Testing the LA/BA chip for dud focus coils driver

[l_oliveira]

A effective way to test the focus/tracking coils for both BA and LA is:


Put multimeter on diode probe/beep mode
(there's a diode symbol on the position)

Find the following signals on the chips:

VCC12v
GND
TR+ (Tracking +)
TR- (Tracking -)
FK+ (Focus +)
FK- (Focus -)

With the multimeter on diode test scale, measure the 4 laser coil pins to GND one time with the black probe on GND. Then again with the red probe on the GND.

With the black probe on GND it should measure something arround 1.800 on all 4 pins.

With the red probe on GND it should measure .650 on the 4 pins.

Testing the inverse, from Focus VCC pin put black probe on it (you can put the probe on the fuse close to the LA or BA chip.

With the black probe on Focus VCC it should measure something arround .750 on all 4 pins.

With the red probe on Focus VCC it should measure something arround 1.750 on the 4 pins.

These values are not absolute, they're aproximated.

Should any of the pins be open (PS2 can't read anything) or shorted (PS2 will burn the coils of a new laser if you replace it) the LA/BA chip must be replaced.

Remember that the laser unit must be disconnected from the motherboard for this test to be performed correctly.

[galevin]

Many thanks for the above. I also found this on this site (probably posted by you also):
Testing your LA6508 chip on the V9/10:
1) If resistance between pins 18, 19 is infinite the LA is bad
2) If resistance between pins 20, 21 is infinite the LA is bad
3) If the laser coil resistances have dropped on either coil to less than 4 ohms. I'm starting a new thread on replacing the BA/LA chip. I'm assuming this takes someone with some serious soldering experience.

[spedmetal]

Great thread l_oliveira! Thank you for this.

[gamecubesuxs]

Nice very helpful

[Rotosound_rb666]

for a BA5815FM, pin #8 goes to ground when those go south, pin 8 being 12v input, the power supply to the chip,
so they ALWAYS take out the onboard fuze PS11 when they
go.
The give-away symptom is a black screen, with no sound, and no blue eject led. oops, too little resistance in the diode pots, again, hence overload.
those are a pain.

[spedmetal]

for a BA5815FM, pin #8 goes to ground when those go south, pin 8 being 12v input, the power supply to the chip,
so they ALWAYS take out the onboard fuze PS11 when they
go.
The give-away symptom is a black screen, with no sound, and no blue eject led. oops, too little resistance in the diode pots, again, hence overload.
those are a pain.

Yeah thats been known and easy to diagnose, however the LA doesnt give its self up that easy.

[Lextor]

Its been long since I last posted...

The give-away symptom is a black screen, with no sound, and no blue eject led.

My V4 US PS2 have the exact symptom(Blue screen,no video sync), but all fuses are fine and the BA5815FM are ok(Pin 8 not shorted to ground).
It was modded with ICE(homebrew, used for 6 months without anny problem). I thought it was some cold solder or loose wires, but its still the same when i totally removed the wires and ICE.

Any solution to my problem? Help is appreciated. Thanks

[patch6]

Kudos to l_oliveria, one of the most helpful people here.

[Gladiator]

Its been long since I last posted...



My V4 US PS2 have the exact symptom(Blue screen,no video sync), but all fuses are fine and the BA5815FM are ok(Pin 8 not shorted to ground).
It was modded with ICE(homebrew, used for 6 months without anny problem). I thought it was some cold solder or loose wires, but its still the same when i totally removed the wires and ICE.

Any solution to my problem? Help is appreciated. Thanks

you must check all fuses, especially the small ones. Once I had this problem it was PS1 fuse which is small and almost unrecognizable

[Lextor]

I checked all 16 fuses, all are ok. I removed BA5815FM today and power it up still the same, no display no sound but able to on it and off it.

If I have time, will remove the BA6664FM.

More suggestion?
Thanks