hey guys,
Finished my total recall today but I'm not getting any love from it. started the biasing procedure but not a sound from the first MN3008 (got them from Paul @diygp). Started taking voltages and I traced the problem to the NE570 compander (got that one from banzai). all voltages check out except for pin 5, 6 and 7. Here are the values, wrong values bold, should-be values in brackets.
NE 570 (all values negative)
13.8 13.8
13.0 13.0
13.0 13.0
14.8 0
7.5 (13.0) 13.0
7.5 (13.0) 8.6
13.5 (4.7) 6.7
13.0 13.0
Supply is the recommended EHX PSU, I'm getting -15.07 V from the 7905 regulator, so that checks out. As a consequence of the increased output voltages from the ne570 (pin 7), also IC3 A pins 2 and 3 are increased. Readings for CD4047BE are also a bit off, but not near as drastic as the NE570.
CD4047BE (all values negative)
7.46 (7.94) 0
7.63 (7.09) 7.4 (7.0)
7.57 (6.91) 15.0
0 7.5
0 7.5
0 15
15.07 15
I've checked the components around the NE570 (R9-R12 & C6-C10), all have the correct value, I also reflowed the area. I measured the components too, everything checks out, but I cant get a reading from C7. Could that mean, it's a bad cap and could that cause the issue? I didn't want to desolder right away as I hate doing that...
I also traced the signal, it reaches Pin 6 of the NE530. Nothing after it.
Here are some pics:
(http://felix.kalium.org/upload/share/IMG_20160326_204644.jpg)
(http://felix.kalium.org/upload/share/IMG_20160326_204710.jpg)
Sorry
I don't understand this procedure
the gain trimmers are after the compander, so I don't quite follow. Also I haven't connected the output, I'm just probing around.
had some luck with my cardinal yesterday, which had a broken electric cap... might just try to replace it and see whats happening
EDIT: just replaced C7. Voltages remain the same and the cap was ok to measure out of the circuit.
Any ideas?