View Full Version : Panasonic implosion


RetroHacker
08-10-2017, 12:05 PM
I found this set at an estate sale a while back - with a "FREE" sign on it, no less. Of course, I had to rescue it - how often do you find tube type tabletop sets these days?
http://i.imgur.com/oIvSPNg.jpg

Before powering it up, I took the back off to check for any major problems, and found one almost immediately:
http://i.imgur.com/QP2Makv.jpg

That horizontal output tube must have gotten seriously hot to melt the glass like that. It's been a while since I saw a tube that had gotten hot enough to implode and fail like this! I really wonder how long the set ran before the tube got hot enough to melt, break, and open the filament shutting down everything?

I haven't investigated this further - I have too many other projects at the moment. I'll have to locate another horizontal tube - which I might have amongst the various boxes of used, unsorted, scavenged tubes. Then I get to figure out what caused it to melt down like this, no doubt loss of horizontal drive. The rest of the set is dirty, but in pretty decent shape, so it's probably worth putting a little effort into resurrecting.

And, another shot of the back of the set, just because: http://i.imgur.com/6qhPvJk.jpg

-Ian

BigDavesTV
08-10-2017, 12:50 PM
Congratulations on scoring that Panasonic! Wish it had been in my area!:) That shouldn't be too difficult to repair, most likely needs the old coupling caps (might be paper-in-oil) caps, replaced, in the horizontal circuit, and, of course, a new tube or two. Look also for burned resistors in that circuit. This is an illustration in the reason why I like to add a cathode fuse in the horizontal output tube circuit, especially when I have to service that circuit first! If you have, or have access to a picture tube checker, it would be worth testing, gently! Looking forward to future progress reports on this NICE classic!

Electronic M
08-10-2017, 02:01 PM
That is a nice one. I've got a later 6 tube hybrid panny....Mine was missing the damper, installing a new one showed the confusing combo of red-plating H Out Tube, and good grid drive. Eventually i found a red 2KV paper in oil cap out side the HV cage above the tubes that was dead shorted to under 2ohms of resistance...The cap was across a winding of the fly. Needless to say it worked a LOT better after I changed that cap....Heck all it needed beyond that was control cleaning and adjustments.

Beware those Japanese paper in oil caps especially the older grey ones...Most of them will test VERY leaky to shorted.

zeno
08-10-2017, 06:21 PM
Both Panasonic & Sharp plus there other of there branded sets suffered
from HO tube failures due to the mica caps going intermittent. They
are the clear ones, silvery inside. Have seen quite a few melt downs.
Always from a dead hoz osc. No drive = 100% conduction 100% of
the time. The G-1 has to be very negative..........

73 Zeno:smoke:
LFOD !

dieseljeep
08-10-2017, 09:41 PM
I found this set at an estate sale a while back - with a "FREE" sign on it, no less. Of course, I had to rescue it - how often do you find tube type tabletop sets these days?
http://i.imgur.com/oIvSPNg.jpg

Before powering it up, I took the back off to check for any major problems, and found one almost immediately:
http://i.imgur.com/QP2Makv.jpg

That horizontal output tube must have gotten seriously hot to melt the glass like that. It's been a while since I saw a tube that had gotten hot enough to implode and fail like this! I really wonder how long the set ran before the tube got hot enough to melt, break, and open the filament shutting down everything?

I haven't investigated this further - I have too many other projects at the moment. I'll have to locate another horizontal tube - which I might have amongst the various boxes of used, unsorted, scavenged tubes. Then I get to figure out what caused it to melt down like this, no doubt loss of horizontal drive. The rest of the set is dirty, but in pretty decent shape, so it's probably worth putting a little effort into resurrecting.

And, another shot of the back of the set, just because: http://i.imgur.com/6qhPvJk.jpg

-Ian
Could be a shorted HV rectifier. Is that horiz output tube a 29KQ6?
I have a newer Panasonic hybrid with low hours. They use tubes, that are generally found in European or British sets. 300 ma heater string, where the US sets used 450 or 600 ma tubes. :scratch2:

dishdude
08-10-2017, 11:52 PM
I clicked on this expecting we'd be talking about the CRT.

zenithfan1
08-11-2017, 09:12 AM
I'd love to find one of these sets, good luck getting her going!

Sandy G
08-11-2017, 10:26 AM
Un-Effin'-believable...

init4fun
08-11-2017, 12:17 PM
I clicked on this expecting we'd be talking about the CRT.

:thmbsp: +1

:scratch2: There is only one tube in a TV set that I've ever heard the term "Implosion" used to refer to it's failure , and the Horizontal output ain't it .....