Ready for my first restoration - Small Sansui integrated!

[jrob]

After collecting Sansui gear for the past 6-8 years i have a number of systems in great working condition that i listen to quite a bit. Unfortunately, i also have a fair number of units that despite my best efforts (cleaning and resetting specs as listed in service manuals w/ oscilloscope and DMM) still don't work. I have a nice soldering station and have used it to recap a number of pairs of vintage speakers, but this will be my first time working on bigger circuits, PBCs etc.

First, i need to pick the unit to put on the bench, based on ease of working on/ finding parts for it and quality of the unit once i get it working properly. In the process, i would at like to at least start replacing electrolytics as well. The candidates are:

an AU 2200 that has one very noisy channel. The static sound is heard on all inputs and varies with the volume control. This model used a few ICs in the output section, etc.

an AU 3900 that has slight noise on one channel. The low static disappears when using the tape monitor input and varies with volume. This unit has two out of four output transistors which appear to be aftermarket.

an AU 222 that has intermittent loud static on both channels that does not respond to the volume control.

Any suggestions as to which one to start with would be greatly appreciated!

 

[stereofun]

I'd begin with Au-222. It is a simple cap coupled amp with few components. Also very accessible. Cheers.

 

[ConradH]

Since it's your first, I'd go for easy access. Not being familiar with the units myself, listen to Tom.

In general, troubleshoot and fix what's wrong before doing any sort of cap replacement project. Sure, caps go bad, but they're the root cause of problems in far fewer cases than you might think. You have a scope, so you're way ahead of many.

 

[Sieb Mulder]

I bought my Sansui AU-222 in 1968. This century it gradually developed the intermittent loud static independant of volume setting like you described, first on one channel later both. Last year I recapped the amp (simple job) and it works perfectly again. I found the static noises were caused by oxidation of the potentiometers on the PCB (Output and current adjustment: VR801, VR802, VR803, VR804). I do not remember which ones exactly, so replace them all to get rid of the static.

 

[smurfer77]

You guys may laugh, but my AU-222 with new semiconductor is one of my favourite amps. I've found that toneboard transistors in two of these to be a touch 'hissy' and replaced the lot. Sounded a lot better after that. Easy to access, not many components, and sounds brilliant to boot. Probably one of the best sounding with my speakers... has that strong bass like the AU-777, Solid-State 350, etc. Wonderful little machine and I can't believe how loud it is .... it's tiny!