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Post subject: Vintage Circuit?
Posted: Sat May 13, 2017 10:10 am
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Is this the right section to ask these questions?
I have what I think is a 5f2 Princeton circuit. Any ideas or opinions would be appreciated.

Transformer - Black ClassicTone 40-18019 166-1445
Transformer - Silver Classicton 40-18031 166-1445
JJ 5Y3S
Electroharmonix 6v6EH
Millard CV400/12ax7


Images to come....

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Post subject: Re: Vintage Circuit?
Posted: Sat May 13, 2017 10:23 am
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Mbeaubs wrote:
Is this the right section to ask these questions?
I have what I think is a 5f2 Princeton circuit. Any ideas or opinions would be appreciated.

Transformer - Black ClassicTone 40-18019 166-1445
Transformer - Silver Classicton 40-18031 166-1445
JJ 5Y3S
Electroharmonix 6v6EH
Millard CV400/12ax7


Images to come....


[url]URL=http://s587.photobucket.com/user/beaubssg/media/IMG_3237.jpg.html]Image[/url][/url]

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Post subject: Re: Vintage Circuit?
Posted: Sat May 13, 2017 10:29 am
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Mbeaubs wrote:
Mbeaubs wrote:
Is this the right section to ask these questions?
I have what I think is a 5f2 Princeton circuit. Any ideas or opinions would be appreciated.

Transformer - Black ClassicTone 40-18019 166-1445
Transformer - Silver Classicton 40-18031 166-1445
JJ 5Y3S
Electroharmonix 6v6EH
Millard CV400/12ax7


Images to come....


[url]URL=http://s587.photobucket.com/user/beaubssg/media/IMG_3237.jpg.html]Image[/url][/url]


[url][URL=http://s587.photobucket.com/user/beaubssg/media/IMG_3238.jpg.html]Image[/url][/url]

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Post subject: Re: Vintage Circuit?
Posted: Sat May 13, 2017 11:10 am
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That does indeed resemble Leo's classic 5F2 circuit.

Pretty clean assembly with first-rate components.

How's it sound?

Arjay

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Post subject: Re: Vintage Circuit?
Posted: Sat May 13, 2017 6:02 pm
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Do you have the schematic that came with the kit?

Thanks!


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Post subject: Re: Vintage Circuit?
Posted: Sat May 13, 2017 7:29 pm
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Retroverbial wrote:
That does indeed resemble Leo's classic 5F2 circuit.

Pretty clean assembly with first-rate components.

How's it sound?

Arjay


Hi Arjay, it growls to be sure. It does have a bit of a hum at higher volume, I am assuming that is inherent to the circuit type?

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Post subject: Re: Vintage Circuit?
Posted: Sat May 13, 2017 7:30 pm
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BMW2002Ti wrote:
Do you have the schematic that came with the kit?

Thanks!


No schematic, wish I did. :(

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Post subject: Re: Vintage Circuit?
Posted: Sat May 13, 2017 9:03 pm
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The hum may merely be a question of lead dress. You might try *very gently* nudging some wires around, one at a time, to isolate and eliminate the issue.

Arjay

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Post subject: Re: Vintage Circuit?
Posted: Sun May 14, 2017 12:55 am
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Looks more like a 5F2-A circuit w/ a hybrid ground buss. Is the ground soldered at both ends, inputs and PSU?
The PSU caps all look like 20UF; the circuit calls for 16/16/8/8. The 5F2 only had a single 22k dropping resistor while the 5F2-A had two 10k/22k. Also looks like the resistor around the 1st cap is just wrapped and not soldered, hard to say from the photo though.


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Post subject: Re: Vintage Circuit?
Posted: Sun May 14, 2017 1:53 am
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Retroverbial wrote:
The hum may merely be a question of lead dress. You might try *very gently* nudging some wires around, one at a time, to isolate and eliminate the issue.

Arjay


+1 lead dress ;

Wires going to tubes's grids must be very short, short as you can and close to chassis.
( 12AX7 pin 2 , 7 ) Easy to quiet the amp if you solder resistor on the socket not on the board.

Heaters ; yellows ones are too long, did not see those on the last tube
Shielded cables must be grounded at one end only.
Cold solders ?
I see many rivets with missing solder or is the poor picture ?
Check if input jacks shorting contact to ground work.

By the way it is not a vintage amp, wrong section :wink:


Last edited by stratele52 on Sun May 14, 2017 1:55 am, edited 1 time in total.

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Post subject: Re: Vintage Circuit?
Posted: Sun May 14, 2017 1:54 am
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sfceric64 wrote:
Also looks like the resistor around the 1st cap is just wrapped and not soldered, hard to say from the photo though.


I noticed that as well.

I sure wish a schematic was available.

Who built this amp?

Arjay

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Post subject: Re: Vintage Circuit?
Posted: Sun May 14, 2017 2:22 am
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sfceric64 wrote:
Also looks like the resistor around the 1st cap is just wrapped and not soldered, hard to say from the photo though.


The next cap/ resistor too. :(


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Post subject: Re: Vintage Circuit?
Posted: Sun May 14, 2017 3:03 am
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It might not be a bad idea to re-heat/re-flow *ALL* of the solder joints.

Arjay

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Post subject: Re: Vintage Circuit?
Posted: Sun May 14, 2017 5:01 am
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Wow, lots of information for a rookie like me. When I have time I am going to photograph the amp in detail with better lighting and then hopefully get some step by step instructions from you all on how to improve - I will enlist a professional to assist in service, although I may get brave, buy a soldering iron, and give a go with all of your assistance! Arjay, I did move some wires around but no improvement on the hum. Based on the previous posts, it sounds like there may be a bit more to it than that. Also, I forgot to mention that the amp does have a switch that cuts the db(?) or at least it does to my ear, lessening the hum quite a bit. That switch is located in between the tubes, set back a bit from them. I am assuming this is a modification to the original circuit. Stay tuned for more photos.

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Post subject: Re: Vintage Circuit?
Posted: Sun May 14, 2017 10:25 am
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Mbeaubs wrote:
Also, I forgot to mention that the amp does have a switch that cuts the db(?) or at least it does to my ear, lessening the hum quite a bit. That switch is located in between the tubes, set back a bit from them. I am assuming this is a modification to the original circuit.


Yes -- that switch is a modification to the original layout. A schematic would be invaluable in figuring out just what it's supposed to do and if it's correctly designed for that purpose.

Arjay

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