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

AA5 hum
#14

as to the IF coil I fried, if all else fails, read the instructions! seems the Crosley service manual spells out, in bold print no less, UNDER NO CIRCUMSTACES SHOULD A GROUND BE CONNECTED TO THIS RECEIVER. in other words, USE AN ISOLATION TRANSFORMER before connecting a [grounded] scope to the chassis. even so, even after using an isolation transformer, I connected the scope ground to the neutral wire. maybe someone can tell me if I was well-advised to do that. or not. I say neutral wire because the isolation transformer has a polarized outlet.

as to the hum, I discovered [with a scope] that the signal from the audio transformer [with the antenna disconnected] looked like a sine wave with the peaks flattened a bit. unlike the signal from a radio that didn't hum. those peaks were narrow and pointy. I switched transformers and NO HUM! while I am pretty much a rookie, at fixing 120V radios anyway, I've never had a transformer cause a hum. nor read any mention of it. i'm curious to know what might be "wrong" with the transformer. the resistances are good. and it did work but introduced the hum even with the volume turned down.

thanks as always.

PS I put an X-Y cap across the AC line. it had no effect on the hum.
PPS the reception was poor because the solder joint on the antenna lead to the stator side of the tuning cap was loose. something this rookie discovered entirely by accident.


Messages In This Thread
AA5 hum - by fenbach - 10-18-2018, 11:02 PM
RE: AA5 hum - by Radioroslyn - 10-18-2018, 11:28 PM
RE: AA5 hum - by Jayce - 10-19-2018, 12:05 AM
RE: AA5 hum - by Chas - 10-19-2018, 12:09 AM
RE: AA5 hum - by fenbach - 10-19-2018, 08:18 PM
RE: AA5 hum - by fenbach - 10-19-2018, 08:20 PM
RE: AA5 hum - by Chas - 10-20-2018, 12:04 AM
RE: AA5 hum - by gregb - 10-21-2018, 12:04 AM
RE: AA5 hum - by David - 11-04-2018, 03:20 PM
RE: AA5 hum - by Jayce - 11-04-2018, 09:24 PM
RE: AA5 hum - by 35Z5 - 11-05-2018, 09:57 AM
RE: AA5 hum - by morzh - 11-05-2018, 10:48 AM
RE: AA5 hum - by Squire - 11-08-2018, 01:12 AM
RE: AA5 hum - by fenbach - 03-16-2019, 11:12 PM
RE: AA5 hum - by Arran - 03-16-2019, 11:49 PM
RE: AA5 hum - by 35Z5 - 03-17-2019, 05:55 PM
RE: AA5 hum - by fenbach - 03-23-2019, 07:54 PM



Users browsing this thread: 2 Guest(s)
[-]
Recent Posts
Philco 38-7 Speaker
I have let this one sit because of other duties. Now I am back, and I have a couple of questions. I hooked up a Hammond ...tludka — 05:34 PM
Philco 42-390, code 121 speaker
>>A closer examination of the very small print schematic indicates that the speaker is a PM type. This shows a ...morzh — 05:18 PM
Philco 60 Squealing
Litz is typically tinned by simply rubbing it with the soldering iron tip while immersed in solder (and a bit of rosin f...morzh — 05:14 PM
Philco 6K7
The suppressor grid (if by G3 you mean the S) is usually at the Cathode potential, which in this caes is GND. I am not ...morzh — 05:10 PM
Philco 16B Parts
Thanks for the reply. Unfortunately the radio was removed before bidding was over so I didn't get a chance to bid.dconant — 04:10 PM
Philco 16B Parts
Hi Dan, Mike is correct, there's a lot of painted stuff on the chassis but it looks pretty good. The sm is all there,sp...Radioroslyn — 03:50 PM
1930s Stromberg-Carlson Tombstone Radio need help identifying model number
Hi Cap'n Clock, Unfortunately, I do not have this radio.  This is a shame because this should be a good performer.  2A...captainclock1988 — 03:43 PM
Philco 42-390, code 121 speaker
Using a 5W  1.5k  ceramic resistor in place of the field coil and using a 4 ohm PM speaker, I was able to bring the radi...Stevelog — 02:57 PM
Philco 60 Squealing
I have taken out the 2nd IF and found a problem or not. I believe the coils are litz wire. There is a very small strand ...dconant — 02:13 PM
Philco 6K7
I am restoring a Philco 37-60. The am reception is very good, but the shortwave is very weak. Run 6 Philco removes the g...bobbyd1200 — 01:35 PM

[-]
Who's Online
There are currently 4559 online users. [Complete List]
» 2 Member(s) | 4557 Guest(s)
AvatarAvatar

>