I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn it
on it starts playing music for a few seconds after it warms up, then the music
fades out and and hum takes over. I don't really know what I'm doing, and the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper caps,
and I'm wondering if the value difference, added up over 8 caps would make a
difference? Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be helpful..

Derwin wrote:

I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn it
on it starts playing music for a few seconds after it warms up, then the music
fades out and and hum takes over. I don't really know what I'm doing, and the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper caps,
and I'm wondering if the value difference, added up over 8 caps would make a
difference? Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be helpful..


Try news:rec.antiques.radio+phono That is why the group was created.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

"Derwin" wrote in message
news:6mzYh.5305$Dq6.3498@edtnps82...

I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn
it
on it starts playing music for a few seconds after it warms up, then the
music
fades out and and hum takes over. I don't really know what I'm doing, and
the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced
the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper
caps,
and I'm wondering if the value difference, added up over 8 caps would make
a
difference?

No.

Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be
helpful..

At this point you need to fault find. Does it work OK with tape or other
music input?

In article 5HzYh.5314$Dq6.1620@edtnps82, says...


"Derwin" wrote in message
news:6mzYh.5305$Dq6.3498@edtnps82...

I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn
it
on it starts playing music for a few seconds after it warms up, then the
music
fades out and and hum takes over. I don't really know what I'm doing, and
the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced
the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper
caps,
and I'm wondering if the value difference, added up over 8 caps would make
a
difference?

No.

That's not what I've read. Are you sure you're not thinking of electrolytics?


Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be
helpful..

At this point you need to fault find. Does it work OK with tape or other
music input?


Perhaps I should have specified that the unit worked fine before I recapped it.
It had a bit of a squishy sound so I figured it could use a re-capping but I
must've screwed up somehow. But re-capping is pretty straight-forward, and I
think I did it right. So now, what could have gone wrong? Switching inputs is
not going to help me track down the problem at all. C'mon, I may be a
'self-taught' novice electronics tinkerer, but that is downright stupid - I
already said the music plays fine for a few seconds after it warms up then it
fades out, so obviously its not a problem of a flakey input.. sheesh.

Perhaps I should have specified that the unit worked fine before I
recapped it.
It had a bit of a squishy sound so I figured it could use a re-capping
but I
must've screwed up somehow. But re-capping is pretty straight-forward,
and I think I did it right. So now, what could have gone wrong?

It does not work now....

Switching inputs is not going to help me track down the problem at all.
C'mon, I may be a 'self-taught' novice electronics tinkerer, but that
is downright stupid - I already said the music plays fine for a few
seconds after it warms up then it fades out, so obviously its not a
problem of a flakey input.. sheesh.


So troubleshoot it and find the problem. The small difference in capacitor
values you replaced is 99.999999999999999999% likely not to be the problem.

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

Hi!

Perhaps I should have specified that the unit worked fine before
I recapped it. It had a bit of a squishy sound so I figured it could
use a re-capping but I must've screwed up somehow.

Perhaps you have a new capacitor that is bad? It is unlikely but *does*
happen. A check would be worthwhile and won't take too long.

So now, what could have gone wrong?

There could be a bad cap, or another component that failed. You will have to
do some testing of the unit.

Switching inputs is not going to help me track down the problem at all.

Yes it can. If you still don't agree, stop and think about the the
construction of most audio amplifying equipment. Many power
amplifier/receiver units have multiple inputs that may be selected. All of
them lead to the same place, but before they are merged, each one is a
separate circuit...and a fault could develop in the circuitry that is unique
to each input. If you haven't tried this idea, hook up your audio source to
another compatible input. For example, if you're using a tuner as an audio
source, you could hook it to any of the tuner connector, tape connector or
even the AUX connector. On most equipment they all use similar signal levels
and characteristics.

Please take the suggestions you receive seriously. No one here can see your
workbench or know some of the things you know about the equipment you're
working on. For that reason, we *have* to cover the basics in an effort to
get on the same page that you are on.

William

In article 40NYh.22211$n_.17913@attbi_s21,
says...


Please take the suggestions you receive seriously. No one here can see your
workbench or know some of the things you know about the equipment you're
working on.

They should at least know that an ancient tube receiver is not going to have
more than one input. It's rare for a tube receiver to even have a single AUX
input, only high-end models had an input. I was hoping to hear from people
with experience with tube receivers, and people who suggest testing a matrix of
inputs clearly do not.

Hi!

They should at least know that an ancient tube receiver is not going
to have more than one input.

That's simply not true. Please look at the following:
http://greyghost.dyndns.org/knight/
and note the source selection knob on the far right of the amp.

I can select from tuner, tape, turntable, and auxiliary inputs on that
receiver. It is very clearly tube powered (4xEL84). This is a 1959 era
receiver. At that time, many people had a desire to hear not only radio
programming, but also selections from their collection of record albums. If
you purchased a separate amp.

Yes, I see you saying something like "that's not the ancient I had in mind"
and I do suppose you have to draw the line somewhere when looking at various
generations of technology. 1959 wasn't exactly yesterday, however. :-) Even
many older systems have at least a switch between tuner and phono sources.

I don't know that I believe it when you say that it is rare for a tube
receiver to have multiple inputs. I don't doubt but what yours could be
different--however, we still have no model number or even a brand name to go
by.

As I said before, please *don't* make it difficult. We're all here to help.
Put quite bluntly, nobody here is in any way required to help you. I
sincerely suggest you consider this when visiting any public forum and
asking for assistance. This desire to help tends to get a bit "squelched" in
the face of rude behavior.

And I still think testing your newly installed capacitors is a good
idea...should you get the amp fixed, I would like to know how it played out,
if you are willing to say.

William

In message zhAYh.5325$Dq6.782@edtnps82, Derwin
writes
It had a bit of a squishy sound so I figured it could use a re-capping but I
must've screwed up somehow. But re-capping is pretty straight-forward, and I
think I did it right. So now, what could have gone wrong?
Hmm, let's think about it for a moment, it worked before you screwed
with it, you screwed around with it, it doesn't work now... Anything
leap out at you? Ten points if you came to the same diagnosis as me...
Switching inputs is
not going to help me track down the problem at all. C'mon, I may be a
'self-taught' novice electronics tinkerer, but that is downright stupid - I
already said the music plays fine for a few seconds after it warms up then it
fades out, so obviously its not a problem of a flakey input.. sheesh.
Flakey downright rude tinkerer IMHO.



--
Clint Sharp

In article ,
says...


Flakey downright rude tinkerer IMHO.

More like tinkerer who doesn't suffer fools gladly. Considering I've been
cordial and thankful to those who have responded cordially and helpfully, why
should I patronize the jerks? As long as non-jerks respond, which they have,
anything posted by the jerk-squad is superfulous, and can be either ignored, or
ridiculed. Either way they're useless responses so it doesn't matter how or
if I reply to them. I've been using usenet for long enough to know that any
time I post to any group looking for information, half of the responses are
likely going to be from socially-deranged usenet-lifers. Socially-deranged
usenet-lifers are always in denial and don't realize that they are
socially-deranged usenet-lifers. Some of the time I think they even believe
they are offering helpful advice, because if they don't pepper their initial
reponses with insults they expect immense gratitude, even if what they said was
inapplicable or irrelevent.

Derwin wrote:
In article ,
says...


Flakey downright rude tinkerer IMHO.


More like tinkerer who doesn't suffer fools gladly. Considering I've been
cordial and thankful to those who have responded cordially and helpfully, why
should I patronize the jerks? As long as non-jerks respond, which they have,
anything posted by the jerk-squad is superfulous, and can be either ignored, or
ridiculed. Either way they're useless responses so it doesn't matter how or
if I reply to them. I've been using usenet for long enough to know that any
time I post to any group looking for information, half of the responses are
likely going to be from socially-deranged usenet-lifers. Socially-deranged
usenet-lifers are always in denial and don't realize that they are
socially-deranged usenet-lifers. Some of the time I think they even believe
they are offering helpful advice, because if they don't pepper their initial
reponses with insults they expect immense gratitude, even if what they said was
inapplicable or irrelevent.


I agree. I am a professional electronics tech for over 40 years and
nowhere in this newsgroup does it say its for professionals only. I
applaud those people who want to challenge themselves and tackle
something they haven't done before. I can say I have made many mistakes,
some rookie mistakes and some that I knew better but made them anyway.
My worst was resting my left arm on a metal TV cabinet with a mirror as
I was making an adjustment. I caught a stand-up resistor in the power
supply right off the rectifier tube with my right arm and almost ended
my life. Pretty dumb. But I am sure we have all made some mistakes like
solder bridges or cold solder, wrong values, etc.

Now...the absolute best advice I can give is that in a new venture that
one has not undertaken before is to ask FIRST in this newsgroup. I
myself would be more than happy to point someone in the right direction
before they start. Remember there are no stupid questions, only stupid
answers.

Jim

Derwin wrote:
In article 5HzYh.5314$Dq6.1620@edtnps82, says...


"Derwin" wrote in message
news:6mzYh.5305$Dq6.3498@edtnps82...


I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn
it
on it starts playing music for a few seconds after it warms up, then the
music
fades out and and hum takes over. I don't really know what I'm doing, and
the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced
the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper
caps,
and I'm wondering if the value difference, added up over 8 caps would make
a
difference?

No.


That's not what I've read. Are you sure you're not thinking of electrolytics?


Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be
helpful..

At this point you need to fault find. Does it work OK with tape or other
music input?



Perhaps I should have specified that the unit worked fine before I recapped it.
It had a bit of a squishy sound so I figured it could use a re-capping but I
must've screwed up somehow. But re-capping is pretty straight-forward, and I
think I did it right. So now, what could have gone wrong? Switching inputs is
not going to help me track down the problem at all. C'mon, I may be a
'self-taught' novice electronics tinkerer, but that is downright stupid - I
already said the music plays fine for a few seconds after it warms up then it
fades out, so obviously its not a problem of a flakey input.. sheesh.


My guess is that it is a heater-cathode short in one of the audio tubes.
My reasoning is that when a tube is cold the elements are not shorting
but after some thermal expansion they may short out. Why it is doing it
now but not before could be from turning the chassis upside/down and
having a piece of crap in side the tube in question move to a sensitive
area.

Electrolytics if leaky will hum first and then play which is the
opposite of what is happening.

Personally, I would change ALL the caps at least in the ausio section
including the power supply electrolytics.

Hope this may shed some light for you.

Jim

Jim Poore wrote:
Derwin wrote:

In article 5HzYh.5314$Dq6.1620@edtnps82, says...


"Derwin" wrote in message
news:6mzYh.5305$Dq6.3498@edtnps82...


I tried to re-cap a tube receiver (amplifier + tuner), and now when
I turn it
on it starts playing music for a few seconds after it warms up, then
the music
fades out and and hum takes over. I don't really know what I'm
doing, and the
wiring inside looks like a mess of spaghetti. I'm pretty sure I
replaced the
caps properly, but I used .068uf WIMA caps to replace .050uf
wax/paper caps,
and I'm wondering if the value difference, added up over 8 caps
would make a
difference?


No.



That's not what I've read. Are you sure you're not thinking of
electrolytics?


Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might
be helpful..


At this point you need to fault find. Does it work OK with tape or
other music input?



Perhaps I should have specified that the unit worked fine before I
recapped it. It had a bit of a squishy sound so I figured it could
use a re-capping but I must've screwed up somehow. But re-capping is
pretty straight-forward, and I think I did it right. So now, what
could have gone wrong? Switching inputs is not going to help me track
down the problem at all. C'mon, I may be a 'self-taught' novice
electronics tinkerer, but that is downright stupid - I already said
the music plays fine for a few seconds after it warms up then it fades
out, so obviously its not a problem of a flakey input.. sheesh.


My guess is that it is a heater-cathode short in one of the audio tubes.
My reasoning is that when a tube is cold the elements are not shorting
but after some thermal expansion they may short out. Why it is doing it
now but not before could be from turning the chassis upside/down and
having a piece of crap in side the tube in question move to a sensitive
area.

Electrolytics if leaky will hum first and then play which is the
opposite of what is happening.

Personally, I would change ALL the caps at least in the ausio section
including the power supply electrolytics.

Hope this may shed some light for you.

Jim
I forgot to mention one thing. What is the voltage rating of the caps
you changed? Is it the same of higher than the ones you replaced? If
the voltage rating is too low that caps might breakdown under voltage.

In tube equipment a good rule of thumb is just go with a 600V rating on
the capacitors. Some amplifiers and I am goin on memory here with
6CA7's may have even higher voltages to deal with.

Jim

In article , says...


I forgot to mention one thing. What is the voltage rating of the caps
you changed? Is it the same of higher than the ones you replaced?

Of course. And from now on, if I don't respond to a question that assumes I am
dumber than I am, assume the answer is that I wasn't that dumb, Ok? For
example, if the next thing someone asks is if I plugged the power cord into a
power socket in the wall, assume that I did when I don't bother responding.

If I didn't know that I had to replace caps with an equal or higher voltage
rating, I wouldn't have tried re-capping the unit in the first place. In fact,
I would think that anyone who didn't know that wouldn't know the difference
between electrolytic caps and wax paper ones anyway.

In article , says...



My guess is that it is a heater-cathode short in one of the audio tubes.
My reasoning is that when a tube is cold the elements are not shorting
but after some thermal expansion they may short out. Why it is doing it
now but not before could be from turning the chassis upside/down and
having a piece of crap in side the tube in question move to a sensitive
area.

Electrolytics if leaky will hum first and then play which is the
opposite of what is happening.

Personally, I would change ALL the caps at least in the ausio section
including the power supply electrolytics.

Hope this may shed some light for you.

The first two paragraphs were helpful, but I certainly don't understand why you
would recommend replacing caps I just replaced. Checking to see if one of the
new caps I installed is bad is one thing, but replacing all the new caps I just
installed with another set of new caps sounds like an excersize in throwing
money down the toilet and nothing else.

Derwin wrote:
In article , says...


My guess is that it is a heater-cathode short in one of the audio tubes.
My reasoning is that when a tube is cold the elements are not shorting
but after some thermal expansion they may short out. Why it is doing it
now but not before could be from turning the chassis upside/down and
having a piece of crap in side the tube in question move to a sensitive
area.

Electrolytics if leaky will hum first and then play which is the
opposite of what is happening.

Personally, I would change ALL the caps at least in the ausio section
including the power supply electrolytics.

Hope this may shed some light for you.


The first two paragraphs were helpful, but I certainly don't understand why you
would recommend replacing caps I just replaced. Checking to see if one of the
new caps I installed is bad is one thing, but replacing all the new caps I just
installed with another set of new caps sounds like an excersize in throwing
money down the toilet and nothing else.

I wasn't implying to change the capacitors all over again, I was saying
that in a new project to change them all. Sorry if I was unclear on that.

Jim

Are these non-polarized caps? Maybe a polarized one is backwards or
leaking. If you have a VTVM or DVM, check biasing in the amplifier to
see if anything changes while it warms up. Also could be a tube with a
heater-cathode short.

Derwin wrote:

I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn it
on it starts playing music for a few seconds after it warms up, then the music
fades out and and hum takes over. I don't really know what I'm doing, and the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper caps,
and I'm wondering if the value difference, added up over 8 caps would make a
difference? Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be helpful..




--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P

**THE-RFI-EMI-GUY** wrote:

Are these non-polarized caps? Maybe a polarized one is backwards or
leaking.

Have you ever seen a 0.050uF polarised cap ?????

Puh-leeeze !


Graham

Eeyore ) writes:
**THE-RFI-EMI-GUY** wrote:

Are these non-polarized caps? Maybe a polarized one is backwards or
leaking.

Have you ever seen a 0.050uF polarised cap ?????

But the problem is we don't really know what he did.

He mentions those capacitors because he couldn't get the exact
value, but he said he recapped the receiver. That implies he
changed all the capacitors.

It would have helped if he'd said why he did the recapping. Because
there was an existing problem, and he hoped it would fix it? Because
he wanted to "improve the sound"? Because he figures they are old
enough that they ought to be replaced?

From what he's said, we don't really know if the problem is due
to the recapping, or existed before.

Michael

"Michael Black" wrote in message
...
Eeyore ) writes:
**THE-RFI-EMI-GUY** wrote:

Are these non-polarized caps? Maybe a polarized one is backwards or
leaking.

Have you ever seen a 0.050uF polarised cap ?????

But the problem is we don't really know what he did.

He mentions those capacitors because he couldn't get the exact
value, but he said he recapped the receiver. That implies he
changed all the capacitors.

It would have helped if he'd said why he did the recapping. Because
there was an existing problem, and he hoped it would fix it? Because
he wanted to "improve the sound"? Because he figures they are old
enough that they ought to be replaced?

From what he's said, we don't really know if the problem is due
to the recapping, or existed before.

Michael


He had mentioned he did so because the audio had a "Squishing" sound to it.
So - I suppose we can take that as he was trying to correct for an audio
issue perhaps.

Michael Black wrote:

But the problem is we don't really know what he did.

He mentions those capacitors because he couldn't get the exact
value, but he said he recapped the receiver. That implies he
changed all the capacitors.

It would have helped if he'd said why he did the recapping. Because
there was an existing problem, and he hoped it would fix it? Because
he wanted to "improve the sound"? Because he figures they are old
enough that they ought to be replaced?

From what he's said, we don't really know if the problem is due
to the recapping, or existed before.


It is common practice for people who restore antique radios. Lots of
the paper insulated capacitors are leaky, so the shotgun that problem
before they damage tubes and other parts from improperly biased tubes.
The extra current can even fry an old power transformer. That was why I
recommended the news:rec.antiques.radio+phono newsgroup. Its an
excellent source of parts and information for this old radios. There
are also people there that make reproductions of hard to find parts and
knobs.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

"Michael A. Terrell" ) writes:
Michael Black wrote:

But the problem is we don't really know what he did.

He mentions those capacitors because he couldn't get the exact
value, but he said he recapped the receiver. That implies he
changed all the capacitors.

It would have helped if he'd said why he did the recapping. Because
there was an existing problem, and he hoped it would fix it? Because
he wanted to "improve the sound"? Because he figures they are old
enough that they ought to be replaced?

From what he's said, we don't really know if the problem is due
to the recapping, or existed before.


It is common practice for people who restore antique radios. Lots of
the paper insulated capacitors are leaky, so the shotgun that problem
before they damage tubes and other parts from improperly biased tubes.
The extra current can even fry an old power transformer. That was why I
recommended the news:rec.antiques.radio+phono newsgroup. Its an
excellent source of parts and information for this old radios. There
are also people there that make reproductions of hard to find parts and
knobs.

I'm not arguing against the practice, just pointing out that why
someone does it might help define where the problem lies.

If there was an existing problem, the capacitors just might not
have been the problem.

If there was no problem, but now there is, then it's indicative of some
issue related to the replaced capacitors (though obviously it can always be
some coincidence that something else failed at this moment).

It's not going to be due to those .068uF capacitors because their
value is different, but obviously it could be a bad electrolytic replacement,
or perhaps a reversed electrolytic. It might be a coupling capacitor
that turns out bad. It could be that in the spaghetti the poster overlooked
a capacitor that ends up being the problem.

It's obviously easy to shotgun replace parts when something fails, but
if that doesn't solve the problem, nothing's been done to figure out
where the problem lies. As it now stands, the capacitors have been
changed and there is still a problem.

Michael

In article , says...

Eeyore ) writes:
**THE-RFI-EMI-GUY** wrote:

Are these non-polarized caps? Maybe a polarized one is backwards or
leaking.

Have you ever seen a 0.050uF polarised cap ?????

But the problem is we don't really know what he did.

He mentions those capacitors because he couldn't get the exact
value, but he said he recapped the receiver.

No Michael, I said that I replacede .050uF wax paper caps with .068uf WIMA
caps. Eeyore is right, it was a stupid reply.


It would have helped if he'd said why he did the recapping. Because
there was an existing problem, and he hoped it would fix it? Because
he wanted to "improve the sound"? Because he figures they are old
enough that they ought to be replaced?

From what he's said, we don't really know if the problem is due
to the recapping, or existed before.

Perhaps you should've read my next post in the thread which answered those
questions, before wasting your time with your irrelevnet post? My post with
those answers was posted long before you decided to post pretending I hadn't
already answered those questions.

In article , says...

Are these non-polarized caps? Maybe a polarized one is backwards or
leaking.

non-electrolytics are not polarized, and doncha think I would've double,
triple, and quadruple-checked the orientation of the electrolytics I just
installed BEFORE posting here, knowing that doing so would be opening myself up
to A) redundant or irrelevent responses and B) abuse from the usenet-lifers who
consider any post for advice to be troll-bait?

Derwin wrote:
I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn it
on it starts playing music for a few seconds after it warms up, then the music
fades out and and hum takes over. I don't really know what I'm doing, and the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper caps,
and I'm wondering if the value difference, added up over 8 caps would make a
difference? Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be helpful..


Obviously what you did caused the problem. Check for cold solder
joints and inadvertent connections via solder flash. If you have
enough information (e.g. a detailed log of what you did, or
before/after photos), go back and recheck your work.

Did it look like spaghetti before you started?

From your description, it sounds like maybe it's drawing more current
now than before, so that the power supply capacitors are no longer
adequate. Does it have a rectifier tube in the power supply? Is it
glowing red? Perhaps you've dramatically changed the bias point in
the output stage by some misconnection.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

In article , says...

Derwin wrote:
I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn
it
on it starts playing music for a few seconds after it warms up, then the
music
fades out and and hum takes over. I don't really know what I'm doing, and
the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced
the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper caps,
and I'm wondering if the value difference, added up over 8 caps would make a
difference? Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be
helpful..


Obviously what you did caused the problem. Check for cold solder
joints and inadvertent connections via solder flash. If you have
enough information (e.g. a detailed log of what you did, or
before/after photos), go back and recheck your work.

Did it look like spaghetti before you started?


YES. Why are you even replying if you obviously have never looked inside an
old tube amp?


From your description, it sounds like maybe it's drawing more current
now than before, so that the power supply capacitors are no longer
adequate. Does it have a rectifier tube in the power supply?

probably

Is it
glowing red?

they're all glowing and I tested every tube a few months ago and they were all
fine. I no longer have a tube-tester to check again, however.

Perhaps you've dramatically changed the bias point in
the output stage by some misconnection.


All the caps I replaced are connected exactly where they were before I replaced
them. What I'm thinking is that the guy who sold it to me, after having
'restored' it from non-working condition wired it up in some jeri-rigged
fashion to get it to look like it was working enough to be able to sell it to
me. Probably one of the caps was bad and compensating for a bad resistor as
someone else mentioned. However, the wiring he added did not contribute to the
'spaghetti' much. Anyone who has ever looked inside any old electronics from
before the days of circuit-boards will know what 'spaghetti' wiring looks like.
Those who havent, try this: Look at a circuitboard populated with a bunch of
components. Look at the traces the circuit makes on the back of the board. Now
imagine each one of those traces being replaced with a wire. Now perhaps you
will be able to envision the 'spaghetti' wiring that a circuit not build on a
PCB will look like.. Anyway now I'm pretty much screwed. I don't own an
oscilliscope so I will probably just sell off the tubes and toss the chassis.
I prefer the sound of solid-state these days anyway, my interest in tube gear
was a folly that only lasted a couple years.

Derwin wrote:

In article , says...

Derwin wrote:

I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn

it

on it starts playing music for a few seconds after it warms up, then the

music

fades out and and hum takes over. I don't really know what I'm doing, and

the

wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced

the

caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper caps,
and I'm wondering if the value difference, added up over 8 caps would make a
difference? Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be

helpful..

Obviously what you did caused the problem. Check for cold solder
joints and inadvertent connections via solder flash. If you have
enough information (e.g. a detailed log of what you did, or
before/after photos), go back and recheck your work.

Did it look like spaghetti before you started?



YES. Why are you even replying if you obviously have never looked inside an
old tube amp?


You know not of what you speak. I was probably repairing tube
equipment before you were born. And much tube equipment is very
un-spaghetti-like.

Or maybe we have different ideas of what spaghetti looks like.



From your description, it sounds like maybe it's drawing more current
now than before, so that the power supply capacitors are no longer
adequate. Does it have a rectifier tube in the power supply?


probably


Is it
glowing red?


they're all glowing and I tested every tube a few months ago and they were all
fine. I no longer have a tube-tester to check again, however.

I meant are the PLATES glowing red. Of course the heaters would be glowing.



Perhaps you've dramatically changed the bias point in
the output stage by some misconnection.



All the caps I replaced are connected exactly where they were before I replaced
them. What I'm thinking is that the guy who sold it to me, after having
'restored' it from non-working condition wired it up in some jeri-rigged
fashion to get it to look like it was working enough to be able to sell it to
me. Probably one of the caps was bad and compensating for a bad resistor as
someone else mentioned. However, the wiring he added did not contribute to the
'spaghetti' much. Anyone who has ever looked inside any old electronics from
before the days of circuit-boards will know what 'spaghetti' wiring looks like.
Those who havent, try this: Look at a circuitboard populated with a bunch of
components. Look at the traces the circuit makes on the back of the board. Now
imagine each one of those traces being replaced with a wire. Now perhaps you
will be able to envision the 'spaghetti' wiring that a circuit not build on a
PCB will look like.. Anyway now I'm pretty much screwed. I don't own an
oscilliscope

.... or even know how to spell it.

so I will probably just sell off the tubes and toss the chassis.
I prefer the sound of solid-state these days anyway, my interest in tube gear
was a folly that only lasted a couple years.



--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

"CJT" wrote in message
...
Derwin wrote:

In article , says...

Derwin wrote:

I tried to re-cap a tube receiver (amplifier + tuner), and now when I
turn

it
on it starts playing music for a few seconds after it warms up, then the

music
fades out and and hum takes over. I don't really know what I'm doing,
and

the
wiring inside looks like a mess of spaghetti. I'm pretty sure I
replaced

the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper
caps, and I'm wondering if the value difference, added up over 8 caps
would make a difference? Other than that, does anyone have any advice
based on my description of the unit's behavior? Any comments whatsoever
might be

helpful..

Obviously what you did caused the problem. Check for cold solder
joints and inadvertent connections via solder flash. If you have
enough information (e.g. a detailed log of what you did, or
before/after photos), go back and recheck your work.

Did it look like spaghetti before you started?



YES. Why are you even replying if you obviously have never looked inside
an old tube amp?


You know not of what you speak. I was probably repairing tube
equipment before you were born. And much tube equipment is very
un-spaghetti-like.

Or maybe we have different ideas of what spaghetti looks like.



From your description, it sounds like maybe it's drawing more current
now than before, so that the power supply capacitors are no longer
adequate. Does it have a rectifier tube in the power supply?


probably


Is it
glowing red?


they're all glowing and I tested every tube a few months ago and they
were all fine. I no longer have a tube-tester to check again, however.

I meant are the PLATES glowing red. Of course the heaters would be
glowing.



Perhaps you've dramatically changed the bias point in
the output stage by some misconnection.



All the caps I replaced are connected exactly where they were before I
replaced them. What I'm thinking is that the guy who sold it to me,
after having 'restored' it from non-working condition wired it up in some
jeri-rigged fashion to get it to look like it was working enough to be
able to sell it to me. Probably one of the caps was bad and compensating
for a bad resistor as someone else mentioned. However, the wiring he
added did not contribute to the 'spaghetti' much. Anyone who has ever
looked inside any old electronics from before the days of circuit-boards
will know what 'spaghetti' wiring looks like. Those who havent, try this:
Look at a circuitboard populated with a bunch of components. Look at the
traces the circuit makes on the back of the board. Now imagine each one
of those traces being replaced with a wire. Now perhaps you will be able
to envision the 'spaghetti' wiring that a circuit not build on a PCB will
look like.. Anyway now I'm pretty much screwed. I don't own an
oscilliscope

... or even know how to spell it.

so I will probably just sell off the tubes and toss the chassis.
I prefer the sound of solid-state these days anyway, my interest in tube
gear was a folly that only lasted a couple years.


--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

Even the best of us who've got years of experience can make errors. Unless
you were in a shop working side by side with or had access to other techs -
"tough dogs" could really cause some wasted time. This forum and many others
like it - provides an invaluable asset to all of us for working on things.
None of us could know ALL the answers. Some things don't make sense
sometimes and aren't always so clear to the eye.
I've seen things appear to buck all theory - but - I still found the cause
and corrected the issue. You have to keep an open mind when doing this
stuff. Unless you can definately say an area/circuit has been isolated as
not being at fault - don't rule it out.

It is those issues where you must stop - analyze what has been done, all
previous and current signs and so on. Any "help" issued - is a plus. Of
course - it helps to give a complete and thorough analysis of the problems
before you started, all steps taken and so on - as none of us can see your
project, have a clue what you've done OR know your experience to know
where/how to proceed to help. Are we to give you "basic" electronics
knowledge to help OR are you advanced with lots of equipment we can tell you
to use, etc.?
You said you left out telling us some of the things you've done - which you
apparently thought mundane items. Who knows - one of those steps - might
have clued one of us in - to your problem!

Maybe not ALL of our ideas will help - but only because we do NOT know your
exact situation. So - rather than shoot down any helpful ideas - take them
in stride - try them out - or mark them all down - take a day and do them -
then get back to us with the results.

OH and as for your new parts - IT IS POSSIBLE to buy defective parts. I've
had it happen. I'm sure others have too. Radio Shack was good for that. As
an example, I ordered a transistor once for a CB set - the issue narrowed
down. I was sent a "replacement". I didn't bother to check it before
installation. Turn on the switch - and smoke appeared. I checked it - and
called the parts supplier. Here - THEY had a transistor "marked in their
records" as a Sub - when in fact it was not. They apologized to me for the
error - sent me a new "correct" part and offered to pay me for my time and
any other damaged parts. And with the RS parts - I've had occasion to plug
in a diode, transistor, etc. and find it to be bad. Took back out of circuit
and tests revealed open parts in most cases. It might be extra work, but I
double check my parts (if I can) - before installing. I'd rather know
they're good BEFORE I put them in than to find out after - they weren't. In
most cases, that few seconds can save a lot more time. And I HAVE caught a
few more "defective" new parts since I've learned to do this from
experience.

As to your caps - I've seen many a chat in these groups discussing some
brands to be very poor in quality - so who knows - maybe you latched on to
some of those? At this point - anything is possible. Some of the other folks
gave some damned good advice - best to just take time to prove out one way
or another - what is happening. For now - we're all guessing - since we're
going by what you say and we're not there to see it.

As for "Spaghetti" - that term could be overkill. Wiring used before PC
boards was often labeled as such. Even afterwards. Be it a lot of wiring or
a little - the term could be being used. It is no big deal. The only way it
could make a difference is if a wire "is" going to a wrong place, a piece of
braid or a stray conductor from one of them is shorting OR something along
the lines of inductance is happening as a result.

Don't give up on the project - "LEARN" from it. The knowledge acquired from
repairing it could outweigh any cost you've got into it thus far. I can't
recall if you've got the schematic for it or not - if not - you may want to
get it and study and compare. That could be immeasureable.

As to the sound being "Squishy" - here's where a scope "may" have come in
handy "BEFORE" tearing into it.
So.......... there are lots of things to look at and consider. NO - you
don't want to "waste" time - no one does. But in this case - working in the
dark - there may be little choice til something starts to present itself.

Just my 2 cents.

Derwin wrote:
I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn it
on it starts playing music for a few seconds after it warms up, then the music
fades out and and hum takes over. I don't really know what I'm doing, and the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper caps,
and I'm wondering if the value difference, added up over 8 caps would make a
difference? Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be helpful..

Sounds like you got an electrolytic cap in backward. They are polarity
sensitive.

Bill

"Derwin" wrote in message
news:6mzYh.5305$Dq6.3498@edtnps82...
I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn
it
on it starts playing music for a few seconds after it warms up, then the
music
fades out and and hum takes over. I don't really know what I'm doing, and
the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced
the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper
caps,
and I'm wondering if the value difference, added up over 8 caps would make
a
difference? Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be
helpful..

Maybe a tube has gone west ... internal leakage caused by mechanical
disturbance when working on it? Tubes get hot and sometimes cathode leakage
follows a brief warm-up period.

Also, you did not mention the voltage ratings of the capacitors.

Often, hum is caused by the power supply filter caps but your symptoms don't
quite fit that.

In article ,
says...


"Derwin" wrote in message
news:6mzYh.5305$Dq6.3498@edtnps82...
I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn
it
on it starts playing music for a few seconds after it warms up, then the
music
fades out and and hum takes over. I don't really know what I'm doing, and
the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced
the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper
caps,
and I'm wondering if the value difference, added up over 8 caps would make
a
difference? Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be
helpful..

Maybe a tube has gone west ... internal leakage caused by mechanical
disturbance when working on it? Tubes get hot and sometimes cathode leakage
follows a brief warm-up period.

Also, you did not mention the voltage ratings of the capacitors.

That's because I already knew that I had replaced the caps with caps of equal
or higher voltage specs. I could've written 20 pages describing every detail,
but I omit the details that don't matter in order to emphasize the details that
do matter. But I do understand that that particular detail matters enough that
I probably should have reassured readers that I was already ontop of it.


Often, hum is caused by the power supply filter caps but your symptoms don't
quite fit that.



Thanks for being one of the few responders who was able to consider the
symptoms and extrapolate some possibilities from the symptoms.

(Derwin) wrote in
news:6mzYh.5305$Dq6.3498@edtnps82:

I tried to re-cap a tube receiver (amplifier + tuner), and now when I
turn it on it starts playing music for a few seconds after it warms
up, then the music fades out and and hum takes over. I don't really
know what I'm doing, and the wiring inside looks like a mess of
spaghetti. I'm pretty sure I replaced the caps properly, but I used
.068uf WIMA caps to replace .050uf wax/paper caps, and I'm wondering
if the value difference, added up over 8 caps would make a difference?
Other than that, does anyone have any advice based on my description
of the unit's behavior? Any comments whatsoever might be helpful..



Do you have a tube manual, look up G1 of the preamp and power output
tubes. Check the dc voltage when it is not working they should not be a
positive voltage on them if so check the new capacitor connected to that
tube. Extremely high negative voltage check the grid resistor.

Of course I assume you have a high imput impeadance voltmeter there.

I would like the brand and model # if you wouldn't mind.

R!

On Apr 27, 8:39 pm, (Derwin) wrote:
I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn it
on it starts playing music for a few seconds after it warms up, then the music
fades out and and hum takes over. I don't really know what I'm doing, and the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper caps,
and I'm wondering if the value difference, added up over 8 caps would make a
difference? Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be helpful..

the squishy sound was due to power supply issues... could have been
a cap issue floating around.. u need to take careful measurements of
ur power supply a VTVM will not load down the circuits when u look at
them.. good luck

On Apr 28, 4:39 am, (Derwin) wrote:
I tried to re-cap a tube receiver (amplifier + tuner), and now when I turn it
on it starts playing music for a few seconds after it warms up, then the music
fades out and and hum takes over. I don't really know what I'm doing, and the
wiring inside looks like a mess of spaghetti. I'm pretty sure I replaced the
caps properly, but I used .068uf WIMA caps to replace .050uf wax/paper caps,
and I'm wondering if the value difference, added up over 8 caps would make a
difference? Other than that, does anyone have any advice based on my
description of the unit's behavior? Any comments whatsoever might be helpful..


Go to paul stenning's 'uk vintage radio repair and restoration
forum' . There you will find numerous specialists. Post the exact
model and make and year if poss.
-B.