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+--- Thread: Help needed - orientation for LED and capacitor (/thread-20506.html)
Help needed - orientation for LED and capacitor - JoeG - 09-15-2023 06:39 PM
I'm building a 264 Cartridge for the Commodore 16, 116, and Plus 4 computers. I bought it from ebay, and I thought it was already built. But it came as a DIY kit, which is fine except that it came without schematics for the two components that are not obvious to me as far as their orientation. The LED and the capacitor. Neither locations on the PCB have marking to indicate their orientation. Please see the attached photos.
The capacitor is at location C1, and it has the marking of 104. The mounting holes on the PCB are vertical. But I can't tell which was the 104 should be facing when installed. Should it face the socket/chip, or the other way?
The LED is located at the upper right corner of the PCB. The mounting holes are vertical on the PCB. Again, no markings for orientation on the PCB.
If it's of any assistance to you, the capacitor has a trace leading from the top connecting point down to the left most resistor legs below the capacitor mounting location. For the LED, there's a trace leading from the top most mounting hole for the LED to the right most leg of the nearby resistor.
Any help would be appreciated!
Thank you!
Joe (Novice)
[attachment=12559][attachment=12560]
RE: Help needed - orientation for LED and capacitor - Steve Simpkin - 09-15-2023 06:54 PM
The capacitor you list is a .1 uF (aka 104) ceramic capacitor and has no polarity. Just install it for C1 without regard to orientation.
The LED should have a flat side as shown in the picture below. From the populated cartridge picture you provided, it looks like the flat side of the LED is toward the bottom of the board. The silk screen on your board also has a flat side on it. Install the LED so that the flat side matches the silkscreen.
[attachment=12561]
RE: Help needed - orientation for LED and capacitor - JoeG - 09-15-2023 07:01 PM
Thank you!
I also just figured it out by checking continuity on pin one on the edge connector (ground) to the mounting hole of the capacitor, and the bottom mounting hole for the LED. Pins 2 and 3 of the edge connector are 5 volts each. That helped.
Joe
RE: Help needed - orientation for LED and capacitor - JoeG - 09-15-2023 07:47 PM
Success! The cartridge works, despite the configuration instructions on the chip being wrong. I used it on my Commodore 16 (which is not having any issues), and then my Commodore Plus 4 which is having issues (bad memory as suspected - MT brand is junk).
Thank you!
Joe
RE: Help needed - orientation for LED and capacitor - Steve Simpkin - 09-15-2023 11:27 PM
Very cool! I had an Atari 800XL computer back in the 1980s while my brother-in-law had a Commodore 64. We had a lot of fun comparing the two systems to each other.
RE: Help needed - orientation for LED and capacitor - teenix - 09-16-2023 01:48 AM
I learned BASIC and 6502 machine code programming on the C64. I made interfaces for the IO port and controlled odds and ends including a home-made plotter. I blew up a few 6525 IO chips in the process.
I made an alarm system controlled by the 64 which dialed a pre-programmed number if a sensor triggered and used a SP0256-AL2 IC to "talk". It sounded like 2001's HAL with half of his transistors disconnected. The silly thing kept ringing my mum who rang the police because she couldn't understand the caller.
Much fun back then.
cheers
Tony