Quote:
Originally Posted by benman94
Well I found a rebuilt 12KP4 to replace my problematic 12LP4.  Though I still plan on performing the repair to the 12LP4, I'm going to hold off for a while seeing as my new tube actually costs less than the supplies needed to create 2 new leads and seal the base back onto the neck. $35 is a lot less than I was planning on shelling out! Anyway, I have a few questions . . .
#1: The Sams photo-facts for the T120 has a complete listing of the set's capacitors. Unfortunately, it doesn't say what type each capacitor is. Papers and electrolytics are given in uF, and micas and ceramics are given in pF. Just looking at the list however, I can't figure out which are paper, which are mica, and which are ceramic (electrolytics are easy to tell due to the can: C1-A, C1-B, C1-C . . .) . I was thinking about replacing them by simply going through the chassis, marking them off, writing down the values, and ordering them (like I've done with all of my radios). This won't work though. There are WAY too many to do that by hand and not screw up. I also can't read through the darkened wax. When I try to scrape it off, I end up taking all the ink with it. The list in the Sams does have a voltage rating column though. Some of the capacitors have ratings given, others don't. Am I correct in assuming that the caps with the ratings are papers or electrolytics?
#2: What is the difference between grid-fed and cathode-fed video?
#3: What resistors, if any, should I be concerned about checking and replacing?
Thanks,
Benny |
From my extremely limited knowledge so far I've found that the big electrolytic caps are listed first. The mica and ceramic caps will have "high" ratings on the parts list. The values will of course be low but the numbers will be higher because they are listed in pf. The paper and electrolytics will have a "low" rating, which will be higher in actuality because they are listed in uf. I found it helpful to have the bottom of the chassis, the capacitor parts list, and the chassis bottom view capacitor alignment identification page all in front of me. Then start on the part list with a capacitor, find it on the alignment page, and locate it in the set itself. When I found it I would write down what value I need and order them.
Just the thoughts of another beginner.