Fault on pace sky digibox.

Hi: Not much technical on sky digibox on the net but hears a start all these fault are based on Pace hope it helps you.


Stuck in standby
Nature of problem.
When the unit powers up, the red light comes on but, even after a minute, it will not come out of standby
For checks to be carried out, see below

(1)
Pins 3 and 4 of CON2O for 5V and 3V3 respectively If NO = Fault associated with the PSU
If OK goto 2
(2)
MEMDATA activity on pin 11 of U272 or the pad if IC not fitted (refer to WF 1) If NO = X370 is producing 27 MHz (pin 6, U370) If YES goto 2a If NO Fault = VCXO cct
(2a) notrst is correct 3 3 V (pin 116, U300) If NO = Housekeeping cct
If OK goto 3
(3)
Activity on pin 73 of U700 (refer to WF 2) = WF 2
If YES goto 5 If NO goto 4
(4)
X700 for 29MHz on pins 66 and 67 of U700 If NO = Check signal on C702 (294 MHz, 26 Vp-p sat on 400 mV) and C703 (29.4 MHz,1 9Vp-p saton 600 my) If low, change U700 and parts in Modem Spares Kit
If YES goto 5
(5)
I2C activity on pin 13 (refer to WF3) and pin 3 (refer to WF4) of U211 If NO = Components on I2C bus
(6)
If revision B1 PCB, suspect ZIF tuner (Note remote command LED usually still flashes when a key on the remote is pressed
(7)
GIVE UP



Primary symptoms
PCB rev.
Secondary symptoms
Checks to be made
Components to be replaced


Intermittently stuck in standby
A2-B1
I2C lines low (not 3v3)
Check for water ingress around the modulator can Rust forming on the PCB can cause a partial short between the I2CBus and ground (There are two pads on the PCB in front of the modulator can, behind L690, which are the I2C data bus ) Clean the affected area with PCB cleaning-fluid

Intermittently stuck in standby
A2-A3
U386

Stuck in standby
A2-A7
No 10 MHz
X401

Stuck in standby
A2-B1
No 29 MHz reference
U700

Stuck in standby
A2-B1
remote command LED flashes when a remote control key is pressed
U7002 and U7006

Stuck in standby
B1
remote command LED flashes when a remote control key is pressed
ZIF tuner

Stuck in standby
A2-B1
Low voltage readings on various PSU rails
Check for short-circuit on U4

Stuck in standby
A2-B1
SDRAM clock OK l2C held at 3V3, with occasional small burst ot data
U900 and U901

Stuck in standby
5512 [Al]
12C data present but not correct (too much activity)
ZIF tuner

No teletext operation
A2-Bl
Control line ttxtrequest is OK, but ttxtdata is held high
U300

No UHF channel 69
A2-B1
Voltage reading on D640 higher than normal over the range of UHF channels
D640

No IR operation via RF2
A2-B1
Remote IR signal is OK going into Q605 IR works OK via the front panel
Check the 5V output of Reg 1, it needs to be very accurate
Reg 1

No IR operation via RF2
A2-B1
8V signal output from RF2, but no operation
Q603 and Q604

No IR operation via RF2
A2-B1
No 8V supply, or supply is low
R70

No IR operation via RF2
A2-B1
No 8V supply, or supply is incorrect
D53

Crackling on audio via Scart
A2-B1
Check for dry joints on R955 and R997. Also, check for dry joints around U903, U907 and U908

No audio or crackling
A2-B1
No PCMDATA on pin 41 of U320
U320


Crackling audio
A2-A4
0550 very hot 0551 pulling down 5V output

U551
No audio via
Scart
(OK via RF)
A2-Bl
Check for short-circuit across C3012

No audio
A2-Bl
No signals at inputs of U551
U320

Tone superimposed on audio
A2-Bl
Tone is being generated by G729 chip and added to the audio signal

03002
High pitch whistle on audio
A2-Bl
U320

No audio
A2-Bi
video OK
Check for dry joints around
U551

No audio on modulator
A2-B1
Audio OK on Scart
U905

Audio disappears or distorts when STB is warm
A2-B1
Fault in 0729 operation
U3002

LNB supply incorrect
A2-Bl
Both H and V measure low
D1O5

Distorted audio
5512 [A1}
Sounds like a Dalek'
BGA chip (0300)

No horizontal channels
A2-Bl
Vertical channels OK
U103 and Q103

No satellite signal
A2-A7
C433 and C434

No satellite signal
A2-A7
Voltage on pin 3 of U451 high, pin 50 is OV
Tuner

No satellite signal
A2-A7
Signal-strength reading is low Signal-quality reading is fluctuating
Tuner

No satellite signal on some channels
A2-A7
Low- and high-frequency transponders are missing Middle ones are OK
Check D405 30V Zener to see whether it is pulling down the tuner volts
D405

No TV listings
A2-Bl
U32O

No TV listings
A2-B1
STB works OK apart from lack of TV listings
07002 and U7006

No TV listings, no video or audio
A2-Bl
Check signals from front end on multiplex outputs (U151,Ul53andUl55) If signals are OK, change U300 If the signal is not correct, the fault lies in the front-end circuit

Fine, colored lines on picture
A2-Bl
U500

Small green squares or small block of lines on screen
A2-Bi
Some channels are worse than others
U321 and LJ322

Blocks on menu
A2-B1
Remote function may lock up Picture OK
U321 and U322

No RF output
A2-Bl
Check for 4 MHz (X640) on crystal side of C653

Black-and-white rolling picture on channels 68 and 69
A2-Bi
OK on other RF channels
C650 and C651

Picture and audio freezing intermittently
A2-A7
U404

Poor picture on AV and RF
A2-B1
Pink, snowy picture Sound OK
U321 and U322

Picture is black and white
A2-Bi
X370 27 MF-lz reference running at wrong frequency
C370

Blank screen
A2-Bi
Audio OK
Check for dry joints around U900 and U901

Blue screen, no audio
A2-B1
No audio output from U901
U900 and U901

Intermittent picture break-up
A2-B1
Menus showing blocks and bars
U321 and U322

Intermittent picture break-up
A2-Bi
Searching tor TV listings on weak signal
R116, R117, C107 and D109

Intermittent picture freezing
A2-A7
Errors on notfecfail
U403

Intermittent I picture freezing
A2-A7
Check pin 22 of U404 for
55 MHz and pin 1 of U402
for stable 5V
U404

At System Test screen, a message is displayed Telephone line not connected'
A2-B1
STB cannot see telephone voltage
U853, U854 and 0854

No switching on Start pin 16
A2-Bi
No RGB operation
Q902 and Q903

No switching on Scart pin 8
A2-B1
No widescreen switching
Q904

Not reading card
A2-A3
Only free-to-air channels available
R391

No 22 kHz tone on horizontal polarity
A2-B1
OK on vertical channels
Q103

On-screen message indicates problem with viewing card
A2-B1
Check 4 5 MHz 5 V p-p waveform on pin 15 of U1100
If not present, check that input on pin 24 is 45 MHz 4 5 V p-p If OK, change U1100

Will not dial out
A2-B1
System test OK
Q0850

Displays purple screen
A2-B1
No SDRAM clock at pin 35 on U321 and U322
U7200

Fails to go off hook'
A2-B1
D854

Sky menus displayed in wrong colour
A2-B1
Video and audio OK
U320

Slow to boot up
A2-B1
Modem IC not running
U700

Access to Open....
interactive services is suddenly lost
5512 {A1)
On-screen display reverts to the main Sky Guide Interactive menu
U300

ERR on front-panel display
X102 on front panel

ERR on front-panel display
Intermittently OK I2C incorrect
C305

No channels viewable
Scans OK If powered down, then powered back up, Welcome screen is displayed
Check U254 for dry joints

Will not tune
U300

Will not switch on
Check U300 for dry joints

No audio
Check that digital audio signals are present from U320 on pins 1, 2, 41 and 42. If they are not present, suspect U320 If they are present, proceed to check from the audio DAC (Digital-to Analogue) onwards.

Modem faulty
Replace the modem IC, U700 (Pace Part No 265-230A2B1) Also, replace all related components, using the Modem Spares Kit (Pace Part No. 903-001675 1)



Will not power up (dead)
Check the resistance of the 3V3 and 5V with respect to ground. If they both measure below 1K, suspect multiple failures (usually caused by a lightning strike) If this is the case, a repair is normally uneconomical.


No short-circuit, but still dead
Check to see if the power lines are pulsing, which would indicate a tripping PSU Note that the PSU may trip very quickly and that this tripping may not be audible. Suspect secondary diodes and Dl If there are no supplies at all, suspect FS1, U1, U2, U3, D45 and C3.
The best place to check the secondary supplies is on C0N20 C0N20 is a series of five pads situated at the front right-hand side of the PCB Figure 2, below~ shows which pad is associated with which rail


CON20=
33v 16v 5v 3v3 0v
o o o o o
33V high
16V high
5V 1k2
3V3 1k

SECONDARY PSU RAILS

Diode Voltage

D20 (+) 3.3V
Components that use the supply:
U151 to U155, U200, U203 to U206, U208, U210, U271 to
U274, U300, U305, U320, U321, U322, U370, U386, U403,
U500, U600, U601, U700, U805, 0854, U10O0, U1100,
U110l, U7002, U7006, U7200, U7202, U7204, U7206

D25=(-)8v

D30
(+) 5.7V = U156, U402 Also used to generate 5V and 5VF
(+) 5V = U156, U211, U350, U388, U404, U702, U703, U802, U902
(+) 5VF = U451
(+) 5VG = U3001 (5VG is taken from the 5V rail via L3000)
(+) 5VA = U551 (taken from the (+) 8V by U550)

D35
(+) 8V = U550, U602, U900, 0901
(+) 8VA = 11903, U905, U907, 0908 (taken from (+) 8V)

D38
(+) 16V = Used for LNB switching

D45
(+) 20V = Used for LNB switching

D50
(+) 33V = U401, TUN400


D51
(+) 27V = U103
(+) 24V = U400 (taken from the (+) 33V rail via D404)