by Rob-NYC »
Wed Jul 20, 2016 7:46 am
Steve, since you are adding credits with the button the first thing to check is the fuse on the credit unit. It is on the board where the credit wiper goes around.
Here is a credit unit with wipers and fuse shown:
http://i.ebayimg.com/images/g/GzgAAOSwL ... s-l300.jpgWhile you have the cover on the credit unit open it is a good idea to clean the traces with an eraser and rinse with rubbing alcohol.
Since these machines use an electro-mechanical search and memory there are contacts in the search unit that hold out the keyboard while the search motor is running and until the pin in the memory is punched. This is the next place to look when you have this sort of problem. The contacts can become pitted and the blades may have inadequate pressure on the points.
Read the post about contact cleaning and care:
viewtopic.php?f=3&t=6404Beyond just getting past this problem, that machine is 43 years old. They are quite reliable -but a service manual is advisable. The amp will likely need at least some rebuilding. In the meantime,. turn on the machine and let it sit w/out playing for at least 15 minutes, check that the heatsink on the amp is not idling hot. If it is, the amp may need to have the bias adjusted or there may be a more serious problem that can lead to failure.
Do not attempt any adjustments until you have service information.
Rob-NYC
"If we believe absurdities, we shall commit atrocities" -- Voltaire