flyback question - Videokarma.org TV - Video

radio nut · #1 03-18-2009, 04:13 PM

When I bought my motorola 21t16 someone had already started working on it. The flyback was bolted in ,but not wired up.I reinforced the coating on it with rtv before I tried using the set. If I play the set for 2 hours or so the flyback is barely even warm. The coating was only a ring around it. It is not fully covered. Is this good enough or do I need to mummify it? Thanks.

*zenithfan1* · #2 03-18-2009, 04:43 PM

I would only worry if it's real close to something. It's probably ok the way it is unless a bunch of coating is missing. Was it covered that way from the factory? Can we see a pic, might be a big help.

radio nut · #3 03-18-2009, 06:11 PM

It was that way from the factory. No on the pictures, I am into all things old and still do not have a digital camera.

old_tv_nut · #4 03-18-2009, 09:57 PM

If it was originally made with just a ring of insulation, it is not good to cover it unless you must to stop corona/arcing. Putting too much on could trap heat, can detune the secondary somewhat and affect HV regulation and losses - lots of little effects that take it away from the original designed performance.

In summary, if it ain't broke, don't fix it.

tubeglow · #5 03-27-2009, 01:03 PM

The first clue is when you said someone had worked on it , and the flyback was not soldered in----I would guess that this was a Merit, or Thord replacement, and probably not the correct one for your Motorola. The next thing you should do is check part numbers on the flyback to your Sam's (you do have a schematic right???) and also
check the Ohmic readings for the flyback against what the Sam's said it should be,
this will help to find open turns or too high or too low values.

radio nut · #6 03-27-2009, 11:14 PM

Quote:

Originally Posted by tubeglow

The first clue is when you said someone had worked on it , and the flyback was not soldered in----I would guess that this was a Merit, or Thord replacement, and probably not the correct one for your Motorola. The next thing you should do is check part numbers on the flyback to your Sam's (you do have a schematic right???) and also
check the Ohmic readings for the flyback against what the Sam's said it should be,
this will help to find open turns or too high or too low values.

My set came from a tv/radio repair shop that closed when the owner died. I (assume) that is is a valid flyback. I checked all resistances on it before I soldered it in. My concern is this;I put a nos flyback in my first tv and it ran hot. I thought it would be ok but it caught on fire and destoyed the set. I did not know about the coating on the fly being critical.I just do not want another fire. My set runs fine right now.

TubeType · #7 03-28-2009, 11:51 AM

Please add the following items to your troubleshooting list.

1. Never assume anything.
2. Always question everything.

Don't forget,
Something caused the original flyback to fail; in this set and the one in your first TV. Normally, flybacks do not run HOT.

Are your flyback's support components within tolerance?
Don't depend on an ohmmeter to check high voltage capacitors.

Good Luck

radio nut · #8 03-29-2009, 02:38 PM

All the voltages in my set are good according to the diagram. As a reminder this flyback does not get hot. No, I did not check the part number on the fly. I just ran with it. I checked all the caps I put in with my heathkit cap checker before I put them in.I do not know how to check for ex. the 3,000 volt cap in the damper circuit on the line that says DO NOT MEASURE. Being fairly new to tv. I put in new filter and paper caps and then did voltage checks for ceramic and mica caps and resistors.After that the set worked well so I left it alone.