Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Dec Fri 15, 2017 2:59 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 269 posts ]  Go to page 1, 2, 3, 4, 5 ... 14  Next
Author Message
 Post subject: Philco amp re-build.
PostPosted: Aug Sun 20, 2017 10:08 pm 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3425
Location: Los Angeles
I have two Philco amps to re-build. Thank you Peter. Model no. SA-1000.
download/file.php?id=187445


Attachments:
philco%20sa1000-amp[1].png
philco%20sa1000-amp[1].png [ 253.91 KiB | Viewed 1280 times ]

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Last edited by john8750 on Aug Mon 21, 2017 5:10 am, edited 4 times in total.
Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Sun 20, 2017 10:21 pm 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3425
Location: Los Angeles
I was thinking that since I will need the 8 ohm tap for the speaker, I t would be better to not connect the cathodes there. Just connect to ground. Don't know what that would do to the FB circuit. What do you suggest? How about A CCS?

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Sun 20, 2017 10:32 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21268
Location: Haledon, NJ, usa
john8750 wrote:
I was thinking that since I will need the 8 ohm tap for the speaker, I t would be better to not connect the cathodes there. Just connect to ground. Don't know what that would do to the FB circuit. What do you suggest? How about A CCS?

Leave as designed... for now.
Then test and see how you like the sound.
first.
If you think it sounds good you can leave it that way and have it match the print.

If you want to modify it after you hear it.. sure we can go for the CCS and change the FB as I show in that colored schematic.

What "8 ohm tap" are you referring to?
The top tap?

I don't know if that's 8 ohms or whatever.
The schematic show a YEL lead for that connection to FB.
Does the paperwork list the partnumber for that transformer and does it show the specs?
I believe somewhere it does.

---- maybe this is it? ----
The actual OT is a Philco #32-8849-1
4300 ohm CT primary
9 ohm secondary ( tap=3-4ohm)

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Sun 20, 2017 11:31 pm 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3425
Location: Los Angeles
That's correct Peter. Looks like it was for a 4ohm speaker. CCS, a definite possibility, later. I do still have the 4ohm speakers from the Zenith console. Might be a good match.
OK. I will follow same schematic. I Like your idea. Will also document with photos.

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Sun 20, 2017 11:35 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21268
Location: Haledon, NJ, usa
john8750 wrote:
That's correct Peter. Looks like it was for a 4ohm speaker. CCS, a definite possibility, later. I do still have the 4ohm speakers from the Zenith console. Might be a good match.
OK. I will follow same schematic. I Like your idea. Will also document with photos.

Why do you say "it looks like it was for a 4 ohm speaker"? Based on What???

The data I showed you above for the OT part number shows 9 ohm... right?

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 1:39 am 
Member
User avatar

Joined: Nov Sat 26, 2011 4:09 am
Posts: 8088
Location: Texas. USA
john8750 wrote:
I was thinking that since I will need the 8 ohm tap for the speaker, I t would be better to not connect the cathodes there. Just connect to ground. Don't know what that would do to the FB circuit. What do you suggest? How about A CCS?
Don't change anything till you understand the circuit and what things do.

The cathodes connect there because the OPT secondary feedback makes the cathode self split approach something akin to being 'balanced'. Without it the circuit is positively dismal.


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 2:36 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3425
Location: Los Angeles
Flipperhome wrote:
john8750 wrote:
I was thinking that since I will need the 8 ohm tap for the speaker, I t would be better to not connect the cathodes there. Just connect to ground. Don't know what that would do to the FB circuit. What do you suggest? How about A CCS?
Don't change anything till you understand the circuit and what things do.

The cathodes connect there because the OPT secondary feedback makes the cathode self split approach something akin to being 'balanced'. Without it the circuit is positively dismal.



Thanks Flip. You and Peter both agree. That's good enough for me.

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 2:43 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3425
Location: Los Angeles
I stripped the chassis of all components. Everything will be modern, except the transformers. One pin on a tube socket broke off, so I replaced it and noticed that the new sockets look better that the old ones. So I replaced them all.
One chassis shows before I touched it. The other one is ready for rewiring.
Attachment:
philco3.jpg
philco3.jpg [ 94.29 KiB | Viewed 1251 times ]

Attachment:
philco2.jpg
philco2.jpg [ 103.51 KiB | Viewed 1251 times ]

Attachment:
philco 1.jpg
philco 1.jpg [ 114.48 KiB | Viewed 1251 times ]

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 3:31 am 
Member
User avatar

Joined: Nov Sat 26, 2011 4:09 am
Posts: 8088
Location: Texas. USA
I believe the posted schematic is incomplete. Here's the full version.

Attachment:
SA1000.jpg
SA1000.jpg [ 161.06 KiB | Viewed 1241 times ]


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 4:04 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3425
Location: Los Angeles
Correct Flip. I am not interested in the outside connections.

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 4:19 am 
Member
User avatar

Joined: Nov Sat 26, 2011 4:09 am
Posts: 8088
Location: Texas. USA
john8750 wrote:
Correct Flip. I am not interested in the outside connections.
I know but yours has none of the tone controls.


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 5:04 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3425
Location: Los Angeles
Flipperhome wrote:
john8750 wrote:
Correct Flip. I am not interested in the outside connections.
I know but yours has none of the tone controls.


WHAT
No tone controls :?:
That's like a day without sunshine.
That must be fixed right now.
Thanks :!:

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 6:23 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21268
Location: Haledon, NJ, usa
Flipperhome wrote:
john8750 wrote:
Correct Flip. I am not interested in the outside connections.
I know but yours has none of the tone controls.

What do you mean?
I sent John two amps... 1606 and SA1000

Both had tone all the control knobs and circuits matching the print..

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Last edited by Pbpix on Aug Mon 21, 2017 6:25 am, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 6:24 am 
Member
User avatar

Joined: Nov Sat 26, 2011 4:09 am
Posts: 8088
Location: Texas. USA
john8750 wrote:
Flipperhome wrote:
john8750 wrote:
Correct Flip. I am not interested in the outside connections.
I know but yours has none of the tone controls.


WHAT
No tone controls :?:
That's like a day without sunshine.
That must be fixed right now.
Thanks :!:
Someone apparently thought they were 'removing' the tone controls but they didn't get it all. The .01 cap in series with the feedback is there to reduce feedback in the bass region so, effectively, it's boosted relative to the rest. That provides the range for the bass control. I.e. when full up it's like the first circuit. Half way it cuts the bass down to the same level as the rest and, of course, the other half is cut below. That's the primary purpose of the negative feedback and any 'distortion reduction' would an ancillary side effect.

The treble control is rather common for low end amplifiers except for having to 'fight' the meager feedback, which tries to compensate for the frequency shift (that's what negative feedback does), but it soon overwhelms feedback and then works as normal.


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 6:25 am 
Member
User avatar

Joined: Nov Sat 26, 2011 4:09 am
Posts: 8088
Location: Texas. USA
Pbpix wrote:
Flipperhome wrote:
john8750 wrote:
Correct Flip. I am not interested in the outside connections.
I know but yours has none of the tone controls.

What do you mean?
I sent John two amps... 1606 and 1005

Both had tone all the control knobs and circuits matching the print..
I mean the schematic he posted at the beginning of this thread doesn't have the tone controls.


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 6:29 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21268
Location: Haledon, NJ, usa
Flipperhome wrote:
john8750 wrote:
I was thinking that since I will need the 8 ohm tap for the speaker, I t would be better to not connect the cathodes there. Just connect to ground. Don't know what that would do to the FB circuit. What do you suggest? How about A CCS?
Don't change anything till you understand the circuit and what things do.

The cathodes connect there because the OPT secondary feedback makes the cathode self split approach something akin to being 'balanced'. Without it the circuit is positively dismal.

I explained all that to him already Flip and advised him not to change the layout until he has it ALL working and he can hear how the original design was intended to sound first.
Thing is.. he does not have the electrostatic tweeters.

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 6:32 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21268
Location: Haledon, NJ, usa
John:
If you haven't stripped both amps yet. I'd leave one original to follow in case you have layout questions later.
Also, sometimes it's easier to replace the old components in the same location one at a time as you go along instead of pulling everything out at once.
... but these are not too complicated.

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 6:36 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21268
Location: Haledon, NJ, usa
Flipperhome wrote:
I mean the schematic he posted at the beginning of this thread doesn't have the tone controls.

I just looked at that schematic he posted :

http://www.antiqueradios.com/forums/dow ... ?id=187445
and I see the tone controls on the left side of the print.

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Last edited by Pbpix on Aug Mon 21, 2017 6:41 am, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 6:40 am 
Member
User avatar

Joined: Nov Sat 26, 2011 4:09 am
Posts: 8088
Location: Texas. USA
Pbpix wrote:
Flipperhome wrote:
I mean the schematic he posted at the beginning of this thread doesn't have the tone controls.

I just looked at that schematic he posted and I see the tone controls on the left side of the print.
Must be in invisible ink, then, because the one I see in the very first post, titled philco%20sa1000-amp[1].png, has no tone controls at all.


Top
 Profile  
 
 Post subject: Re: Philco amp re-build.
PostPosted: Aug Mon 21, 2017 6:42 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21268
Location: Haledon, NJ, usa
Flipperhome wrote:
Pbpix wrote:
Flipperhome wrote:
I mean the schematic he posted at the beginning of this thread doesn't have the tone controls.

I just looked at that schematic he posted and I see the tone controls on the left side of the print.
Must be in invisible ink, then, because the one I see in the very first post, titled philco%20sa1000-amp[1].png, has no tone controls at all.

I'm looking at the link print:
http://www.antiqueradios.com/forums/dow ... ?id=187445

Yes the other one is something I think I made up 4 years ago.. maybe I cut stuff out... lol

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
Post New Topic Post Reply  [ 269 posts ]  Go to page 1, 2, 3, 4, 5 ... 14  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: WoodchuckTN and 7 guests



Search for:
Jump to:  


















Privacy Policy :: Powered by phpBB