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judge 12-13-2018 09:25 AM

Hi
 
Hi,

Just saying hello - big Predicta fan - I just finished restoring a Predicta Siesta, my first TV repair!

old_tv_nut 12-13-2018 09:34 AM

Sounds great! Welcome!

bandersen 12-13-2018 10:31 AM

Welcome to VK and congratulations on the Predicta

madlabs 12-13-2018 03:11 PM

Hi Judge,

Tell us more about your Siesta repair. I did a Holiday for my first TV and it was a journey. Never would have gotten it running without the folks on this site.

judge 12-13-2018 04:55 PM

4 Attachment(s)
Quote:

Originally Posted by madlabs (Post 3206648)
Hi Judge,

Tell us more about your Siesta repair. I did a Holiday for my first TV and it was a journey. Never would have gotten it running without the folks on this site.

It was almost completely plain-sailing, though I needed the help of one of the guys from ARF to trouble-shoot a problem I was having. I bought it from another member of ARF local to me, un-restored. My Avatar shows what it was like after I cleaned the outside. Before I started restoration I used a modified version (to take into account the lower filament voltage) of the circuit described here to perform a partial check of the CRT, and it seemed good, so then I basically scoured the internet for information. There was this site mainly and a few youtube videos. So I decided that I should get the original factory manual as well as the SAMs. I also bought a wire-wrap tool so that I could unwrap and re-wrap all of the 50-odd connections to the main PCB. Then I just took it apart, cleaned it up and did an inventory of all of the capacitors I would need and checked all the resistors. I ended up replacing about 10-15 resistors that had drifted out of spec and I replaced all the couplates with a set from Crist Rigotti, in addition to all the electrolytics and black-beauties.

So then I re-attached all the wires, powered it up and there was no video and the sound was always at full volume. Someone from ARF ('analog.tv') helped me figure out that there was no horizontal oscillation, which I tracked down to a bad couplate. I replaced it with the old one and everything was good - apart from the sound.

I left everything out on the bench until I got a replacement couplate from Crist. I didn't really fix the sound until I was putting everything back together - I had re-attached one of the 50 wires to the wrong point! I also detached a power lead from the clock switch while I was putting it all back together. So I had to take it all out again to re-attach that lead to the clock properly. BTW here is a video.

Celt 12-13-2018 05:06 PM

Welcome aboard! :wave:

Peternith 02-15-2019 11:57 AM

Welcome aboard! You've come to the right place.

Titan1a 02-16-2019 01:25 AM

Looks like you can fix anything. Good show!

electronjohn 02-16-2019 10:22 AM

Glad you're here!

Gleb 02-17-2019 08:23 AM

Hi! Always nice to see a new member!
Predictas are adorable, congrats on successful restoration!

Quote:

Originally Posted by judge (Post 3206654)
...I replaced all the couplates...
...I tracked down to a bad couplate. I replaced it with the old one...

What is a couplate? A hybrid network on a small separate board?

Electronic M 02-17-2019 09:58 AM

Quote:

Originally Posted by Gleb (Post 3208669)
Hi! Always nice to see a new member!
Predictas are adorable, congrats on successful restoration!



What is a couplate? A hybrid network on a small separate board?

Basically...Some look like ceramic disc caps, some look like 1/2"-3"X1/2"-3" ceramic squares, some squares with tubular lumps on a side. They all are just some resistors and caps in a module. The names varied a bit too Couplates, K-components, etc. They were most common in TV vertical integrator networks and AA5 radio audio stages but were found in other applications as well.
PCB based sets tended to be heavier users of couplates.

Gleb 02-18-2019 02:43 AM

Thanks for the explanation! I remember that I've met 'couplates' restoring a Dynaco FM-3 tuner. They were responsible for de-emphasis there, so I had to replace them by some crafted networks recalculated for the European time constant.


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