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

half the tubes check bad
#1

I got a 48-1263 some time back and yesterday I got around to recapping it. Someone had already been there and I only had to replace 4 paper/wax caps and both can caps and one 15K resistor that was reading 27K. Plugged it in and got nothing but dial lights glowing. I checked the tubes and 4 of the 8 showed bad or questionable. Is this likely or is my old Heathkit tester on the fritz? When I picked it up the owner had it turned on with the turntable running to show me "it works". I  immediately unplugged it and took it home, but could she have done something then that wrecked those tubes? Yes, I am very new to restoring radios. Help! 
#2

Bad or weak tubes on a tester don't always translate into non functioning tubes. I would start by doing voltage checks (assuming you have a DMM) on the tube pins to make sure they are within reason of what is provided on the schematic. What other testing tools (sig gen, tracer, etc...) so you have, if any?
#3

There are more to the radio than just tubes. RF coils that can get open, oxidized panels and switches, speaker, transformer.....so, start telling us what you have checked so far.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#4

It's also possible that the tester is not reading properly. 

Which model Heathkit are you using??
#5

Also unclear about the radio as displayed to you in the shop: was it actually receiving radio stations? 
#6

(07-13-2015, 01:04 PM)Nick3092 Wrote:  Bad or weak tubes on a tester don't always translate into non functioning tubes. I would start by doing voltage checks (assuming you have a DMM) on the tube pins to make sure they are within reason of what is provided on the schematic. What other testing tools (sig gen, tracer, etc...) so you have, if any?

I have a multimeter and an old heathkit signal generator.
#7

(07-13-2015, 01:14 PM)morzh Wrote:  There are more to the radio than just tubes. RF coils that can get open, oxidized panels and switches, speaker, transformer.....so, start telling us what you have checked so far.

I haven't checked anything else but tomorrow I am going to buy a magnifying lens so I can read the voltages on the schematic and we'll go from there.
#8

(07-13-2015, 01:41 PM)TA Forbes Wrote:  Also unclear about the radio as displayed to you in the shop: was it actually receiving radio stations? 

No. I bought it from a private individual who was moving; when I got to her house the radio was the only thing left, and she had the turntable running. I didn't hear any sound out of the speaker. The turntable will run very well right now so am I correct in assuming this means the power transformer is okay?
#9

The schematic in nostalgia air is tough to follow, BUT:

1. No, the power to the turntable is house current, switched. 

2. If half the tubes are reading ? then that could be the problem. 

PM me with what tubes are bad, I may be able to help. 

Once you KNOW all tubes are good, then we can start troubleshooting. 

If your sig gen has an audio output signal you can use separately or modulate with an RF signal, recommend this:

1. Inject an audio signal on the wiper of the vol control. If you hear it in the speaker and can control the volume by turning the vol control shaft, then trouble probably not in the audio section. 
#10

Sorry for the long hiatus...but I want to tell everyone that the tubes WERE bad. New tubes and the 48-1263 is playing like a new radio! Got a new cartridge ordered from Ed Crockett of Vintage Electronics in Hattiesburg so the phonograph will soon be back to life also.
#11

Icon_thumbup Icon_thumbup Icon_thumbup
#12

Glad you got it going.
I've bought a couple of radios, where some unscrupulous seller had put all his old non working tubes in.
Both times it was through -bay. Maybe they were unhappy that the radio didn't sell for more, so they were trying to cut their losses.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Part numbers to model cross
Thank you morzh, that is exactly what I was looking for. Now , is there some where that shows pinouts for Philco power ...Jim Dutridge — 11:37 AM
Restoration of the Canadian General Electric A-87
Thanks for your help Michael. In fact, this video is only an intermediate result. Later I had to apply another tinting l...RadioSvit — 09:01 AM
Restoration of the Canadian General Electric A-87
Great job on the cabinet. PS. In the US notation, "kenotron" refers to specific type of tubes; we call re...morzh — 08:24 AM
Part numbers to model cross
This document has at least some tables of models and parts used. Example: Choke 32-7572, used in 604 radio. Search f...morzh — 08:19 AM
Restoration of the Canadian General Electric A-87
I also checked all the radio tubes on my Hickok 530 tube tester. The 5Z3 kenotron turned out to be faulty, all the other...RadioSvit — 08:02 AM
Restoration of the Canadian General Electric A-87
Well... While the varnish is drying up, I started repairing the chassis... Of course I started by replacing the pa...RadioSvit — 07:12 AM
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

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

>