Help with Sansui 551

[toymanmsp]

Greetings all, I'm starting to post more on AK. It's fantastic that there are so many members that are willing to help newbies like myself. I've replaced all of the caps in the 551 with the exception of the tuner, which I will do once I've finished replacing the transistors (Pre-Power-phono) on the mainboard. It sounded fantastic until I started to replace the transistors (this seems to be my Achilles heel when working on my gear). So, before I get too far I thought that I should confirm that I have the correct replacements for the transistors that I'm planning to replace.

Original - Replacements?

TR01, 02 2SC1313 (mine has 2SA1211's) - KSC1845
TR03,04 2SC711 - KSC1815
TR05,06 2SC1000 - KSC1815
TR07,08 2SCA697 - ZTX694B / 1013 / 1220
TR09,10 2SC1166 - 2690?
TR11,12 2SA661 - 992?
TR17 2SD330E - MJE15032B?
TR18,19 2SC1364 - KSC945C / 2383

Would it also be worthwhile to replace the diodes?

D01,02 SV-03F - IN5955B
D03,04 10D-1 / IN5392
D05 RD-13E-C / IN5821G
D06 10DC-1 / IN5821G

I will replace the filter cap with an EPCOS 3300uf 100V once she's running again. Any other suggestions?

Please, let me know if there are any questions. Thanks in advance!

 

[sregor]

Your transistor choices look ok - for tr09 and 10 I would use ksc2383, for tr11 and 12 I'd use ksa1013.
Your diode choices, however, will never do.
1n5392 is 1.5 amp diode, and will work for the rectifiers, D03 and D04, and 2 could be used for D06.
D01 and D02 are bias diodes, and are actually 3 diodes in one case. So that sub is no good. I would only change if Bias problem or broken part. You would need to take 3 regular diodes in series and mount them on the heat sink.
D05 is a 13 volt zener diode, so your sub would not work at all. 1n5928b will work.
At this point, I would refrain from changing diodes unless they are bad.

 

[toymanmsp]

Your transistor choices look ok - for tr09 and 10 I would use ksc2383, for tr11 and 12 I'd use ksa1013.
Your diode choices, however, will never do.
1n5392 is 1.5 amp diode, and will work for the rectifiers, D03 and D04, and 2 could be used for D06.
D01 and D02 are bias diodes, and are actually 3 diodes in one case. So that sub is no good. I would only change if Bias problem or broken part. You would need to take 3 regular diodes in series and mount them on the heat sink.
D05 is a 13 volt zener diode, so your sub would not work at all. 1n5928b will work.
At this point, I would refrain from changing diodes unless they are bad.

Greetings,

Many thanks for your message. I will heed your advice on the diodes. I was more concerned with the transistors, thank you for confirming and providing your recommended replacements. Where in New England are you from? I lived around the Boston area for ~20 years, before we moved back to the midwest. Thanks again.

 

[sregor]

Greetings,

Many thanks for your message. I will heed your advice on the diodes. I was more concerned with the transistors, thank you for confirming and providing your recommended replacements. Where in New England are you from? I lived around the Boston area for ~20 years, before we moved back to the midwest. Thanks again.

North Reading - about 15 miles north of Boston

 

[dly66]

Big thing with replacement transistors and getting the pin arrangements right. A number of old ones were B-C-E and replacement may be E-C-B. If it sounded great before and has issues after transistor replacement the replacement(s) may not be installed in the right orientation. Having a cheap transistor tester can help in that department.

 

[sregor]

Big thing with replacement transistors and getting the pin arrangements right. A number of old ones were B-C-E and replacement may be E-C-B. If it sounded great before and has issues after transistor replacement the replacement(s) may not be installed in the right orientation. Having a cheap transistor tester can help in that department.

+1.
Your meter is your friend. Since you have collector in the center, it is easy with meter to determine which lead is the base. I usually test, then put a slight bend in the base lead. A basic sanity check.