| Author |
Message |
G M
Guest
|
 Posted:
Sat Feb 05, 2005 5:26 am Post subject:
Newbie question re: AV Receiver |
|
|
I am a total newbie to electronics in general so please bare with me.
I am looking at a used Denon Av receiver that can be purchased for literally
pennies on the dollar, but the unit doesn't work. The owner says that all
that is wrong with it that it has an OPEN PRIMARY, and it should be a cheap
repair.
If someone could explain to me what an OPEN PRIMARY is, and what that sort
of repair should cost it would be much appreciated.
Thanks in advance for whatever help anybody can offer.
|
|
| Back to top |
|
 |
Charles Schuler
Guest
|
| Posted:
Sat Feb 05, 2005 5:48 am Post subject:
Re: Newbie question re: AV Receiver |
|
|
"G M" <nyteryder@hotmail.com> wrote in message
news:swTMd.271618$6l.162290@pd7tw2no...
| Quote: | I am a total newbie to electronics in general so please bare with me.
I am looking at a used Denon Av receiver that can be purchased for
literally pennies on the dollar, but the unit doesn't work. The owner says
that all that is wrong with it that it has an OPEN PRIMARY, and it should
be a cheap repair.
If someone could explain to me what an OPEN PRIMARY is, and what that sort
of repair should cost it would be much appreciated.
|
Usually means that the power transformer winding that is connected to the AC
mains is open. If that is so, a new transformer will be required to fix it. |
|
| Back to top |
|
|
NSM
Guest
|
| Posted:
Sat Feb 05, 2005 10:31 am Post subject:
Re: Newbie question re: AV Receiver |
|
|
"G M" <nyteryder@hotmail.com> wrote in message
news:swTMd.271618$6l.162290@pd7tw2no...
| Quote: | I am a total newbie to electronics in general so please bare with me.
I am looking at a used Denon Av receiver that can be purchased for
literally
pennies on the dollar, but the unit doesn't work. The owner says that all
that is wrong with it that it has an OPEN PRIMARY, and it should be a
cheap
repair.
If someone could explain to me what an OPEN PRIMARY is, and what that sort
of repair should cost it would be much appreciated.
|
$100 maybe?
--
N
|
|
| Back to top |
|
|
Mark D. Zacharias
Guest
|
| Posted:
Sat Feb 05, 2005 5:33 pm Post subject:
Re: Newbie question re: AV Receiver |
|
|
The power transformer is bad. Sometimes a knowledgeable type can bypass a
thermal link, but if not done properly this can be dangerous. A new
transformer is best, but this is the most expensive part in the receiver,
and may not even be available anymore, depending on the age of the unit.
Mark Z.
"G M" <nyteryder@hotmail.com> wrote in message
news:swTMd.271618$6l.162290@pd7tw2no...
| Quote: | I am a total newbie to electronics in general so please bare with me.
I am looking at a used Denon Av receiver that can be purchased for
literally pennies on the dollar, but the unit doesn't work. The owner says
that all that is wrong with it that it has an OPEN PRIMARY, and it should
be a cheap repair.
If someone could explain to me what an OPEN PRIMARY is, and what that sort
of repair should cost it would be much appreciated.
Thanks in advance for whatever help anybody can offer.
|
|
|
| Back to top |
|
|
worldcitizen
Guest
|
| Posted:
Sat Feb 05, 2005 9:45 pm Post subject:
Re: Newbie question re: AV Receiver |
|
|
G M wrote:
| Quote: | I am a total newbie to electronics in general so please bare with me.
I am looking at a used Denon Av receiver that can be purchased for
literally
pennies on the dollar, but the unit doesn't work. The owner says that
all
that is wrong with it that it has an OPEN PRIMARY, and it should be a
cheap
repair.
If someone could explain to me what an OPEN PRIMARY is, and what that
sort
of repair should cost it would be much appreciated.
Thanks in advance for whatever help anybody can offer.
|
This is almost always an open thermal fuse that is tucked into the
windings right where the ac power goes into the transformer. It is
pretty important that you NOT bypass this fuse as it is supposed to
keep your transformer from catching fire. I've been sucessful on
several occasions with unsoldering the primary winding enamal wires
from the very small "terminal board" that is part of the transformer
and thereby gain access to the thermal fuse after removing (carefully)
that board. Sometimes you will have to semi-destroy that board to get
to the fuse. Just be sure to preserve as much of the terminals that
you can. The fuse is wired in series with one of those two wires and it
will probably have it's own terminal on that board. The fuse will be
tucked way down into the transformer core and you may only be able to
see its two wires. As gently and as carefully as you can try to pull
the fuse out by it's wires so as not to damage the windings of the
transformer. Once you get it out (if you can get it out), read the
temperature value on its side and try to replace it with one of egual
or LESS value. They are usually in the range of about 260 degrees
Farenheit. If possible, tuck the new one back in where the old one came
out. It needs to be in "intimate" contact with the windings of the
transformer. If you cannot tuck it back into its original location,
one thing I've done is to lay it tightly against the "bare" windings
that were exposed upon removing the covering terminal board, making as
much surface contact as possible with the actual windings ,not the
paper or plactic covered windings. The whole purpose of this fuse is
to monitor the temperature of the transformer core and open up if it
gets too hot. If you cannot put the fuse back in its original tucked
in position and must instead resort to laying against the side of the
windings as I've suggested, then it is advisable to use a thermal fuse
that opens at several degrees less, maybe 20 degrees or more less.
Once the fuse is soldered in place and right where you want it, then
glue it down with silicon rubber glue. BE SURE TO HEAT SINK THE
THERMAL FUSES LEADS WHEN YOU ARE SOLDERING AND LIMIT THE TIME YOUR IRON
IS ON THE LEADS TO AS SHORT A TIME AS POSSIBLE, IF NOT YOU MIGHT OPEN
THE FUSE WITH YOUR SOLDERING PROCESS. Then you are ready for power.
You should run the unit under full load for a while (30 minutes?) to
see if the transformer is running hot. If it is, then your next step
is to find out why it is running hot. Good Luck. |
|
| Back to top |
|
|
James Sweet
Guest
|
| Posted:
Sat Feb 05, 2005 9:45 pm Post subject:
Re: Newbie question re: AV Receiver |
|
|
"worldcitizen" <duncan@koyote.com> wrote in message
news:1107620912.381233.189340@z14g2000cwz.googlegroups.com...
| Quote: |
G M wrote:
I am a total newbie to electronics in general so please bare with me.
I am looking at a used Denon Av receiver that can be purchased for
literally
pennies on the dollar, but the unit doesn't work. The owner says that
all
that is wrong with it that it has an OPEN PRIMARY, and it should be a
cheap
repair.
If someone could explain to me what an OPEN PRIMARY is, and what that
sort
of repair should cost it would be much appreciated.
Thanks in advance for whatever help anybody can offer.
This is almost always an open thermal fuse that is tucked into the
windings right where the ac power goes into the transformer. It is
pretty important that you NOT bypass this fuse as it is supposed to
keep your transformer from catching fire. I've been sucessful on
several occasions with unsoldering the primary winding enamal wires
from the very small "terminal board" that is part of the transformer
and thereby gain access to the thermal fuse after removing (carefully)
that board. Sometimes you will have to semi-destroy that board to get
to the fuse. Just be sure to preserve as much of the terminals that
you can. The fuse is wired in series with one of those two wires and it
will probably have it's own terminal on that board. The fuse will be
tucked way down into the transformer core and you may only be able to
see its two wires. As gently and as carefully as you can try to pull
the fuse out by it's wires so as not to damage the windings of the
transformer. Once you get it out (if you can get it out), read the
temperature value on its side and try to replace it with one of egual
or LESS value. They are usually in the range of about 260 degrees
Farenheit. If possible, tuck the new one back in where the old one came
out. It needs to be in "intimate" contact with the windings of the
transformer. If you cannot tuck it back into its original location,
one thing I've done is to lay it tightly against the "bare" windings
that were exposed upon removing the covering terminal board, making as
much surface contact as possible with the actual windings ,not the
paper or plactic covered windings. The whole purpose of this fuse is
to monitor the temperature of the transformer core and open up if it
gets too hot. If you cannot put the fuse back in its original tucked
in position and must instead resort to laying against the side of the
windings as I've suggested, then it is advisable to use a thermal fuse
that opens at several degrees less, maybe 20 degrees or more less.
Once the fuse is soldered in place and right where you want it, then
glue it down with silicon rubber glue. BE SURE TO HEAT SINK THE
THERMAL FUSES LEADS WHEN YOU ARE SOLDERING AND LIMIT THE TIME YOUR IRON
IS ON THE LEADS TO AS SHORT A TIME AS POSSIBLE, IF NOT YOU MIGHT OPEN
THE FUSE WITH YOUR SOLDERING PROCESS. Then you are ready for power.
You should run the unit under full load for a while (30 minutes?) to
see if the transformer is running hot. If it is, then your next step
is to find out why it is running hot. Good Luck.
|
Bypass it to test, if the reciever works ok then get a new thermal fuse. |
|
| Back to top |
|
|
GM
Guest
|
| Posted:
Sun Feb 06, 2005 5:09 am Post subject:
Re: Newbie question re: AV Receiver |
|
|
G M wrote:
| Quote: | I am a total newbie to electronics in general so please bare with me.
I am looking at a used Denon Av receiver that can be purchased for literally
pennies on the dollar, but the unit doesn't work. The owner says that all
that is wrong with it that it has an OPEN PRIMARY, and it should be a cheap
repair.
If someone could explain to me what an OPEN PRIMARY is, and what that sort
of repair should cost it would be much appreciated.
Thanks in advance for whatever help anybody can offer.
Thanks for all your replies, The info really helped |
|
|
| Back to top |
|
|
|
|
|
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in