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

Loud hum when i turn on my Model 70
#1

All the tubes light up but all I hear is a loud hum. 

Adjusting the volume does nothing. 

Any ideas?
#2

First and foremost, DO NOT power up old radios until the capacitors and any drifted resistors have been replaced. Components in old radios degrade with age (especially capacitors), and can cause damage to other components (most which are much more expensive and harder to find). Caps are relatively inexpensive and replacing them will help keep other parts from being overloaded. Take care and BE HEALTHY! Gary

"Don't pity the dead, pity the living, above all, those living without love."
Professor Albus Dumbledore
Gary - Westland Michigan
#3

+1 what Gary said. Here's some more information courtesy of this site:

https://philcoradio.com/library/index.ph...urn-it-on/

Bottom line, your radio will need some components replaced under the chassis before it will play without that loud hum.

Greg V.
West Bend, WI
Member WARCI.org
#4

Welcome to the Phorum!
Icon_wave

The capacitor and resistor replacements are not too difficult especially if you have a little knowledge about soldering and electronics. If not, questions to the group here can help you through it or you can find someone to do the restoration for you.
#5

From what I have read, the hum is most likely caused by the old electrolytic filter capacitors. Those are very important and should be replaced.




Users browsing this thread:
[-]
Recent Posts
Philco 42-345 Restoration/Repair
Hi OSanders, Look carefully at the band switch. Turn it slowly and "wiggle" it around the desired band. ...MrFixr55 — 12:33 AM
5U4 vs 5Z4 tubes
I think that RCA and GE introduced metal tubes in the USA in 1936.  I don't know if they were being made by RCA, GE or b...MrFixr55 — 11:20 PM
Philco 42-345 Restoration/Repair
Vlad95, Thank you for the stringing guides and wow there are so manyosanders0311 — 06:01 PM
5U4 vs 5Z4 tubes
A pre war Hallicrafters, and an early one too, very nice! 1936 is pretty early for metal tubes too, which would explain ...Arran — 05:58 PM
Philco 42-345 Restoration/Repair
Thanks Rod, "When you hear the background hiss and no station it usually indicates that the oscillator quit" ...osanders0311 — 05:52 PM
Philco 42-345 Restoration/Repair
RodB :beerchug:Vlad95 — 10:22 AM
Philco 42-345 Restoration/Repair
Vlad, you nailed it. Swiss and German roots.RodB — 09:54 AM
5U4 vs 5Z4 tubes
Well this is a Hallicrafters SX/9 circa 1936. No real issues so far although I dodged a real bullet with a cap that was...bridkarl — 07:59 AM
5U4 vs 5Z4 tubes
The pinout is the same but the 5U4 has a 3 amp filament, verses 2 amps or less on the 5Z4. I think that the pinout of a ...Arran — 12:04 AM
Philco 42-345 Restoration/Repair
By the way. osanders0311 Take a look here: Dial cord stringing Guides May be here you can fount correct string settin...Vlad95 — 11:15 PM

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

>