the paper insulting?:D

Yes, I've seen that cool video. This flyback wasn't that bad though. Just some shallow surface cracks. It's also been rather dry lately and I've have the set running a while so I'm hoping moisture won't be an issue.

Here it is before the RTV.
http://farm9.staticflickr.com/8318/8014644447_f140a2cf26.jpg (http://www.flickr.com/photos/70039806@N00/8014644447/)

I've been having fun with the dead power switch tonight. I was able to get it apart and clean it up so it makes good contact, but the latching mechanism just isn't working right.

After a couple clicks, it stops working :( The contacts are also pretty worn down so even if I did get it working I don't think it would last long.

I've read that replacements are impossible to find. It's label "CTS Type J" on the bottom. Any ideas ?

I'll go looking through my old junk control box and see what I can find.

http://farm9.staticflickr.com/8052/8075410613_470e296945_c.jpg (http://www.flickr.com/photos/70039806@N00/8075410613/)

Bob: look at Lowe's or = and get a push on / push off canopy switch, used in a lot of light fixtures. You should be able to rig that behind the control pretty easily.

I found this push on/off switch at Menards. The throw is just about the same as the old one. I also sorta got the original switch working and got a tip about some NOS replacement switches. I try them all and go with whatever works best.

http://farm9.staticflickr.com/8048/8078595226_bf544d6044_z.jpg (http://www.flickr.com/photos/70039806@N00/8078595226/)

http://www.flickr.com/photos/70039806@N00/8057590443/

(picture of the back side of a module, with circuit board style traces with values printed on, seen in post #100)
One could get some of the larger surface mount resistors and mount them between those traces. And if the voltage requirements and tolerances are reasonable and compatible with surface mount capacitors, those too.

Yes, I bet surface mount parts would work fine.

After replacing the bad tube sockets and re-installing the painted replica K-networks, I did a bit of rust removal and re-assembled the set. I'm happy to say, it's still working :) Next up, I'm going to tinker with using a capacitor in place of the series filament dropping resistor.
http://farm9.staticflickr.com/8469/8098040355_6acf3524c6_c.jpg (http://www.flickr.com/photos/70039806@N00/8098040355/)

http://farm9.staticflickr.com/8329/8098040825_d364076acc_c.jpg (http://www.flickr.com/photos/70039806@N00/8098040825/)

Next up, I'm going to tinker with using a capacitor in place of the series filament dropping resistor.


At my web page http://pw2.netcom.com/~wa2ise/radios/compaa3.html#hcap I have a DOS program http://pw2.netcom.com/~wa2ise/hv.exe and an Excel spreadsheet http://pw2.netcom.com/~wa2ise/heater.xls for calculating the capacitor.

Thanks. I plugged in 125VAC @ 60Hz with a heater of 97 VAC @ 600mA and came up with about 20uF. Note that's with a replacement 6.3 VAC picture tube rather than the original 2.35 VAC one.

Success! I installed the Ametherm thermistor and a 20uF motor run cap. The power up surge current was about 870mA which quickly settled down to slightly under 600mA. That should help extend the life of the tubes and eliminated about 13 watts of waste heat. More importantly the set is still working fine.

I'll pop the plastic screen cover off and see if I can clean it up a bit.
http://farm9.staticflickr.com/8049/8098760172_e003968838_c.jpg (http://www.flickr.com/photos/70039806@N00/8098760172/)

This is definitely the most extensive electronic restoration on a Predicta I've ever seen. Great work!!

Thanks! I figure if I explore all possibilities on this set, other Predictas will be a piece of cake.

The NOS power switch I ordered arrived today. Looks like a perfect match other than the color.
http://farm9.staticflickr.com/8333/8101592926_cd05a3fecb_c.jpg (http://www.flickr.com/photos/70039806@N00/8101592926/)

What's this 1.5M resistor doing on the contrast pot ? The schematic shows a 1M pot with no resistor.
I lifted one end and measured about 2.3M on the pot. Ah, that was put in parallel to drop it down closer to 1M. The pot has a Philco part # and looks original. Could they have fudged it in the factory :scratch2:
http://farm9.staticflickr.com/8048/8101594286_6d8d274aff_c.jpg (http://www.flickr.com/photos/70039806@N00/8101594286/)

I carefully bent back the metal tabs and swapped in the switch. It's working fine :)
http://farm9.staticflickr.com/8331/8101599442_e3d897c8c4_c.jpg (http://www.flickr.com/photos/70039806@N00/8101599442/)

Nice work, and pictures.

Those rusty primer modules turned out great :yes:

I took ownership of a pedestal Predicta last weekend, with I believe the same chassis as the set you're working on. Never thought I'd own one of these weird looking TV's, but apparently nobody else around here likes blonde things. :D

That switch looks like a perfect fit. Where did you get it?

Phil Nelson

There's even a current production of that switch available, but it looks like the mounting tabs have been changed. May still work if you swap out the complete pot cover? But you need to buy the complete pot to get the switch.

http://www.newsensor.com/ProductHighLight.aspx?ProId=826

Those rusty primer modules turned out great :yes:

I took ownership of a pedestal Predicta last weekend, with I believe the same chassis as the set you're working on. Never thought I'd own one of these weird looking TV's, but apparently nobody else around here likes blonde things. :D

Thanks. Nice score and, yes, I believe it is the same chassis. Phil restored one of those a while back. (http://antiqueradio.org/philc12.htm)

That switch looks like a perfect fit. Where did you get it?

Phil Nelson

ETF classifieds (http://www.earlytelevision.org/classifieds_parts_for_sale.html)

There's even a current production of that switch available, but it looks like the mounting tabs have been changed. May still work if you swap out the complete pot cover? But you need to buy the complete pot to get the switch.

http://www.newsensor.com/ProductHighLight.aspx?ProId=826

I found a closeup on another site. They do look promising.
http://ep.yimg.com/ca/I/torresengineering_2230_7257543


With the power resistors out of the way, I found a good spot to mount the filament cap and wired it in along with the 120 VAC LED pilot light.

I better stick a note inside the set to explain my changes or some poor future tech will be mighty confused ;)

That wraps up the electrical restoration so I'll move on to cosmetic issues.
http://farm9.staticflickr.com/8190/8103646735_4c4b87fb21_z.jpg (http://www.flickr.com/photos/70039806@N00/8103646735/) http://farm9.staticflickr.com/8336/8103661360_6ecc60dc8f_z.jpg (http://www.flickr.com/photos/70039806@N00/8103661360/)

I have a few of those newer ones for guitar amp work, so I opened one up. Actuator look the same? They're stamped CTS Made in ROC.

Hmm. No, not really. The Predicta shaft is hollow and fits over a piece of metal protruding from the switch. These still might work though.

Now that you've put the RTV on the flyback this may be a moot point for this particular discussion, but what does the jury say about using the High Voltage Corona Dope that comes in the jar with the little brush? I've never tried it to completely recover a flyback, but it works great for insulating other sensitive points in the HV cage. Why not recoat a fly with that?

I've used dope to touch up a few hotspots on flybacks with good results. It might not work so well on the whole donut and over the remains of the old coating though. The RTV is very tough and flexible while the dope it hard and brittle.

Hmm. No, not really. The Predicta shaft is hollow and fits over a piece of metal protruding form the switch. These still might work though.

Figures with that concentric shaft setup. Mine aren't the exact same as the the ones I linked to earlier. Mine are possibly a 20 year old OEM part with a plastic shaft. Anyhoo...

Did anyone ever use that tool handle insulating dip for covering a flyback or other parts? Should be able to brush it on.

Not sure if it would have the required dielectric properties.

Rather than tool dip, liquid tape might do it. Available in spray or brush on. They say:

"Liquid Tape has the strongest dielectric protection on the market; 1,200 v/mil, 5 – 7 mils per coat."

They recommend applying several coats.

Bob, did you see this on the Early TV website?

I have a number of the Push-Push Off-On switches for Predicta televisions. These are new old stock and are $19.99 plus $5.20 Priority Mail. I take Pay Pal. Don, dpatterson002 at comcast dot net. (1/18/12)

Bob, did you see this on the Early TV website?

I have a number of the Push-Push Off-On switches for Predicta televisions. These are new old stock and are $19.99 plus $5.20 Priority Mail. I take Pay Pal. Don, dpatterson002 at comcast dot net. (1/18/12)

Yes, that's where I got my switch :)

I've been working on the screen this weekend. There were some gouges in the plastic but wet sanding has mostly gotten them out.
http://farm9.staticflickr.com/8327/8109720944_97fc3956fe_c.jpg (http://www.flickr.com/photos/70039806@N00/8109720944/)

A bit more buffing and I'll call it done.
http://farm9.staticflickr.com/8465/8109749098_c9547e1398_c.jpg (http://www.flickr.com/photos/70039806@N00/8109749098/)

The CRT sure was dirty :yuck:
http://farm9.staticflickr.com/8049/8109711423_92eddcd58d_c.jpg (http://www.flickr.com/photos/70039806@N00/8109711423/)

Wow, is it supposed to be that yellow-green?

Yes, it is. The later models like the Princess used a different kind of plastic that is clearer, harder and doesn't stink.
http://farm3.staticflickr.com/2669/4168230384_b941468ff8_z.jpg (http://www.flickr.com/photos/70039806@N00/4168230384/)

I KNOW that stink! I brought it all the way over to Australia!

A mixture of well worn athlete's runners, parmesan cheese, BO and goat vomit!
Fantastic job on the polishing, hope mine comes out like that when the time comes. Does the stink become less when you clean it? I've heard that it does. Looking at the cloth you used to clean the face of the tube, I wonder how many brighteners may have been fitted over the years that needn't have?

Looks great, curious what you used to wet sand it with? ie. grit and what you wet it with, just water? I have a GE portable with a plastic screen that has gouges I need to sand out too.

I KNOW that stink! I brought it all the way over to Australia!

A mixture of well worn athlete's runners, parmesan cheese, BO and goat vomit!
Fantastic job on the polishing, hope mine comes out like that when the time comes. Does the stink become less when you clean it? I've heard that it does. Looking at the cloth you used to clean the face of the tube, I wonder how many brighteners may have been fitted over the years that needn't have?

Yes, the stink is reduced with a good cleaning, but it's does creep back - especially on warm, humid days. Yes, it was quite dirty and I'm hoping it wil be noticeably brighter once back together.

Looks great, curious what you used to wet sand it with? ie. grit and what you wet it with, just water? I have a GE portable with a plastic screen that has gouges I need to sand out too.

Thanks. 320, 600, 1000, 1500 then Novus #3 and #2. Yes, I just used water.

Bob, I didn't realize that apparently the on-off switch on my new Philco set had at some point in the past been changed to a push-pull type, so I made the false assumption that your switch was the same type. The switch I posted the link to is a push-pull. Didn't realize yours had a push-push until I watched your last video. :o

Bob,

I usually hang out in the vintage color section, but while perusing the B&W came across your Predicta restoration site. I was hooked and read it start to finish. Great photos and step by step progress reports. Looking forward to seeing the finished set with your choice of cabinet restoration.

Thanks for sharing,
-Steve D.

Bob, I didn't realize that apparently the on-off switch on my new Philco set had at some point in the past been changed to a push-pull type, so I made the false assumption that your switch was the same type. The switch I posted the link to is a push-pull. Didn't realize yours had a push-push until I watched your last video. :o

Hey, if it works, I don't see any problem with using a push-pull switch.

Bob,

I usually hang out in the vintage color section, but while perusing the B&W came across your Predictor restoration site. I was hooked and read it start to finish. Great photos and step by step progress reports. Looking forward to seeing the finished set with your choice of cabinet restoration.

Thanks for sharing,
-Steve D.


You're welcome. It's taken some twists and turns I didn't expect. As for the cabinet, I'm on the fence about using veneer or Di-NOC (http://www.tiptopsigns.com/3M-Di-NOC-Mahogany-Dark-Wood-Grain-Wrap-Vinyl-p-3464.html).

Here's a shot with the safety plastic removed. That's quite a difference! It reminds me of the Hoffman "Easy Vision" safety glass.

http://farm9.staticflickr.com/8043/8126846278_68901c0663_z.jpg (http://www.flickr.com/photos/70039806@N00/8126846278/) http://farm9.staticflickr.com/8049/8098760172_e003968838_z.jpg (http://www.flickr.com/photos/70039806@N00/8098760172/)

I wonder if they were that green when new or if time has taken a toll?
Also the 17" sets have a clear screen so that would indicate they didn't intend for the 21" models to be green but the type of plastic may deteriorate with time.

It has to be harder on the CRT as well having to be cranked up to compensate for the darkness of the cover.

The Hoffman is a little greener but also a lot clearer because it's actual glass and not 50 year old plastic, though there is a lamination layer.

http://www.vintagetvsets.com/images/bee2.jpg

Your cover is much greener than the one on my 21" barberpole. It sits about three feet away from my 17" Siesta and I just turned them both on for a comparison.

Now that I'm looking for it, I guess the 21" screen appears very slightly green next to the 17" set, but I have played the TVs together many times and that never occurred to me.

That cover has also been less stinky than what some people report. Until I read about it in forums, I hadn't noticed any smell at all. Perhaps the two are related (more stink = darker green).

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

This comment not related to tint but directed toward focus of the picture:

Both the 21" and the 17" models have a focus "jumper". Usually one position is superior to the other, so try it in both.

... Perhaps the two are related (more stink = darker green).
http://antiqueradio.org/index.html

LOL - could be. I'll see how it compares to my Tandem sets.

This comment not related to tint but directed toward focus of the picture:

Both the 21" and the 17" models have a focus "jumper". Usually one position is superior to the other, so try it in both.

I tried both positions are barely noticed any difference. I've observed that in other sets too :scratch2:

I received a sample of Mahogany Di-Noc today. I think it looks great and plan on using it. it sure will save time versus using real veneer and having to glue, fill stain and finish it.

It's not quite the same color as the old finish though. So I'm pondering if I can get away with just coating the damaged center section or should I redo all the photo finish areas :scratch2:

http://farm9.staticflickr.com/8466/8130023831_6bb31fd95d_c.jpg (http://www.flickr.com/photos/70039806@N00/8130023831/)

From the picture it looks enough different in color that you'd probably wish you had done the whole set, if you only did the middle.

Yeah, I agree. I'm currently leaning towards trying to replicate the photo finish using these techniques (http://www.radioatticarchives.com/features/schooley_photo-finish.htm). It won't cost much to give it a shot.

Meanwhile, I've moved on to cleaning the CRT housing.
http://farm9.staticflickr.com/8185/8149270301_1bcf86f2fc_c.jpg (http://www.flickr.com/photos/70039806@N00/8149270301/)

Years of cigarette nicotine attracted by the HV I bet :yuck: It cleaned out easily with some "Spray Nine" my new favorite multi-purpose cleaner.
http://farm9.staticflickr.com/8326/8149270525_c4bfdff2c0_c.jpg (http://www.flickr.com/photos/70039806@N00/8149270525/)

The CRT inside is a genuine Philco replacement 21FDP4.
http://farm9.staticflickr.com/8472/8149269835_94a1ca4594_c.jpg (http://www.flickr.com/photos/70039806@N00/8149269835/)

http://farm9.staticflickr.com/8196/8149300332_302d7b419e_c.jpg (http://www.flickr.com/photos/70039806@N00/8149300332/)

http://farm9.staticflickr.com/8474/8149269649_c3e29b37c1_c.jpg (http://www.flickr.com/photos/70039806@N00/8149269649/)

Most of my sets have that nicotine film on them when I get them. I suppose we are all used to it. I am amazed when one doesnt have it. My Predicta and my Admiral had none. And both are in super nice shape. I really think they spent their lives in one house and obviously no smokers. I sure have enjoyed this thread.

You may want to look up "retrobrite" online.

From what I can see, this stuff is ideal for our vintage projects.

You can't buy it, you simply make it yourself. There are recipes and it looks pretty easy. In the instance of the CRT case on a Predicta, I'd try some on the inside first in case it takes the colour back too far.

It consists of hydrogen peroxide and a few other things. When time permits, I want to try it out and I think it'll remove that faded yellow/brown colour.

I'd love to hear if anyone has already tried this!

It's really not necessary on this set. The color of the case is correct and the gunk on the inside cleaned right off.

I have read about using similar products on vintage computers and gaming consoles with mixed results.

That brown color is correct for the Predicta, the discoloration on newer stuff is caused by the Fire Retardant additives according to what I read, probably not an issue in 1959.

I see a lot of newer Plastic sets that have discolored though, especially if they are White or Pink to start with.

It's really not necessary on this set. The color of the case is correct and the gunk on the inside cleaned right off.

Great news!! :D

I regularly look for Tandems on ePay, and it's interesting to note that the CRT case seems to show in a range of shades on the various Predictas that show up. I can't tell if it's the white balance setting on the camera, or if the plastic goes darker over time.

I too have read about the flame retarding chemicals in plastic going browny yellow. Does anyone know if the green area at the front edge of the screen should be tan in colour? Mine is green and it looks OK.

Catchya,

Adam

Great news!! :D

I regularly look for Tandems on ePay, and it's interesting to note that the CRT case seems to show in a range of shades on the various Predictas that show up. I can't tell if it's the white balance setting on the camera, or if the plastic goes darker over time.

I too have read about the flame retarding chemicals in plastic going browny yellow. Does anyone know if the green area at the front edge of the screen should be tan in colour? Mine is green and it looks OK.

Catchya,

Adam


I suspect it's the camera and lighting. All the Predicta CRT cases I've seen in person (including four Tandems) are pretty much the same color. You mean the border around the picture tube ? It's definitely greenish :yes:

http://farm4.staticflickr.com/3429/3314746405_529d86594a.jpg (http://www.flickr.com/photos/70039806@N00/3314746405/) http://farm8.staticflickr.com/7114/7024737283_f2082822b2.jpg (http://www.flickr.com/photos/70039806@N00/7024737283/)

[QUOTE It's definitely greenish [/QUOTE]

Ah! That's exactly how mine looks. I like it actually, I think it looks better than a tan border would. I only hope when I get time to look at my Holiday, the tube has some life in it.
I LOVE your Tandem!

I decided to give this veneer a try. It's real mahogany sliced very, very thin with a paper backer.

I've got about 10 feet on ebay for 12 bucks so plenty to experiment with. First I'll try a test with red mahogany stain.

http://farm9.staticflickr.com/8350/8173811682_51e7b68133_c.jpg (http://www.flickr.com/photos/70039806@N00/8173811682/)

I think I am posting about the right set.

Been thinking about your restoration in the...
Predicta "Holiday" restoration p13o?

http://www.youtube.com/watch?v=UlHtGky46r4

at about 16:05 the LED Back light was staying lit for quite a while.

I believe if you connect the high side (ungrounded) lead of the LED to the high side of the filament string it would stop the strange behavior.

My theory is that since LED lighting will stay lit with only 3.2v across them at
a very low current, the capacitor is holding enough charge to cause the LED to stay lit until the charge is depleted.

If you relocate the lead to the (top) of the filament string the resistance of the tubes will drain the charge at that point almost immediately, so the LED will extinguish almost immediately.

The voltage at this point is AC and there is no DC path back to the filter capacitors.

Have a good day...
Love your restoration videos...

rrrhre2s

Thanks, yes, this is the same set. I'll give that a try next time I get it up on the workbench.

I did some searching on the web and discovered Ametherm (http://www.ametherm.com/) 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-detail/en/SL03%2022101/570-1087-ND/1873490?cur=USD

2 Amp max, 0.9 ohm hot
http://www.digikey.com/product-detail/en/SL15%2022102/570-1073-ND/1873476?cur=USD

Been using this thread as a guide for quite a bit here, thanks for being so in depth on this Bob :)

Which one did you end up using? I'm assuming it replaces the circled part in the diagram.

Also, the disc cap that's just below that, in the Sams it lists it as C47, having a value of 82 @ 5 kV. I assume that's 82 PF?

I used two of the 1 Amp max versions in series to best approximate the 400 ohm original.
The steady state resistance of these devices depend on the current through them. Running only 0.6A through the 2A version would result in a fairly high "hot" resistance.

Yes, 82pF. I left all the original ceramic caps in place.

Just about ready to plug in the variac and give my Predicta a first go. The only thing I can't find nor figure out is.....while attaching the picture tube, there are two single long leads.....one of which goes to pin 2 on the picture tube, the other goes to pin 6.

I can't see where the heck they're supposed to plug into the chassis. Anyone know offhand?

I believe pin 2 is the video which goes to a post on the main board. Pin 6 is focus which goes to either ground or boost - which ever gives better focus.

Any idea of *where* on the board these go? I can't find any info on it anywhere.....and there are a lot of posts on the main board.....

The one that doesn't have any wire wrapped around it.

I believe that I found pin 6's connection to chassis, please confirm that I'm correct here:

http://antiqueradio.org/art/predicta16.jpg

Now, just have to figure out where the other wire goes. I swear that I noted this somewhere, but the set's been apart for two months now, and I can't find anything I might have written.

I think you have the CRT pin numbering off a little. Pins 2&6 are connected internally to the focus element. Pin 7 is the cathode which connects to the video output.

Page 17 of the Sams Photofact shows how the wires connect to the main board. That's what they call "CircuiTrace Numbers". #20 goes to the cathode of the CRT (pin 7 not 6). That's what you have labelled as "CRT lead"

The last wire should end in a spade terminal. There are two possible places for it to connect on a little terminal strip in the center of the chassis. If all else fails, you can just leave it disconnected. The CRT may be a little out of focus but will work.

I found the wire, finally. It came unsoldered from one of the chassis plugs.......d'oh.

Now that the weather is FINALLY warmer, I started work on the cabinet.

I found the thermistor disc while cleaning out the cabinet. I wonder how many sets were retired because the disc fell out ?
https://farm8.staticflickr.com/7121/13944948603_a2b27e7a7a_z.jpg (https://flic.kr/p/nfgvok)

The sides and front are in pretty good shape.
https://farm3.staticflickr.com/2920/13944950343_ba3f344893_c.jpg (https://flic.kr/p/nfgvUk)

I figure they used a metal mesh bottom for ventilation.
https://farm3.staticflickr.com/2916/13944951093_f6b69bda0a_c.jpg (https://flic.kr/p/nfgw8g)

I'll try to touch up all the nicks and dings.
https://farm4.staticflickr.com/3701/13921794772_e1a349c1bf_c.jpg (https://flic.kr/p/nddQym)

Legs and bottom removed.
It may looks like real mahogany, but I'm pretty sure it's poplar painted red.
https://farm8.staticflickr.com/7424/13921795392_d185d93dae_c.jpg (https://flic.kr/p/nddQK3)

Fully disassembled cabinet. I made an attempt to touch up the large area of finish loss on top, but it looks terrible.
https://farm3.staticflickr.com/2926/13945353264_fd4abd49ba_c.jpg (https://flic.kr/p/nfizFf)

So off it comes. Much was scrapped off and liquid stripped used in the stubborn areas.
https://farm4.staticflickr.com/3720/13921797361_ac5b1b065f_c.jpg (https://flic.kr/p/nddRjZ)

New paper veneer prepared. I coated both surfaces with TiteBond Wood Glue and allow to dry.

This particular glue can be reactivated with heat for seven days.
https://farm3.staticflickr.com/2903/13921817266_1e5b37e151_c.jpg (https://flic.kr/p/nddXfb)

Not bad, but I might give it another try. This veneer is so thin that any defect, including variation in glue thickness, is telegraphed onto the surface. It's so thin that they can;t be sanded out.
https://farm4.staticflickr.com/3721/13945370174_9025f4c3b4_c.jpg (https://flic.kr/p/nfiEGN)

Finally, after a little Brown Mahogany Mohawk toner. It's a little darker and redder than the original but not bad. If I were to do it again, I'd try Prefect Brown toner instead.
https://farm8.staticflickr.com/7219/14008002833_7ca7fe38df_c.jpg (https://flic.kr/p/nkQFde)

As for the sides, a little light sanding with 400 grit and a fresh coat of lacquer works well. No issues with finish compatibility.
https://farm8.staticflickr.com/7243/13944906095_192db989e8_z.jpg (https://flic.kr/p/nfghKr) https://farm8.staticflickr.com/7211/13921814596_379e9e017f_z.jpg (https://flic.kr/p/nddWs9)

Switching gears a little to the antenna. All this set had left when I got it was the plastic base. A few months back I came across this great ARF thread on fabricating one (http://www.antiqueradios.com/forums/viewtopic.php?t=142723) using salvaged rabbit ears.

Luckily, I have more of mine left and just need a replacement telescoping rod. Eventually, I managed to find one and it's a perfect fit :)

https://farm8.staticflickr.com/7306/13998202074_3f89b5c3cd_c.jpg (https://flic.kr/p/njYrMC)

https://farm8.staticflickr.com/7121/13994589751_e4922b27aa_c.jpg (https://flic.kr/p/njDVYc)

https://farm8.staticflickr.com/7315/13974667266_ab7fb963b5_c.jpg (https://flic.kr/p/nhTPH5)

https://farm8.staticflickr.com/7210/13994576752_761fb83177_c.jpg (https://flic.kr/p/njDS75)

Looking mighty fine. :thmbsp:

I think I am posting about the right set.

Been thinking about your restoration in the...
Predicta "Holiday" restoration p13o?

http://www.youtube.com/watch?v=UlHtGky46r4

at about 16:05 the LED Back light was staying lit for quite a while.

I believe if you connect the high side (ungrounded) lead of the LED to the high side of the filament string it would stop the strange behavior...

I tried your suggested and it works perfectly :) Only downside is the cap now retains a charge for a long time. I suppose I could add a high value bleeder resistor across it.

I stripped and refinished the front edge and I think it's as good as I'm going to get without mixing my own custom lacquer dye.

Next up, a little clear coat.
https://farm6.staticflickr.com/5095/14008072862_340dc39b86_z.jpg (https://flic.kr/p/nkR32C) https://farm6.staticflickr.com/5053/14008085481_3b0056a1bd_z.jpg (https://flic.kr/p/nkR6Mc)

I tried your suggested and it works perfectly :) Only downside is the cap now retains a charge for a long time. I suppose I could add a high value bleeder resistor across it.

A 100 K. 1 watt should help quite a bit.

rrrhre2s

That is looking really nice, Bob.

Another note, regarding the bad thermistor: I had a bad one in an RCA CTC-16 combo chassis. One wire was broken off, and the other one came off as I tried to fix the first side. However, I was able to scrape both sides of the disc and find usable "good" spots that would accept solder. So, I was able to repair it, and it has been fine for several years (though I have not watched the set for, say, three hours straight or anything). It might be worth trying that trick on yours.

I did some searching around and found another source for replacement Predicta antenna rods - Zenith Chromantennas. Apologies to any Chromantenna fans.

https://farm8.staticflickr.com/7322/14085848824_d33d6d644d_z.jpg (https://flic.kr/p/nsHE7u)

Here are the patients with broken or missing rods.
https://farm3.staticflickr.com/2898/13898758919_402c0ce49b_z.jpg (https://flic.kr/p/nbbLNt)

Here's the inside of the Chromantenna.
https://farm6.staticflickr.com/5031/14085360375_441372b6df_z.jpg (https://flic.kr/p/nsF9UX)

I used a Dremel tool with cutoff wheel to carefully cut the plastic rod supports out. Then a sharp utility knife to trim off the support ribs around the cylinders.
https://farm8.staticflickr.com/7057/13933642069_8f5fecaec2_z.jpg (https://flic.kr/p/negym6)

The diameter is perfect, but they have a beveled shoulder while the originals are right angles. They will still work as is, but not fit quite as snuggly. I suppose they could be squared up with a file.

The newer plastic (mid 70s ?) is not as strong as the late 50s stuff but should hold up OK.
https://farm3.staticflickr.com/2938/13933623687_c169219119_z.jpg (https://flic.kr/p/negsTa)

I should also point out that these will not collapse inside like the originals did. There will always but about a foot sticking out.
https://farm6.staticflickr.com/5321/14120385335_4691413762_z.jpg (https://flic.kr/p/nvLEBz)

Here's the cabinet back together. I removed the rust from the legs which also took off any remaining trace of the brass plating so they look like bare steel now.
https://farm8.staticflickr.com/7450/14129818052_70672ce1e8_z.jpg (https://flic.kr/p/nwB1CC)

A few years ago I picked up a Caswell brass plating kit and also one from AES. Might as well give them a try...

First up, the Caswell kit. This is a brush system where you dip a positive "wand" into a plating solution and rub it against a negative item to be plated.
Rather than use the little wall wart power supply it came with, I'm using an HP bench supply with voltage and current limiting set to about 12 volts and 1/2 amp.

Just as when I've used it before, the results look dark and irregular. Buffing will take care of that.
https://farm8.staticflickr.com/7403/14134197324_2aed221174_z.jpg (https://flic.kr/p/nwZsrj)

Hmm. After a few passes it barely has any brass color.
https://farm8.staticflickr.com/7301/13947277659_dc3679ec85_z.jpg (https://flic.kr/p/nftrJt)

Time to try the stuff from AES. Wow! This stuff is great! It immediately turns a lovely gold/brass color.
https://farm6.staticflickr.com/5196/14134198564_cefbd2b44c_z.jpg (https://flic.kr/p/nwZsNG)

Must be the Potassium Cyanide :thmbsp:
https://farm8.staticflickr.com/7436/14134200284_e26fcdd0da_z.jpg (https://flic.kr/p/nwZtjm)

Here are the final results after a few passes and polishing. Note that after remove the rust, the metal has lots of little pits which I did not attempt to grind out. Even so, I think they look 100% better.
https://farm6.staticflickr.com/5198/14133946625_f87ec83f80_z.jpg (https://flic.kr/p/nwYaUV)

I sprayed them with a light coat of clear lacquer and mounted on the cabinet.
https://farm3.staticflickr.com/2929/13947320238_ce9bcf247f_z.jpg (https://flic.kr/p/nftEoA)

Finally, here's a preview of the assembled set minus the CRT. I'm waiting on some new tubes from ESRC then I'll perform an alignment and put it all together.
https://farm3.staticflickr.com/2897/13952389430_c349b327e0_b.jpg (https://flic.kr/p/nfVDhs)

I forgot to mention that ESRC is having a dollar sale on TV tubes that ends soon. Stock up while it lasts: http://www.esrcvacuumtubes.com/dollar_days.html

Here's the electroplating solution from AES. You will need the brush and a DC power supply too. http://www.tubesandmore.com/products/S-F222

Looks great Bob! :thmbsp: