CurtPalme.com Home Theater Forum

[ncc1701d]

while waiting for a new tube to my usual 1208/2, i moved the old tubes to my other 1208 (which worked before tube swapping). I accidentally connected green deflection-coil connector the wrong way

the first time i started i had scanlines visible for 10-15sec then it shut off and restarted with no scanlines at all.

Now i have no image. But no red led's either.

What has happened? Easy to fix or is it major repair for it?

[ncc1701d]

No one have any ideas?

[Curt Palme]

So there's no scan fail LED and the EHT light is off?

[Curt Palme]

So there's no scan fail LED and the EHT light is off?

[ncc1701d]

Ooops.. i missed the EHT led. Should it be lit when working?

The fuse was blown, and the led was off.

In the servicemanual it says it should be T2.0A, but the fuse was T3.15A (T=slow)

I put in a T2.0A as said in the manual, but it blows right away. My other pj have a T2.0A in it's module.
So i guess som STUPID person (not me) have replaced a 2A fuse with a 3.15A

Hmm.. the fuse is for +300v to the quadrupler? Please don't say the quadrupler is gone..?

So what next?

[ncc1701d]

UPDATE: Got a tips on a swedish forum to measue Q7 on EHT board for shorts.

Shorts between all legs...

In the schematics Q7 is a BF623 (250v pnp) but on my board there is a APT1001RBN which is a powermos rated
1000v.

http://www.ortodoxism.ro/datasheets/philips/BF621_623_3.pdf
http://www.ortodoxism.ro/datasheets/AdvancedPowerTechnology/mXuuzuv.pdf

But can i measure shorts that way on a MOS transistor? it measures 0.001-0.002 ohms between all pins.
Is it possible that this is the only bad component?

Also if i remove the quad connector with the white wires then the fuse does not blow. But the red led does not turn on either.

The quad is marked: 761743/2/9416 (haven't removed it yet so i don't know if there are any more markings on it)

[Curt Palme]

THat MOSFET is shorted. THere might be other parts blown on the board, but that's it. I'm sure the quad is OK.

Cheers!

[Curt Palme]

THat MOSFET is shorted. THere might be other parts blown on the board, but that's it. I'm sure the quad is OK.

Cheers!

[ncc1701d]

I can probably not get that specific mosfet, is there any i can use instead?

[Curt Palme]

No, I've only ever used the BArco ones from sets I've scrapped here.

[Curt Palme]

No, I've only ever used the BArco ones from sets I've scrapped here.

[ncc1701d]

Well i looked at teh wron place in the schematics. There were 2 Q7, the one blown is named IXTH12N100. It's the driver for then quad.

Maybe it's that one you mean you take from scraps?

Maybe the APT1001RBN is easier to get?

Here are the specs of XTH12N100. I'm going to compare them.

http://pdf1.alldatasheet.com/datasheet-pdf/view/126013/IXYS/IXTH12N100.html

[macgyver655]

The APT1001RBN and the IXTH12N100 are the same part.They are replaced by IXFH12N100, available at Digikey plus others. IXYS is replacing that part with IXFH12N100P, but engineering hasn't released it yet. At least thats what I've been told. The IXFH12N100 will work just fine though.

[ncc1701d]

I ditched this project of repairing as i had one 1208 working, but now i am in short of cash and was thinking of selling the pj, but i want to sell it working.

So if someone have a APT1001RBN or IXTH12N100 to sell me it would be great. I don't want to spend time searching for it on the web so i hope someone here have a spare for me.

I can pay via paypal.

[macgyver655]

My post right above yours is still valid. You can get the IXFH12N100 from Digikey. I have used the newer ones, IXFH12N100P and they work great also but I'm not sure if Digikey has them yet. They were just released last fall.

[WTS]

Digikey has them for about $14USD plus shipping.

[ncc1701d]

Ok i ordered 2pcs today.. hope it works ok from digikey..

[tse]

If there is a resistor in series with the gate (pin 1) check to see if it has changed value. When those big mosfets go it usually takes out the gate resistor. It's not unusual for the driver IC to be gonzo if that resistor is poofed, too. A couple of checks can save blowing those $14 parts again.

Scott

[ncc1701d]

ok i'll check that too. what driver ic is that? (have not looked at it yet)

Gaah.. $32 for shipping of 2 small transistors (1 extra)?? That was really expensive from digikey.

[ncc1701d]

I took an hour today and quickly installed the new transistor, checked for bad resistors but did not find any.
So i plugged it in and it started up right away. Working perfect again


Just one thing that annoys me, and this machine has always done so, when switching on either on remote or pad it takes about 20 sec before it starts. Why?

My regular 1208 start right away.

[Ile]

[ncc1701d]

Ok, but this is a regular 1208, my other i am using (the quick) is a 1208/2, should'nt the newer one be better on that?