Post by gjaky on Feb 10, 2014 16:11:30 GMT -5
I was in need of a philips VAM1202/21 laser unit, but that is quite rare and expensive to come by, so decided to transplant the little PCB to a VAM1202/12 which has (supposedly) the same laser unit but the /12 has on board laser driver circuit, /21 does not have this, break out cable is also different.
So the transplant was successfull, but the laser current trimmer was set for the old laser, after the transplantation the new pickup was not much better, in terms of reading discs. I added a little more current to the laser and after that it read the cds well, but now I'm unsure if I'm overstress the laser diode. I found the service manual of the philips CDM12.1 which is a close relative to the VAM1202/12, the manual says 4-6V and 60-90mA supply for the laser, but after installation I only could measure 2V on the laser, and the current was 160mA ,that's quite far from the "ideal" but mine is a VAM the manual is for the CDM. How can I determine the optimal laser current?
By the way the CD player is an USHER CD100, and has a TDA1300T as laser driver/amplifier
So the transplant was successfull, but the laser current trimmer was set for the old laser, after the transplantation the new pickup was not much better, in terms of reading discs. I added a little more current to the laser and after that it read the cds well, but now I'm unsure if I'm overstress the laser diode. I found the service manual of the philips CDM12.1 which is a close relative to the VAM1202/12, the manual says 4-6V and 60-90mA supply for the laser, but after installation I only could measure 2V on the laser, and the current was 160mA ,that's quite far from the "ideal" but mine is a VAM the manual is for the CDM. How can I determine the optimal laser current?
By the way the CD player is an USHER CD100, and has a TDA1300T as laser driver/amplifier
