Denver DTV-1401MKII User manual

SERVICE MANUAL
DENVER DTV-1401MKII
MODEL

- 2 -
IMPOTANTSAFETYNOTICE
Manyelectricaland mechanicalpartsinthischassishavespecialsafety-related characteristics.Thesepartsare
identified byinthe SchematicDiagramand ReplacementpartsList.
It isessentialthatthesespecialsafetyparts’shouldbe replaced withthe samecomponentsasrecommended in
thismanualtopreventX-RADIATION,Shock,Fire,orotherHazards.
Donotmodifythe originaldesign withoutpermission ofmanufacturer.
SAFETY PRECAUTIONS
GeneralGuidance
An lsolation Transformer should always be used during
the servicing of a receiver whose chassis is not isolated
from the AC power line. Use a transformer of adequate
power rating as this protects the technician from accidents
resulting in personal injury from electrical shocks.
It will also protect the receiver and it’s components from
being damaged by accidental shorts of the circuitary that
may be inadvertently introduced during the service
operation.
If any fuse (or Fusible Resistor) in this TV receiver is blown,
replace it with the specified.
When replacing a high wattage resistor (Oxide Metal Film
Resistor,over 1w),keep the resistor 10mm away from PCB.
Keep wires away from high voltage or high temperature
parts.
Due to high vacuum and large surface area of picture tube,
extreme care should be used in handling the picture Tube.
Do not lift the picture tube by it’s Neck.
x-RAY Radiation
Warning:
The source of X-RAY RASIATION in this TV receiver is the
High Voltage section and the picture Tube.
For continude S-RAY RADIATIONprotection , the
replacement tube must be the same type tube as speci-
fied in the Replacement parts List
To determine the presence of high voltage,use an accu-
rate high impedance HV meter.
Adjust brightness, color,contrast controls to minimum.
Measure the high voltage.
The meter reading should indicate 23.5+1.5KV:14-19 inch,
26 +1.5kv:19-21inch,lf the meter indication is out of
tolerance,immediate serviceand correction is required to
prevent the possibility of premature component failure.
Before returning the receiver to the customer
always perform an AC leakag current check on the
exposed metallic parts of the cabinet,such as antennas,
terminals,etc;to be sure the set is safe to operate
without damage of electrical shock.
Leakage current cold check (Antenna cold check )
with the instrument AC plug renoved fron AC source,
connect an electical junper across the two AC plug prongs.
Place theAC switch in the on position, connect one lead of
ohm-meter to the Ac plug prongs tied together and touch
other ohm-meter lead in tum to each exposed metallic parts
such as antenna terminals,phone jacks,etc.
If the exposed metallic part has a return path to the chassis,
the measured resistance should be beween1MΩand 5.
2MΩWhen the exposed metal has no return path to the
chassis the reading must be infinite,An other abnormality
existsthatmustbecorrectedbeforethereceiverisreturned
to the customer.
Leakage Current Hot Check(See below Figure)
plug the AC cord DIRECTLY into the AC outlet.
Do notuse a line lsolation Transformer during this check.
Connect 1.5k/10watt resistor in parallel with a 0.15uF
capacitorbetween a known good earth ground (Water pipe,
Conduit,etc.)and the exposed metallic parts.
Measure the AC voltage across the resistor using AC
voltemeter with 1000 ohms/volt or more sensitivity.
Reverse plug the AC cord into the AC outlet and repeat AC
voltage measurements for each exposed metallic part.Any
voltage measured must not exceed 0.75 volt RMS which
is corresponds to 0.5mA.
In case any measurement is out of the limits specified,
there is possibility of shock hazard and the set must be
checked and repaired before it is retumed to the customer.
Leakage Current-Hot Check circuit
AC Volt-meter
To Instrument’s
exposed
METALLICPARTS
Good Earth Ground
such as WATER
PIPE,CONDUIT EIC
1.5Kohm/10W
0.15 uF

- 3 -
CAUTION:Beforeservicing receiverscovered bythisser-
vicemanualitssupplementsand addenda,read and follow
the SAFETYPRECAUTIONSon page 3ofthispublication.
NOTE:lfunforeseen circumstancescreateconflictbetween
the following servicing precautionsand anyofthe safety
precautionson page 3ofthispublication,always follow
the safetyprecautions.Remember:SafetyFirst.
GeneralServicing precautions
1.Always unplgthe receiverACpowercordfromthe AC
powersourcebefore:
a.Removing orreinstalling anycomponent,circuitboard
moduleoranyotherreceiverassembly.
b.Disconnecting orreconnecting anyreceiverelectrical
plug orotherelectricalconnection.
c.Connecting atestsubstituteinparallelwithan electro
lyticcapacitorinthe receiver.
CAUTION:Awrong partsubstitution orincorrectpolarigy
installation ofelectroiyticcapacitorsmayresultinan
expiosison hazard.
d.Discharging the picturetube anode.
2.Testhigh voltage onlybymeasuring itwithan appropri
atehigh voltage meterorothervoltage measuring de
vice(DVM,FETVOM,etc)equipped withasuitablehigh
voltage probe.
Donottesthigh voltage by“drawing an arc”.
3.Discharge the picturetube anode onlyby(a)firstcon
necting one end ofan insulated cliplead tothe degauss
ing orkine aquadag grounding systemshieldatthe point
wherethe picturetube socketground lead isconnected,
and then (b)otuchthe otherend ofthe insulated diplead
tothe picturetube anode button,using an insulating
handietoavoidpersonalcontactwithhigh voltage.
4.Donotspraychemicalson ornearthisreceiveroranyof
itsassemblies.
5.Unless specified otherwiseinthisservicemanual,clean
electricalcontactsonlybyapplying the following mixture
tothe contactswithapipe cleaner,cotton-topped stick
orcomparablenonabrasiveapplicator:10%(byvolume)
Acetoneand90%(byvolume)isopropylalcohol(90%-90%
strength)CAUTION:Thisisaflammablemixture.
Uniess specified otherwiseinthisservicemanual,lubri
cation ofcontactsinnotrequire
6.Donotdefeatanyplug/socketB+voltage interlocks with
whichreceiverscovered bythisservicemanualmightbe
equipped.
7.DonotapplyACpowertothisinstrumentand/oranyof
itselectricalassembliesunless all solid-statedeviceheat
sinks arecorrectlyinstalled.
8.Always connectthe testreceiverground lead tothe re
ceiverchassisground beforeconnecting the testreceiver
positivelead.
Always removethe testreceiverground lead last.
9.Usewiththisreceiveronlythe testfixturesspecified in
thisservicemanusl.
CAITION:Donotconnectthe testfixtureground strap to
anyheatsinkinthisreceiver.
ElectrostaticallySensitive(ES)Devices
somesemiconductor(solidstate)devicescan be damaged
SERVICINGPRECAUTIONS
easilycalled ElectrostaticallySensitive(ES)Devices.Ex-
amplesoftypicalES devicesareintegrated circuitsand
somefieldeffecttraansistorsand semicounductor
“chip”components.Thefollowingtechniquesshouldbeused
tohelpreducetheincidenceofcomponentdamagecaused
bystaticbystaticelectricity.
1.lmmediatelybeforehanding anysemiconductorcom-
ponentorsemiconducotr-equipped assembly.drainoff any
electostaticcharge onyourbodybytouchingaknownearth
ground.Alematively.
Obtainand wearacommerciallyavailabledischarging
wrislstrap device.whichshouldbe removed topreventpo-
tentialshock reasonspriortoapplying powertothe unit
undertest.
2.Afterremoving an electricalassemblyepuipped with
ESdevice.placethe assemblyon aconductivesurtacesuch
asaluminumfoil.topreventelectrostaticcharge buildup or
exposureofthe assembly.
3.Useonlyagrounded-tipsoldering iron tosolderor
unsolderES devices.
4.Useonlyan anti-statictype solderremovaldevice.
Somesolderremovaldevicesnotclassified as“anti-
static”can generateelectrecalchargessufficenttodemage
ES devices.
5.Donotusefreon-propelled chemicals.Thesecan gen-
erateelectricalchargessrffienttodamage ES devices.
6.DonotremovearepalcementES devicefromitspro-
tectivepackage until immediatelybeforeyou arereadyto
install it.(MostreplacementES devicesarepackage with
leadselectricall shorted togetherbyconductivefoam,
aluminumfoil orcomparableconductivematerial).
7.lmmediatelybeforremoving the protectivematerial
fromthe ieadsofareplacementES devicetouchthe pro-
tectivematerialtothe chassisorcircuitassemblyintowhich
the devicewill be installed.
CAUTION:Besureno powerisapplied tothe chassisor
circuitand observeall othersafetyprecautions.
8.Minmizebodilymotionswhen handling unpackaged
replacementES devices.(Otherwiseharmless motion
suchasthe bruching togetherofyourclothesfabricorthe
lifting ofyourfootfromacarpeted floorcan generatestatic
electricitysufficienttodamage an ES device.)
GeneralSoldering Guidelines
1.Useagrounded-tip.low-wattage soldering iron and
appropriatetipsizeand shape thatwill maintan tip
temperturewithen the range or500kto600k.
2.Usean appropriategauge ofRMAresin-coresolder
composed of60partstin/40partslead.
3.Keep the soldering iron tipclean and well tinned.
4.Thorohlyclean the surfacestobe soldered Useamall
wirebristle(0.5inch.or1.25cm)brushwithametalhandle.
Donotusefreon-propelled spray-on cleaners.
5.Use the following unsoldering technique
a.Allow the soldering iron tip to reach normal temperature
(500k to 600k)
b.Heat the component lead until tne solder melts.
c.Quicklydraw themelted solderwithananti-statlc,suc tion-

- 4 -
type solder removal device or with solder braid.
CAUTION:Work quickly to aviod overheating the
circuiboard printed foill.
6.Use the following soldering technique.
a.Allow the soldering iron tip to reach a normal temperature
(500k to 600k)
b.First,hold the soldering iron tip and solder the strand.
Against the component lead the solder melts.
C.Quickly move the soldering iron tip to the junction of the
compontent lead and the printed circuit foil and hold it
there oniy until the solder flows onto and around both
the component lead and the foil.
CAUTION:work quickly to avoid overheating the circuit
board printed foil.
d.Closely inspect the solder area and remove any excess
or splashed solder with a small wire-bristle brush.
IC Remove/Replacement
Some chassis circuit boards have slotted holes (oblong)
through wheic the IC leads are inserted’and then bent ftat
against the circuit foil. When holes are the slotted type the
following technique should be used to remove and replace
the IC. When working with boards using the familiar round
hole use the standard technique as outlined in parapraphs
5 and 6 above.
Removal
1. Desolder and straighten each IC lead in one operation
by gently prying up on the tead with soldering iron tip as
the solder melts.
2.Draw away the melted solder with an anti-static suction-
type solder removal device (or with solder braid) before
removing the IC.
Replacement
1.Carefully insert the replacement IC in the circuit board
2.Carefully bend each IC lead against the circuit foil pad
and solder it.
3.Clean the soldered areas with a small wire-bristle brudh.
(It is not necessary to reapply acrylic coating to the areas).
“Small-Signal” Discrete Transistor
Removal/Replacement
1.Remove the defective transistor by clipping its leads as
close as possible to the component body.
2.Bend into a “u” shape the end of each of three leads
renaining on the circuit board.
3.Bend into a “u” shape the replacement transistor leads.
4.Connect the replacement transistor leads to the corre
sponding leads extending from the circuit board and crimp
the “u”with long nose pliers to insure metal to metal to
metal contacttehn solder each connection.
Power Output, Transistor Device
Removal/Replacement
1.Heat and remove al solder from around the transistor
leads.
2.Remove the heatsink mounting screw (if so equipped).
3.Carefully remove the transistor from the heat sink of the
circuit board.
4.Insert new transistor in the circuit board.
5.Solder each transistor lead and clip off excess lead.
6.Replace heatsink.
Diode Removal/Replacement
1.remove defective diode by clipping its leads as close as
possible to diode body.
2.Bend the two remaining leads perpendiculay to the cir
cuit board.
3.Observing diode polarity wrap each lead of the new
diodearound the corresponding lead on the circuit board.
4.Secruely crimp each connection and solder it.
5.Inspect (on the circuit board copper side)the solder joints
of the two “original” leads. If they are not shiny reheat
them and if necessary apply additional solder.
Fuse and Conventional Resistor
Removal/Replacement
1.Clip each fuse or resistor lead at top of the circuit board
hollow stake.
2.Securely crimp the leads of replacement component
around notch at stak top.
3.Solder the commections.
CAUTION:Maintain original spacing between the replaced
component and adjacent component and the circuit board
to prevent excessive component temperaures.
Circuit Board Foil REPAIR
Excessive heat applied to the copper foil of any printed
circuit board will weaken the adhesive that bonds the foil
to the circuit board causing the foil to separte fron or “lift-
off” the board. The following guidelines and procedures
should be followed whenever this condition is encountered.
At IC Connections
To repair a defective copper pattem at IC connections use
the following procedure to install a jumper wire on the cop-
per pattem side lf the circuit board.9 (use this technique
ony on IC connections)
1.Carefully remove the damaged copper pattem with a
sharp knife.(Remove only as much copper as absolutely
necessary).
2.Carefully scratch away the solder resist and acrylic
coating(if used) from the end of the remaining copper
patten.
3. Bend a small “U” in one end of a small gauge jumper
wire and carefully crimp it around the IC pin.Solder the
IC connection.
4.Route the jumper wire along the path of the out-away
copper patten and let it overlap the previously scraped
end of the good copper pattem.Solder the overlapped
area and dip off any excess jumper wire.
At Other Connections
Use the following technique to repir the defective copper
pattem at connections other than IC pins.This technique
involoves the installation of a jumper wire on the compo-
nent side of the circuit board.
1.Remove the defective copper pattem with a sharp knife.
Remove at least 1/4 inch of copper,to ensure that a haz
ardous condition will not exist if the jumper wire opens.
2.Trace along the copper pattem from both sides of the
pattem break and locate the nearest component that is
directly connected to the affected copper pattem.
3. Connect insulated 20-gauge jumper wire from the lead
of nearest the nearest component on one side of the
pattem break to the lead of the nearest component.on
the other side,Carefully crimp and solder the connections.
CAUTION:Be sure the insulated jumper wire is dressed
so the it does ot touch componets or sharp edges.
SERVICING PRECAUTIONS

- 5 -
1. Speaker
2. Power Button
3. Remote Sensor
4. Channel Buttons
5. Open/Close Button
6. DVD Loader
7. Volume Buttons
8. DVD Play Button
9. DVD Stop Button
10. TV Menu Button
11. TV/AV/DVD Button
12. Earphone Jack
13. Video (1) Input
14. Audio(1) Input (R+L)
15. 75 Ohm Antenna Socket
16. Video/Audio(2) Input
17. Video/Audio Output
18. Audio digital Out Socket (For
DVD only)
LOCATION OF CONTROLS
1 12 4 6 8 10 12 14
3 5 7 9 11 13
15 16 1718