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Search: Posts Made By: R_J
Forum: General Electronics Technical Discussion Today, 01:21 PM
Replies: 7
Views: 82
Posted By R_J
Re: bad cap cause fuse to blow?

Ok, then it is a fault in the high voltage section, I mentioned the switches because it is a common problem with microwave ovens.
Forum: General Electronics Technical Discussion Today, 11:46 AM
Replies: 7
Views: 82
Posted By R_J
Re: bad cap cause fuse to blow?

You wont be able to check the diode with a regular multimeter unless the diode is dead short. it is a high voltage diode, it has several diode junctions stacked in series internally, the capacitor...
Forum: Troubleshooting TVs and Video Sources Yesterday, 05:24 PM
Replies: 16
Views: 330
Posted By R_J
Re: [REPAIR] Help in diagnosing my Old Panasonic Quintrix F TC-21P50R CRT TV

Start by replacing C811 47f/50v, it is likey weak, I would also replace C826 47f/160v as a precaution.
Forum: General Electronics Technical Discussion Yesterday, 05:06 PM
Replies: 7
Views: 82
Posted By R_J
Re: bad cap cause fuse to blow?

In most cases when the fuse blows it is caused by a defective door switch. The primary interlock door switches is likely bad (stays closed) and when the interlock monitor switch closes it blows the...
Forum: General Electronics Technical Discussion Yesterday, 10:12 AM
Replies: 15
Views: 775
Posted By R_J
Re: IC identification JBL Boombox 2

Q3 is in post #3 on the right side of the picture (next to the glue) It looks like a DFN8 3034 seems to be the part number,
Forum: Troubleshooting TVs and Video Sources 05-25-2022, 02:35 PM
Replies: 7
Views: 747
Posted By R_J
Forum: Troubleshooting Computer Displays 05-22-2022, 06:54 PM
Replies: 24
Views: 2,709
Posted By R_J
Re: Benq BL3200PT with a cooked PSU.

If the resistors etc check ok, then like I said I suspect the ic is bad.
Forum: Troubleshooting TVs and Video Sources 05-21-2022, 06:37 PM
Replies: 114
Views: 10,571
Posted By R_J
Re: Sharp LC-60SQ15U TV DPS-167CP - No power

What do you have in place for D7950? Maybe disconnect whatever is in there and see if the vcc comes up.
The ic's startup cell IS providing the initial 9volts, (at low current) so there can't be...
Forum: Troubleshooting TVs and Video Sources 05-21-2022, 04:55 PM
Replies: 5
Views: 123
Posted By R_J
Re: Strange Power Supply Behavior on Skyworth 55U5A14G

This is an always on power supply that outputs 12 volts at low current, The stb pin voltage is supplied by the main board and turns on the pfc circuit etc on the power supply so it will operate at a...
Forum: Troubleshooting TVs and Video Sources 05-21-2022, 04:45 PM
Replies: 114
Views: 10,571
Posted By R_J
Re: Sharp LC-60SQ15U TV DPS-167CP - No power

Here is the block diagram of the ic I have no idea why you have 0 volts on pin4
Is R7918 (0Ω) open?
Are these NEW ic's or used?
Forum: Troubleshooting TVs and Video Sources 05-21-2022, 03:08 PM
Replies: 114
Views: 10,571
Posted By R_J
Re: Sharp LC-60SQ15U TV DPS-167CP - No power

This is why I asked you to isolate pin 4 of the ic and check the voltage on just the ic pin4, This would eliminate EVERYTHING else connected to the ic.
Forum: Troubleshooting Computer Displays 05-20-2022, 08:07 PM
Replies: 24
Views: 2,709
Posted By R_J
Re: Benq BL3200PT with a cooked PSU.

Also check R651, it is a low value (likely under 1Ω). It is connected between the modfet source and the primary (hot) ground, if this resistor is open, the ic would have been damaged.
Forum: Troubleshooting Computer Displays 05-20-2022, 08:01 PM
Replies: 24
Views: 2,709
Posted By R_J
Re: Benq BL3200PT with a cooked PSU.

The components are connected between the ic's output and mosfet gate. You need a multimeter to check them to see if they are good or bad. as for the ic, it can't be tested but is likely bad.
Forum: Troubleshooting Power Supplies and Power Supply Design 05-20-2022, 07:55 PM
Replies: 8
Views: 146
Posted By R_J
Re: What is this part? (OG XBox Delta PSU)

Yes 102 would be a 1k pot, I suspect once you check it you will find it to be ok, Check between the two leads on the one side, then check between the single lead and each of the other leads, that...
Forum: Troubleshooting Computer Displays 05-20-2022, 07:46 PM
Replies: 24
Views: 2,709
Posted By R_J
Re: Benq BL3200PT with a cooked PSU.

Q651 is the main switching mosfet, if the pins were shorted, then the gate saw a very high voltage, so it likely destroyed the resistors and diodes in the gate circuit and also the driver ic located...
Forum: Troubleshooting Power Supplies and Power Supply Design 05-20-2022, 07:02 PM
Replies: 8
Views: 146
Posted By R_J
Re: What is this part? (OG XBox Delta PSU)

VR501 is the pot location, not it's value, check it with a meter or look for numbers printed on the pot. Are you sure it is bad, as I doubt it is burnt.
I see other pictures that have the same...
Forum: Troubleshooting Power Supplies and Power Supply Design 05-20-2022, 06:46 PM
Replies: 8
Views: 146
Posted By R_J
Re: What is this part? (OG XBox Delta PSU)

That may just be glue to seal the controls position
Forum: Troubleshooting Computer Displays 05-20-2022, 05:11 PM
Replies: 24
Views: 2,709
Posted By R_J
Re: Benq BL3200PT with a cooked PSU.

What is the board number? which transistor? what do you mean the transistor was "dead"? was it shorted?
Forum: Troubleshooting TVs and Video Sources 05-20-2022, 04:50 PM
Replies: 114
Views: 10,571
Posted By R_J
Re: Sharp LC-60SQ15U TV DPS-167CP - No power

PC7904 is used to turn on Q7902 to supply vcc_on so it can be left out of circuit for now.
If you also remove pc7903 and D7908, pin 4 of ic7903 should be about 7volts, If it does not come up, try...
Forum: Troubleshooting TVs and Video Sources 05-20-2022, 04:22 PM
Replies: 114
Views: 10,571
Posted By R_J
Forum: Troubleshooting TVs and Video Sources 05-20-2022, 04:16 PM
Replies: 114
Views: 10,571
Posted By R_J
Re: Sharp LC-60SQ15U TV DPS-167CP - No power

Yes, check pins 1 & 4
The vcc voltage is initially supplied by the ic's internal startup cell which is bout 9volts, that part of the ic is working. When the power is first applied the internal...
Forum: Troubleshooting TVs and Video Sources 05-20-2022, 03:50 PM
Replies: 114
Views: 10,571
Posted By R_J
Re: Sharp LC-60SQ15U TV DPS-167CP - No power

Your board is different from the DPS-167CP I was using Your board is a DPS-162KP, I was going by the original post title
Forum: Troubleshooting TVs and Video Sources 05-20-2022, 03:45 PM
Replies: 114
Views: 10,571
Posted By R_J
Forum: Troubleshooting TVs and Video Sources 05-20-2022, 03:33 PM
Replies: 114
Views: 10,571
Posted By R_J
Re: Sharp LC-60SQ15U TV DPS-167CP - No power

WHY? because if that feedback winding is open circuit you will not get the boosted vcc voltage to make the ic work.
Look at the schematic, It's pins for this winding are 1&4, on your board they are...
Forum: Troubleshooting TVs and Video Sources 05-20-2022, 03:14 PM
Replies: 114
Views: 10,571
Posted By R_J
Re: Sharp LC-60SQ15U TV DPS-167CP - No power

Check the transformer winding between pins 4 and 5, it should be almost 0Ω, then check the resistors R7908,R7909,R7913, if they are good, check the diode D7904, also check the zener diode D7909

If...
Showing results 1 to 25 of 500

 
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