[TechAssist] Re: RCA PS35682LW1
- From: "Robert McPherson" <rm502@xxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Wed, 28 Dec 2005 20:34:20 -0500
Gary: Here are some tips that I've collected over time on the CTC170 &
CTC171 Chassis.
The only service data available on them (As far as I know) are the
"MiniManuals" that were tucked into the sets at the factory and Microfiche
data (Still available from RCA) Maybe You'll find something here that will
help you.
GE ProScan RCA CTC170 CTC171
CTC170
Q: No power/functions A: CR4151?
Q: No video, bad quality video, dark, flashing raster A: Q2510?
Q: No OR Intermittent turn on A: U4150?
Q: Dead. A: HV block? U4150? (Diode board attached to deflection board)
CR4151? 16 volts off cathode? U4100 regulator? U3102 EEPROM? SMD .01uf
capacitor across 4.7 VDC Zener diode in regulator circuit 1200uf @ 200VDC
electrolytic? CR4050? C4050? (140VDC?) CR4101? C4401? C4402? R4300 & 16
volts? U3101 Pin 2 3.7 volts? Q3501? R4051 SMPS area? Q3602 12 VDC @
emitter?
(Proscan Model PS35680)
Q: Cycles on and off whether cold or warm. Loud thump heard from speakers.
A: CR3604 (RCA # 146015 or 1N4001) (Small glass diode on signal board next
to R3608 (1 ohm @ 10 watts)) lead wires oxidized? (Caused by yellow glue
which covers the diode).
Q: Shuts down if deflection or Diode SIP boards are tapped on. All other
voltages at the secondary of the Power supply were normal. B+ on Collector
of Q4301 (Horizontal driver transistor) measured 0. A: Found a bad trace
connecting R4300 to the 16 volt source. (A twist tab for a heat sink was
twisted in the wrong direction during assembly, tearing the trace).
(Proscan Model PS35682)
Q: Cycles on and off three times, then shuts off. A: 9 volt source OK? 3.7
volts on pin 2 of U3101? (CPU) These two voltages are critical to the
operation of the D.C. detect circuit. U1902 (Audio output IC) defective?
Q:No Raster, no audio, no OSD. No 12 volt supply at Q3602 emitter. A: Foil
between R3608 and Q3602 Collector damaged?
Q: Dead. High pitch chirp from the power supply. No voltage at Pin 16 of
U4100. Has short circuit at stand-by run supply. A: CR4101 leaky? (Found by
isolating the loads from the IC)
Q: Shuts down. Loosing horizontal drive. Still has B+ at collector of
Horizontal output. Appears to be going into Xray shut down. (X-ray
protection circuit appears to be malfunctioning) Defeating the X-ray
restores normal operation. A: Install components in the X-ray latch circuit
listed as an XRP kit replacement for CR4902.
Q: Shuts down. A: SIP module solder joints?
Q: Turns on, but shuts down and cycles 3 times. 12 volts supply
intermittently disappears. A: 26 volt source was the cause of the fault
(FB2409 (Ferrite Bead) in the Progressive scan processor, was fractured -
causing the loss of the 2h horizontal signal) A: Remove FB2409 and install a
jumper wire (On newer models, a jumper wire.is used insread of a ferrite
bead)
Q: Shuts down. Check the supply of the 140 VDU. Supply (In standby) is
running at 85 vdc. The rest of the secondary voltages do not appear too low.
A: CR4050 (140 VDC source rectifier) defective? C4050 (Filter capacitor)
defective?
Q: Shuts down A: Burn spot in Z-match Circuit board? HV block?
Q: Intermittently shuts down then restarts. Appears to be going into Xray
protection shutdown. CR4901 running 27 volts. Originally, set had
insufficient horizontal sweep. A: C4401 defective? C4402 defective? A
decrease in value of these capacitors causes the high voltage to increase
(Reducing the HZ sweep)
Q: Shuts down when deflection board is touched. No B+ on collector of Q4302.
A: Open connection from R4300
Q: Intermittent shutdown & top hooking in picture shortly after turn on.
Sometimes blanks out then back on again displaying the message "Unit has
experienced a power failure" (Means the set got a hard reset) A: CR3604?
(RCA # 146015 or 1N4001) (Small glass diode on signal board next to R3608 (1
ohm @ 10 watts)) lead wires oxidized? (Caused by yellow glue which covers
the diode).
Q: Top hooking in pix. Intermittent no mater what video source is being
used. A: Check out the 2H adjustment on chassis, and determine the correct
free running condition. Also, FB2409 (Ferrite Bead) in the Progressive scan
processor, fractured? Causes loss of the 2h horizontal signal) Remove FB2409
and install a jumper wire (On newer models, a jumper wire.is used insread of
a ferrite bead)
Q: 1/4 second delay in the audio when changing from any channel to channel
7. The audio will delay 1/4 second in the SAP mode before switching to
stereo. A: RCA sys this is normal due to the design of MTS circuitry. It
must sample SAP briefly to determine its presence.
Q: Dead. Turns on, then immediately shut off as soon as high voltage begins
to rise. A: Remove HV feed to HV distribution block to see if HV comes up
and stays on. If so, the HV block is probably shorted.
Q: Horizontal ripple across screen. Set sometimes shuts off then restarts
displaying the message "Unit has experienced a power failure" (Means the set
got a hard reset). Voltages on Q3602 (12 volt regulator) are very unstable
when horizontal instability is present. A: Q3601 is intermittently causing
Q3602 to fall out of saturation (By varying its base voltage). Q3501 & Q3502
are unstable (Causing a partial reset of the CPU and shutting off Q3602)
Replace Q3501 & Q3502? & Others listed?
Q: Horizontal sync being lost. A: Horizontal retrace caps? Reference pulse
at pin 3 of U4350 was 5 vpp. Flyback comparison pulses input to pin 5 or
U4350 were normal. R4310 adjustment needed? U4350 defective?.
Q: No raster, audio OK. Heat sinks on PTV aux board were cold. None of the
power handling devices had any voltages on them. A: Short on the -15 volt
rectifier on the PTV aux power supply?
Q: No Raster or OSD. Heat sinks of the convergence output are cold. A: Short
on the +15 volt output of the PTV Aux power supply rectifiers?
Q: Set comes on in different states (With boxes / With Designs ? Or Normal
start) Same problem existed after replacing CR3602, Q3600, Q3607, and Q3610.
The OSD is NOT produced by the Microprocessor. The Pixel Graphics module
handles ALL of the OSD display activities. The television will operate
without the Pixel Graphics module, but there will be no OSD. Try
disconnecting or replacing the Pixel Graphics module to see if the problem
goes away.
CTC170RA
(Proscan Model PS35882)
Shuts down after 2 to 3 minutes. Looses the 12 volt run supply. FB2409
problem?
CTC171
(Proscan Model # PS52682)
Q: Dead & no standby B+ A: R4051 open? (SMPS area of main chassis)
Q: Dead. Relay clicks. A: Loose connections on and around the SIP diode
board?
Q: Shuts down. (Runs in standby mode, but shuts down when the set is turned
on) 140 volt source jumps to 185 vdc, causing the set to execute the X-ray
protection circuit instantly. A: R4148 open? (Feedback resistor) This
resistor, and another in series with it, supply a sample of the 140 vdc
supply to the run regulator on the Diode SIP board.
Q: Shuts down. Will shutdown even if X-ray protect is defeated. A: FB2409
(In the Progressive scan circuit) problem? 26 volt source was the cause of
the fault (FB2409 (Ferrite Bead) in the Progressive scan processor, was
fractured - causing the loss of the 2h horizontal signal) A: Remove FB2409
and install a jumper wire (On newer models, a jumper wire.is used insread of
a ferrite bead)
Q: Shuts down. Message "Unit has experienced a power failure" (Means the set
got a hard reset) A: SIP module, C4116, C4117 on the 16 and 7.5 volt supply
line were replaced. Check the B+ output of the SMPS power supply. Power
supply was stable but the 12 and 5 volt run supplies kept shutting off.
These are switched by the microprocessor and the reset transistors. Q3502
was leaky.
Q: Brightness fluctuates. HZ raster instability. A: Ferrite beads 2405,
2406, 2409 damaged? (Replace with jumpers)
Q: Dead, power led not lit, fan not running. A: HZ Output transistor
shorted? AC line fuse open? R702 (Deflection board) overheated?
Q: Audio problem. When the audio level is selected to minimum the audio goes
to minimum. When the when graphical display is moved to two notches above
minimum, the audio blasts. A: D/A converter is causing the problem. (Since
BOTH channels are affected - U1601 (RCA # 204290) is probably the defective
IC)
(Proscan Model # PS60682)
60" PTV DOP 10/93 Bloomington No HSPF Data No TCE Disc Data No TCE Paper
Data TCE sells Microfiche data for this model.
Circuit Board (6W81166-40C 8Q61006-01C) Located behind Green CRT
R35VZ (Blue Screen Control) R37VZ (Green Screen Control ) R39VZ (Red Screen
Control)
R11VZ (Blue Focus) R21VZ (Green Focus) R31VZ (Red Focus)
HV Divider Block RCA # 213986 (NLA) ASTI makes sub
Blue CRT (Hitachi 180BTB22B) Green CRT (Hitachi 180BTB22G) Red CRT (Hitachi
180BTB22R)
Q: No turn on.All standby supplies are running 30% too high. A:CR4103?
(Diode in stand by feedback circuit)
Q: Shuts down. Message "Unit has experienced a power failure" (Means the set
got a hard reset) A: SIP module, C4116, C4117 on the 16 and 7.5 volt supply
line were replaced. Check the B+ output of the SMPS power supply. Power
supply was stable but the 12 and 5 volt run supplies kept shutting off.
These are switched by the microprocessor and the reset transistors. Q3502
was leaky.
Q: Dead. No turn on. All standby voltages are normal. The 143 vdc source
drops to 46 volts at turn on, cycles on and off 3 times, then stops. A:
Remove HV feed to HV distribution block to see if HV comes up and stays on.
If so, the HV block is probably shorted.
Q: E/ W Pincushion (Severe hour glass distortion) A: CR4402 shorted? C4402?
Q: Insufficient horizontal sweep. Popping. High voltage lead in HV block is
burned. A: Replace HV block.
Q: No Raster, audio OK. All heat sinks on the PTV Aux power supply &
Convergence Amp transistors are cold. PTV Aux power supply is not running.
A: Check the rectifiers in the PTV AUX Power supply. CR7059 shorted? (In the
+15 volt source).
Q: No Raster. Has sound when PIP is invoked. Problem in scan loss circuit?
(Scan loss is being triggered, causing the raster to mute) All other stand
by voltages from the main supply are normal. A: Check the power supply
voltages from the secondary side of the PTV AUX board. There was a short in
the PTV AUX board and the +15 volt supply was being shorted to ground.
BOARDS 2H Dig Aux (7XXX) AC In (40XX) Adaptor (9XXX) Audio (1XXX) Control
Pod FPA (34XX)
Control/Signal (2XXX) (3XXX) Convergence (8XXX) CRT Socket (5XXX)
Deflection/PS Regulator (4XXX)
Diode (41XX) Dolby Surround (13XX) Edge Replacement (25XX) HV Regulation
(47XX) HZ Center (74XX)
IOSIP (6XXX) OSD (68XX) PIP Micro (89XX) ProLogic (12XX) TPIP (8XXX)
Robert McPherson
Computer & Television Service
1322 Durrett Lane Louisville, KY 40213
Telephone (502) 367-9324 Cellphone (502) 298-6997
Email rm502@xxxxxxxxxxxxx
----- Original Message -----
From: "Valley TV" <valleytv@xxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Wednesday, December 28, 2005 4:39 PM
Subject: [TechAssist] RCA PS35682LW1
RCA PS35682LW1 (CTC170RA chassis) comes on as soon as set is plugged in. No=
snd..no raster..Odd noise from vicinity of flyback (fly rang ok).. I have=
no schematic for this model and REALLY need a tip to help. Keypad does no=
t turn set on or off (keypad ok. No remote action either...Found a tip for=
CTC170 saying replace U6802 if set turns on after plug in BUT could NOT lo=
cate U6802 on the board.. MUST be time for glasses!!!!!
Thanks in advance!!!
Gary
Valley TV
Drums, PA office
--=20
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