Sansui Six Service Manual ? - (...and funny FM reception)

stereofun

Super Member
Been looking here at the site and Hifi-engine. No Sansui Six manual to be found ?

I just need to do the dc-offset and bias setting. The amp section looks very similar to the Seven - assuming the procedure is the same, all I would need is the Bias mA, then follow the Seven procedure ?

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Also came across something curios with this Six. Fm reception is extremely limited using just the onboard antenna - however once a 10 inch wire is connected to the 300 ohm post, the signal is in full force with great stereo sound but you really have to "hold" the wire right. The other 4 single digits I have had all managed reasonable reception with onboard antenna, and where far more forgiving when connecting a wire. hmm ??

Thanks for help as always!!!
 
DC offset is VR801
bias is VR802
Same as seven, remove fuses under the rear cover, put ammeter in place of fuse, set for 15 ma. Start with fully counterclockwise, which is no bias.

You can run more bias. experiment.

the output transistors are the same on Six and Seven.

the tuner's rf trimmers could stand a tweak. there is no internal antenna.
 
Thanks DCinDC!!

RF trimmers, is that something you can mark the position they are in, then deox the trimmers and work them a little then set back to mark....or is it better to leave to a shop. Are the trimmers on the 1450 fm board or the mutiplex.

I meant the onboard antenna, the one attached to the back, or is that am only ? Thanks
 
The bar antenna is for AM only.

The rf trimmers TC101, 102 and 103 are in the tuning cap can, and have cutouts for them. Adjust them with a plastic screwdriver. Just peak them on a station. With a short antenna...

With the receiver facing you; tc 101 is the far right one. Going left, skip one then tc102, skip one then tc103. The skipped ones are for AM, if you want to tweak that.

TC104 is on the far left next to an adjustable inductor. It is for the local osc to get the dial to match the station.

Don't use any chemicals. Just twirl them around a few times to clean them. They go around 360 degrees. Just peak them back, after twirling a few times, one at a time.

Read the tuning cap cleaning sticky. I think it is in the tuners forum. If it sounds wooshy or grumbly while tuning between stations on the lower end of the scale, it needs to be cleaned.

edit: for pics just use the Seven manual.
 
If you use the phono section consider replacing all the small signal transistors in the phono preamp and tone boards. It can make a big difference.


PS peak those trimmers tuned to a station on the upper end of the scale.
 
Been looking here at the site and Hifi-engine. No Sansui Six manual to be found ?

I just need to do the dc-offset and bias setting. The amp section looks very similar to the Seven - assuming the procedure is the same, all I would need is the Bias mA, then follow the Seven procedure ?

---------------------
Also came across something curios with this Six. Fm reception is extremely limited using just the onboard antenna - however once a 10 inch wire is connected to the 300 ohm post, the signal is in full force with great stereo sound but you really have to "hold" the wire right. The other 4 single digits I have had all managed reasonable reception with onboard antenna, and where far more forgiving when connecting a wire. hmm ??

Thanks for help as always!!!

E-mail Norman he can hook you up with a HQ pdf
http://www.analogalley.com/m_sansui.htm
 
Thanks Avionics - checked out site, great place.

DCinDC - tweaked the RF trimmers - this was a great help to get the max reading on the signal meter. Just wandering if there is a FM sensitivity pot somewhere its like the tuner can perform flawlessly, but only with the stronges of stations. My other six, picks up way more, even without any wire attached to the antenna. This unit is otherwise in a rare pristine condition.
 
edit: there's no 'sensitivity' pot, it's broken.

It could be a bias resistor that has gone out of spec or a leaky transistor.

Start checking dc voltages in the tuner, starting with the input PS voltage.

I have a couple around here that are like that but I haven't gone after the problem yet, so I can't just point and say "check this or that".

I think the tuners are the same in Six and Seven, so you can use Seven's svc manual if you have to.
 
I realize this is an old thread, but I have a SIX that has the same FM signal problem. I was listening to it one day and the signal kept dropping out and coming back. So I opened the hood to have a look. I started with TR201 and checked voltages. The emitter voltage read 2.1v as in the SM, but when the signal dropped it went up to 2.9. Hmmm... Base and collector voltages remained stable. So I went ahead and changed out TR201, 202, and 203 with 2SC930 (as originally there), changed the 0.022 ceramic cap and now the voltage is stable at 2.0v. Buuuut signal is still weak though very slightly improved. It is like it lost sensitivity. I put it off the the side for now unless someone has an idea what might be causing it.
 
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