Sansui 661/771 Bias adjust

[VintageFr]

I have two Sansui receivers, one 661 and one 771. I'm checking them over before I connect them to anything.

I'm working on the 661 first and I did some voltage checks and so far, everything looks good. I was able to adjust the DC offset at the speaker terminals but I'm not getting anything for the bias on either side.

Yes, I have my DMM set to amperes, on the right scale. The manual says to check the current with the fuses F1 and F2 out. The amp is set to speakers A, volume @ 0.

I checked the 771 for reference, in case there's something wrong with the 661 and I get the same thing. A reading of zero, on both sides.

Am I missing something here?

 

[Starbender]

Is your dmm probes plugged at correct position?
Use mA range..
Method is right. Remove fuse at the f1 and f2, connect dmm probes between them and measure with mA range..

 

[VintageFr]

Yes, as stated in my original post, the DMM is cabled properly

These two receivers were in very rough shape when I got them so there could ver well be an issue on both. I'll do more investigation when I have the time. I'm suspecting some bad transistors on the driver board.

 

[Sriskie]

Blown fuse in the DMM?

 

[VintageFr]

You beat me to it. I went over all the voltages, checked over everything. Its all looks good.

Then, I decided to check both my DMMs for their fuse. Both were out! What are the odds of that? Its all good now. Bias is nice and steady and I'll be testing through speakers soon to make sure there are no crackles or pops before final assembly.