Table of Contents
Advertisement
3700 Portable Samplers
Section 6 Servicing
Contact Technical Service
6.3 Preliminary
Electronics
Troubleshooting
6-8
is acceptable. Conductive grounding mats are available for
workstations and are worthwhile if you have a consider-
able amount of repair to do.
4. The degree of hazard depends on the relative humidity. Be
particularly careful if the work area is extremely dry, or if
the work is being done in the winter, when indoor forced
heating and outdoor low temperatures cause the relative
humidity level to be very low.
5. Keep yourself grounded when handling disassembled
equipment. When you arrive at the work area after a unit
has been opened for repair, make an effort to always touch
the metal chassis before touching any of the circuit compo-
nents.
6. Be especially careful handling the CMOS-integrated cir-
cuits when removing them from the rest of the circuitry.
Being connected to the rest of the circuitry provides some
protection. Most of the circuitry is well protected from
damage caused by static discharge when the unit is pow-
ered up. However, an IC should never be replaced when the
unit is on.
7. Individual CMOS semiconductors and built-up printed cir-
cuit boards should always be transported in conductive
packaging. Foil is satisfactory; metallic plastic bags are
also available and work well. If you purchase replacement
components that do not come in marked, protective pack-
aging, do not use them. They may already be destroyed.
8. Once assembled and soldered, printed circuit boards are
easily damaged by improper repair procedures. Do not
attempt to remove components, particularly ICs, from
printed circuit boards unless you are skilled at this proce-
dure. You can locate and change a defective component,
and the unit may still not work if excessive heat or pres-
sure has broken the foil traces or pulled the cores from
holes on the board.
If trouble symptoms persist and you are unable to locate the
cause, call the Technical Service Department at (800) 775-2965.
Teledyne Isco suggests checking the following possible problem
areas before attempting to service the microprocessor CPU and
associated circuitry.
1. Be sure that the supply voltage is correct.
2. Check to see that the wiring harnesses, connectors, and
solder joints are in good condition.
3. Look for signs of physical damage, such as burned or bro-
ken components, overly hot components, or evidence of
water damage.
4. Check for shorted or open diodes and transistors, espe-
cially driver transistors.
5. Ensure that voltage regulators working properly.
Advertisement
Table of Contents
