| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 878.1 | Close. | UFHIS::TLACEY | A crime in the wink of an eye | Wed Jul 31 1991 16:02 | 9 |
|
No idea, but try asking in MALLET::UK_AUDIO, thats
where the techies hang out.
Tim.
|
| 878.2 | Hope I have explained this clearly enough | CRATE::HAZEL | Million-to-one chances crop up nine times out of ten | Wed Jul 31 1991 16:16 | 39 |
| This hum sounds like it might be mains hum. I have had this problem
occasionally, and it is often caused by the signal line being shorted
to the earth line in one of the phono connectors.
If the connectors are the type which unscrew, try opening them up and
checking the wiring inside them. If it looks as though the wire
soldered to the middle pin might touch the earth connection, then this
could be the problem. You need to stop the two touching.
Here is a diagram showing a cross-section of a phono plug, to try to
clarify things:
---------------------++--------------- <-- earth connection
||
||
================ <--- signal connection
||
|| <-- insulating material
++---------------
The signal connection is surrounded by the earth connection, which
forms a sort of cylinder. The wire comes in from the back (left hand
side of diagram), and is of the coaxial type. The screen of the coaxial
cable (that is, the wire mesh which surrounds the central insulated
strand of wire) is soldered to the earth connection of the plug, and
the central strand is soldered to the signal connection.
Check whether any part of the earth connection, or the coaxial screen,
touches any part of the signal connection or the signal wire.
You may need to check both plugs, and also any connections to them at
the record deck end.
Is it only the deck which gives this trouble?
Dave Hazel
|
| 878.3 | | CHEFS::IMMSA | adrift on the sea of heartbreak | Wed Jul 31 1991 16:52 | 12 |
| Thanks for the info so far.
Yes it is only the deck and of course when I tape a record (gasp - for
use in the car of course ;-) ) the hum comes out and makes it
unlistenable to.
I will certainly try the advice in -.1 and if it does not work, will go
to the audio conference.
Thanks again
andy
|
| 878.4 | | CHEFS::IMMSA | adrift on the sea of heartbreak | Wed Jul 31 1991 16:55 | 11 |
| I forgot.....
The hum persists even without the phono plugs - when the two ends of
the wires are separated, twisted together and taped with insulating
tape.
My son is a qualified electrician and has helped my with the technical
bits but he is not an electronics man, so finding the actual cause of
the problem is rather beyond both of us!
andy
|
| 878.5 | | ODDONE::FIDDLER_M | | Wed Jul 31 1991 17:39 | 5 |
| It might be something to do with impedance and wires matching and
loadsa techy stuff like that. The audio conf is a great place to aslk
this sort of Qn.
Mikef
|
| 878.6 | Thanx for the help | CHEFS::IMMSA | adrift on the sea of heartbreak | Thu Aug 01 1991 09:21 | 8 |
| OK Thanks.
I'm on my way to the audio conference.......
dum di dum di dum...(cough)
andy
|