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DA100 (50Hz) Chassis – Article for Television Magazine
Page 54 of 80
Sharp Electronics (UK) Limited - March 2003
Revision 2
EPROM’s and NVM’s
To enable the microprocessor to control its various external devices correctly, it needs a program to
run its internal operations. This program is stored in an external storage device that is normally
referred to as the EPROM, but this is not totally correct for all models.
There are three types of storage devices fitted to Sharp television receivers. These are EPROM’s,
OTP’s and MTP’s. EPROM’s have a small transparent window in the top of the device to allow ultra-
violet light to erase the memory - OTP’s and MTP’s do not have this window. OTP’s (One Time
Program) are devices that can only be programmed once. This makes them cheaper than EPROM’s, but
less flexible. MTP’s (Multi Time Program) are similar to OTP’s but can be programmed many times,
hence the name Multi Time Program. Note that all these devices are static sensitive, so anti-static
precautions need to be adhered to when handling them.
NVM’s are used for storing various values that are adjusted while in the service mode and any changes
made by the user while setting up the television. They are also used to store various transient data
values made during the operation of the microprocessor.
If a blank NVM is fitted, a set of default data stored in the EPROM is downloaded into it via the
microprocessor during the boot procedure. This process takes about a minute to complete and only
occurs at initial switch on after replacing the NVM. It is important that this process is not
interrupted as doing so may cause corruption of the data. Note that if a set switches on within ten
seconds after fitting a new NVM, this writing procedure has not been completed and there may be a
problem elsewhere in the set.
If a NVM has been changed, it is possible that when the television is powered on, the picture may have
problems such as poor geometry, incorrect audio and picture setting, etc. This is because the default
data needs to be modified by the engineer to take account of CRT and component tolerances and any
customer preference data will have been lost.
It is advisable to check that the correct EPROM version is fitted before blanking or changing the
NVM. Refer to the list at the start of this article for more information on the type of IC1002 used
for a particular chassis.
run its internal operations. This program is stored in an external storage device that is normally
referred to as the EPROM, but this is not totally correct for all models.
There are three types of storage devices fitted to Sharp television receivers. These are EPROM’s,
OTP’s and MTP’s. EPROM’s have a small transparent window in the top of the device to allow ultra-
violet light to erase the memory - OTP’s and MTP’s do not have this window. OTP’s (One Time
Program) are devices that can only be programmed once. This makes them cheaper than EPROM’s, but
less flexible. MTP’s (Multi Time Program) are similar to OTP’s but can be programmed many times,
hence the name Multi Time Program. Note that all these devices are static sensitive, so anti-static
precautions need to be adhered to when handling them.
NVM’s are used for storing various values that are adjusted while in the service mode and any changes
made by the user while setting up the television. They are also used to store various transient data
values made during the operation of the microprocessor.
If a blank NVM is fitted, a set of default data stored in the EPROM is downloaded into it via the
microprocessor during the boot procedure. This process takes about a minute to complete and only
occurs at initial switch on after replacing the NVM. It is important that this process is not
interrupted as doing so may cause corruption of the data. Note that if a set switches on within ten
seconds after fitting a new NVM, this writing procedure has not been completed and there may be a
problem elsewhere in the set.
If a NVM has been changed, it is possible that when the television is powered on, the picture may have
problems such as poor geometry, incorrect audio and picture setting, etc. This is because the default
data needs to be modified by the engineer to take account of CRT and component tolerances and any
customer preference data will have been lost.
It is advisable to check that the correct EPROM version is fitted before blanking or changing the
NVM. Refer to the list at the start of this article for more information on the type of IC1002 used
for a particular chassis.
Blanking the NVM
As the data stored in the NVM is vital to the televisions functionality, if a fault occurs, it can be
difficult to determine if the problem is due to hardware or software (data corruption) failure.
In such cases it is helpful to be able to identify which situation is present. This is achieved by
ensuring that the NVM contains correct data. If the NVM is loaded with a working set of default
values the television will either work (if data corruption was the problem) or will remain faulty (if a
hardware defect is present).
Problems caused by faulty software can be many and varied, some of which may appear to be a
hardware fault. Some of the worst memory corruption’s can lead to premature failure of the power
output stages (horizontal and vertical). Most problems though are permanent such as no sound, blank
raster, blanking faults (half a picture, missing parts of the picture, etc), OSD and teletext problems.
The list of faults can be quite extensive.
Without access to an NVM programmer or blanking jig, the engineer has little option but to replace
the NVM, turn the set on and wait. In all Sharp FW, HW and GS range of televisions, when a blank
NVM is fitted, it takes about a minute for default data to be downloaded from the ROM. If this
process is interrupted, corruption can occur and the whole process has to be repeated.
There are two types of blanking jigs for the DA100(50Hz) chassis, one for the FW/GF televisions and
one for the HW. These jigs come in the form of an EPROM (OTP or MTP) as below:
difficult to determine if the problem is due to hardware or software (data corruption) failure.
In such cases it is helpful to be able to identify which situation is present. This is achieved by
ensuring that the NVM contains correct data. If the NVM is loaded with a working set of default
values the television will either work (if data corruption was the problem) or will remain faulty (if a
hardware defect is present).
Problems caused by faulty software can be many and varied, some of which may appear to be a
hardware fault. Some of the worst memory corruption’s can lead to premature failure of the power
output stages (horizontal and vertical). Most problems though are permanent such as no sound, blank
raster, blanking faults (half a picture, missing parts of the picture, etc), OSD and teletext problems.
The list of faults can be quite extensive.
Without access to an NVM programmer or blanking jig, the engineer has little option but to replace
the NVM, turn the set on and wait. In all Sharp FW, HW and GS range of televisions, when a blank
NVM is fitted, it takes about a minute for default data to be downloaded from the ROM. If this
process is interrupted, corruption can occur and the whole process has to be repeated.
There are two types of blanking jigs for the DA100(50Hz) chassis, one for the FW/GF televisions and
one for the HW. These jigs come in the form of an EPROM (OTP or MTP) as below:
FW/GF Blanking Jig FW-SERV-JIG01
HW Blanking Jig HW-SERV-JIG01
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