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Old 23rd March 2013, 10:12 PM   #2901
работник
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Is the same problem present on L and R?

This is certainly not expected.

More check points:

- C3 is certainly connected to R8 and R5?
- R5 is 150R?
- R8 is certainly 3.3K?
- Voltage between supply+ and filament + is 2.1 to 2.4V?
- No oscillation on C1.

If no progress, please send me a close-up photo of the Regulator, preferably both sides of the board.
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Old 23rd March 2013, 10:14 PM   #2902
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Quote:
Originally Posted by nicoch58 View Post
try bypass the L2/c2 just fast test
I tried this, but no change. Thanks!

Abe
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Old 23rd March 2013, 10:32 PM   #2903
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Quote:
Originally Posted by Rod Coleman View Post
Is the same problem present on L and R?

This is certainly not expected.

More check points:

- C3 is certainly connected to R8 and R5? Yes!
- R5 is 150R? Yes(Brn-Gr-Brn-Gold)
- R8 is certainly 3.3K? Yes (Orng-Orng-Red)
- Voltage between supply+ and filament + is 2.1 to 2.4V?No (L channel=3.4, R=3.6)
- No oscillation on C1. Not sure as it is not accessible.

If no progress, please send me a close-up photo of the Regulator, preferably both sides of the board.
I will disconnect the regulator and take pics.

Abe
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Old 23rd March 2013, 10:33 PM   #2904
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Quote:
Originally Posted by CV6045 View Post
Do you have a copy of the RCA TT3 Tube Data Book....if not I can email you a copy....page 75 to 77 is worth a read, and it may point you in different direction
Hello,

Thanks. Please email it to me. I sent you a PM for my address.


Abe
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Old 23rd March 2013, 10:42 PM   #2905
CV6045 is offline CV6045  United Kingdom
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Default Extract RCA TT4

Abe, I can't send you the whole book as its 13 megabytes, However I am sending you here the relevant pages as an extract (5 pages) covering Choke/Capacitor relationships in power supplies. As I said it may point you in a different direction



Quote:
Originally Posted by amandarae View Post
Hello,

Thanks. Please email it to me. I sent you a PM for my address.


Abe
Attached Images
File Type: jpg Extract RCA TT4 page 73.JPG (196.9 KB, 228 views)
File Type: jpg Extract RCA TT4 page 74.JPG (199.1 KB, 222 views)
File Type: jpg Extract RCA TT4 page 75 JPG.JPG (175.8 KB, 220 views)
File Type: jpg Extract RCA TT4 page 76 JPG.JPG (174.0 KB, 219 views)
File Type: jpg Extract RCA TT4 page 77 JPG.JPG (154.5 KB, 215 views)
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Old 23rd March 2013, 11:52 PM   #2906
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If I were you this is what I'd do.

1) work on one channel only
2) disconnect the filament regulator and replace it with a simple filtered 12V supply. If you have a computer supply it'll do. Or, power the filament from a 1.5V lab supply and bias the grid with a 9V battery. If it's still oscillating then it's the HV regulator that's got a problem. If it's not oscillating, then it's the filament regulator that needs fixing.

What I'm saying is, leave high quality aspirations aside for a moment, you're in debug mode now. Divide and conquer.
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Old 23rd March 2013, 11:57 PM   #2907
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Quote:
Originally Posted by CV6045 View Post
Abe, I can't send you the whole book as its 13 megabytes, However I am sending you here the relevant pages as an extract (5 pages) covering Choke/Capacitor relationships in power supplies. As I said it may point you in a different direction
Hello,

Thanks for this! I tried understanding it but I am afraid I do not have a grasp of what it means.

My circuit is a AZ1 tube(I have 4Vac for filament). From spec sheet, I assume I am operating at about 2x300 V (Va max) and 100mA (Ia max). I am using a Hammond 250-0-250 power transformer.

After the tube, I have 20H then 47uF, then 10H, then 47uF, then 0.36H, then 47uF. Do you think there's something wrong as far as the L and C values according to the excerpts that you sent me?

Thanks,

Abe
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Old 24th March 2013, 12:17 AM   #2908
AJT is offline AJT  Philippines
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Abe,

the book can be downloaded here.... http://www.tubebooks.org/tubedata/TT3.pdf

these are links from Patrick Turner's website... http://turneraudio.com.au/powersupplies.htm and http://turneraudio.com.au/powertranschokes.htm

The ARRL handbooks are also a good source of info about designing choke input psu.... http://www.tubebooks.org/Books/intro_arrl_1941.pdf
http://www.tubebooks.org/Books/arrl_1941.pdf

FWIW, psu designs always starts with the load....
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Old 24th March 2013, 12:56 AM   #2909
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Quote:
Originally Posted by Rod Coleman View Post
Is the same problem present on L and R?

This is certainly not expected.

More check points:

- C3 is certainly connected to R8 and R5?
- R5 is 150R?
- R8 is certainly 3.3K?
- Voltage between supply+ and filament + is 2.1 to 2.4V?
- No oscillation on C1.

If no progress, please send me a close-up photo of the Regulator, preferably both sides of the board.
Hello Rod,
I sent pics to your email. Just in case, here they are.
Below are pics of two identical reg boards. The one with the heatsink was disconnected from the preamp. Second pic shows the underside. They are identical as far as components(omitting the transistors of course).
Click the image to open in full size.
Click the image to open in full size.



Below is a pic that shows the ground point on the main chassis. here, IEC, 0V, chassis, and cable shields connects to. The IEC from PSU chassis is taken here through the umbilical. The chassis connected to this point as well(which connects to IEC) is taken back to the PSU chassis through the umbilical.

The umbilical(8 pin)wiring is: +1 and -1(filament 1), +4 and -4 (filament 2), +3 and -3(B+, 0V), +2 and -2(chassis and shield, IEC GND). The last pic is the PSU chassis.


Click the image to open in full size.
Click the image to open in full size.
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Old 24th March 2013, 12:59 AM   #2910
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Quote:
Originally Posted by Tony View Post
Abe,

the book can be downloaded here.... http://www.tubebooks.org/tubedata/TT3.pdf

these are links from Patrick Turner's website... powersupplies and powertranschokes

The ARRL handbooks are also a good source of info about designing choke input psu.... http://www.tubebooks.org/Books/intro_arrl_1941.pdf
http://www.tubebooks.org/Books/arrl_1941.pdf

FWIW, psu designs always starts with the load....
Thanks Tony!

Abe
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