Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Was working, now trying to burn up!
#20

Yes, it's possible something else could have damaged it, but it's questionable. It may have been a 73 year old vacuum tube that finally went south. It's a Philco tube, probably original. (Also not a rare or expensive tube, so no major loss). I powered it up a good many times and it always worked. Then suddenly it went bad. The tube died when I tried to power it up again, not in the middle of use.

I am going to see about replacing things that are obviously bad before I power it up again.

However, replacing new modern capacitors just for the sake of doing so would be really wasteful and pointless unless there is a pattern of the same tube blowing out. We're talking about a vacuum tube that may have been 73 years old when it went out.

If after I replace the bad wires and it blows the same tube quickly, then I'll know something else is wrong. In the meantime, I will stick the chassis back in and leave it until I get new wires for the speakers and other things. I will also build and utilize a bulb tester thing. I also want to add a fuse for the transformer to protect it in general.

Also, the fellow who tested the tubes for me said that when I laid the chassis on it's side AFTER I smelled burning, unplugged it and pull it out of the cabinet (when the tube went bad), that it may have caused further shorting in the tube from loose filament inside which is why it went even worse with the blue sparking I witness. (Note to self, don't power up vac tubes on their sides)

So all signs point to that one bad tube. You have to start small and troubleshoot things. If your car stalls on the side of the road, you don't just decide to rebuild the entire engine right then and there. I suppose you could.. but why if nothing is wrong except the fuel filter?

Since the chassis has already been retrofitted with modern capacitors, there's little reason to suspect a problem there at this particular moment. It was operating fine with good audio, no strange sounds and no burning smell until this one vacuum tube went bad.


Messages In This Thread
Was working, now trying to burn up! - by BenWA - 09-12-2014, 08:43 PM
RE: Was working, now trying to burn up! - by sam - 09-13-2014, 09:04 AM
RE: Was working, now trying to burn up! - by BenWA - 09-13-2014, 05:30 PM
RE: Was working, now trying to burn up! - by sam - 09-13-2014, 07:25 PM
RE: Was working, now trying to burn up! - by sam - 09-13-2014, 10:55 PM
RE: Was working, now trying to burn up! - by sam - 09-13-2014, 11:27 PM



Users browsing this thread:
[-]
Recent Posts
Philco Model 38-7: what caps & resistors do fail typically?
Hello Martin, Welcome aboard our little community what great Model 38-7 Sincerely Richardradiorich — 12:30 AM
Philco Model 38-7: what caps & resistors do fail typically?
Welcome to the Phorum Martin. I count about 9 paper caps, the 3 electrolytic caps and 2-Y2 safety caps to replace th...RodB — 09:44 PM
Part numbers to model cross
Jim, We have this index put together by Dale Cook but I don't think that is quite what you are looking for. The Parts...klondike98 — 09:37 PM
Philco Model 38-7: what caps & resistors do fail typically?
Yep the dim bulb test is OK but I'd definitely replace all those electrolytics before I did it. Since those #47 conden...klondike98 — 09:18 PM
Philco 42-345 Restoration/Repair
The resistor is a 2.2 Meg, it was the last one I hadn't replaced. The broadcast is coming in after replacing it.osanders0311 — 09:09 PM
Philco 42-345 Restoration/Repair
What does the resistor measure? I think it should be 3.3 Meg. If the oscillator coil has continuity and the resistanc...RodB — 09:03 PM
Philco Model 38-7: what caps & resistors do fail typically?
Good idea to check the coils... then I'll get hold of an incadescent light bulb and see what happens when the unit is sw...Musaeum — 08:49 PM
Philco 42-345 Restoration/Repair
I have that same set, ain't too much shortwave I like anyway.....it is a good AM DX set. PaulPaul Philco322 — 08:32 PM
Philco Model 38-7: what caps & resistors do fail typically?
Welcome to the Phorum, Martin! Open a new thread in Philco Electronic Restoration when you begin working on your 38-7. ...GarySP — 08:28 PM
Philco Model 38-7: what caps & resistors do fail typically?
Welcome to the Phorum! :wave: Here's the schematic for that radio from our digital library: Something to do bef...klondike98 — 08:05 PM

[-]
Who's Online
There are currently no members online.

>