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#1
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You can also put a regular 75 watt bulb in place of the fuse.
Look up "dim bulb" on U tube. Diode looks like damper. 99% of time they dead short. BUT most are built in to HOT so be sure your replacements dont have a built in one ! You may find a FBT but its a big gamble. Zeno |
#2
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Yes that is the damper diode, and if it was shorted the HOT would blow instantly without giving a picture. I got my set to run fine for a few minutes until I killed the HOT by changing focus while the TV was on.
I measured the diode with the diode test mode on my multimeter. Few hundred ohms resistance in one direction if I remember correctly. I don't have a lightbulb socket that'd make such a mod convenient. And what purpose would that serve? Fuse only blows when HOT is blown. Maybe you should smoke less weed (no offense)! |
#3
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Also, your pictures of the tube are not in any way conclusive as to it's health; a weak tube will still get bright, it just won't focus anymore at an acceptable level of brightness. Just be aware that you could be spending time and money trying to fix a set that will never look right If you are just doing it for fun, and you're not that invested in the outcome, then great, but if you really are counting on it to look good in the end, you might want to skip this set and look for something cleaner that is obviously low hours |
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Besides all the important tips said here, is good anyway to check +B to see if it is too high, starting measuring the video output supply voltage (one pin of L351), if derives from flyback. Typically it have 180V, and above 200V is considered very suspicious.
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So many projects, so little time... |
#5
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Well mine died the instant I'd touched the knob. If that's really the case, something is very wrong.
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ALSO it'd be nice to have the Sams' for this model. |
Audiokarma |
#6
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About the measurement... yes, this one requires the system functioning. Is good to measure "in a hurry", with the + lead of the multimeter attached to the point (negative from multimeter will be to circuit ground, like the channel selector shield or some easy point), and then powering up the TV, watching as fast you can the measured voltage (before damage). Just when you are able to read the stable measurement, turn off the TV.
Then you can repeat for the HOT PSU, to take note. Same fast principle. Is interesting both measurements, tyo see if one or both deviates from normal, to try to find soem culprit. Another possible test, and more challenging, to check the PSU, is to remove the HOT and uses a resistor to emulate the HOT current, to independent test the PSU, before HOT eating. Some old PSU reacts bad to no load, hence the need for some load: some linear PSU rises the output voltage without load, making no-load measurement useless; and some older SMPS explodes without load. A small lamp for emulating load... it depends, some PSU can be damaged by the filament in-rush current.
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So many projects, so little time... |
#7
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To expand on that a cheap thing can be done. Follow the wire from L351 to the main chassis. On that line is a @4.7 mfd @350V. I can almost guarantee it is bad & may be the problem. It can cause a lot of different symptoms on ALL brands, its in the top ten of common fails. Also there is a SCREEN control on the CRT board. If to high it gives too bright a pix & poor focus. Looking at the screen shots I see too bright a pix & poor focus. Too much bright will draw too much current & stress the HOT. Build a dim bulb tester. It will cost < $10 and will be very useful. ( socket, 2 alligator clips, some wire & a real bulb ). enuf fer now Zeno |
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Audiokarma |
#11
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See U tube for discharge vids.
You set is solid state. On turn off MOST of them bleed off in a few seconds. It will not kill you, just teach respect. In fact in theory if you have an irregular heart beat ( afibs) it may cure you ! Same thing as they do in the hospital. ( cardioversion) I got bit at least once a week for 40 yrs and I am still here The dangerous part of anything is where the AC comes in. BTW I will take the weed thing with humor But I came from South Acton, the beer side of town The pot heads came from West Acton or Acton Center. 73 Zeno LFOD ! |
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