Sharp 51AT15H Service manual

Sharp Electronics (UK) Limited
Reference TB-T9905070
Revision 1
White – Carry out as required, Yellow – Carry out as required and whenever the unit comes in for service, Red – Carry out on all units
CTV990704
Month of Issue: July 1999
Classification: White
TELEVISION TECHNICAL BULLETIN Page 1 of 2
MODELS 51AT15H
SYMPTOM Vertical stage problems
ACTION Listed below are a few fault conditions and their suggested remedies
Fault Counter measure
Output transistors running hot R508 high or open circuit
No front button operation D506 leaky
Will not come out of standby R508 open circuit
Top of frame distorted C501 and/or C514
Too much height Change R520 to 68kΩ(was
56kΩ)/R508
Fold over at the top of the frame Scanning coils (should read 9.9Ω)
Cramping (top or bottom) D709, C713 and check all
semiconductors in vertical stage
Loss of picture (may be intermittent) D504 and/or C502 leaky
Notes
1. When replacing semiconductors in the vertical output stage, it is strongly recommended that all parts are purchased
from the Sharp Spare Parts Center or Willow Vale Electronics using the part numbers in the service manual
(reproduced on page two).
2. C713 must be replaced with a high temperature type (use the part number below).
3. Always check the +5Vb line fed into the bias network of Q507. If Q708 (+5Vb regulator/switch) goes leaky it may
cause intermittent operation problems, but the fault symptom appears to be the vertical stage.
4. If the vertical pulse to the microprocessor is missing or distorted (pin 46 of IC1001), then the key scan will not work.
5. Q509 must be the correct device.
6. When R508 is open circuit, both vertical output transistors turn on, thus overloading the power supply. This can
cause the power supply to buzz.
7. Q503 (BC828) may be a BD830 supplied as an alternative under part number RH-TX0204BMZZ.
8. Q509 (BC635) may be supplied under an alternative part number – RH-TX0118BMZZ. This is an identical device.

Sharp Electronics (UK) Limited
Reference TB-T9905070
Revision 1
White – Carry out as required, Yellow – Carry out as required and whenever the unit comes in for service, Red – Carry out on all units
CTV990704
Month of Issue: July 1999
Classification: White
TELEVISION TECHNICAL BULLETIN Page 2 of 2
51AT15H Vertical Stage Schematic Diagram
REF NO DESCRIPTION PART NUMBER PRICE CODE
C501 Capacitor 220µf, 25V VCEAGA1EW227M AB
C502 Capacitor 100µF, 35V VCEAGA1VW107M AC
C514 Capacitor 220µF, 25V VCEAGA1EW227M AB
C713 Capacitor 1000µF, 16V 105oCVCEAHA1CN108M AD
D504 Diode, 1N4148 RH-DX0045BMZZ AA
D506 Diode, BZX79C5V1 RH-EX0408BMZZ AB
D709 Diode, 1N4935 RH-DX0529BMZZ AB
Q502 Transistor, BD825-16 RH-TX0140BMZZ AE
Q503 Transistor, BC856 RH-TX0153BMZZ AB
Q504 Transistor, BD828 RH-TX0141BMZZ AC
Q505 Transistor, BC546 RH-TX0154BMZZ AA
Q506 Transistor, BC846 RH-TX0152BMZZ AA
Q507 Transistor, 2SA1037 VS2SC1037KQ-1 AA
Q508 Transistor, BC557 RH-TX0143BMZZ AA
Q509 Transistor, BC635 RH-TX0108BMZZ AC
R508 33ΩSMD Source locally -
R520 56kΩor 68kΩ0.5WSource locally -