Hello all,
At 1st, I found a manual at ebay, located in the US for 39$ plus shipment 25$ - this is a bit expensive I think. I'm not sure if I will buy this.
In the mean time, I found the time to have a closer look on the device.
At 1st, I had to find out, where loose wires in power supply section have been attached. During this work, I draw the shematic for the power supply section. It was also interesting, that TR1 must have been repaced and this must have been done in the german language area, as the label text for wire colors of this transformer is written in german. It is also assembled with metric M3 screws, while moste of the remaining srews have impirial dimensions.
Schematic of the power supply:
TR1 left side, TR2 right side, and bridge rectifier, top view:
TR2 on seperate electric insulated mounting plate with 3 teflon feed throughs:
TR1 right side, TR2 left side, here the shieldig of TR1 is visible:
TR3 with the small PCB for the main power supply for the bridge:
The power generated from TR3 is used to supply the the bridge and the detecor circuitry.
I do not have an idea, for what purpuse the voltage, generated from TR2 is used. It is rectified, but not filtered, and the the enoumous effort, for insulating TR2 is interesting. One thing here is strange: the mounting plate for TR2 is electrically floating, as it is not connected to any net of the device. Only shields of 3 cables are connected to this mounting plate. I would have expected that its is connected to guard net - what are you thinking?
At the end I did measure 3 resistors with the bridge, and compared the results with my HP34401a:
Nominal value: 3,75k, 1%
L&N Bridge: 3.76282k
HP34401a: 3.76265k ± 0.4761
Nominal value 100k, 1%
L&N Bridge: 99.9766k
HP34401a: 99.9686k ± 10,997
Nominal value 1M, 1%
L&N Bridge: 1.00822M
HP34401a: 1.008015M ± 110.80
Looks not to bad I think. I added the uncertainty of measurement taken with the HP34401a, calculatet out of 1year spec. from datasheet.
Guido
Edit: spelling, photo links inserted between image tags,