General - TTI TSX Series Service Manual

This manual has been prepared to aid the experienced engineer in the maintenance and repair of
this series of high current power supplies. For detailed operating information the user should
refer to the appropriate instruction manual.
Service Precautions
Recalibration or repair should only be attempted by skilled personnel in conjunction with high
quality test equipment. If the user is in any doubt as to his competence to carry out the work, the
supply should be returned to the manufacturer or their agent overseas for the work to be carried
out.
The tracks on the printed circuit boards are very fine and may lift if subjected to excessive heat.
Use only a miniature temperature-controlled soldering iron and remove all solder with solder wick
or suction before attempting to remove a component.
Safety
When the power supply is connected to the AC line, terminals may be live and the opening of
covers or removal of parts (except those to which access can be gained by hand) is likely to
expose live parts. The supply shall be disconnected from all voltage sources before it is opened
for any adjustment, replacement, maintenance or repair. Capacitors inside the supply may still be
charged even if the supply has been disconnected from all voltage sources, but will be safely
discharged about 10 minute after switching off power.
Any adjustment, maintenance and repair of the opened supply under voltage shall be avoided as
far as possible and, if inevitable, shall be carried out only by a skilled person who is aware of the
hazard involved.
Dismantling the Instrument
Observe the above safety warning before attempting to dismantle the power supply.
1. To remove the case upper, remove the 6 screws (3 each side) and lift off.
2. To remove the upper (CPU) pcb on programmable versions remove the 3 flat cables and the
2-way supply connector next to the regulator heatsink; note the orientation of the flat cables
(red stripe to pin 1). Remove the 2 RS232 and 2 GPIB screwjacks which secure the
connectors (and therefore the pcb) to the rear panel. Remove the 2 self-tap screws which
secure the pcb to the forward mounting pillars and lift it off.
3. To remove the main board disconnect the 2 leads to the output terminals from the M3 studs
at the front of pcb and unplug the nearby sense connections, noting the polarity of both.
Disconnect the flat cable from the control pcb (non-programmable versions only) and the 2
push-on connections at the rear of the pcb which feed the AC supply to the pcb from the
power ON-OFF switch. Remove the self-tap screws which secure the heatsink to the case
lower (1 for each heatsink). Remove the 9 screws which secure the main pcb support pillars
to the case lower (i.e. the screws accessible underneath the case lower) and lift the pcb
clear with its mounting pillars attached.
4. To remove the keyboard (programmable versions) or control board (non- programmable
versions) first remove the control knob (keyboard) by undoing the collet nut beneath the
knob cap or disconnect the output ON- OFF switch (control board) from the pcb. Remove
the screws which secure the board to the front panel and lift free.
5. Reassemble in the reverse order. Take great care to ensure that the connections to the
output terminals (front and rear) are exactly as found before dismantling and that no
insulation creepage and clearance distances have been compromised. Ensure that the foil
screen over the output wires in the case lower is properly earthed via the appropriate pcb
support pillar.
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WARNING!

General