Philips EM5A NTSC Service Manual Download

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Service Modes, Error Codes and Fault Finding

EN 30

EM5A NTSC

Table 5-4 Repair tips

Phenomenon

Possible Cause

Repair tip

No picture, no LED.

Standby Supply defective.

Measure circuitry (see diagram A2). Start at test point A19.
When the set is connected to the power supply, this voltage must always be
available

No picture, no LED.

Bad connection of SSB in
SIMM-connector.

If there is a bad connection, there may be no picture, and the Standby LED
may not be controllable. Replace the SSB.

No picture, red LED blinking
at 3 Hz.

Set is in protection due to
various causes. For error
codes see error code list.

You have no picture, so:
Read the error buffer via ComPair (error buffer is accessible when set is in pro-
tection, ComPair will guide you to this)
Read the blinking LED information via standard remote command
<mute>06250X<ok>
Or read the error code sequence via standard remote command
<mute>062500<ok>.
When you have found the error, check the circuitry related to the supply volt-
age and I

C-communication or the circuitry that triggers the protection.

No picture, red LED blinking
with code 6-6-6 or 18-18-18.

No communication on slow
I

C- or fast I

C-bus.

If processor cannot communicate with one of the 2 busses, the standby-LED
starts blinking 6-6-6... or 18-18-18....
If error 6 or 18 is in the error buffer, these have the highest priority in starting
the blinking.
Depending on the error, measure to determine which device is loading the I

C-

bus. (Use I

C -overview)

No picture, red LED blinking
with code 1-1-1.

No communication on NVM-
I

C bus to the µP.

Since the µP cannot communicate with the NVM I

C bus, it spontaneously

starts blinking 1-1-1. Note: when there is no access to the NVM, many picture
settings can go wrong.

No picture, no sound. Set is
making audible squeaking
sound

Supply is possibly in hiccup-
mode, which is audible via a
squeaking supply transform-
er.

Possible causes:
VBAT is shorted (caused by short circuited line transistor 7421), or
Sound winding is shorted (amplifier is shorting the power supply lines), or
Remove excessive load, to see what causes the failure, or check feedback cir-
cuit. See repair tip "Main Power Supply" (supply needs a minimal load).

No picture, no sound. Green
LED works fine

Supply does not work cor-
rectly.

If, for example, VBAT is only about 90 V, it is possible that the regulator IC
(7506) is defective.

No RC-reception. Red LED
does not echo RC-com-
mands.

µP circuitry or RC-receiver is
defective.

If the set reacts to a local keyboard operation, you must check the RC-receiver
circuitry (diagram E).

Relay (degaussing) is not au-
dible when set is switched
from "off" or "standby" to
"on."

µP is not working correct-
ly.When pin 115 is low, the
degaussing must be activat-
ed.

Check RESET-circuitry on diagram B5. Check the level on pin 115 when you
switch the set "on." Signal must initially be low and go to high after approx. 12s.

No sound, only picture.

Measure A7/A8 on diagram
A1. Possibly the audio ampli-
fier is defective (but not
shorted), or the 'sound ena-
ble' line is high (diagram A5).
Also measure the audio sig-
nal path (HIP-MSP-Switch
ICs-Amplifier).

In ComPair, a beep test can determine where the signal stops (use loudspeak-
ers or headphone).
Possible cause is also the 'PROT1' protection (see diagram. A6). This is a
loudspeaker DC protection, which the µP cannot sense. Via circuitry 7701/
7707, this signal can put audio amplifiers 7700 and 7702 in standby mode (tri-
state input). Warning: Find out which amplifier is causing the problem, be-
cause it is possible that the other one is OK.

No sound at headphone out-
put.

HP amplifier (7681) on dia-
gram B10, or the supply to it,
is malfunctioning.

Measure pin 3 input left and pin 1 output left; repeat this for pin 3 (input right)
and pin 7 (output right), and the supply line (+8V_AUD) on diagram B10.

Picture is rotated.

Rotation circuitry on diagram
A5, or supply related to it, is
malfunctioning.

Measure test points A52 and A53 on diagram A5.

Picture is continuously
switching "off" and "on,"
showing heavy "switch"
spots (set does not go into
protection).

200 V is missing on CRT
panel.

Probably a bad connection from LSP connector 1424 to CRT connector 1224
(diagram F1), or an interruption of the 200 V supply line (for example, R3341
on circuit F1 is interrupted).

Picture is not sharp.

Focus is possibly misaligned,
or SCAVEM-circuitry does
not work correctly.

Realign the focus potmeter on the Line Output Transformer, or check the
SCAVEM circuitry on the CRT panel (diagram F2). It is also possible that the
DAF circuitry is defective (see diagram I). Check the Vdc values.

Picture is not synchronized.

The sync is derived in the
HIP from xtal 1305 and/or
1308.

The crystal(s) 1305 and/or 1308 may not be making good contact.

Picture is distorted.

Check video path in Service
Default Mode.

Determine whether there is an error code present in the error buffer. If one is
present, check the I

C-bus and/or supply lines (see supply lines over-

view).Measure and check signal path Tuner-HIP-PICNIC-HOP-RGB amplifier.
If it is a geometry issue, check opto-coupler 7482 on diagram A4, OpAmps
7440/7450 and the Frame circuitry alignments, or a possible corrupted NVM
(7011) on diagram B5.

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