Fender Deluxe Reverb Question

Discussion:

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guitarPsych

2006-05-25 01:57:02 UTC

I have resistors on my pilot light yet cannot find an amp layout that
shows this. The resistors are burned too bad to tell the color code.
Suggestions?

I have a DR from about 1972 (date based on silverface, no aluminum
trim on grill, no late 70s pull/volume pot).

I started to replace the caps today and thought about a time about a
month ago when my pilot light burned out. I replaced it, but since I
had the chassis open today, I looked inside, and noticed there are two
resistors coming off the pilot light. They are both fried. When I
look on an amp layout printout, I don't see these resistors, instead it
just goes to FIL. Should I replace the resistors? If so, anyone know
the value of the resistors (they are too burned to accurately read the
color codes). Anyone have a layout that shows these two resistors?

MikeyMann

2006-05-25 03:16:43 UTC

Permalink

I have resistors on my pilot light yet cannot find an amp layout that shows
this. The resistors are burned too bad to tell the color code.
Suggestions?
I have a DR from about 1972 (date based on silverface, no aluminum
trim on grill, no late 70s pull/volume pot).
I started to replace the caps today and thought about a time about a
month ago when my pilot light burned out. I replaced it, but since I
had the chassis open today, I looked inside, and noticed there are two
resistors coming off the pilot light. They are both fried. When I
look on an amp layout printout, I don't see these resistors, instead it
just goes to FIL. Should I replace the resistors? If so, anyone know
the value of the resistors (they are too burned to accurately read the
color codes). Anyone have a layout that shows these two resistors?

Those are 100ohm resistors. Their function is to form an artificial center
tap for the filaments to help reduce filiment hum. If you use the 100ohm
resistors to ground, you Don't want to use the center tap wire to ground
from the power transformer, if the PT has a filament center tap. You want to
use one or the other, but not both at the same time. Personally, I use the
100ohm resistors to ground off the pilot light. I use some heat shrink on
the end of the filament center tap wire on the PT, and just roll it up and
place it out of the way.

Another benefit of using those 100ohm resistors, is that they also can act
like a fuse if a short develops, and can save the PT from some serious
damage. I was checking some voltages on V7 one evening, and I accidentally
touched my DMM probe against 2 pins on the power tube socket. There was a
quick arc/flash and then I watched as the 100ohm resistors fried right in
half. I replaced them and all was well. Better to lose a 10 cent resistor
than a $150.00 power tranny.

Replace those resistors. If they're fried in half, then your not getting a
center tap ground and you're probably getting noise from the heater string.

Mikey

guitarPsych

2006-05-25 04:45:12 UTC

Permalink

Thanks.
I believe what you are saying, about it acting like a fuse, is what
happened. Somehow, the key on one of the power tube sockets did not
work correctly once when changing tubes and a tube got in the socket
incorrectly. I turned it off quickly. The pilot light went out and I
believe this is when the resistors on the pilot light blew. There was
also a bad resistor on the tube socket (a 470k resistor) which I
replaced. Thanks for the info. Very helpful.

Post by MikeyMann

I have resistors on my pilot light yet cannot find an amp layout that shows
this. The resistors are burned too bad to tell the color code.
Suggestions?
I have a DR from about 1972 (date based on silverface, no aluminum
trim on grill, no late 70s pull/volume pot).
I started to replace the caps today and thought about a time about a
month ago when my pilot light burned out. I replaced it, but since I
had the chassis open today, I looked inside, and noticed there are two
resistors coming off the pilot light. They are both fried. When I
look on an amp layout printout, I don't see these resistors, instead it
just goes to FIL. Should I replace the resistors? If so, anyone know
the value of the resistors (they are too burned to accurately read the
color codes). Anyone have a layout that shows these two resistors?

Those are 100ohm resistors. Their function is to form an artificial center
tap for the filaments to help reduce filiment hum. If you use the 100ohm
resistors to ground, you Don't want to use the center tap wire to ground
from the power transformer, if the PT has a filament center tap. You want to
use one or the other, but not both at the same time. Personally, I use the
100ohm resistors to ground off the pilot light. I use some heat shrink on
the end of the filament center tap wire on the PT, and just roll it up and
place it out of the way.
Another benefit of using those 100ohm resistors, is that they also can act
like a fuse if a short develops, and can save the PT from some serious
damage. I was checking some voltages on V7 one evening, and I accidentally
touched my DMM probe against 2 pins on the power tube socket. There was a
quick arc/flash and then I watched as the 100ohm resistors fried right in
half. I replaced them and all was well. Better to lose a 10 cent resistor
than a $150.00 power tranny.
Replace those resistors. If they're fried in half, then your not getting a
center tap ground and you're probably getting noise from the heater string.
Mikey

MikeyMann

2006-05-26 01:58:02 UTC

Permalink

Post by guitarPsych
Thanks.
I believe what you are saying, about it acting like a fuse, is what
happened. Somehow, the key on one of the power tube sockets did not work
correctly once when changing tubes and a tube got in the socket
incorrectly. I turned it off quickly. The pilot light went out and I
believe this is when the resistors on the pilot light blew. There was
also a bad resistor on the tube socket (a 470k resistor) which I replaced.
Thanks for the info. Very helpful.

Yep, sounds like that may be what happened. Just think what may have
happened to your power tranny if those resistors weren't there to sacrifice
themselves.
Also, that bad screen resistor on the tube socket is a 470ohm resistor, NOT
a 470K. Double check to make sure that you put a 470ohm resistor on the
socket.

Mikey

Phil S.

2006-05-25 03:21:32 UTC

Permalink

I have resistors on my pilot light yet cannot find an amp layout that shows
this. The resistors are burned too bad to tell the color code.
Suggestions?
I have a DR from about 1972 (date based on silverface, no aluminum
trim on grill, no late 70s pull/volume pot).
I started to replace the caps today and thought about a time about a
month ago when my pilot light burned out. I replaced it, but since I
had the chassis open today, I looked inside, and noticed there are two
resistors coming off the pilot light. They are both fried. When I
look on an amp layout printout, I don't see these resistors, instead it
just goes to FIL. Should I replace the resistors? If so, anyone know
the value of the resistors (they are too burned to accurately read the
color codes). Anyone have a layout that shows these two resistors?

I have reservations about telling you about this. It is about basic amp
construction. To a person, almost anyone who reads this group and has ever
been inside an amp knows the answer. I'm not poking fun or anything of the
sort. I assure you my reply is sincere.

It's my judgement that you don't know enough to be fixing your amp and you
should be taking it to a competent tech. I'm serious when I say that your
life is worth the $200 or so you will pay to get your amp in tip-top shape,
and get it done safely. I think you don't realize that you are an accident
looking for a place to happen. You are performing maintenance that you
don't understand.

Yes, those resistors need to be replaced. The keep your filament string
from introducing hum into the circuit. Maybe you can Google this group for
something like "filament resistor" and see what comes up? There is no
guarantee that replacing them will address to cause. The cause needs to be
found!

Sorry for the non-answer. It's out there. You will find some good reading
with it. Get an education before you poke around further.

Phil

guitarPsych

2006-05-25 04:40:42 UTC

Permalink

Thanks for the advice. I agree it is dangerous. I am learning and
attempting to take precautions. I drain the capacitors before poking
around. I need to learn a lot more, that is for sure. Trying to take
things slowly.

Post by Phil S.

I have resistors on my pilot light yet cannot find an amp layout that shows
this. The resistors are burned too bad to tell the color code.
Suggestions?
I have a DR from about 1972 (date based on silverface, no aluminum
trim on grill, no late 70s pull/volume pot).
I started to replace the caps today and thought about a time about a
month ago when my pilot light burned out. I replaced it, but since I
had the chassis open today, I looked inside, and noticed there are two
resistors coming off the pilot light. They are both fried. When I
look on an amp layout printout, I don't see these resistors, instead it
just goes to FIL. Should I replace the resistors? If so, anyone know
the value of the resistors (they are too burned to accurately read the
color codes). Anyone have a layout that shows these two resistors?

I have reservations about telling you about this. It is about basic amp
construction. To a person, almost anyone who reads this group and has ever
been inside an amp knows the answer. I'm not poking fun or anything of the
sort. I assure you my reply is sincere.
It's my judgement that you don't know enough to be fixing your amp and you
should be taking it to a competent tech. I'm serious when I say that your
life is worth the $200 or so you will pay to get your amp in tip-top shape,
and get it done safely. I think you don't realize that you are an accident
looking for a place to happen. You are performing maintenance that you
don't understand.
Yes, those resistors need to be replaced. The keep your filament string
from introducing hum into the circuit. Maybe you can Google this group for
something like "filament resistor" and see what comes up? There is no
guarantee that replacing them will address to cause. The cause needs to be
found!
Sorry for the non-answer. It's out there. You will find some good reading
with it. Get an education before you poke around further.
Phil

Phil S.

2006-05-26 01:16:33 UTC

Permalink

Post by guitarPsych
Thanks for the advice. I agree it is dangerous. I am learning and
attempting to take precautions. I drain the capacitors before poking
around. I need to learn a lot more, that is for sure. Trying to take
things slowly.

Post by Phil S.

Post by guitarPsych
I have resistors on my pilot light yet cannot find an amp layout that
shows this. The resistors are burned too bad to tell the color code.
Suggestions?
I have a DR from about 1972 (date based on silverface, no aluminum
trim on grill, no late 70s pull/volume pot).
I started to replace the caps today and thought about a time about a
month ago when my pilot light burned out. I replaced it, but since I
had the chassis open today, I looked inside, and noticed there are two
resistors coming off the pilot light. They are both fried. When I
look on an amp layout printout, I don't see these resistors, instead it
just goes to FIL. Should I replace the resistors? If so, anyone know
the value of the resistors (they are too burned to accurately read the
color codes). Anyone have a layout that shows these two resistors?

I have reservations about telling you about this. It is about basic amp
construction. To a person, almost anyone who reads this group and has
ever been inside an amp knows the answer. I'm not poking fun or anything
of the sort. I assure you my reply is sincere.
It's my judgement that you don't know enough to be fixing your amp and
you should be taking it to a competent tech. I'm serious when I say that
your life is worth the $200 or so you will pay to get your amp in tip-top
shape, and get it done safely. I think you don't realize that you are an
accident looking for a place to happen. You are performing maintenance
that you don't understand.
Yes, those resistors need to be replaced. The keep your filament string
from introducing hum into the circuit. Maybe you can Google this group
for something like "filament resistor" and see what comes up? There is
no guarantee that replacing them will address to cause. The cause needs
to be found!
Sorry for the non-answer. It's out there. You will find some good
reading with it. Get an education before you poke around further.
Phil

If I could only have one book, "How to Service Your Own Tube Amp", but Tom
Mitchell would be it. It's written for a beginner, but is good for more
than that. Book plus optional video tape if you can find it. I haven't
seen the tape, but I think the book is first class. About $30 and well
worth it. I think AES carries it www.tubesandmore.com along with a pile of
other books. I also have Ritchie Fleiger's book and it's half the price and
one-fourth as informative (not recommended).

I've heard that Gerald Weber's books are a good read and so are Dave Funk's
and Aspen Pittman's but I haven't seen any of them..

Don't buy this stuff from Amazon or Barnes and Noble. The will take months
to get it to you as they are not connected like the tube guys. I suspect
AES has it in stock. A phone call is in order to see if they do. There may
be others who stock it.

guitarPsych

2006-05-25 04:46:43 UTC

Permalink

By the way, where would you suggest getting more training?

Post by Phil S.

I have resistors on my pilot light yet cannot find an amp layout that shows
this. The resistors are burned too bad to tell the color code.
Suggestions?
I have a DR from about 1972 (date based on silverface, no aluminum
trim on grill, no late 70s pull/volume pot).
I started to replace the caps today and thought about a time about a
month ago when my pilot light burned out. I replaced it, but since I
had the chassis open today, I looked inside, and noticed there are two
resistors coming off the pilot light. They are both fried. When I
look on an amp layout printout, I don't see these resistors, instead it
just goes to FIL. Should I replace the resistors? If so, anyone know
the value of the resistors (they are too burned to accurately read the
color codes). Anyone have a layout that shows these two resistors?

I have reservations about telling you about this. It is about basic amp
construction. To a person, almost anyone who reads this group and has ever
been inside an amp knows the answer. I'm not poking fun or anything of the
sort. I assure you my reply is sincere.
It's my judgement that you don't know enough to be fixing your amp and you
should be taking it to a competent tech. I'm serious when I say that your
life is worth the $200 or so you will pay to get your amp in tip-top shape,
and get it done safely. I think you don't realize that you are an accident
looking for a place to happen. You are performing maintenance that you
don't understand.
Yes, those resistors need to be replaced. The keep your filament string
from introducing hum into the circuit. Maybe you can Google this group for
something like "filament resistor" and see what comes up? There is no
guarantee that replacing them will address to cause. The cause needs to be
found!
Sorry for the non-answer. It's out there. You will find some good reading
with it. Get an education before you poke around further.
Phil

Ether

2006-05-25 06:49:18 UTC

Permalink

Post by guitarPsych

Post by Phil S.
Sorry for the non-answer. It's out there. You will find some good reading
with it. Get an education before you poke around further.

By the way, where would you suggest getting more training?

There are various good books on amps, and the internet is a good
source. Take a look at the tech pages on Doug Hoffman's site for
starters. www.hoffmanamps.com.

--E

Ether

2006-05-25 07:00:39 UTC

Permalink

Post by guitarPsych
I have resistors on my pilot light yet cannot find an amp layout that
shows this.

That's typical of many Fender amps.

Post by guitarPsych
The resistors are burned too bad to tell the color code.
Suggestions?

100 ohms. (As Mikey said.)

Post by guitarPsych
I have a DR from about 1972 (date based on silverface, no aluminum
trim on grill, no late 70s pull/volume pot).

Why guess? There are date codes all over the amp. Look at the
transformers.

Post by guitarPsych
I started to replace the caps today and thought about a time about a
month ago when my pilot light burned out. I replaced it, but since I
had the chassis open today, I looked inside, and noticed there are two
resistors coming off the pilot light. They are both fried.

Replace them with two 100 ohm 1/2 watt resistors.

Post by guitarPsych
When I
look on an amp layout printout, I don't see these resistors, instead it
just goes to FIL. Should I replace the resistors? If so, anyone know
the value of the resistors (they are too burned to accurately read the
color codes). Anyone have a layout that shows these two resistors?

Here's a schematic--

Loading Image...

And a layout--

Loading Image...

--E

guitarPsych

2006-05-25 17:41:58 UTC

Permalink

Thanks for the info.
I now have replaced the 100 ohm resistors. Yes, I should just look at
the transformer codes to get the date. I've just never until now really
needed an exact date.

Here's a couple of difficulties with the info you sent:

1) the schematic you sent is a later model, it has the volume boost
knob. Mine does not have that.

2) the layout you sent is for bandmaster.

3) the link you gave for hoffman amps doesn't seem to work.

I've been to many web sites. For some reason I cannot find a layout of
this particular amp. The layouts available are either for the blackface
or for the model with the volume boost.

Post by Ether

Post by guitarPsych
I have resistors on my pilot light yet cannot find an amp layout that
shows this.

That's typical of many Fender amps.

Post by guitarPsych
The resistors are burned too bad to tell the color code.
Suggestions?

100 ohms. (As Mikey said.)

Post by guitarPsych
I have a DR from about 1972 (date based on silverface, no aluminum
trim on grill, no late 70s pull/volume pot).

Why guess? There are date codes all over the amp. Look at the
transformers.

Replace them with two 100 ohm 1/2 watt resistors.

Here's a schematic--
http://www.ampwares.com/ffg/schem/deluxe_reverb_10-6-77_schem.gif
And a layout--
http://www.ampwares.com/ffg/schem/bandmaster_reverb_aa1069_layout.gif
--E

Ether

2006-05-26 01:48:58 UTC

Permalink

Post by guitarPsych

Post by Ether

Post by guitarPsych
I have resistors on my pilot light yet cannot find an amp layout that
shows this.

That's typical of many Fender amps.

Post by guitarPsych
The resistors are burned too bad to tell the color code.
Suggestions?

100 ohms. (As Mikey said.)

Post by guitarPsych
I have a DR from about 1972 (date based on silverface, no aluminum
trim on grill, no late 70s pull/volume pot).

Why guess? There are date codes all over the amp. Look at the
transformers.

Replace them with two 100 ohm 1/2 watt resistors.

Here's a schematic--
http://www.ampwares.com/ffg/schem/deluxe_reverb_10-6-77_schem.gif
And a layout--
http://www.ampwares.com/ffg/schem/bandmaster_reverb_aa1069_layout.gif
--E

Ignore the volume boost.

Post by guitarPsych
2) the layout you sent is for bandmaster.

Here's a little secret--the Bandmaster Reverb, Super Reverb, and Deluxe
Reverb are all pretty much the same. (Don't tell anyone.)

I mainly gave you that layout to show you the 100-ohm resistors.

Post by guitarPsych
3) the link you gave for hoffman amps doesn't seem to work.

http://www.hoffmanamps.com

Works fine.

Post by guitarPsych
I've been to many web sites. For some reason I cannot find a layout of
this particular amp. The layouts available are either for the blackface
or for the model with the volume boost.

Like I said, you can just follow a layout for a Bandmaster Reverb or
Super Reverb from the same period. Check the AB763 DR schematic for
component values, as a few may be different.

--E