First, some pics...
The transformer provides two symmetric secondary windings (in series), 10V AC RMS each (without load). Secondary resistance is approx 0.4Ohm (0.8 for both). I guess unregulated DC after bridge rectifier is approx. +/- 13V.
As all the PCB copper traced oxidated due to the acid from the batteries. The traced turned into green Copper(II)acetate. It is hard to see the green PCB traces on green base material. A Sunday morning kitchen Xray vision hack with 100W light bulb, DSLR and macro lens shows the details.
A bit of Inkskape-kung-fu later...
Printed out, this matches the original mounting points and outline. Components should be flexible enough to deal with my drawing tolerances.
I NEVER EVER did this before, so I guess this is a great first result. Printed on glossy photo paper with b/w laser printer, cleaned PCB with some 120 grid sand paper, poured acetone on the PCB, layed the printout with the printed side on it, poured some more acetone over the back side and finally clamped it all tight together with a piece of wood and C clamps. 5 hours later, peeled the paper off with the help of some water and a soft sponge.
Etched (ferric oxide), Toner removed (acetone), tinned (soldering iron) and populated:
Most parts were reused, except 5V set potentiometer and vertical fuse holder.
After checking the output voltages and connecting it the unit is alive again =D
Powersupply to Mainboard cable
|Power Supply Pin||Color||Signal||Mainboard connector pin||current (mA)||usage|
|11||blue||-5 Volt (from 7905)||7||80...100||scale power (40...50 per)|
|12||white||backup battery +||8||?|
|15||red||+5 Volt 3 (emitter follower from 7805)||6||500+||7seg. LED (ca. 5mA per LED) ~650mA max?|
|16||white||+5 Volt 1 (from 7805)||3||2||controller? oscillator?|
|17||red||+5 Volt 2 (emitter follower from 7805)||1|
|logic? micro? stays ~ constant|
|18||green||unregulated positive ...15 Volt||4||5||<7V = controller reset (no display but no power decrease)|
Voltages from analysis of broken power supply, not actually measured! Voltages on big buffer caps go down to ~12 V for positive and ~13V for negative supply under load. This means 7V at approx 1 Amp = approx 7 Watts are dumped into the heat sink (= renew thermal grease!)
This board contains a big red sticker: "C-MOS warning!". VD 200 (2 axis) and VD 300 (3 axis) seem to use the same board. For 2 axis variant all components for the 3rd axis are not populated (7 segment LEDs, input connector, ...). Connectors to sensors can be desoldered and soldered in from back (footprint available) for easier (dis-)assembly.
Big Thanks to Fagor for providing me a copy of the manual as PDF!