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Subject: Re: Help! I've messed up my Pianocorder.


Author:
Roger Dalziel
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Date Posted: 16:03:32 10/26/09 Mon
In reply to: Steve Mull 's message, "Re: Help! I've messed up my Pianocorder." on 12:40:37 10/26/09 Mon

Download the schematics from Mark Fontana's website.

Set up a comfortable, well-lighted work station. This is going to take a while. I like a clamp-on magnifying lamp with a circular fluorescent bulb.

Start by making a list of all 28 ICs on the playback board and on the solenoid driver boards. After making your list and checking it twice (like Santa when looking for those who are naughty and nice, seek out a well stocked surplus electronics store or check prices at Digi-Key in Thief River Falls, Minnesota, or at Jameco. You might have trouble finding the 74L121 timer chip. Substitute a 74LS121; you might also find that the 4N37 opto-isolator (U11) survived the catastrophe. Order also the appropriate number of 14- or 16-pin sockets.

I do not recommend using a desoldering tip. Better to cut the legs off the chips, because of the delamination of the printed wiring mentioned by Mark Fontana. The boards are constructed of the very cheapest material available. They can't tolerate much heat. I had to install jumpers where that occurred.

Adding to the woes, in a few places (not many) the IC pin is used to connect the top layer to the bottom layer of the printed circuit wiring. This makes for difficulty in installing a socket.

Contact me. I might have overlooked something here.

Also, never, never ever use a piece of grounded test equipment. That's what got me into my mess when I fried everything.

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Replies:
Subject Author Date
Re: Help! I've messed up my Pianocorder.Steve Mull11:56:05 10/27/09 Tue

Re: Help! I've messed up my Pianocorder.Steve Mull12:02:54 10/27/09 Tue


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