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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sun 24, 2017 2:27 am 
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Flipperhome wrote:
Pbpix wrote:
Flipperhome wrote:
While that's physically true you have to remember that the 6AQ5 voltage limits are less than a 6V6.

Yes.. true... but GE set the parameters for this circuit design.

Data sheets show 6V6 max Plate +315v and only +250 for 6AQ5.

In MY 6v6GT / 6AQ5 amp I run 292v on the plate.... so far hasn't exploded.
What does 'GE" have to do with the circuit design?

You're closer than you think because plate is actually B+ minus cathode voltage.

John is repairing a GE radio with 2 6AQ5 tubes ans a 12AX7 etc...
GE designed that radio.
... read his earlier post.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sun 24, 2017 2:32 am 
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Pbpix wrote:
Flipperhome wrote:
Pbpix wrote:
Yes.. true... but GE set the parameters for this circuit design.

Data sheets show 6V6 max Plate +315v and only +250 for 6AQ5.

In MY 6v6GT / 6AQ5 amp I run 292v on the plate.... so far hasn't exploded.
What does 'GE" have to do with the circuit design?

You're closer than you think because plate is actually B+ minus cathode voltage.

John is repairing a GE radio with 2 6AQ5 tubes ans a 12AX7 etc...
GE designed that radio.
... read his earlier post.
The "GE design" has B+ = 268 volts, which will have plate voltage B+ minus the cathode V. Right spot on the spec of 250V.

It's YOUR stated 292 V B+ that I wondered what "GE" had to do with.


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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sun 24, 2017 2:41 am 
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Pbpix wrote:
John:
That GE looks a bit like this RC1671A set.

http://www.antiqueradio.com/Jun10_Schoo ... ation.html



Yes, it does. The exact same turn table. The am-fm radio, and separate amp look the same.
I wonder if one of those manufactures mass produced them for others.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sun 24, 2017 2:43 am 
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The unit sounds very good. It has SE amps, and plenty of volume.
Having problems with the idler wheel. I cleaned it with alcohol but still slips.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sun 24, 2017 2:46 am 
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Flipperhome wrote:
The "GE design" has B+ = 268 volts, which will have plate voltage B+ minus the cathode V. Right spot on the spec of 250V.

It's YOUR stated 292 V B+ that I wondered what "GE" had to do with.

It doesn't.
I was just adding a foot note comment that my amp is operating with those values for better or for worse.

+292v -19v cathode bias = +273v

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sun 24, 2017 4:19 am 
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I think the amp is a model GE 'RC-1641' from 1964, according to Beitmans.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sun 24, 2017 5:38 am 
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john8750 wrote:
I think the amp is a model GE 'RC-1641' from 1964, according to Beitmans.

Here's the schematic:
http://www.radiomuseum.org/schemaviewer ... Fsch%2Epdf

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sun 24, 2017 6:24 am 
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Pbpix wrote:
john8750 wrote:
I think the amp is a model GE 'RC-1641' from 1964, according to Beitmans.

Here's the schematic:
http://www.radiomuseum.org/schemaviewer ... Fsch%2Epdf



They wont let me in.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sun 24, 2017 7:33 am 
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john8750 wrote:
Pbpix wrote:
john8750 wrote:
I think the amp is a model GE 'RC-1641' from 1964, according to Beitmans.

Here's the schematic:
http://www.radiomuseum.org/schemaviewer ... Fsch%2Epdf



They wont let me in.

Try this:
http://pbpix.com/radio/ge%20rc1641.pdf

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Sun 24, 2017 8:41 am 
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That worked, and is the correct schematic.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Mon 25, 2017 1:06 am 
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john8750 wrote:
That worked, and is the correct schematic.

You may want to get membership to www.radiomuseum.org John.
$25 for lifetime.
I had to do some gyrations of trying to copy and save that print then upload it to my web page server and then link you to it there.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Mon 25, 2017 6:02 pm 
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Pbpix wrote:
john8750 wrote:
That worked, and is the correct schematic.

You may want to get membership to http://www.radiomuseum.org John.
$25 for lifetime.
I had to do some gyrations of trying to copy and save that print then upload it to my web page server and then link you to it there.



I will do that peter. Will be handy to use.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Mon 25, 2017 6:06 pm 
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In that schematic, it shows power output for the tuner, on a separate chassis.
That chassis has a selenium rectifier, and a multi section filter. It sits on top in a metal can.
The tuner sounds very good. Should this 50 YO cap still be changed?

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Mon 25, 2017 7:21 pm 
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Yes change it.


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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Mon 25, 2017 10:15 pm 
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john8750 wrote:
Should this 50 YO cap still be changed?

Think about that.
No matter how good it sounds... no electrolytic cap should be kept in service that long. Yikes.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Mon 25, 2017 10:23 pm 
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I must agree with you guys. I will need to pull the chassis to get to it. Might also consider the audio coupling
caps just for the adventure.
Thank you men, again.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Mon 25, 2017 10:24 pm 
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Pbpix wrote:
john8750 wrote:
That worked, and is the correct schematic.

You may want to get membership to http://www.radiomuseum.org John.
$25 for lifetime.
I had to do some gyrations of trying to copy and save that print then upload it to my web page server and then link you to it there.



Thanks special for that Peter.
You are the best.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Mon 25, 2017 11:40 pm 
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john8750 wrote:
Thanks special for that Peter.
You are the best.



Image

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Tue 26, 2017 6:52 am 
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That's great Peter.
The turn table has a rubber idler wheel. I cleaned it up good.
Tightened up the spring, and lubed the wheel.
The turn table drags with a record on it.
The idler wheel turns a little stiff, even after some light oil lube.
Don't know what else to do.

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 Post subject: Re: Philco amp re-build.
PostPosted: Sep Tue 26, 2017 8:27 am 
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john8750 wrote:
That's great Peter.
The turn table has a rubber idler wheel. I cleaned it up good.
Tightened up the spring, and lubed the wheel.
The turn table drags with a record on it.
The idler wheel turns a little stiff, even after some light oil lube.
Don't know what else to do.

other than that...I don't know either... maybe other forums here or elsewhere?

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