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2nd one now, this one is mine, I have had it for over a year but never touched it due to the horror stories of working on a Predicta (this is the 17" princess model, red with metal frong grill).
Started by removing the main chassis (left the tuner in place for now). Very easy well thought out engeerning to get it out.
It not that bad at all, infact the compact sturdy chassis make it easy to flop over on the bench to get at the pcb (well the parts that are exposed anyway).
cleaned it with a soft brush and compressed air. Then moved on to alchol and q tips on the pcb to get the schmutz off the top of the pcb (I like to see what I am working on).
Popped off the IF strip cover, same deal Air, brush, q tip.
Stuffed the smaller can cap, it was complety open, was a bypass cap (low volt hi cap) for the vert amp, and a couple screen bypass caps in there.
I like the fact that there are no resistors tied to the can lugs just wires (this is the case on all 3 cans). Much easier to remove wire with out other stuff in the way.
Check the single doubler, fine, checed one section of the remaining 3 section cap, it check fine, I have found that if one section is good the remaining ofter are as well. I will get around to checking later.
Next up I start replacing all the black beauties, the 1st 4 all tested bad, I stopped checking after that.
There were a few that were standing up, I was able to use radials on those for a neater apperance.
I was able to replace about 70% of the caps from under the board, solder wick is your friend her since the solder sucker cant always get in tight places.
I am assuming the pcb is not though plated on the holes so you hav to bend the leads down flush to the board when soldering (I did not notice this on the 1st one, but figued it out quickly, I had not worked on such a old pcb before).
On the ones that just had no access at all I clipped, cleaned, and pig tailed the replacement cap, careful to use hemostats as heat sinks and to make sure the wire remnant did not fall though.
there were a few resistors that were out of spec. same deal as with the caps was able to do some from below.
The biggest problem was a big 390 ohm resistor next to the HOT. It was reading 470 but had a 10% band on it so I went ahead and replace it with a sand resistor, it was tight and I had to work from above, but got it in.
there were a couple I did not have so will have to make a surplus store run today (or pick up at the hamfest tomorrow).
I check all the tube resistance reading, all good to go.
checked all the coils (tranny,fly,vert,audio) again good to go.
the 17" crt was very very weak (no emmisons at all)
put the CR70 sencore to work (rejuv and auto restore) worked like a charm, strong emmisons and good cut off, and surprize good life test!
lubed the trim pots (little rusty and stuck) they seem fine now, beside I have some spare JIC.
cleaned and lubed the other pots (they were kinda funky on the resistance checks, seem ok now)
I am going to sharpen up my pick and tighten up some of the tube sockets that seem a bit loose, then will clean sockets, check tubes, clean pins.
I am thinking of making up a replacement for the fusistor (its there and good).
the replacement will be a couple thermistors in series and a fast blow fuse. That should soft the start to the caps and tube on the B+ and provide a sensitive fuse (with the soft start I will be conservative with the fuse rating).
Will also put a thermistor on the primary side to take some load off the switch.
Lastly will finsh up with a replacement saftey cap (the orig was a BB and was gone but the remaings where in there).
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