"Thierry Delaitre" wrote ...
Hi,

I've replaced the 2 bax17 in the detection part by by281 but no
success. I've posted the schematic at
http://www.cpc.wmin.ac.uk/~delaitt/PM3240/circuit.jpg

and the following pictures taken with an oscilloscope:

1) http://www.cpc.wmin.ac.uk/~delaitt/PM3240/P1010339.JPG
collector of TS1308 when intensity is in maximum
voltage goes from 7v to 75v (using 1/10 probe)

2) http://www.cpc.wmin.ac.uk/~delaitt/PM3240/P1010340.JPG
collector of TS1308 when intensity is in minimum
voltage goes to 50v

3) http://www.cpc.wmin.ac.uk/~delaitt/PM3240/P1010341.JPG
emitter of TS1306
voltage goes from 8v to 28v when intensity is in maximum

4) http://www.cpc.wmin.ac.uk/~delaitt/PM3240/P1010343.JPG
emitter of TS1306
voltage is 8V when intensity is in minimum

Cheers,

Thierry.


What I don't trust is the oscillation that is on the collector of TS1308. The signals on TS1306
seems to be correct.

Did you try to disconnect the fillament from its supply? It can be that there is a short between the
fillament and the grid or at the supply of the fillament voltage, and then lighting up the neon
lamp?

Anyways, I dont know if the by281 (correct nr btw??) is a good replacement. The BAX17 cross
reference shows up this diode:
http://www.fairchildsemi.com/pf/FD/FDH400.html

When you put back the original diodes how is the signal at the collector of TS1308? Still
oscillating?

Al