Hi, I'm recently into refurbing some old
vintage radios, I'm talking here of just
getting them going to as close as original
spec with minimal changing of componants
I've done three so far a Hallicrafters S-77
an R1155 and in the process of a Collins
TCS12, they all seem to follow the same
condition, ie from switch on after changing
obvious faults shorts on caps supply
electrolytics etc there is much crackling
musty smell poor spec etc then over the
next few hours they make a remarkable
recovery! spec comes back and the crackles
and pops subside to an almost acceptable
level, but here's the rub they never really
subside completely, you are left with this
background crackle and if you leave the set
off for a few days it gets worse again, its
nothing specific as I've tried to trace it
it seems to come from all over IF AF front
end etc, I'm not talking backgound hiss, its
a crackle, sometimes quite bad other times
almost completely gone? is this a general
breakdown of componant material? ie carbon
in the resisters or similar? has anyone else
out there found this problem if so whats the
answer?
from Ron.

Ron wrote:
recovery! spec comes back and the crackles
and pops subside to an almost acceptable
level, but here's the rub they never really
subside completely, you are left with this
background crackle and if you leave the set
off for a few days it gets worse again, its
nothing specific as I've tried to trace it
it seems to come from all over IF AF front
end etc, I'm not talking backgound hiss, its
a crackle, sometimes quite bad other times
almost completely gone? is this a general
breakdown of componant material? ie carbon
in the resisters or similar? has anyone else
out there found this problem if so whats the
answer?

The most common reason for popcorn noise is bad resistors, but sometimes
you'll find some weird offenders (like bakelite tube sockets that have
arced over and formed conductive carbon paths inside). The best thing to
do is get a wooden rod and start tapping on resistors. Often the more
noisy of them will also be microphonic and you'll find it when you tap on
it. Use a dowel or something else nonconductive that will let you put
some good force on larger resistors.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Ron wrote:
recovery! spec comes back and the crackles
and pops subside to an almost acceptable
level, but here's the rub they never really
subside completely, you are left with this
background crackle and if you leave the set
off for a few days it gets worse again, its
nothing specific as I've tried to trace it
it seems to come from all over IF AF front
end etc, I'm not talking backgound hiss, its
a crackle, sometimes quite bad other times
almost completely gone? is this a general
breakdown of componant material? ie carbon
in the resisters or similar? has anyone else
out there found this problem if so whats the
answer?

The most common reason for popcorn noise is bad resistors, but sometimes
you'll find some weird offenders (like bakelite tube sockets that have
arced over and formed conductive carbon paths inside). The best thing to
do is get a wooden rod and start tapping on resistors. Often the more
noisy of them will also be microphonic and you'll find it when you tap on
it. Use a dowel or something else nonconductive that will let you put
some good force on larger resistors.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Ron" wrote in message
...
Hi, I'm recently into refurbing some old
vintage radios, I'm talking here of just
getting them going to as close as original
spec with minimal changing of componants
I've done three so far a Hallicrafters S-77
an R1155 and in the process of a Collins
TCS12, they all seem to follow the same
condition, ie from switch on after changing
obvious faults shorts on caps supply
electrolytics etc there is much crackling
musty smell poor spec etc then over the
next few hours they make a remarkable
recovery! spec comes back and the crackles
and pops subside to an almost acceptable
level, but here's the rub they never really
subside completely, you are left with this
background crackle and if you leave the set
off for a few days it gets worse again, its
nothing specific as I've tried to trace it
it seems to come from all over IF AF front
end etc, I'm not talking backgound hiss, its
a crackle, sometimes quite bad other times
almost completely gone? is this a general
breakdown of componant material? ie carbon
in the resisters or similar? has anyone else
out there found this problem if so whats the
answer?
from Ron.


Carbon resistors, dirty contacts inside switches and poor solder joints are
all suspect. On your S-77 and may be the others, you may have silver
migration on the capacitors inside the IF transformers. Robert Casey has a
very helpful article he

http://www.geocities.com/wa2ise/radios/repair.htm#if

Frank Dresser

"Ron" wrote in message
...
Hi, I'm recently into refurbing some old
vintage radios, I'm talking here of just
getting them going to as close as original
spec with minimal changing of componants
I've done three so far a Hallicrafters S-77
an R1155 and in the process of a Collins
TCS12, they all seem to follow the same
condition, ie from switch on after changing
obvious faults shorts on caps supply
electrolytics etc there is much crackling
musty smell poor spec etc then over the
next few hours they make a remarkable
recovery! spec comes back and the crackles
and pops subside to an almost acceptable
level, but here's the rub they never really
subside completely, you are left with this
background crackle and if you leave the set
off for a few days it gets worse again, its
nothing specific as I've tried to trace it
it seems to come from all over IF AF front
end etc, I'm not talking backgound hiss, its
a crackle, sometimes quite bad other times
almost completely gone? is this a general
breakdown of componant material? ie carbon
in the resisters or similar? has anyone else
out there found this problem if so whats the
answer?
from Ron.


Carbon resistors, dirty contacts inside switches and poor solder joints are
all suspect. On your S-77 and may be the others, you may have silver
migration on the capacitors inside the IF transformers. Robert Casey has a
very helpful article he

http://www.geocities.com/wa2ise/radios/repair.htm#if

Frank Dresser

Thanks for that!! that is an extremely interesting article !!!
certainly some more ideas to work on now
from Ron...


Carbon resistors, dirty contacts inside switches and poor solder joints are
all suspect. On your S-77 and may be the others, you may have silver
migration on the capacitors inside the IF transformers. Robert Casey has a
very helpful article he

http://www.geocities.com/wa2ise/radios/repair.htm#if

Frank Dresser

Thanks for that!! that is an extremely interesting article !!!
certainly some more ideas to work on now
from Ron...


Carbon resistors, dirty contacts inside switches and poor solder joints are
all suspect. On your S-77 and may be the others, you may have silver
migration on the capacitors inside the IF transformers. Robert Casey has a
very helpful article he

http://www.geocities.com/wa2ise/radios/repair.htm#if

Frank Dresser

In article ,
(Ron) writes:

spec comes back and the crackles
and pops subside to an almost acceptable
level, but here's the rub they never really
subside completely, you are left with this
background crackle and if you leave the set
off for a few days it gets worse again

Years ago on rec.antique.r+p there was a thrad on "Thunderstorms" -- that's
where the crackles build up to big static crashes and rumbles. The consensus
was leaky capacitors, specifically the paper dielectric types.

But I wouldn't doubt resistors could do it too -- in fact, ISTR finding one
such by tapping around. Of course loose tube sockets are the No. 1 cause, and
switch contacts. Keep that DeoxIt handy. --Mike K.

Oscar loves trash, but hates Spam! Delete him to reply to me.

In article ,
(Ron) writes:

spec comes back and the crackles
and pops subside to an almost acceptable
level, but here's the rub they never really
subside completely, you are left with this
background crackle and if you leave the set
off for a few days it gets worse again

Years ago on rec.antique.r+p there was a thrad on "Thunderstorms" -- that's
where the crackles build up to big static crashes and rumbles. The consensus
was leaky capacitors, specifically the paper dielectric types.

But I wouldn't doubt resistors could do it too -- in fact, ISTR finding one
such by tapping around. Of course loose tube sockets are the No. 1 cause, and
switch contacts. Keep that DeoxIt handy. --Mike K.

Oscar loves trash, but hates Spam! Delete him to reply to me.