I got a schematic from someone on this site some time ago now but have lost the guys email etc (and I have a new ISP) so can't get in touch to request the rest of the manual! 
Several days have been wasted over the last ten years or so in trying to repair this measuring amp but to no avail
It ain't going to happen without a complete service manual.
All voltage rails are correct, all electrolytics and tantalums are OK. The unit does work but the meter is hard against the reverse end stop (anti-clockwise) until a big enough signal is applied to get it moving upwards... It sounds like a fairly simple offset problem but there appears to be more to it than that. There are lots of pre-sets which if they have been played with at some time in the past could be the cause.... hence I need the full details with the calibration procedure, performance checks etc.... Anyone?
Several days have been wasted over the last ten years or so in trying to repair this measuring amp but to no avail
It ain't going to happen without a complete service manual.
All voltage rails are correct, all electrolytics and tantalums are OK. The unit does work but the meter is hard against the reverse end stop (anti-clockwise) until a big enough signal is applied to get it moving upwards... It sounds like a fairly simple offset problem but there appears to be more to it than that. There are lots of pre-sets which if they have been played with at some time in the past could be the cause.... hence I need the full details with the calibration procedure, performance checks etc.... Anyone?
I found brief performance check instructions and it gets more bizarre...
It passes all the performance checks in as much as that a calibrated 100mV RMS signal shows 100mV on the meter and at 100mV FSD the AC and DC outputs are exactly correct
Remove the signal though and the needle pins to the opposite end stop..... To zero the meter you have to input sufficient signal to give around 35mV RMS from the AC output.... And even more curious is the fact that at this level the DC output shows precisely 2 Volts.... Tends to suggest that it's supposed to give 2 V out for zero input which then goes up to 5 V for FSD ???? Maybe they made a chart recorder or some such which required this 2 - 5V range ????
Surely someone must have a manual for it... Please!
It passes all the performance checks in as much as that a calibrated 100mV RMS signal shows 100mV on the meter and at 100mV FSD the AC and DC outputs are exactly correct
Remove the signal though and the needle pins to the opposite end stop..... To zero the meter you have to input sufficient signal to give around 35mV RMS from the AC output.... And even more curious is the fact that at this level the DC output shows precisely 2 Volts.... Tends to suggest that it's supposed to give 2 V out for zero input which then goes up to 5 V for FSD ???? Maybe they made a chart recorder or some such which required this 2 - 5V range ????
Surely someone must have a manual for it... Please!
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