Help Troubleshooting Toshiba 32AV502R power supply

[akajester]

Hello! I'm new here. Thanks for reading this and helping me out. I'm new to electronics troubleshooting but I'm eager to learn. Thanks.

So, this TV will power on and seem to work just fine, however, it randomly will power cycle itself. Usually once it does this it'll power cycle over and over and stay on just long enough to show some video output, maybe an HDMI source or TV signal.

I've disconnected everything, cleaned contacts and put it back together. No change. Anyways...

I checked for obvious things like burned connections or bulging caps, but I don't see anything out of the ordinary.

I watched some videos that show you how to test all the pins for proper voltage. I added a jumper on the board between the power and ground pin and I can get it to power on while out of the TV. All the marked pins test slightly higher than the listed voltage, except the two 12v pins which test as 11.7 volts. Does this sound like it could be an issue?

I've attached some pictures of the board. Thanks again for any guidance, it's much appreciated!

[budm]

Re: Help Troubleshooting Toshiba 32AV502R power supply

You can try this fix:
https://www.badcaps.net/forum/showth...02R#post471219

[nomoresonys]

Re: Help Troubleshooting Toshiba 32AV502R power supply

could be a capacitor issue, I'd replace the aluminum capacitors, try those six on the left, without an esr meter, you can't accurately test them, a lot of people strain their brain trying to figure out how to test everything, some end up replacing board after board, sometimes its just a cap or two on the power supply, they don't have to bulge to be bad, as always be careful when working with power supply, HIGH VOLTAGE, on primary side can be deadly.

[akajester]

Re: Help Troubleshooting Toshiba 32AV502R power supply

I ordered the caps, so once those come in I'll swap them and see how it goes. Thanks for the tip.

I don't see anything visually wrong with D200. Is that something I can easily test?

[nomoresonys]

Re: Help Troubleshooting Toshiba 32AV502R power supply

with caps about a buck or so, at least its a good way to rule them out and move on with testing.

[budm]

Re: Help Troubleshooting Toshiba 32AV502R power supply

Did you see the pictures in the link? It is SMD Diode on the bottom side of the board.
You can replace the set of caps and see what happen. I did that but did not fix the problem.

[nomoresonys]

Re: Help Troubleshooting Toshiba 32AV502R power supply

ok bud I see it, they are prob. inexpensive, are they hard to replace?

[budm]

Re: Help Troubleshooting Toshiba 32AV502R power supply

I replace it with 1N4148 through hole, just bend the legs.

[nomoresonys]

Re: Help Troubleshooting Toshiba 32AV502R power supply

I replace it with 1N4148 through hole, just bend the legs.

your the man Budm, its very cool how you figure out how to replace it with other parts,

[akajester]

Re: Help Troubleshooting Toshiba 32AV502R power supply

Thanks for all the responses and ideas so far.

I replaced all the caps tonight and it's doing the exact same thing as before, shutting itself off/on repeatedly. I looked at D200, and even put the DMM on it. I checked it against other diodes that look identical and they all came up with the same reading. If they read the same, does that mean D200 is fine? Thanks. I'm not sure what else to check.

[nomoresonys]

Re: Help Troubleshooting Toshiba 32AV502R power supply

I guess you cant be positive about diodes, unless you test m out of circuit, but with my bad solder skills, I dont take m out if theyr tiny.

[akajester]

Re: Help Troubleshooting Toshiba 32AV502R power supply

I checked all the small diodes while in circuit. My DMM manual says they should all read OL one direction and .400 to .700V otherwise. All check out in that range except D308, which gives a .004V reading each way. I wonder if that's something to be concerned about.

[nomoresonys]

Re: Help Troubleshooting Toshiba 32AV502R power supply

I checked all the small diodes while in circuit. My DMM manual says they should all read OL one direction and .400 to .700V otherwise. All check out in that range except D308, which gives a .004V reading each way. I wonder if that's something to be concerned about.

careful, some diodes, snubbers I believe, do give readings in both directions, when in circuit, i think I remember budm saying read them in ohm, but I'm not exactly sure.

[budm]

Re: Help Troubleshooting Toshiba 32AV502R power supply

Just put in 1N4148 in place of D200 and see what happen, you already remove the D200, just bend the legs and solder it in place.

[akajester]

Re: Help Troubleshooting Toshiba 32AV502R power supply

Ok budm, I'll take it out and test D200. I don't have a replacement yet. Thanks.

[akajester]

Re: Help Troubleshooting Toshiba 32AV502R power supply

I took out the D200 and D308 diodes which look identical. Both give identical readings on the DMM.

[akajester]

Re: Help Troubleshooting Toshiba 32AV502R power supply

I can't believe I just lost D308 somewhere. I set it on the board to test it, next thing I know it's gone and no where to be found! Damn. Fortunately it was identical to D200, other than that. argh.

Does anyone have the service manual for this set? Thanks.

Update: I ordered a pack of 1N4148 diodes to replace the one I lost. I might as well swap out D200 too. I'll report back in about a week. Thanks!

[akajester]

Re: Help Troubleshooting Toshiba 32AV502R power supply

Using Budm's pictures linked above I was able to swap D200. However I think I messed up D308. I'm not sure on the direction it needs to go and I think I broke the connections on the board when it twisted off. Does anyone have pictures of D308 or some type of schematic for reference to show the connections it requires? argh. I screwed this up.

[budm]

Re: Help Troubleshooting Toshiba 32AV502R power supply

https://www.badcaps.net/forum/showpo...39&postcount=4
I do not see D308.

[akajester]

Re: Help Troubleshooting Toshiba 32AV502R power supply

Here's a picture. You can see where D308 fell off and took a bunch of stuff with it, right in the middle. The number off the board is PK101V1070I. Thanks!