Problems with Ragtime UP/DOWN Counters -- Pianocorder Forum

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Subject: Problems with Ragtime UP/DOWN Counters

Author:
Pete Knobloch

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Date Posted: 21:03:14 05/13/03 Tue

Hello all,

This is the first time that I have used this forum. I am working on a customers Pianocorder that also has the Ragtime option (model PC1145). The unit has a $.25 slot to insert quarters to start the 8 track recorder to play. There is also a switch in the back of the unit that is called the "Happy Birthday" switch that stops the 8 track tape deck and starts the normal cassette deck to play. A special "Happy Birthday" tape is put into the Cassette unit so that it will play when the button in the back is pushed.

The piano plays OK from either the 8 track or cassette players (but not perfectly). My current problem is with the counter logic that is found on the UP/DOWN counter board.

When I first looked at the unit, the piano wouldn't stop playing from the 8 track player. The play switch was in the NORMAL position. It was like the switch was set to 8 track continuous play. When you dropped quarters into the coin slot, the 2 LED counter lights would never turn on. With a scope, I found a problem in the NOR gate IC (CD4001BE). When I replaced this chip, the LED's are now counting as seen by the lights changing as the coins are put into the coin slot. The other thing that is now fixed is that when the piano is first turned ON, the 8 track is turned OFF until a quarter is placed in the slot. With the bad CD4001IC you couldn't stop the 8 track unless you flipped the toggle switch to "Continuous Cassette".

At this point I still have a problem. When the coin is put into the slot, the music starts playing but doesn't stop on the next song. It is like 5 or 10 quarters have been put into the slot. What is even more puzzling is that if I push the coin switch down 10 times or so, the 8 track tape will stop. This indicates to me that the logic for the Up/Down counters is having problems. I had the customer replace the 2 CD4510BE BCD counter chips and we still have the same problem. What is puzzling me is that with 2 counters wired together as they are, the counters should overflow at a count of 100 and not stop when I push the coin switch down 10 more times. Could there be a problem with the setup time between the pulsing of the UP/Down pin 10 and the clock pin 15?

Have other technicians seen these types of problems? Is there a known ECO (Engineering Change Order) that should be put onto the board?

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Replies:

Subject	Author	Date
Re: Problems with Ragtime UP/DOWN Counters	Tom Lear	01:11:36 06/21/03 Sat