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Sansui au-555a flying saucer transistor replacement

quadmatrix82

quadmatrix82

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Hi all I’m restoring a Sansui au-555a and wondering if bd-139 and bd-140 are suitable replacements for cdc8002/90002 transistors? Given ksc2690 and ksa1220 are getting hard to find now I have a lot of the bd transistors on hand which I’d prefer to use given they are still readily available any thoughts would be appreciated thanks!
 
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I don't have personal experience with using the BD-139 and BD-140 transistors in the AU-555A, but the KSC2383 and the KSA1013 can be used to replace the stock 8002-1 and the 9002-1 transistors.
 
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I've had a grand total of ONE 555A on the bench. There were 871s, 495s, and other suspects. I used 992s and 1845s for the most part. In other units, I have used the similar BC550C/560C devices with good success. They are very quiet and have respectable current gains if you cannot find the 992s and 1845s.

For TR807-809 I used the 1120AY and 2690AY devices, but the BD139/140 might be acceptable IF it can tolerate the reduced hFE of the Philips devices.

As for other points to consider in the 555A:

Replace 27Ω resistors at R835 and R836 with 150Ω (metal film)
Parallel R835/R836 with 1N4004 diodes to improve symmetrical loading of drivers, and reduce zero point crossover distortion;
Add 0.33μF/100V film capacitors across E-C of TR805 and TR806 to improve high frequency;
Replace R823/R824 with 825Ω resistors to improve bias control;
Replace 2SC632As in all positions on phono and tone amps with KSC1845F or BC550C;
Replace XA-495Gs in main amp first stage with KSA992F or BC560C;
Replace main amp filter C822 (220µF/75V) with larger/higher voltage cap (330µF/80V);
Replace power supply filter caps with increased rating and voltage;
Replace power supply rectifiers with 3A rated diodes (1N5402G or better).
 
Leestereo said:
I don't have personal experience with using the BD-139 and BD-140 transistors in the AU-555A, but the KSC2383 and the KSA1013 can be used to replace the stock 8002-1 and the 9002-1 transistors.
Click to expand...
Thanks for the tip I might try these instead I have them on hand - I’ve used the bd139-140 in the past with no issues but with following your resto mod process was keen to hear any opinions of these transistors are still a good match given the other mods at play.
 
Th
Watthour said:
I've had a grand total of ONE 555A on the bench. There were 871s, 495s, and other suspects. I used 992s and 1845s for the most part. In other units, I have used the similar BC550C/560C devices with good success. They are very quiet and have respectable current gains if you cannot find the 992s and 1845s.

For TR807-809 I used the 1120AY and 2690AY devices, but the BD139/140 might be acceptable IF it can tolerate the reduced hFE of the Philips devices.

As for other points to consider in the 555A:

Replace 27Ω resistors at R835 and R836 with 150Ω (metal film)
Parallel R835/R836 with 1N4004 diodes to improve symmetrical loading of drivers, and reduce zero point crossover distortion;
Add 0.33μF/100V film capacitors across E-C of TR805 and TR806 to improve high frequency;
Replace R823/R824 with 825Ω resistors to improve bias control;
Replace 2SC632As in all positions on phono and tone amps with KSC1845F or BC550C;
Replace XA-495Gs in main amp first stage with KSA992F or BC560C;
Replace main amp filter C822 (220µF/75V) with larger/higher voltage cap (330µF/80V);
Replace power supply filter caps with increased rating and voltage;
Replace power supply rectifiers with 3A rated diodes (1N5402G or better).
Click to expand...
Thanks for your insight I’ll measure the gain on the bd transistors and originals will be good to see if close or not. Appreciate the other tips you mentioned I’m following the leestereo mods which these seem to be for this resto can’t wait to hear the end result :)
 
Hi

BC639/BC640 are also good substitutes for the flying saucers. They are harder to get these days as they have been made obsolete, but a few of the major suppliers still have some stock. The min gain of the standard part number is 40, but there are higher min gain variants with -10 or -16 suffixes available. I have measured quite a few of the CDC8002/CDC9002 flying saucers and the gains have all been less than 60, and most of the 9002’s were around 20-35.

Re the BD139/140, they also have the -10 and -16 higher min gain suffixes available, but these variants are mostly out of stock with long lead times being quoted.

Agree with the comments re the BC550C/BC560C use for small signal replacements, I have used these with good results (just have to “manipulate” the lead orientation in most instances).

Cheers
John
 
skippy124 said:
Hi

BC639/BC640 are also good substitutes for the flying saucers. They are harder to get these days as they have been made obsolete, but a few of the major suppliers still have some stock. The min gain of the standard part number is 40, but there are higher min gain variants with -10 or -16 suffixes available. I have measured quite a few of the CDC8002/CDC9002 flying saucers and the gains have all been less than 60, and most of the 9002’s were around 20-35.

Re the BD139/140, they also have the -10 and -16 higher min gain suffixes available, but these variants are mostly out of stock with long lead times being quoted.

Agree with the comments re the BC550C/BC560C use for small signal replacements, I have used these with good results (just have to “manipulate” the lead orientation in most instances).

Cheers
John
Click to expand...
Thanks John I have some stocks of those bd transistors I got many years ago and never failed me in previous restorations so I might as well use them keen to see the end result combined with the leestereo mods. I will use 2sa970 for xa495 and 2sc2240 for the 2sc871 in the phono stage. I used ksc1845 gain matched for the tone board circa 420 hfe :)
 
Was anyone able to find good data sheets for CDC8002 and CDC9002? Can't find anything good online. I have a Sherwood 7100A I'm refurbishing and having trouble finding a proper replacement. Was recommended MJE340G/MJE350G respectively, but not seeing those mentioned on this thread...

I see BD139/140 and KSC2383/KSA1013 are both in stock at Mouser. Mine also have a "C" hFE classification as well.
 
pioneervibes said:
Was anyone able to find good data sheets for CDC8002 and CDC9002? Can't find anything good online. I have a Sherwood 7100A I'm refurbishing and having trouble finding a proper replacement. Was recommended MJE340G/MJE350G respectively, but not seeing those mentioned on this thread...

I see BD139/140 and KSC2383/KSA1013 are both in stock at Mouser. Mine also have a "C" hFE classification as well.
Click to expand...
Never had an issue using bd139/140 or ksa1220/2690 don’t have a data sheet sorry
 
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