Have sound but No picture.
The high voltage is going to 40KV and opening the heater filament.
The high voltage module is a stand alone high voltage generator with a 130 V supply and a control line for on and off.
Has anyone had this problem?
Why is Philips so had to get information from?
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Blowing fuses, was caused by many thing.
Short of rectifier,resistor,elco,tube heater,tube pin, and also trafo itself (primary or secondary winding). It must check step by step. CAUTION :
THIS IS HIGH VOLTAGE AREA.
RISK OF ELECTRIC SHOCK THAT CAN KILL.
DON'T DO THIS IF YOU ARE NOT TECHNICIAN OR NOT FAMILIAR WITH VACUM TUBE CIRCUIT. THE CIRCUIT MAY STILL CONTAINS ELECTRIC SHOCK EVEN IF IF THE AMP IS NOT POWER PLUGGED.
The simple steps (see picture) are:
Disconnect all connection from secondary of power trafo (PLV,PDCH,PACH and PHV).
Power ON the amp. If fuse is not blowing,trafo is good.
Power OFF the amp. Unplug the cord.
Connect PLV1-PLV2-PLV3 (this are Bias voltage,+/-15VDC and Backlight PCB voltage) to power trafo.Power ON the amp. If fuse is not blowing,PLV circuit is good.If fuse blowing,there are parts is damage (dioda,elco,7815/7915,resistor) in this PLV circuit.
If step 2 is good,go to next step.
Power OFF the amp. Unplug the cord.
With PLV circuit stay connected,connect PDCH 1-2 and PACH 1-2 to power trafo. Power ON the amp.
If fuse is not blowing,PDCH and PACH circuit is good and all tubes heater/filaments are lights after a few seconds.
If fuse blowing,there are parts is damage (dioda,elco,tube heater pins) in this PDCH/PACH circuit.
If step 3 is good,go to next step.
Power OFF the amp. Unplug the cord.
With PLV,PDCH,PACH circuit stay connected,connect PHV 1-2 to power trafo.
Power ON the amp. CAUTION: HIGH VOLTAGE AREA is ON.
If fuse is not blowing,PHV circuit is good.
If fuse blowing,there are parts is damage (dioda,elco,tube pins) in this PHV circuit.
Steps had to be done sequentially from 1 to 4, not upside down.
If tube/heater pin is short,it can't be repair. The tube must be replacing.
PDCH circuit is voltage for V1-2-3-4 heater/filaments.
PACH circuit is voltage for V5-6-7 heater/filaments.
If it has a picture tube first look with set on, three tiny filaments will be lit if good, not real bright as 6.3 volts ac voltage across two pins on the actual tube.
If you can see them lit they are ok---most sets mark them on the board at the end of the neck for the picture tube with H for heater.
Very carefully as high voltages on the board measure for 6.3 volts AC across those pins. If for example its 3 volts that is too low and the voltage from those pins can be physically traced back to the High voltage transformer creates it off two pins.
less than 12 connections between source and the board on the tube, if missing voltage at the tube follow it back--a single cracked or bad solder connection can cause this.
Its a older set, if you are able to open safely and run set JUST look to see if the faint filaments in the neck of the picture tube are lit, 6.3 volt filaments, and if they are not somewhere between source at High voltage transformer up to the PC board and socket at end of tube neck you have either a broken/bad solder connection or a open part--only about a dozen connections/parts between the two----set will have a ground and a voltage source at both ends of this chain, a bad solder connection will do this if filaments not lit(3 of them in neck of tube).
WE can presume if static electricity on screen you have high voltage (most sets will not have sound if no high voltage).
If voltages appear to get good:
TAKE A CLOSE LOOK IN THE NECK OF THE PICTURE TUBE: all these sets the filaments in the tube should be lit when the set is on.
All are 6.3 volts AC (two filament pins on crt board--one is the ground and the other the AC--use that ground and carefully.
If no filaments or very very dim (they will be hard to see) the source for the voltage (if no or low filaments) comes from the high voltage transformer to the crt----usually one of two issues in this case---a part has opened or gone way up in value (resistor?)
It is a very simple circuit---just follow it back as usually on board that plugs to crt you will see something like H1 and H2. Follow both back and look for a broken connection or an open part between the tube and the source.
Let me know what you find and ask if more questions.
The reason there is no picture is (95%, certainty) the loss of the high voltage. The high voltage is what produces the energy for the raster lines upon which the video is modulated.
Therefore, the video and deflection circuits may be working just fine but you cannot see because there is no high voltage to the picture tube.
Now, it is possible, also that power to the picture tube filaments has been lost, or that the power supply to the biasing voltages is defective or that the picture tube sockets are corroded, but the overwhelming cause among TV sets is loss of high voltage.
Refurbishing the high voltage will probably cost $250 or from anywhere you go. Even if you do it yourself and buy the parts wholesale you will not save a tremendous amount. So, unless you are very handy and know how to troubleshoot, solder, repair and test, I think you are better off finding a good shop for the repair.
Replacing the high voltage regulator should fix the problem.
check the high voltage with the screen control turned up high where there is no raster. suspect problem within the video circuit where there is no high voltage or defective picture tube.some time when the screen is black and the screen control advanced,you can see if the tv has video or vertical or horizontal problems on the screen.service the high voltage circuit if there is no raster or high voltage is seen.no raster can be caused by the no heater or filament in the CRT.----
a defective picture tube can cause many problems, such as, poor brightness ,missing colors,intermittent picture,poor focus,a single-colored raster,arching in the gun assembly,retrace lines in the picture,negative picture,chassis shutdown,noheater or filament lit and no raster to name a few.an open filament or heater can cause no picture or no raster symptom.a defective CRT can have an extremely bright screen.loose particles of the cathode element can lodge between the grids and cause an intermittent black and white picture. simply tap the ends of the CRT gun assembly and notice if the picture begins to flash off and on.----
with a leaky picture tube after turn on the raster dims and get extremely bright.a dim picture with no green in the raster can result from a bad green assembly. a heater-to-cathode short can cause a raster to change colour or a result in no raster at all.replace the picture tube if there is severe arching in the neck of CRT.
excessive brightness with retrace lines and a vertical collapse to a thin line can be caused by a bad coil on the neck board of the picture tube.rejuvenate the picture tube when there is very bright green screen.
check for the resistance change on the resistors of the CRT neck board for an excessively bright picture with retrace lines.excessive dust inside the CRT spark gaps within the picture tube socket can cause the very bright raster and the chassis shutdown.a defective video amp,luminance buffer,or reference transistor can cause a bright picture with retrace lines.
for getting any required parts to replace you can get it from
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THAT MAKES SENSE, CHECK FOR HIGH VOLTAGE- YOU CAN SIMPLY HOLD A NY SMALL NEON BULB[LIKE THOSE USED IN PILOT AMPS] NEAR THE ANODE LEAD OR FLYBACK TRANSFORMER IF IT'S ACCESSABLE, AND IT SHOULD GLOW. THE NEXT STEP IS TO CHECK THE FILAMENT CIRCUIT FOR THE PROJECTION TUBES- OFTEN IN MODERN SETS, THE FILAMENT [HEATER]VOLTAGE IS OBTAINED WITH A COUPLE WINDINGS AROUND THHE FLYBACK. IF YOU HAVE HIGH VOLTAGEE, AND NO FILAMENT, A 'HACK' THAT WORKS IS TO USE A SMALL POWER TRANSFORMER [MOST FILAMENTS [HEATERS] ARE 6.3 VOLTS, BUT DOUBLE CHECK THAT- IF YOU HAPPEN TO HAVE ONE OF THE LESS COMMON LOW VOLTAGE HEATERS, AND YOU OVER-VOLTAGE IT, YOU'VE JUST DESTROYED A VERY EXPENSIVE TUBE.THE 2SD921 IS IN AL LIKEYHOOD THE HORIZONTAL OUTPUT, WHICH DRIVES THE HIGH VOLTAGE CIRCUIT. IF YOU HAVE A SCOPE, CHECK FOR APPROX 15KHZ SIGNAL AT THE EMMITTER OR BASE- BUT BE CAREFUL ABOUT THE GROUND LEAD- USE A 3 PRONG ADAPTER, AND DEFEAT THE EARTH GROUND OF THE SCOPE, OR YOU COULD DAMAGE THE TV'S POWER SUPPLY