Question about Projection Televisions

3 Answers

Power Supply fuse blows HOT checks ok But does have a short somewhere.

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  • Ray Jones Mar 14, 2008

    Brand Symphonic Mfg. Funi Corp.Inc. Board#2642308 alt.#80211477 It has Toshiba Transistor for HOT# D2638

  • Ray Jones Mar 14, 2008

    This is not a projection tv it is a symphonic 27' picture tube model. Ray Jones

  • Ray Jones Mar 14, 2008

    Jamie867 Brand is Symphonic 27" Picture Tube type Board Sticker has two numbers top row is 2642308 bottom row is 80211477. Mfgr. Funi Corp. Inc. Model # WF27F4

  • Jaime Hernandez May 11, 2010

    Can you provide us with more info on brand, model and chassis number?

    The more info we have the better we can point you where to check.

×

3 Answers

Ray Jones
I posted the solution that you notified me about . I thought it might help someone else. I do thank you for your help Jamie867.

Posted on Mar 25, 2008

The problem was two IN5406 diodes in the switching power supply was blown and replacing these got the set up and running again thanks for your help.

Posted on Mar 21, 2008

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  • Master
  • 2,267 Answers

I look for an schematic diagram but i was unable to find one. I guess we can try to fix this one the old fashion way without the schematic.
I would suggest to check the voltage regulator for a shorted condition and all the diodes and capacitors near it. If your horizontal transistor is good the short is somewhere the power supply but you can also check any other part that has the B+ 130VDC.
Let me know if you need more assistance.

Posted on Mar 15, 2008

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1 Answer

RCA HD52W58 has a short somewhere in the deflection board


TL010 which is the HOT its attached to the heat sink directly in front of the flyback. Unsolder that and see if the fuse stops blowing.

Oct 21, 2012 | RCA HD52W56 52" Rear Projection HDTV

1 Answer

I have a RCA HD50LPW175 TV and it keeps blowing the 6-Amp fuse125v. Why?


Either you have a dead short or you used the wrong fuse--not all 6a fuses are the same---buy a cheap generic one from Radio shack etc and it can blow for no reason.

If not the wrong fuse---the fuse you are talking about should be where power enters the set--means a short on primary side of set's power supply---somewhere between power cord and input side----possible the bridge rectifier is shorted.

l have usually seen this when there was a power outage or a surge on the incoming power line.

May 28, 2012 | RCA Projection Televisions

1 Answer

Tv wont turn on?


Hello,
first you have to open the back cover of the television to check for blown fuses.

A blown fuse is a very common type of fault due to poor design very often triggered by power surges due to outages. However, the most likely parts to short are easily tested, usually in-circuit, with an ohmmeter and then easily removed to confirm.

Note that it *may be* useful to replace a fuse the *first* time it blows (though it would be better to do some basic checks for shorted components first as there is a small chance that having a fuse blow the second time could result in additional damage which would further complicate the troubleshooting process). However, if the new one blows, there is a real problem and the only use in feeding the TV fuses will be to keep the fuse manufacturer in business!

Sometimes, a fuse will just die of old age or be zapped by a power surge that caused no damage to the rest of the TV. However, it must be an EXACT replacement (including slo-blow if that is what was there originally). Else, there could be safety issues (e.g., fire hazard or equipment damage from too large a current rating) or you could be chasing a non-existent problem (e.g., if the new fuse is not slo-blow and is blown by the degauss circuit inrush current but nothing is actually wrong).

If the fuse really blows absolutely instantly with no indication that the circuits are functioning (no high pitched horizontal deflection whine (if your dog hides under the couch whenever the TV is turned on, deflection is probably working).) then this points to a short somewhere quite near the AC power input. The most common places would be:

Degauss Posistor - very likely.
Horizontal output transistor.
Power supply regulator if there is one.
Power supply chopper (switchmode) transistor if there is one.
Diode(s) in main bridge
Main filter capacitor(s).

You should be able to eliminate these one by one.



Test the rectifiers individually or remove and retest the resistance.


If these test good, use an ohmmeter with the set unplugged to measure the horizontal output transistor. Even better to remove it and measure it.

C-E should be high in at least one direction.
B-E may be high or around 50 ohms but should not be near 0.

If any readings are under 5 ohms, the transistor is bad. The parts sources listed at the end of this document will have suitable replacements.

If the HOT tests bad, try powering the set first with your light bulb and if it just flashes once when the capacitor is charging, then put a fuse in and try it. The fuse should not blow with the transistor removed.

Of course, not much else will work either.

If it tests good, power the set without the transistor and see what happens. If the fuse does not blow, then with the good transistor (assuming it is not failing under load), it would mean that there is some problem with the driving circuits possibly or with the feedback from the voltages derived from the horizontal not regulating properly.

Look inside the TV and see if you can locate any other large power transistors in metal (TO3) cans or plastic (TOP3) cases. There may be a separate transistor that does the low voltage regulation or a separate regulator IC. Some TVs have a switchmode power supply that runs off a different transistor than the HOT. There is a chance that one of these may be bad. If it is a simple transistor, the same ohmmeter check should be performed.

If none of this proves fruitful, it may be time to try to locate a schematic.

A blown fuse is a very common type of fault due to poor design very often triggered by power surges due to outages or lightning storms. However, the most likely parts to short are easily tested, usually in-circuit, with an ohmmeter and then easily removed to confirm.
But if otherwise your power supply board is dead, It can be dead at anytimes.Tries websites Shopjimmy.com,Ebay.com to buy a refurbish power supply board for the replacement.
Hope this helps....

.

Jun 05, 2010 | Zenith R57W46 57" Rear Projection...

1 Answer

No power


hello,
First check if the TV plug is connected to the mains socket.
A blown fuse is a very common type of fault due to poor design very often triggered by power surges due to outages or lightning storms. However, the most likely parts to short are easily tested, usually in-circuit, with an ohmmeter and then easily removed to confirm.

Note that it *may be* useful to replace a fuse the *first* time it blows (though it would be better to do some basic checks for shorted components first as there is a small chance that having a fuse blow the second time could result in additional damage which would further complicate the troubleshooting process). However, if the new one blows, there is a real problem and the only use in feeding the TV fuses will be to keep the fuse manufacturer in business!

Sometimes, a fuse will just die of old age or be zapped by a power surge that caused no damage to the rest of the TV. However, it must be an EXACT replacement (including slo-blow if that is what was there originally). Else, there could be safety issues (e.g., fire hazard or equipment damage from too large a current rating) or you could be chasing a non-existent problem (e.g., if the new fuse is not slo-blow and is blown by the degauss circuit inrush current but nothing is actually wrong).

If the fuse really blows absolutely instantly with no indication that the circuits are functioning (no high pitched horizontal deflection whine (if your dog hides under the couch whenever the TV is turned on, deflection is probably working).) then this points to a short somewhere quite near the AC power input. The most common places would be:

Degauss Posistor - very likely.
Horizontal output transistor.
Power supply regulator if there is one.
Power supply chopper (switchmode) transistor if there is one.
Diode(s) in main bridge
Main filter capacitor(s).

You should be able to eliminate these one by one.

Unplug the degauss coil as this will show up as a low resistance.

First, measure across the input to the main power rectifiers - it should not be that low. A reading of only a few ohms may mean a shorted rectifier or two or a shorted Posistor.

Test the rectifiers individually or remove and retest the resistance.

Some sets use a Posistor for degauss control. This is a little cubical (about 1/2" x 3/4" x 1") component with 3 legs. It includes a line operated heater disk (which often shorts out) and a PTC thermister to control current to the degauss coil. Remove the posistor and try power. If the monitor now works, obtain a replacement but in the meantime you just won't have the automatic degauss.

If these test good, use an ohmmeter with the set unplugged to measure the horizontal output transistor. Even better to remove it and measure it.

C-E should be high in at least one direction.
B-E may be high or around 50 ohms but should not be near 0.

If any readings are under 5 ohms, the transistor is bad. The parts sources listed at the end of this document will have suitable replacements.

If the HOT tests bad, try powering the set first with your light bulb and if it just flashes once when the capacitor is charging, then put a fuse in and try it. The fuse should not blow with the transistor removed.

Of course, not much else will work either.

If it tests good, power the set without the transistor and see what happens. If the fuse does not blow, then with the good transistor (assuming it is not failing under load), it would mean that there is some problem with the driving circuits possibly or with the feedback from the voltages derived from the horizontal not regulating properly.

Look inside the TV and see if you can locate any other large power transistors in metal (TO3) cans or plastic (TOP3) cases. There may be a separate transistor that does the low voltage regulation or a separate regulator IC. Some TVs have a switchmode power supply that runs off a different transistor than the HOT. There is a chance that one of these may be bad. If it is a simple transistor, the same ohmmeter check should be performed.

If none of this proves fruitful, it may be time to try to locate a schematic.

A blown fuse is a very common type of fault due to poor design very often triggered by power surges due to outages or lightning storms. However, the most likely parts to short are easily tested, usually in-circuit, with an ohmmeter and then easily removed to confirm.
Good luck

May 21, 2010 | Samsung HCN4226W 42" Rear Projection...

1 Answer

MY HITACHI TELEVISION IS NOT COMING ON


Hello, Firstly, check if power plug of the television is in contact with the power socket of the house. if this is done and not coming on. Then you are require to open the back cover of the television. A blown fuse is a very common type of fault due to poor design very often triggered by power surges due to outages or lightning storms. However, the most likely parts to short are easily tested, usually in-circuit, with an ohmmeter and then easily removed to confirm.
Note that it *may be* useful to replace a fuse the *first* time it blows (though it would be better to do some basic checks for shorted components first as there is a small chance that having a fuse blow the second time could result in additional damage which would further complicate the troubleshooting process). However, if the new one blows, there is a real problem and the only use in feeding the TV fuses will be to keep the fuse manufacturer in business!
Sometimes, a fuse will just die of old age or be zapped by a power surge that caused no damage to the rest of the TV. However, it must be an EXACT replacement (including slo-blow if that is what was there originally). Else, there could be safety issues (e.g., fire hazard or equipment damage from too large a current rating) or you could be chasing a non-existent problem (e.g., if the new fuse is not slo-blow and is blown by the degauss circuit inrush current but nothing is actually wrong).
If the fuse really blows absolutely instantly with no indication that the circuits are functioning (no high pitched horizontal deflection whine (if your dog hides under the couch whenever the TV is turned on, deflection is probably working).) then this points to a short somewhere quite near the AC power input. The most common places would be:
Degauss Posistor - very likely. Horizontal output transistor. Power supply regulator if there is one. Power supply chopper (switchmode) transistor if there is one. Diode(s) in main bridge Main filter capacitor(s).
You should be able to eliminate these one by one.
Unplug the degauss coil as this will show up as a low resistance.
First, measure across the input to the main power rectifiers - it should not be that low. A reading of only a few ohms may mean a shorted rectifier or two or a shorted Posistor.
Test the rectifiers individually or remove and retest the resistance.
Some sets use a Posistor for degauss control. This is a little cubical (about 1/2" x 3/4" x 1") component with 3 legs. It includes a line operated heater disk (which often shorts out) and a PTC thermister to control current to the degauss coil. Remove the posistor and try power. If the monitor now works, obtain a replacement but in the meantime you just won't have the automatic degauss.
If these test good, use an ohmmeter with the set unplugged to measure the horizontal output transistor. Even better to remove it and measure it.
C-E should be high in at least one direction. B-E may be high or around 50 ohms but should not be near 0.
If any readings are under 5 ohms, the transistor is bad. The parts sources listed at the end of this document will have suitable replacements.
If the HOT tests bad, try powering the set first with your light bulb and if it just flashes once when the capacitor is charging, then put a fuse in and try it. The fuse should not blow with the transistor removed.
Of course, not much else will work either.
If it tests good, power the set without the transistor and see what happens. If the fuse does not blow, then with the good transistor (assuming it is not failing under load), it would mean that there is some problem with the driving circuits possibly or with the feedback from the voltages derived from the horizontal not regulating properly.
Look inside the TV and see if you can locate any other large power transistors in metal (TO3) cans or plastic (TOP3) cases. There may be a separate transistor that does the low voltage regulation or a separate regulator IC. Some TVs have a switchmode power supply that runs off a different transistor than the HOT. There is a chance that one of these may be bad. If it is a simple transistor, the same ohmmeter check should be performed.
If none of this proves fruitful, it may be time to try to locate a schematic or contact the manufacturer.

May 20, 2010 | Projection Televisions

2 Answers

I have a KP-46WT510 and have replaced both STK chips and 1 fuse on the power supply board. Under the heat sink there is another fuse burnt. The value of the fuse needed is 3.15 A. I put in a 3 A fuse and...


I have worked on about 5500 projectors in the past 10 years.
There is a dead short already somewhere so you cant blow anything else up if its a fast blow fuse.
Disconnect the Convergence Amp from the pwr sply then power it up for a few seconds with your 4amp fuse. Does the fuse still blow? If so, check the HOT transistor. (3 pin chip againts the largest heat sink)
Good luck


Dec 30, 2009 | Sony KP-46WT510 46" Rear Projection HDTV

1 Answer

DEAD SET NO LED NO CLICK JUST DEAD


hello check glass fuse inside if it's black it's blown if you put another 1in and it blows again then you have a dead short somewhere the fuse will be in the power supply might be rated at 2.5amp or 3.15 amp good luck

shaun

Nov 02, 2009 | Projection Televisions

1 Answer

No sound or picture on austar channel


This is most likely the power supply module that has failed, or the main fuse is blown. If the main fuse is blowing, then there is a serious short somewhere in the system.

Jerry G.

May 04, 2008 | Projection Televisions

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