Hi everybody,
Just wondering if anybody knows a source in Sydney for a Mitsubishi M52472P
4-Input 3-Channel Analog Switch IC. I believe the M52470AP IC would also do the job. I can't find it in the Wagner Electronics catalogue nor do RS Components have a record of it. The IC is used in a video distribution box which has one output for a television, and allows me to select between four separate composite or S-Video inputs via four buttons on the front panel.The data sheet is available here:
So far I've blown two of these boxes and only just realised why. Both boxes failed when I was plugging in my laptop computer using a standard RCA composite connection. I just used a multimeter and measured a full 110V AC between the RCA socket ground connections of the television and the laptop. It seems to be similar to the zap you can get from the antenna socket on some TV sets. Further investigation shows that the IC the switchbox uses, the M52472P, is susceptible to transient currents. Sometimes the input or output circuits burn out, causing either distorted output or no output at all. I'm getting no output at all from one box, and distorted output through Input #3 on the other box. Frustrating.
I would probably need two or three ICs, two to fix these blown boxes and one as a spare. I'd be really grateful if somebody could suggest a supplier, otherwise maybe I'll just see if a TV repair shop can order me a few.
Secondly, can anybody suggest a fix for this problem (apart from just not connecting my laptop up to the box!) - I've seen RCA line isolation boxes for sale, but they are usually used with audio gear and I don't know if they'll work with composite video. The distribution box circuit is almost identical to the 'Application Example' circuit shown in the PDF data sheet. I'm not sure if changing the components to higher voltage ratings would help, or if I need to somehow put some sort of isolator in the circuit.
Any suggestions are welcome.
Thanks! David