Sansui BA 3000 problems after restoration / recapping

[Black.Audio.Co]

Dear Friends,

I need help and advise on my BA 3000.

I purchased this two years ago and fully recapped all the boards (with Elna Silmic ii) and reflowed the solder (audio note) on all the boards. Ran trouble free for six months then the transistors blew on the left channel. Replaced the Sanken with the Motorola MJ 15024 and 15025 and worked fine for a another three months.
Then got static coming from both channels even with the preamp (CA 3000) disconnected and the gains turned all the way down. Upon checking the technician says the bias was way off from the earlier setting and does not want to stabilise. connected to the multimeter the numbers keep on floating all over the place.

The VU meters also keep jumping with the Gain setting all the way down.

I am at a loss and am replacing all components on the left and right driver boards. Including the transistors and the ceramic caps to the Silver film type.

Currently running B&W 683 floor standers in a biamp configuration along with a mcintosh mc 7200 on the top end. And it sounds wonderful.

Please kindly request advice on what to do.....

Thanks in advance.

 

[JOMARK911]

Check all the components on the filter board , just underneath the power meters. Then check again the driver boards and the regulator board next to the driver boards.
BA3K does that , both of mine have done it , and it appeared to be some problems with the subsonic filter switches and the like in the close vicinity.

 

[JOMARK911]

Clean the switches the best you can and make sure you don't have any problematic transistors on that board apart from the caps. If it ever does the crackling set speakers switch to the off position immediately to protect your speakers from been executed.

 

[Tom B]

Hi,
Before you replace "All the components", I would suggest first just replacing the Differential pair transistors (TR01, and TR02) on one of the driver boards to see if this fixes your problem.
From my experience, these transistors can get Noisy, and cause the type of problems you are experiencing which is the inability to stabelize the bias as well as static noise being produced.

Replacing all the components can open you up to more problems in my opinion.

KSC1845FTA fairchild transistors are very nice replacements

 

[ManyMoonsAudio]

You need to get this amp to a tech that knows what they are doing. This amp has problems, and they are more than a couple problems.

Where are you located?

 

[Black.Audio.Co]

Dear Friends,

Thanks for the support especially Jomark and Tom. I will have my tech check on these issues before going through the driver boards completely. I am located in Jakarta, Indonesia and tech help is limited here for these vintage amps. My Tech is a young guy graduate from local university and he is honest (does not replace my parts with inferior chinese stuff) and very neat white his soldering skills. So far he has done wonders for my CA 3000.

If you know anyone here who can help i will be grateful.

Thanks and Regards

 

[slimecity]

Another thing to look out for is the troublesome VD1212 diodes, you generally want to replace these outright. If these are present in this unit (Im not sure, and havent checked this) they may play a role in bias stability.

 

[ManyMoonsAudio]

Well in that case, add your location to your profile.
The pass through joints on the amp module circuit boards can become intermittent and cause the amp to blow. This is likely why your amp went into nuke mode.
The unstable bias is very likely the driver transistors and or the pre-driver transistors getting flaky. Experience talking to you here, as I think I have worked on damn near every AU-20000 here in the US, and almost as many BA-3000 amps.

Other things to look for are bad solder joints on the pin headers under the driver and supply boards.

 

[Black.Audio.Co]

Hi ManyMoons,

Thanks for the input. I am located in Jakarta Indonesia. And will have the tech check on the above. Will get back to you soon.

Cheers

 

[Black.Audio.Co]

Hi Friends,

I sorted out the previous problems and and had the tone board completely redone with new transistors and resistors. The sound improved a lot and the clarity is amazing. However after 3 months the problem of the jumping meters as recurred. I have enclosed the video of the same.

The Preamp is Sansui CA 3000 running a Mcintosh MC7200 for the top end of a B&W 683 and the Sansui BA 3000 for the bottom end.

There is no clicking sound from the speakers like earlier but am a bit worried, please give me some pointers guys.

 

[damacman]

Hi Friends,

I sorted out the previous problems and and had the tone board completely redone with new transistors and resistors. The sound improved a lot and the clarity is amazing. However after 3 months the problem of the jumping meters as recurred. I have enclosed the video of the same.

The Preamp is Sansui CA 3000 running a Mcintosh MC7200 for the top end of a B&W 683 and the Sansui BA 3000 for the bottom end.

There is no clicking sound from the speakers like earlier but am a bit worried, please give me some pointers guys.

While I have no idea, I'd like to point out the obvious - that's one helluva system to have assembled in Indonesia! Well done indeed. Pics!?!

 

[musicman999]

Change those 726 and 1313 transistors on the Power regulation Board(F2508). (Ksa992 and Ksc1845). I believe these are transistor 13 and 14