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  #31  
Old 08-10-2016, 09:21 AM
madlabs madlabs is offline
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Bob, great and thanks. I'll get some ordered up this week. Drat, I ordered a 1kV cap for the cap (don't remember number, I'm at work) on the board that needs to match the cap on the vertical network. Oh well, I'll order another.
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  #32  
Old 08-10-2016, 09:50 AM
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bandersen bandersen is offline
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1kv is enough. I didn't have the schematic in front of me earlier.

I made a bunch of extra couplates. If you rather just get them from me, let me know.
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  #33  
Old 08-10-2016, 10:08 AM
madlabs madlabs is offline
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Bob, I meant to mention that the odd ceramic tube cap that you thought might be a replacement in one of your videos was in my Holiday too, so it must have been a stock item. Strange kinda cap. Good that 1kV is enough. I'll send you a PM about the couplates.
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  #34  
Old 08-11-2016, 08:36 AM
madlabs madlabs is offline
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Are 1n4007 diodes OK to replace the HVDC diodes? I hope so, I already soldered some in. :-)

Also, what value resistor to sub in for the CRT filament for testing purposes. Bob mentions it in one of his videos but I can't seem to find it.

Still chugging along. The container of replaced parts is getting full!

NEVER MIND: Found Bob's video that answered both of those questions, yes and 10 ohm.

Last edited by madlabs; 08-11-2016 at 09:01 AM. Reason: I RTFM'd
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  #35  
Old 08-11-2016, 09:05 AM
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1N4007 (rated for 1,000 volts @ 1 A) are fine but I've switched to beefier IN5408 ( 1,000 volts @ 3A) lately. I've heard some guys use two diodes in series for extra protecting in case one shorts. Seems like overkill but wouldn't hurt.

Use ohms law. Resistance = filament voltage / current = (2.35 or 6.3) volts / 0.6 A. Really though you don't need to be exact - something around 3.9 - 15 ohms is fine.
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  #36  
Old 08-11-2016, 01:40 PM
madlabs madlabs is offline
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Hey Bob, thanks for the reply. I may order some 5408s, all I have on hand is 5406s. The 4007s will be good enough for testing purposes.
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  #37  
Old 08-22-2016, 01:13 PM
madlabs madlabs is offline
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Hi All,

Well, a busy week here but still managed to get a lick in on the Predicta. I got the main PCB removed and started to remove and replace components. I am going with a blanket replacement of paper caps, couplates and resistors. I've come up with a few questions from the components values.

C25: Looks like a little resistor with two black bands. Sam's says it is a 1uF?! I must be reading that wrong, but it would seem that 1pF is the only other interpretation.

R49 and R52: R49 is a 3600 ohm. The notes says this goes with a PCB marked with a yellow dot. R52 is a 2.7mOhm and the notes says this goes with a PCB that has an orange dot. I see no dots on my PCB but I do see a green stripe. I'm guessing I should stick with the values that are in the board, but anyone have any insight?

Over all the board is in decent shape. I have one 7 pin socket that needs replacement. All the 9 pin sockets look OK. In my stash I found some PCB mount 9 pin sockets, one of which is the same make and number but appears a little later. The other ones I have are even cheaper looking than the originals. I'm not sure if I should replace all of them or just the borked one.

Jonathan
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  #38  
Old 08-22-2016, 02:13 PM
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Sams says 1.0 mmfd for C25. That's short for micro micro Farad which is the same as pico Farad (pF).

I'd go with the resistor values currently in the board - especially if they look to be originals.

As for the tube sockets, if you stick with the originals be very gentle when inserting and removing tubes. The metal used is fairly thin and breaks easily.
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  #39  
Old 08-22-2016, 06:22 PM
madlabs madlabs is offline
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OK, so what kind of cap is the 1pF? I am assuming it's a ceramic and hence no need to replace out of hand. Are these resistor looking caps common?

Thanks Bob! Also, I'm going to take you up on your offer to buy the couplates. I'll send you an email.

Jonathan
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  #40  
Old 08-22-2016, 09:09 PM
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Yes, ceramic - no need to mess with it. You will mostly see these caps in tuners and other RF circuits where very small capacitance is needed.
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  #41  
Old 08-25-2016, 10:12 AM
madlabs madlabs is offline
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So, I've been looking for sockets. I can't seem to find any that have the center solderable pin. I'm not sure how important that is, but some of the center pins have traces that meet up with component traces. Some of them are just little islands unto themselves. Lots of 7 and 9 pin ceramic sockets available but noe with center pins. Any oPINions on how important they are?

Jonathan
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  #42  
Old 08-25-2016, 11:19 AM
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If the tube that goes in the socket don't have a center pin, and the tube is not in the IF or video stages the center pin is irrelevant...If it is in the IF or video it still may not matter, but those stages can be picky about capacitance changes that tiny redress (like removing that piece) can cause. If IF and video stages have working sockets I'd leave well enough alone.
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  #43  
Old 08-25-2016, 01:30 PM
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Surplus Sales of Nebraska - scroll down and you'll find 7 and 9 pin that are perfect replacements -

https://www.surplussales.com/Tube-So...ubeSkts-2.html

7-pin
(TUA) MSM-1441-200 or (TUA) 7P-CP - the shield is easy to remove if you don't need it.

9-pin
(TUA) 751V504C06

I think you'll find it helpful to read through other Predicta restoration threads where the same issues have come up before. Here's one of mine showing the new sockets.
http://www.videokarma.org/showthread...=255328&page=3
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  #44  
Old 09-03-2016, 12:10 PM
madlabs madlabs is offline
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Got some time in on the set this week. All parts that I had on hand have been mounted on the main PCB. Spent quite a bit of time cleaning all of the contacts on the board and the board itself. Did a lot of chassis cleaning. Ordered the remaining parts and some spare tubes, along with some replacement sockets. Ordered some Novus plastic polish. With any luck all should arrive next week.

I really can't wait to see a picture on this thing.

Jonathan
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  #45  
Old 09-08-2016, 11:44 AM
madlabs madlabs is offline
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Well, the main PCB is done! Hopefully anyway. I bought a set of couplates from Bob and they look great! Really fine work. While I feel a little dirty for not making my own, Bob's look so good I'm glad I didn't. I can't seem to figure out the inline attachments but here is the main board.

I'm waiting for Rio to re-connect the board and test this thing out! I hope she knows what an act of love that is! The anticipation is killing me. Remember the Wide World of Sports intro? The thrill of victory or the agony of defeat! Which awaits me?

While I'm killing time waiting to find out, I have a radio shack RF modulator that I am playing with to see if I can come up with a way to see an image, assuming the thrill of victory prevails. I am guessing that the Predicta has a 300 ohm input and that I need the little balun to connect it. Is this correct? Is there anyway to whip up something, just to see if I can get any kind of image?

Thanks for all the help folks!

Jonathan
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