Sansui 5050 problem on board F-2701

Merci guys.
There's something odd about this board, when I take a look at all the pictures of this board I could find, I can see that these R612 and 613 resistors are always 10 ohms, but on this schematics (looks like it's the right one, as there is the F2700 board wich is not on the f2648) the value is 2.2 ohms instead...

Anyway, I'm gonna change these burned diodes, and tell you in a few days if the unit is fixed ;)
 

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Merci guys.
There's something odd about this board, when I take a look at all the pictures of this board I could find, I can see that these R612 and 613 resistors are always 10 ohms, but on this schematics (looks like it's the right one, as there is the F2700 board wich is not on the f2648) the value is 2.2 ohms instead...

Anyway, I'm gonna change these burned diodes, and tell you in a few days if the unit is fixed ;)

Don't worry too much about it, 10Ω is the value that Sansui eventually selected for that component, the schematic diagrams didn't keep up with late changes in component values. Always replace like-for-like what you find in the board, and first assume that the schematic is wrong if there are any differences. I realise you had a bit of a problem here as you couldn't 'see' what the values were as they were burnt/broken, and the schematic wasn't any help :no:

As usual the AK community is on hand to give help :)

Keep us posted on developments :thmbsp:
 
A bit of news from this unit:

The dead diodes in the bridge have been replaced, the amp now works perfectly!!
So, I can confirm, the R612 and 613 are 10 ohms ones ;)

Now that the bridge is ok, the resistors don't take much current as before and don't burn anytime I pull power on ^^

The volume and mic volume potentiometers were a bit oxydized, but after some WD40 they are now working good.

The amp now works perfectly and roxxes much!!

I wish to thank everyone that has been trying to help me, you all did great!!
I'm willing to continue the adventures of repairing old sound stuff like this, I enjoyed it much :3 so I guess we'll cross roads again in some near future ;)

Thanks to you all, you roxxx :)
Good luck and cya!

P.S: sorry again for my english, hope you didn't lose time trying to translate what I wrote ;)
 
<snip>....

The volume and mic volume potentiometers were a bit oxydized, but after some WD40 they are now working good.

The amp now works perfectly and roxxes much!!

Oh dear - you should Never Ever use WD40 on audio controls :nono: (WD40 IS NOT a 'contact cleaner' and this is what you need.)

You should use a proper contact cleaner (like DeOxit) followed by a proper potentiometer lubricant (like Faderlube).

I am glad you got it working, and well done for that :yes: - but I must make this post just in case others get the idea it is OK to use WD40 too :nono:

PS: Your English writing is very good.
 
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Hi!
Sorry for reopening this post but I have a problem with my 5050 Sansui. I bought it cheap, it was not working and I`m trying to fix it. Someone was already trying and made a mistake with transistors, they put only NPN, and fried them. I have F-2701 board and in schematics there are 2SD188A and 2SB545 in push-pull. They both are T0-3 package, but mountings for transistors are TO-66. I don`t understand! Can someone tell me which transistors are in this amp?
Please help!
 
I doubt that there were different resistances for Euro vs US receivers.

I would test the diodes in the bridge first.

I looked in the 5050/6060/7070 schematics that I have and could find. No F-2701 board. All I did find was a snippet for setting the bias. Odd. Attached

Sansui parts has the board for sale for 30 euros. They look like 10 ohm resistors to me too.
130.jpg


http://www.sansui-parts-shop.com/index.php?page=details&prod=130&cat=85&group=9
F-2701 board

Mine has a 2701 board and here are the resistors attached

Hi Guys, interesting thread about the 5050. Could someone give me the references for the TR-601 and TR-602 on the 2701 board? All schematics available and for the other board. Thanks bunches
 
Did anybody ever find a complete schematic for a unit with a 2701 board? every one I can find has half the schematic missing.
Hi there, google 'sansui 5050 Service Manual', there is a PDF file from vintageshifi to download. This file has both schematics in it. Oddly the board description is for the F-2648 as well as the first schematic, but there is a schematic right at the end has the F-2701.....good luck.
 
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Hmm I grabbed that. And the last two schematics neither has the F2701 schematic. So the last one is the F2701 but its labeled F2648? I ordered a full 27 page copy of the original service documents today. From an outfit that makes great quality reproductions.
 
Hmm I grabbed that. And the last two schematics neither has the F2701 schematic. So the last one is the F2701 but its labeled F2648? I ordered a full 27 page copy of the original service documents today. From an outfit that makes great quality reproductions.
Did you go right to the end, not Page 15 which has the F-2648?
 
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