M
Michael Caplan
This 1986, 27" set (chassis SCC-552U-A) has excellent video but very low
audio when in TV mode (using the RF input). I suspect the IC in the IF
Block, but would appreciate confirmation and information about the IC.
With the volume at maximum, the program audio can be heard on the bench, but
is still far below what is needed in a normal viewing situation.
When using the Video input mode (e.g. signal from a VCR), the sound levels
are normal.
I have the Sams Photofact (2514). The symptoms along with several other
tests the guide describes suggest a fault in the IF Block, IFB-450M.
The DC voltages at the IF block connection to the pcb are close to the
schematic levels except at pin 6 and pin 10. Pin 6 should be 4.3 V but is
2.8 volt and somewhat unsteady (varies several tenths of a volt) and pin 10,
the MPX out, should be 3.5 V but is 0.7 V. Both pins go directly to the IC
inside, a Sony 20014X.
I've checked the solder joints in the IF block, especially at the coils and
at the pcb to case grounds, and have touched up any that looked doubtful.
I've also pulled the tuner and checked it for bad joints, to no avail.
(This set does not have the problematic stereo board with the bad SM caps so
that is not a factor.)
The IF Block , p/n 1-464-598-11, is quite expensive. However, I found a
cross-reference for the IC itself, labelling it as a CX20014A, which, if
this is the correct part, is available at much more reasonable cost (p/n
8-752-050-08). But I have not been able to find a data sheet for the
CX20014A that would confirm it is the same as the 20014A in this set.
Google did not come up with anything on this model/chassis.
Has anyone had experience with audio problems caused by a failed IF block
IC? If so, have you replaced the IC and can you confirm that the part
number above for the IC applies to the IC in the IF Block of this KV-2771R.
Michael Caplan C.E.T.
audio when in TV mode (using the RF input). I suspect the IC in the IF
Block, but would appreciate confirmation and information about the IC.
With the volume at maximum, the program audio can be heard on the bench, but
is still far below what is needed in a normal viewing situation.
When using the Video input mode (e.g. signal from a VCR), the sound levels
are normal.
I have the Sams Photofact (2514). The symptoms along with several other
tests the guide describes suggest a fault in the IF Block, IFB-450M.
The DC voltages at the IF block connection to the pcb are close to the
schematic levels except at pin 6 and pin 10. Pin 6 should be 4.3 V but is
2.8 volt and somewhat unsteady (varies several tenths of a volt) and pin 10,
the MPX out, should be 3.5 V but is 0.7 V. Both pins go directly to the IC
inside, a Sony 20014X.
I've checked the solder joints in the IF block, especially at the coils and
at the pcb to case grounds, and have touched up any that looked doubtful.
I've also pulled the tuner and checked it for bad joints, to no avail.
(This set does not have the problematic stereo board with the bad SM caps so
that is not a factor.)
The IF Block , p/n 1-464-598-11, is quite expensive. However, I found a
cross-reference for the IC itself, labelling it as a CX20014A, which, if
this is the correct part, is available at much more reasonable cost (p/n
8-752-050-08). But I have not been able to find a data sheet for the
CX20014A that would confirm it is the same as the 20014A in this set.
Google did not come up with anything on this model/chassis.
Has anyone had experience with audio problems caused by a failed IF block
IC? If so, have you replaced the IC and can you confirm that the part
number above for the IC applies to the IC in the IF Block of this KV-2771R.
Michael Caplan C.E.T.
