TNY276 instead of TNY176
The power supply from my Philips DVP5990K DVD player had a malfunction from an unknown reason. My DVD player was in stand-by mode and I turned it on from the remote control. I heard a short circuit sound and sone smoke went out from DVD case. When I opened the unit I found the fuse exploded, U1 (TNY176) exploded, C2 had high ESR, all rectifier diodes blown (D1-D4), and D8 blown too (see schematic attached, in red). I replaced all bad components. I couldn't find a TNY176PN, so I replaced it with a TNY276PN. To my surprise the power supply didn't come to life, all output voltages were ZERO. I replaced for good measure the components marked in blue too. Still nothing.
So my questions are:
1) Why do you think the power supply 'exploded' when it was turned on from stand-by?
2) Was it a bad idea to replace TNY176 with TNY276? Do I have to make any modification?
Thank you.
Comments
Have you looked at TNY176 and TNY276 datasheets before replying? Because my question was not generic, but very specific. I didn't see other difference than 276 having an extra undervoltage feature, which if not used, makes 276 equal to 176.
I am sorry about my delay to reply your entry. I was looking for the datasheet for TNY176. I found out that this product is for exclusive use of few customers. I can not know what are the specs. It may be that it is similar than TNY276 but I do not know. DO you have a copy of the datasheet? if you have I may take a look and try to find out why the failure of your power supply.
I see the datasheet, thank you
You need to connect the oscilloscope probe to your DRAIN node. Also connect the current probe to measure the current into the DRAIN
With your input voltage adjusted to 0VAC, slowly increase your input voltage until the controller starts to switch. AT this point record the voltage and the current. Check the DRAIN snubbed for properly clamping the DRAIN voltage from the leakege inductance spike.
When the controller is running, you should have some have some dc voltage at the output. Make sure this voltage does not exceed the nominal voltage.
The device is damaged because too much voltage at the DRAIN node or too much current. So you should be able to see what waveform is damaging the device. You can post the waveforms here an dI can take a look
When you have a switching power supply running with one controller and you install a different controller, you need to do a complete review of the design. You need to know what is your new flux density in the transformer.
If you are not expert in power supplies, then I suggest you buy a new power supply