Eprom question - opinions please! :)

[Britguy1]

Question about an Eprom chip (2716)....

I am in the UK which as I am sure you know has 230 volt standard AC. I have an eprom chip and I am building a copy of another circuit board - a nice little light chaser from the 1980's, as far as I can see tracing the tracks on the original board, several of the pins on the Eprom chip are wired directly 230 volts on the actual chip - I even meter'd the original board while live and found 230volts feeding a number of the pins on the original Eprom!!!. I am relatively inexperienced with electronics and thought Eproms used 5 volts - have I gone mad and having a late night or does it sound about right that certain chips on an Eprom do and can use 230 volts. The pins on the chip on the original board have metered at 230 volts and the original board is flashing away in front of me as it always has done. Slightly confused. Any help much appreciated!

 

[davenn]

Hi Britguy
welcome to the forums

several of the pins on the Eprom chip are wired directly 230 volts on the actual chip

I seriously doubt it !!! you have either mis-traced tracks or its not an eprom

Show us sharp well lit pics of both sides of the circuit board

cheers
Dave

 

[Britguy1]

Thanks for the reply, so I have attached two pictures, and as you can see on the front, top center is the mains input - 230volts live and Neutral, and on the back there is a very wide, clear track that is bridged by a fuse across the live mains input and then carries the mains directly from the mains voltage input down to a number of the pins on the Eprom (2716) chip (bottom center), and also to a couple of the pins on the 4093 chip and the 4040 chip. Its bizarre but its for sure this way and I have even metered it across the Neutral mains input and suspected mains pins, and it does indeed carry 230 volts ...any more thoughts would be appreciated.

 

[Britguy1]

Just took some pictures of the board

 

[(*steve*)]

That possibly goes to the centre tap of the secondary winding and is a DC ground.

It certainly seems to be connected to the ground pin of the chip.

 

[davenn]

there's somethin g really freaky with that cct layout

I have to agree with britguy that IF that terminal at the tol labelled L is really mains live ( appears to be connected to the red wire), then it appears to go via the fuse to one side of the transformer and also down to the 2716 and other chips it also goes down that long stripline on the component side from top to bottom of the board

there really has to be something screwball there


Dave