Sanyo DP47460 On Then Back Off

[johnboy1313]

It doesn't seem to be IC1670.

My buddy brought this to me. Like many, many other Sanyos, this one turns on for a second, shows the Sanyo logo, and then turns off. I removed IC1670 from the board and still have the same problem. I've tried jumping the PSU on. With the main disconnected, I get no backlights when jumpered from 5V to PS_ON. I'm not sure what pin to jump to get backlights. With a jumper to PS_ON, the PSU just clicks on, then off over and over with no backlights.

If IC1670 was bad, would removing it entirely let the set turn on with no volume? If IC001 was bad, wouldn't removing IC1670 from the board isolate IC001? Thanks

[CapLeaker]

Re: Sanyo DP47460 On Then Back Off

Disconnect everything from the PSU and force it on. See what you get on the output rails.

[johnboy1313]

Re: Sanyo DP47460 On Then Back Off

I tried that. It just clicks on and off over and over with no backlights. I'm not even sure I'm doing it right. I have a resistor between PS_ON and 5V. I don't see BL_ON on this PSU.

[CapLeaker]

Re: Sanyo DP47460 On Then Back Off

I wouldn't frig with the main board until I can force on the power supply and it stays on. Do any of the outputs come up for a split second, or are they just 0V? Did you check IC602, the fets and diodes?

[johnboy1313]

Re: Sanyo DP47460 On Then Back Off

With the main connected, all voltages other than 5V come up and then die. With the main disconnected, I get all voltages on the connector J617 for a second and nothing on the connector to the inverter.

[CapLeaker]

Re: Sanyo DP47460 On Then Back Off

Can we see a pic of the back of the TV with all board connected?

[johnboy1313]

Re: Sanyo DP47460 On Then Back Off

Here you go.

[CapLeaker]

Re: Sanyo DP47460 On Then Back Off

I guess it is one of these weird made TVs where is no BLon on the PSU itself. Here it comes from the main board. So... by right's if you force the PSU on, the 24V rail should be up as well, but the BL itself should stay off. So there must be another switch on the inverter that gets the BLon command from the main board. Uff. That is complicated. I am not sure yet, what that Line OFF pin does.

With the main board connected, you said all the voltages but not the 5V rail came up. There is a power failure circuit. When the unit sees something not fit, it will shut down. I would poke around there and see if that is true.

[johnboy1313]

Re: Sanyo DP47460 On Then Back Off

No, the 5V is the standby. Everything comes up and then drops out except the 5V. It doesn't drop out. Sorry if I wasn't clear.

[ReeceyBurger123]

Re: Sanyo DP47460 On Then Back Off

Have you checked all the diodes on the output, primary fets, and the pfc are all running ?
Also could you take pictures of the Ic that you replaced ?

[johnboy1313]

Re: Sanyo DP47460 On Then Back Off

No, I haven't checked any diodes or FETs yet. PFC seems to be working. Main cap jumps from 170 to 390 while it's on. I didn't replace the IC, I removed it and reinstalled it once I found that the fault continued.

[ReeceyBurger123]

Re: Sanyo DP47460 On Then Back Off

No, I haven't checked any diodes or FETs yet. PFC seems to be working. Main cap jumps from 170 to 390 while it's on. I didn't replace the IC, I removed it and reinstalled it once I found that the fault continued.

Start checking them and replace that Ic...

[johnboy1313]

Re: Sanyo DP47460 On Then Back Off

I don't know if the IC is bad. The power supply clicks on and off with the main disconnected. The IC is on the Main.

[ReeceyBurger123]

Re: Sanyo DP47460 On Then Back Off

Could you take photos please ?

[CapLeaker]

Re: Sanyo DP47460 On Then Back Off

No, I haven't checked any diodes or FETs yet. PFC seems to be working. Main cap jumps from 170 to 390 while it's on. I didn't replace the IC, I removed it and reinstalled it once I found that the fault continued.

So PFC is o.k. then

[budm]

Re: Sanyo DP47460 On Then Back Off

The BL-ON cable is connected directly between the main board and the inverter board.
The connector K8L pin 3 is the BL-ON, service manual page 26.
If you remove K8L, the backlights should then come on., it uses the same setup as the 26". This 26" has the same problem, no backlghts, the main board was bad.
http://s807.photobucket.com/user/bud...ml?sort=3&o=21

[johnboy1313]

Re: Sanyo DP47460 On Then Back Off

Cool. Thanks for that info bud. Ill be digging back into it later this afternoon. Reeseyburger123, I'll get pics then too. Thank you.

[johnboy1313]

Re: Sanyo DP47460 On Then Back Off

So now the backlights aren't coming up at all anymore and the PFC is not working anymore. The relay clicks just like it did before. Then it clicks off, just like it did before but no PFC or backlights.

Here's that pic of IC1670. The 1uf 50v cap at C1676 came off when I used hot air on the chip. I didn't see it come off. I replaced it with an extra I had from the last Panasonic I fixed.

[johnboy1313]

Re: Sanyo DP47460 On Then Back Off

I apparently broke the relay being heavy handed. I replaced it and now I have PFC and backlights for a second again only with the main connected. When I disconnect K8L, I get no backlights at any point, both with the main connected or with the main disconnected and a jumper from 5V to PS_ON.

[ReeceyBurger123]

Re: Sanyo DP47460 On Then Back Off

I apparently broke the relay being heavy handed. I replaced it and now I have PFC and backlights for a second again only with the main connected. When I disconnect K8L, I get no backlights at any point, both with the main connected or with the main disconnected and a jumper from 5V to PS_ON.

So non of the voltages still dont come up, just check the soldering on that chip no offence but it looks a little rough.