Read Sharp 76FW-54H Service Manual online
DA100 (50Hz) and DA50W Chassis – Repair Notes
Page 7 of 80
Introduction
The DA100 (50Hz) chassis and its derivatives (DA50W) are fitted in many Sharp widescreen television sets.
Production started in 1999 with the FW models and continued up to the HW models. There have been a number
of changes to the circuit configuration, layout and operation but the overall circuit theory and fault finding
techniques remain the same for all chassis.
This article will endeavour to assist the engineer in various faultfinding procedures that have been found to be
beneficial in reducing repair times and cost. One important item to note is that the large and expensive
(microprocessor, VDP, MSP, etc) IC’s only rarely fail.
It is worthwhile considering that there have been a number of different types of CRT used with this chassis for
the same model type. Philips, Thomson (Videocolor) and LG CRT have been used. Note that the scanning coils are
supplied with the CRT and therefore the horizontal output stage components will be different for different CRT
types. With the Philips CRT there are two focus anodes, so the fly-back transformer is also different in these
models.
Most of the problems on this chassis are related to either the power circuits (chopper and horizontal) or
memory. Resetting or replacing the memory can easily cure many faults that appear to lie in the picture
processing circuitry or drive areas.
Production started in 1999 with the FW models and continued up to the HW models. There have been a number
of changes to the circuit configuration, layout and operation but the overall circuit theory and fault finding
techniques remain the same for all chassis.
This article will endeavour to assist the engineer in various faultfinding procedures that have been found to be
beneficial in reducing repair times and cost. One important item to note is that the large and expensive
(microprocessor, VDP, MSP, etc) IC’s only rarely fail.
It is worthwhile considering that there have been a number of different types of CRT used with this chassis for
the same model type. Philips, Thomson (Videocolor) and LG CRT have been used. Note that the scanning coils are
supplied with the CRT and therefore the horizontal output stage components will be different for different CRT
types. With the Philips CRT there are two focus anodes, so the fly-back transformer is also different in these
models.
Most of the problems on this chassis are related to either the power circuits (chopper and horizontal) or
memory. Resetting or replacing the memory can easily cure many faults that appear to lie in the picture
processing circuitry or drive areas.
Figure 1: DA100 (50Hz) Chassis – model 56FW53H
Sharp Electronics (UK) Limited - May 2003
Revision 3
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