Sansui 210, board F-1301-2, transistor replacement and other pointers

[zeferinoj]

Hello!

I'm in the process of fixing a Sansui 210, looking at the transistors now. This excellent thread already covers the process but I believed it's based on a later board, an F-1301-4. The one on my set is an F-1301-2, and most noticeably the original transistors are different. I'm looking for comments on the proposed replacements, mostly put together by browsing AK.

ID ---------------- Original --------------- Replacement
TR601/602 2SC871(91F)* KSC1845 (* features a red dot on top)
TR603/604 2SC871(64E) KSC1845
TR701/702 2SC871(64E) KSC1845
TR801/802 2SC694(FD)** KSC1845 (** looks like a little ball, I think it's this one)
TR803/804 2SC634A KSC1845 or KSC1815
TR805/806 2SC634A KSC1845 or KSC1815
TR807/808 2SA678(AD60) KSA992 or KSA1013 (pairing with KSC1845 or KSC1815, respectively)

Also,

• All the electrolytic capacitors have been replaced on the main board. Should I do the same in the RF one? I'm concerned about the alignment, as I couldn't find instructions for it.
• There are two variable resistors, VR801 and VR802, for "AC balance". On the F-1301-4 schematic there's a 21 V reading next to these variable resistors, across C817 and C818. Should I adjust these until that voltage reads 21 Volts?
• It was relatively easy to spray contact cleaner on the volume pot, but power, bass and treble look sealed. Any ideas on cleaning these?

Thank you very much in advance for any insight.

All the best,
Joao

 

[playittwice]

Good luck getting this receiver going! Its my favorite low-powered sounding amp in the house!

 

[zeferinoj]

Good luck getting this receiver going! Its my favorite low-powered sounding amp in the house!

I sure hope to get it running properly.

Out of the box the left channel was not working at all and it produced about 5V over a dummy load on the right one. The volume pot was cleaned multiple times as it was stuck, so much that only found later that this set actually has a balance adjustment on the same shaft.

The left channel outage was caused by a broken fuse holder and after a recap and a voltage check some cheap speakers were connected to it.

It sounds OK-ish at the moment, resembling a hall effect. Mostly, there's a constant hum even with volume at minimum, like it's missing some filtering or having bad contacts. I started poking it around with a chopstick (yet another great trick learned from that thread above) to search for bad contacts. No joy, but when TR808 was touched it almost blew my right ear off. Touching up the solder doesn't fix it, hence my interest on replacing transistors at the moment.

Any assistance/comment is very appreciated.

Thank you.
Joao

 

[zeferinoj]

I went with the following replacement list:

ID ---------------- Original --------------- Replacement
TR601/602 --- 2SC871(91F)*-------- KSC1845
TR603/604 ----2SC871(64E) ---------KSC1845
TR701/702 ----2SC871(64E) ---------KSC1845
TR801/802 ----2SC694(FD)** --------KSC1845
TR803/804 ----2SC634A --------------KSC1845
TR805/806 ----2SC634A --------------KSC1845
TR807/808 ----2SA678(AD60)------- KSA992

VR801 and VR802 have been adjust for 21V across C817 and C818 (were at 26V before). Pots were cleaned successfully. Thank you so much for all the help, playittwice!

It does sounds much, much better. The hum is somewhat less evident but still perceptible. The audio and power lines are bundled together from factory and routed next to the transformer, so I tried to re-route the audio lines. No audible improvement. Same result after replacing D001, 002 and 003 and checking ground points.

I've never experienced it in a working condition before, but as low powered/economic as it may have been marketed as I believe it shouldn't have hit the stores with this hum.

Any troubleshooting suggestions are very welcome.

Thank you.
Joao

 

[mreyero]

Newbie here, just picked up a Sansui 210. Like the original poster, I get no sound from the left channel, just hum. I have sound from the right. I checked the fuses, both looked good. I even swapped them.

Now the weird thing.... I remove the fuse from F0002, the left and right channels both work. I am connected to a dim bulb tester when I do this little experiment.

My plan is to replace the transistors, per zeferinoj suggestion.