I love old electronics and recently purchase a Panasonic TR-4CT5, it powers on and volume text is normally bright. Just have issues when I plug line in. Brightness of the input is fine for a minute then fades to super dark.
Volume label stays at right brightness so I figured it;s not the CRT or bri ghtness, feel it's a capacitor somewhere or something to do with the video input as on UHF noise is OK and doesn?t fade dark.
I scoured google for a manual or service manual but I could not find anythi ng. Any help or guidance would be appreciated as I think it?s an electr onic I really want to conserve.
rs on and volume text is normally bright. Just have issues when I plug lin e in. Brightness of the input is fine for a minute then fades to super dar k.
rightness, feel it's a capacitor somewhere or something to do with the vide o input as on UHF noise is OK and doesn?t fade dark.
hing.
tronic I really want to conserve.
Yes, it's always a capacitor...
Get the numbers off any IC you can find and get the datasheets off the web. The datasheets will tell you what they are and what the inputs and output s are as well as what voltages should be on the Vcc. Unless it's mostly di screte transistors, datasheets are almost as good as a schematic.
With some searching, you may be able to identify another Panasonic model th at might be virtually identical from a chassis standpoint, and you might fi nd the schematic to that.
On Wednesday, 19 September 2018 18:41:53 UTC+1, snipped-for-privacy@gmail.com wrote :
rs on and volume text is normally bright. Just have issues when I plug lin e in. Brightness of the input is fine for a minute then fades to super dar k.
rightness, feel it's a capacitor somewhere or something to do with the vide o input as on UHF noise is OK and doesn?t fade dark.
hing.
tronic I really want to conserve.
can't work out what you mean at several places. It doesn't sound like a bad electrolytic capacitor, they don't work ok for a bit then not.
wers on and volume text is normally bright. Just have issues when I plug l ine in. Brightness of the input is fine for a minute then fades to super d ark.
brightness, feel it's a capacitor somewhere or something to do with the vi deo input as on UHF noise is OK and doesn?t fade dark.
ything.
ectronic I really want to conserve.
ad electrolytic capacitor, they don't work ok for a bit then not.
I'd probably start by prodding the pcb with a plastic stick, see if one spo t is sensitive.
On Wednesday, September 19, 2018 at 4:33:13 PM UTC-4, snipped-for-privacy@gmail.com wro te:
te:
wers on and volume text is normally bright. Just have issues when I plug l ine in. Brightness of the input is fine for a minute then fades to super d ark.
brightness, feel it's a capacitor somewhere or something to do with the vi deo input as on UHF noise is OK and doesn?t fade dark.
ything.
ectronic I really want to conserve.
I think he means that the only source that goes dark after a minute is the video input. The UHF snow and the on screen display maintain normal bright ness at all times, so he correctly assumed the CRT as well as the HV and CR T circuitry are OK.
If it goes dark after running normally for a minute or so, I'd try cheating by applying freeze spray. Might turn up a gimpy IC or transistor in a cou ple of minutes.
If it's not thermally sensitive, I would check to see if the composite swit ching is done by a mechanical select switch or by logic control. A schemat ic would be a big help but on a b&w TV there's not much to them. If it's g ot ICs, that's half the battle as datasheets provide a partial schematic.
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