That time when you've been battling with a board, but when you put it in reverse... you get the same side... only backwards. No clue. Utterly ... no clue. Doesn't do it all the time either. It works about 10% of the time... but I've had enough for now. I'm giving in for the night. Prodding at things without the service manual is only getting me so far. - *sigh*
I'm working on a tape deck with the same issues, thought it would be an easy belt change but the gears aren't engaging, so I have to break down the transport again... It will be a nice little deck when I'm down though...
I think I killed my transport. The unit has two pins which solder to the motherboard... and I think I applied too much heat, once to often, and I've fried something, because it doesn't want to power up now. I transferred the working innards from the dented green case to the nicer black case, so I have a working walkman at least, but the other one is dead and also has a fault, and with no service manual, I'm shooting in the dark. So, time to move on to the PX303 units I think.
I do that a lot but I usually put the batteries in backwards..... Here's a little tip for you, I love Casio Keyboards, I used to get non-working ones for cheap. They need a Casio Wall Wart, or I have a Radio Shack Multi-Voltage Unit because the polarity is different on the Casios. With the RSMVU I can unplug the tip and turn it to change the polarity, I've saved a bunch of Casios from the trash bin with this method....
A cheap way to see how you messed up is to lightly apply alcohol to the board, it will show any acid damage done to the board. then try to lightly sprinkle it with some baking soda, it will get rid of any acid residue.
I'd already cleaned the board with baking soda. I think that while I was replacing some dead microswitches, and fighting with another (which was my fault for not understanding how it worked) that I have heat damaged something. I believe that there is a mechanical operation from the mechanism, that actually flips an electrical switch on the board, to control which audio inputs are fed to the amplifier... but without the manual for the P505, I can't confirm my suspicions. And as I killed the transport to boot... (again, possibly by sending too much solder iron heat down a pin) ... I'm likely never going to find this out for certain, unless I can find out what voltage to send to the motor and bypass the circuitry ... (again, need the service manual) This is an abject lesson in having the service manual, and studying it properly, before even taking a screwdriver to the unit.
