Hey Ron I'm able to power up both right and left channels now but I'm having trouble setting the bias and power supply voltages for some reason..Here are Amp8's examples from:
http://amp8.com/sansui/x-xx/x1/au-x1-5.htm
Make it look like this and you'll be good.
I got to double check that SM now and see if it's indeed in error.
I've been trying to set the bias current using the middle pin as seen in the pic.it's supposed to be 25mv but I can't get it past 12mv and on the power supply f-2778 the left and right -10v are right on but I can't get the -47.5v past -33v I'm wondering if I have the wrong trimmers in there?
Give it some time to let the large lytics and all others to settle.
I've been working on it all day,re did the right side main caps,replaced all the small signal transistors and diodes in both F-2775 boards,stared at F-2778 for an hour but couldn't find anything wrong with it then replaced all the small diodes in F-2819,put all the outputs in like the manual said then switched them back the right way.Kinda tired of looking at right now..
I'm getting there slowly but surely..
Why does the service manual point out the 3 prong test point for setting bias and dc offset?To quote myself from http://audiokarma.org/forums/index.php?threads/diy-au-d11-ii-bias-adjustment.686243/
In the case of the X1, using grabber probes long enough to reach the output transistors to be measured, attach each of the two voltmeter probes to anything that directly touches the emitter legs of the two output transistors designated as the driver/VR 2 measuring point.
The emitter legs will touch / sit installed in the sockets on the socket array on the inside of the driver to be adjusted.
This picture shows the socket array.
Make sure the probes grab those points where the emitter legs are as directly as possible.
All of those measurements were taken with the it plugged in to the dbt and using a 75 watt light bulb. should I plug it directly in to power and try again?Willy for bias current you want the OUTER 2 pins of that connector, the middle pin doesn't go anywhere.
For measuring DC offset I always used either end of the big varnished copper coil measured to chassis ground.
If you can only get -33v from the regulated PSU you may have a grounding problem, OR incoming voltage from the rectifiers too low, OR the wrong zeners installed, OR a downstream short or back to front capacitor dragging the voltage down, OR something wrong with the 'series pass' regulator transistors (on the heatsinks). There are TWO separate regulators - are they both the same?.... big clue!
I would doubt that big a voltage shortfall would be due to wrong trimmers - but check them anyway.
Even though they test good I decided to replace all of those because I read one of kale's threads about black corrosion on the leads can creep inside the plastic case and contaminate the device and most of them have black corrosion on the leads.
