Hi there, I am repairing a Cambridge Audio A1 that has the LM4766T chip, and I can only find Chinese versions these days, ebay seems to be pretty much the only outlet since TI stopped manufacturing them. No stock on RS, Rapid, etc
I have had mixed experiences with Chinese semiconductors over the years. Does anyone have tales to tell on the quality of these particular chips, good or bad? There are some that are described as being made by National Semiconductor. Are there any particular stamps or codes to watch out for?
Thanks,
Dan
I have had mixed experiences with Chinese semiconductors over the years. Does anyone have tales to tell on the quality of these particular chips, good or bad? There are some that are described as being made by National Semiconductor. Are there any particular stamps or codes to watch out for?
Thanks,
Dan
Hard to find aren’t they?! I got one definite fake (markings rubbed off!) but it has worked (and is working) fine. I have tested it with oscilloscope as best as I can and all seems fine. The A1 is not really top drawer stuff in any case so who know what was in it to start with - they were all assembled in China.
BTW. It seems that Cambridge Audio in their wisdom did not fit insulating washers between chip and heatsink. There is a comical warning on the PCB (something about the ‘crust’ - I presume it means ‘ground’. ). Anyway the heatsink sits at -30v dc so take care not to short it to the case.
Thanks. Yeah, saw that 😏 But that’s the funny thing, there is no voltage on the heatsink (no insulator either). The IC pins are getting both rails but nothing on the tab, and no voltage at the mute pins. This leads me to conclude that the heatsink must have blown a rail internally and gone into protection mode.