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Re: Insignia NS-39L700A12 backlight transformer high pitched wine
If the 18v is stable then it should be ok, if it is slow to build up to 18v then there is a problem. To be sure of the voltage I would need the part numbers on N504 & N501Comment
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Re: Insignia NS-39L700A12 backlight transformer high pitched wine
Should the voltage on the emitter fluctuate like this with the tv off? https://streamable.com/x4o0z1Comment
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Re: Insignia NS-39L700A12 backlight transformer high pitched wine
18 volts is fine for the main & pfc ic's The emitter voltage will be higher in standby because the transistor is turned off. So is the vcc voltage in standby 21.5v or is iI changing? In standby, N503 is in burst mode so the vcc voltage could be changing, or the capacitor for that voltage is bad. The standby ic also uses this voltage but only requires it to be around 15 volts (stop voltage is 8.1v) in standbyLast edited by R_J; 01-25-2021, 12:55 PM.Comment
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Re: Insignia NS-39L700A12 backlight transformer high pitched wine
I replaced all the electrolytic caps with known good ones and it's still got the high pitched noise coming from the transformer. What causes transformer whine?Comment
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Re: Insignia NS-39L700A12 backlight transformer high pitched wine
L601 is NOT a transformer, it is just a coil (inductor) In this case it is used to boost the led voltage, Is the base supply voltage ok and clean? If the supply is not filtered properly, there can be a beat frequency between the main supply transformer frequency and the led driver frequency.
Or it could just be due to loose windings or cracked core in the coil. Are the backlights ok and does the whine change with if you change the backlight level?Last edited by R_J; 01-25-2021, 04:14 PM.Comment
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Re: Insignia NS-39L700A12 backlight transformer high pitched wine
I've decided to scrap the tv it was free anyways.Comment
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Hello!
I'm looking at an original Xbox PSU: Foxlink ftps-0002 rev. B. The 12 V output is too low, and the 5 V output is too (?) high. Unfortunately I don't have an oscilloscope but only a DMM for diagnosis.
Measured voltages with no load:
After rectifier diodes
12V: 6.17 V
5V: 5.67 V
Secondary transformer pins AC measurement (really don't know if this says anything)
12V: 2-2.5 V
5V: 1.04 V
I also have another (working) Xbox psu from Delta. The same measures there, in order, being: 10.79,... -
Issue: Funai FW55D25F - High Pitched Squeal Upon Power-on.
Solution: Replace C3208 and C3209 on main board. These are surface mounted capacitors. Values unknown so I just used same physical size capacitors from a donor board. -
Hi all,
Got this local made DC power supply (12/14V) given free as the transformer has melted. There is no marking or indication to identify what type or rating of transformer used.
Fyi,. I had a busted autogate mainboard with transformer with marking 13-0-13 . Is this the 13v dc type transformer?
My questions are
1. How do i test to see if the transformer is in good working condition?
2. Can this transformer (marking 13-0-13) be used to replace the melted transformer on the DC power supply?
Hope you guys understand what i was asking. My intention is... -
I have a blown smps and I am looking for some reassurance as to the amount of diagnosis I have to do. It blew the instant I plugged it in not under any load.
As you can see from the attached pix, the damage is located around the main or bulk capacitor (since removed for testing) and the resistor array/network that drives it (the bunch of SMD components to the left of the YAMAHA YC775 AMPS logo). The burn mark on the frame clearly shows the pins of the capacitor. And, for the avoidance of doubt, there is no way the board could have contacted the frame, it was correctly mounted on... -
Hi folks, I have an issue with my 7 year old Panasonic TX-L50B6B that has appeared within the last few days.
The symptoms are:
- A high pitched "buzzing" / "whining" noise coming from the TV when it is turned on. There is no noise during standby, and the noise persists with all AV connections removed.
- There are noticable horizontal lines in the picture. Upon closer inspection it looks like every few rows of pixels are dead/black.
Attached is a close-up of the picture in "test mode", to demonstrate the rows of black lines.
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