Need Regulator Help Please!!!

[Dgtech]

I have been looking at a data sheet for both the APL1117 and the AMC1117. I need to know if they are interchangable. The TV that I'm working on (Toshiba LCD) has this APL1117(u11) on the mainboard and I'm questioning it.

All of the regulators:
u13 = 11.93 in and 8.97 out
u14 = 8.97 in and 5.04 out
u12 = 5.06 in and 3.26 out
u11 = 3.28 in and 2.08 out

The only other markings on this chip is W4E5 directly under the APL1117. I'm assuming that this is a date code.

[Toasty]

Re: Need Regulator Help Please!!!

What's the Toshiba P/N from manual? Sometimes a cross from original can be judged better from that.

Could you give the Toshiba model / series and perhaps post the 2 datasheets?

[Dgtech]

Re: Need Regulator Help Please!!!

The only service manual I could find has no parts list in it.

The pinout of the APL1117 and the AMC1117 are the same. Both are adjustable LDO regulators. I can only find the AMC's on Ebay. Is there another choice?

[PlainBill]

Re: Need Regulator Help Please!!!

The only service manual I could find has no parts list in it.

The pinout of the APL1117 and the AMC1117 are the same. Both are adjustable LDO regulators. I can only find the AMC's on Ebay. Is there another choice?

The 1117 family comes in several different current ratings. DigiKey has four or five variants. Search for 1117, select PMIC-LDO, in stock, adjustable, cut tape, SOT-223 and SOT-223-3.

The adjustable ones are easy to test. Check the voltage between pin 1 and pin 2, if it is anything other than 1.25 volts there is a problem, either with the regulator, with the input voltage, or with the load.

PlainBill

[Dgtech]

Re: Need Regulator Help Please!!!

I just checked pin 1 to pin 2 and it shows exactly 1.25V.

To back up and explain why I'm looking at the mainboard is - This TV has no picture and no sound. Red light when powered off switches to green when switched on. Power supply voltages are all correct. Inverter checks out (caps, driver chip, fets).

[Dgtech]

Re: Need Regulator Help Please!!!

I got a replacement mainboard from ebay and now this TV works fine now.

Toshiba 37av50u

[Dgtech]

Re: Need Regulator Help Please!!!

I have a different LDO regulator question - different tv set. On a Vizio L42HDTV10A (0171-2272-2213 Mainboard) I found U18 to be bad. I replaced it onced and the set worked for a little bit then died. After replacing it again, it runs hot. I shut it down so it wont burn the new one out. The input voltage is dead solid 5 volts with no deviation. The output is 3.3 as it should be. Does this then mean that the load on it is too great and drawing more current than it can produce ???
I searched the service manual for this set hoping it would give me a clue to what could be the problem but the service manual has no schematics. Anyone have a clue?? or should I just be looking for a replacement board??

[PlainBill]

Re: Need Regulator Help Please!!!

I have a different LDO regulator question - different tv set. On a Vizio L42HDTV10A (0171-2272-2213 Mainboard) I found U18 to be bad. I replaced it onced and the set worked for a little bit then died. After replacing it again, it runs hot. I shut it down so it wont burn the new one out. The input voltage is dead solid 5 volts with no deviation. The output is 3.3 as it should be. Does this then mean that the load on it is too great and drawing more current than it can produce ???
I searched the service manual for this set hoping it would give me a clue to what could be the problem but the service manual has no schematics. Anyone have a clue?? or should I just be looking for a replacement board??

There are a couple of options. The 1117 regulators are rated for .8 or 1.0 Amps. The 1080 family are rated for 3 amps. One option would be to insert a 1080 family regulator with a big heat sink. Another would be to add a 3 ohm 3 watt resistor between input and output. In either of these cases see if you can identify another component that is running hot.

Or you could just bite the bullet and replace the main board.

PlainBill

[Dgtech]

Re: Need Regulator Help Please!!!

There are two other regulators, both 1.8v I believe, that are running off of the 3.3 volts that this one provides. Could this voltage feeding the HDMI inputs as well? Cause they dont work either. Maybe this board has multiple problems.

[Th3_uN1Qu3]

Re: Need Regulator Help Please!!!

There's been a case last month with a fried HDMI chip, so yes, that could be what's loading the supply down.

[PlainBill]

Re: Need Regulator Help Please!!!

Two points: I had a 'brain fart' in my earlier post; the regulator is a 1084 type, not 1080.

If the HDMI ports aren't working, replace the main board.

PlainBill

[Dgtech]

Re: Need Regulator Help Please!!!

Ok, thanks.