Panasonic SA-HT820V Home Theater System

[R_J]

Re: Panasonic SA-HT820V Home Theater System

Any way to find out if it's either one of those?

Nope, no way to tell

[CapsDude]

Re: Panasonic SA-HT820V Home Theater System

If D1270 cathode (white band) to ground measures 4.6M Ohms you either damaged a trace or the transformer winding is open.

Any way to find out if it's either one of those?

[R_J]

Re: Panasonic SA-HT820V Home Theater System

Didn't get -30 on TL1030.

TL1030 read 7.8 M Ohms
D1270 read 4.6 M Ohms

If D1270 cathode (white band) to ground measures 4.6M Ohms you either damaged a trace or the transformer winding is open.

[CapsDude]

Re: Panasonic SA-HT820V Home Theater System

Didn't get -30 on TL1030.

TL1030 read 7.8 M Ohms
D1270 read 4.6 M Ohms

[R_J]

Re: Panasonic SA-HT820V Home Theater System

Pin number 6 is reading .6V. All other pins are good.

Without -30 volts you won't get a display. To make sure there are no shorts on that line, CARFULLY remove the flat cable from P1102 and check if the negative -30v is on TL1030, if not, Unplug the unit and check the resistance of TL1030 to ground, it should be very high. Then as a last check, measure the transformer winding resistance It can be checked between D1270 cathode and ground (W56)

[CapsDude]

Re: Panasonic SA-HT820V Home Theater System

And the voltage is?

Pin number 6 is reading .6V. All other pins are good.

[R_J]

Re: Panasonic SA-HT820V Home Theater System

And the voltage is?

[CapsDude]

Re: Panasonic SA-HT820V Home Theater System

Got the part and soldered it. Nothing shows up on the display. It powers up tho because the vhs side starts up. The connector tape is fine.

[CapsDude]

Re: Panasonic SA-HT820V Home Theater System

200ma 200v would be the minimum, that -30v supply is fairly low current, so any fast recovery diode greater than 200ma/200v would work.

Ok, I'll get some and try it out. I appreciate your help so far.

[R_J]

Re: Panasonic SA-HT820V Home Theater System

200ma 200v would be the minimum, that -30v supply is fairly low current, so any fast recovery diode greater than 200ma/200v would work.

[CapsDude]

Re: Panasonic SA-HT820V Home Theater System

Just replace the diode, that should get the display back to normal. and then you can get back to the other problems. Any 1 amp 200v fast recovery diode will work

Oh ok, I was already searching for a Panasonic 200V 200mA diode since thats what the schematic said it was. So it doesn't matter?

[R_J]

Re: Panasonic SA-HT820V Home Theater System

Just replace the diode, that should get the display back to normal. and then you can get back to the other problems. Any 1 amp 200v fast recovery diode will work

[CapsDude]

Re: Panasonic SA-HT820V Home Theater System

It is likely shorted, You can unplug P1102 and check the diode again (don't damage the cable) just to be sure, or unsolder one end of the diode.
If the diode is shorted, that would explain the way the display looks. It is likely that when the flat cable twisted and partly came out of the socket it shorted the unregulated -30 to ground as the pins are side by side.

P1102 was already unplugged when I was doing the test. So if I wanted to fix it, is it a new diode or the power board itself?

[R_J]

Re: Panasonic SA-HT820V Home Theater System

Negative (L) Positive (R): .324V
Positive(L) Negative(R): .202V

It is likely shorted, You can unplug P1102 and check the diode again (don't damage the cable) just to be sure, or unsolder one end of the diode.
If the diode is shorted, that would explain the way the display looks. It is likely that when the flat cable twisted and partly came out of the socket it shorted the unregulated -30 to ground as the pins are side by side.

[CapsDude]

Re: Panasonic SA-HT820V Home Theater System

Check it on the board first, Use you meter in diode test and check it one way then reverse the leads and check it the other way.

Negative (L) Positive (R): .324V
Positive(L) Negative(R): .202V

[R_J]

Re: Panasonic SA-HT820V Home Theater System

Do I have to desolder and take the diode out to test it?

Check it on the board first, Use you meter in diode test and check it one way then reverse the leads and check it the other way.

[CapsDude]

Re: Panasonic SA-HT820V Home Theater System

Your problem seems to be that you are missing the Display -30 volts (UNREG_-30V) I suspect D1270 might be damaged. OR you have something on the unregulated -30v line that is shorted.
I suspect the the diode is burnt open or is shorted, and this is where the burnt smell came from.

Do I have to desolder and take the diode out to test it?

[CapsDude]

Re: Panasonic SA-HT820V Home Theater System

My post #5 i wrote its mechanic issue and need to put all at zero point.

yours display photo its tell same you have Order JAM ( because the lost of zero point and there are 2 or more micro switch sending order.) though this can damage the main IC. not C or R.

I think we set the VCR to zero point but not the DVD. How do you go about doing that?

Here's the top and bottom. Do I need to take the trays out?

[R_J]

Re: Panasonic SA-HT820V Home Theater System

Your problem seems to be that you are missing the Display -30 volts (UNREG_-30V) I suspect D1270 might be damaged. OR you have something on the unregulated -30v line that is shorted.
I suspect the the diode is burnt open or is shorted, and this is where the burnt smell came from.

[CapsDude]

Re: Panasonic SA-HT820V Home Theater System

4.94 what?
P1102 pins 3&4 are the same connection, how can you have 2 different voltages? You must be reading the pins wrong. Check the voltages on the test points TL10xx instead. IP1240 is a fuse, check if it is still good.

4.94 Volts.

Ok so I was reading the schematic wrong because its a little different from my power board. I was reading it in the opposite direction. So it should read:

Pin 2: 31.8V
3: 6V
4: 6V
5: 16.5V
6: -.03V
11: 3.5V
12: 13.4V

TL1004: 3.5V
TL1006: 6V
TL1009: 13.4V
TL1016: 16.4V
TL1030: -.33V
TL1038: 31.6V

Fuse read good.