Yoder

November 10, 2013

From what I've read, you can bridge TR4 and it will work...it will just turn on regardless of whether the power switch is on or not. It would at least allow you to further test the unit.

November 10, 2013

Hey guys,

I couldn't pass up a Sunnyvale 6-switch for $10, even though I was told it wasn't working. I got it home and found that the 7805 was ouputting zilch, so I changed that. Then it powered up, but I had no picture (just lines and squggles), so I checked the three big chips in my other Atari and they're fine. I reflowed all the cartridge slot solder points, but no go. Then I decided to change the green chiclet capacitor wit a .22 uF one from RS (C103) and it worked! I saw Crystal Castles bright and clear! For about two minutes... :-(

So the screen started to mess up and then went back to what I was getting before...same whether there is a cartridge in there or not.

I wanted to see what you guys thought. I could put in another chiclet capacitor in case it fried some how, but it may just burn it out again. Or maybe I got a faulty one?

Also, the one I pulled out said 220K on it...I was assuming something more like the other Atari's I've worked on that read 22M or something similar to that. Probably not a big deal as the service manual states that it is a .22 uF for the original 2600.

One other piece of info is that the console looks like it was sitting in a puddle at one point. The RF shield was badly oxidized and there was a lot of rust in the bottom of the case (from the screws and RF box case). It seems like it didn't touch the main board or any major components, but I figured I'd mention it.

Please let me know if you have any ideas.

Thanks!

January 16, 2012

Yeah, I could use a brain re-wire ;-) I agree, it will just take some getting used to. Yes, a joystick is the way to go...I just don't have one yet.

January 15, 2012

Ok, it's A and Z but Caps Lock must be down! I guess I didn't try that :-/

Thanks for the tip! Now, if only I could play it worth a damn! That's not an easy key combination!

January 15, 2012

Trust me, I tried all the keys several times! Not sure why those keys didn't register. Yes, I grew up in the 70s, so I think retro ;-) BTW, I just fixed that IIc...well, I got a board from another one and used my kbd, etc.. I'll post back in that thread when I have some more info. I may swap the socketed ICs just to rule those out for good.

January 15, 2012

It does it both on the emulator and hardware. I can't get her to go up or down...only left or right with the arrows. I googled for instructions with no luck, and see no options or instructions in the software....

I figured some of you must have played this :-) Any pointers?

January 2, 2012

Yeah, I used the orange oil version which is less aggressive, but it it still softened the IIc logo to a point where it just smeared off. I was bummed, but I have realize that the case looks 1000X better even though it's missing that logo.

January 2, 2012

Notice that the IIc logo was gone before retrobrighting. It came off when I used orange goo-gone to remove the sticker residue that was on it.

40 Volume Creme peroxide is 12%, BTW. I've never had it damage any labels, silkscreen, etc...but I'm sure it's possible. Yes, you never want whatever you're using to dry because the concentration of H202 increases as it does. I saw a little streaking in couple of spots in this IIc, but they all bleached out upon re-application of peroxide.

January 2, 2012

That's it! Just Creme 40! It seems to do a great job without adding oxy clean. You just have to really keep after it because it starts to dry and then can leave streaks where it overbrightens. I've used it on NESs, SNESs, Apples (this IIc and a IIgs), Commodores (64C, C128, and an A500), and Ataris (800XL and an 800). I'm hesitant to use it on a C64 since they're kinda dark and more apt to streak. I have a broken case I can test it on, though.

I really should consider adding some xantham gum to it to help the dehydration issue. That stuff is just so expensive that I haven't done it yet...it's like $14 a bag at the grocery store :-/ Plus it makes it more work. I really like that I can just brush this stuff on and go with it.

January 1, 2012

Ok, the retrobirght is done. This ugly IIc now looks like it did in the 80s.

The first pic is after removing all the residue from the stickers that had been on this thing. The "IIc" logo was a casualty unfortunately. It doesn't look bad, though. This was about 1.5 to 2 hr in the Tampa sun with probably 25-50 cents' worth of Creme 40 peroxide from Sally's. The majority of the whitening happened in the first hour or less. It turned out nearly perfectly. Now I just need to get the guts working :-/

January 1, 2012

Cool, thanks for the link to the IIc book! I hadn't come across that page... Definitely a great book.

Yeah, I replaced the POKEY chip in my Atari 800 XL recently too. Not a single key was working on that one....

As far as retrobright...i just do it DIY. I've found that just using 40 volume creme H2O2 from Sally's works perfectly. I'll post pics today!

December 31, 2011

Keatah, thanks for all of your input. I agree completely. I thought of jumping some pins on the connector to simulate a keypress, but I checked the continuity of the keyboard harness out to the female connector and it's good, so I'm confident that I'll see the same thing if I short pins on the mobo connector.

OK, I was wondering if the AY-5-3600 was custom. I figured they have to have the keyboard matrix in there. So that most likely means that only the encoder from a IIc will work (as opposed to a IIe, etc).

At this point, this project is at a hold stage. I'll either pull an encoder from another dead IIc (I'm not good at desoldering large chips, though) or I'll use this as a donor. It has several good roms, a good drive, keyboard, etc. I'll probably start retrobrighting the case and keys this weekend so that I'll be ready to roll when I get another board!

And I saw the thread on your haul! Congrats! That's amazing! I'll post back in this thread when I get the IIc up and running...maybe it will help someone in the future.

Oh, and thanks for mentioning the computerfacts book. Were you reading the one for the IIe or is there a IIc pdf floating around? It's only 60 pages, but there's some great info in there! I have a C64 project, so I may look through the Commodore version of that book. I think the one C64 I have (firtst one I bought last year) may become a donor too. I pulled the PLA to fix another one with two bad ICs, and the SID is dead...plus the bottom half of the case was damaged in shipping.

Thanks again...

December 31, 2011

Thanks Keatah. Yeah, I realized that the C60 cap is a filtering cap...I'm not going to mess with it for now. I checked the 7905 and I'm getting -11.34 in and -5.0V out. Then I checked pins 15, 27, and 30 of the keyboard encoder for ground, -12V and +5V, respectively and it was good. The only thing I'm seeing is that -11.3V, which I guess comes out of that big voltage converter under the shield. Hopefully that's close enough to -12V for the encoder and the other components.

I also changed the C45 capacitor with a new .022 uF one I had in my toolbox...no help.

I checked the RP1 resistor network, although I really don't know how to do it the right way. I measured resistance between each post and got 1000 ohm for all of them except two or so that had 500 and 650 ohms resistance. Is that network suspect? I wonder if I can pull one out of a bad sega console I have? I'll have to check.

UB16 is not labeled on the board. Is that the AY-5-3600? Unfortunately, it's not socketed, which is a bummer. Looks like they're not common anymore and they're $20 and up from what I've found. They only support 90 key switches, I believe, so I'm sure these aren't used much anymore. I think I'll just get another IIc. There's on on ebay with a bad keyboard....maybe I'll consider it.

BTW, I have about 12 keys that aren't working at all...but I verified that the switches are good. I traced the series of switches on the keyboard and found that there are 4 strings of keys that do not work, and these each lead to a distinct pin on the encoder and the traces to it are good. I bet there is an internal short in the decoder. Good news is the power supply I made seems to be working OK :-)

Thanks for your help! If anyone has a IIc around that they want to let go, let me know :-)

December 30, 2011

Ok, I'm trying to post the figures from the ref manual. I had to attach it. It shows the schematic and has a description...pretty cool.

Oh, and from reading here: http://staff.bcc.edu/eet/Capacitor_Coding.html that 223 C45 debounce capacitor is really 22 X10^3 pF or .022 uF :-) It looks like debouncing just addresses an issue with a few extra characters being displayed (Wikipedia)...I don't think a bad cap here would cause an indefinite repeat. It seems that it may be a key release issue, to me.

December 30, 2011

Ok, I attempted booting into ProDOS from a floppy w/the keyboard disconnected, but it actually doesn't seem to finish its boot sequence. I get the screen full of colored tiles (the one that flashes on a normal boot). I also tested each key and all of them repeat, but there are a few (G,YUIOP[) that are not working so I'm going to see if these are connected to a common trace that may be damaged or something.

About the capacitor (C60). It's one of the few electrolytic capacitors, it's right next to the kbd connector, and it appears that it's connected to it by a trace, so I assume it has some role. I actually just found a schematic in the Apple IIc Reference manual I dug up online (haven't found a reference to C60 yet). It looks like C46 and the resistor network next to it handle kbd scanning rate, and C46 modulates the key bounce mask which was addressed in this post about a IIe: http://www.appleii.info/repeating-key-how-can-i-fix I don't think ceramic capacitors go bad, but C46 looks a little "fat". I do know that resistors can also go bad, so maybe that's worth looking into also. The C45 cap is a funky poly-style one that has 223 on one side (223 pF?) and A5K or R5K on the other side. I've actually similar style capacitors go bad on Atari's I've fixed. I'll have to dig a bit deeper.

Anyways, it looks like the IIc is thinking that I'm pressing the key longer than one second, initiating the repeat, (from below) or maybe it's not getting the key release signal? I suppose I could have a bad AY-3600 keyboard decoder or maybe it's the IOU that's interpreting the AY-3600 signal?

Will try to post the manual pics in the next post...it's giving me issues when I click "Post"...

Oh, I was wondering if that was Dvorak mode with that key! Still trying to get it switched to 80-column mode in DOS, but I booted Hitchiker's guide and said "Y" for 80-column and it's still doing it...but this seem software driven as opposed to switch-driven. Fortunately I could type a "Y" by switching to Dvorak style keyboard :-)

Ok, off to my multimeter and a beer!

Actually this is a lot of fun! Thank you for the help, guys!

December 30, 2011

Thanks guys. I reseated all socketed ic's as well as the kbd cable to no avail. I see no damaged traces, etc. I'm gonna replace the electrolytic cap near the kbd connector. And just reiterate, ALL keys repeat forever...

I'll update after the cap replacement.

Thanks...

December 29, 2011

Hey guys,

I just got an untested Apple IIc in the mail today for a pretty decent price. It's ugly as hell, but I'll retrobright it to address that :-)

Anyways, it didn't have a power supply so I made one from an 18V 1.1A switching power supply from an HP laptop and a 7 pin DIN female connector I bought a few months back (since I've been hunting for one of these). Specs for this are15V/1.2A so I'm pretty close. I've read that they can take up to 23V. Maybe it has a 12V voltage regulator inside?

Anyways, it seems to work fine and it loads disks, but when I pull up DOS, any key I press just repeats indefinitely or until I press a different key, which does the same thing. I've tried pressing every key on the keyboard including the "keyboard" button at the top (not sure what that even does) to no avail.

Does anyone have any pointers on this? I'm going to open it up and re-seat a keyboard cable if it has one, and look for bad capacitors, etc, but I wanted to see what you guys thought.

Thanks!

November 14, 2011

Nevermind... Came to the conclusion that they're tan in color as it appears that graphics on the keys actually comes from the tan plastic from the bottom half of the key cap.

November 13, 2011

Hey guys,

I've retrobrighted a horribly browned Atari 800 and 810 and they look really good. The last step is doing the key caps. I'm wondering, though. Were the graphics on these bright white like C64s or are they an off-white or tan color (like the inside of the key cap)?

I put them out for an hour or two yesterday and they're not white yet so I want to make sure I'm not going for a goal that's futile!

Thanks!

October 31, 2011

Unfortunately, sports games aren't worth the shipping cost, and the other games aren't worth more than $1 or $2 a piece. Yeah, look at completed listings on ebay.... Shame to see it go into the trash :-/ Honestly, if you threw away the sports games and only included the sonic games, quackshot, MK, and Ms Pac-man it would be more attractive since shipping would be less. Another bummer is that the power supplies for these aren't that easy to find. Good luck.

October 31, 2011

Price? Location?

October 23, 2011

I have several (ten or so) original working Infocom games for Atari 8-bit if you're into text adventures. They're all disk-only with Infocom jackets and in great shape...well preserved.

September 29, 2011

Ohhhh yeah, that fixed it! I checked the mouse to make sure that it wasn't the offender, and I used my mini needle-nose pliers and slowly pulled the pins out. Now my mouse is working! Thanks for the help!

Now just to test the serial null modem cable I just soldered :-)

September 29, 2011

Oops, I didn't click "Attach". Here is the pic. I already took the mouse apart and cleaned, but no luck. Yep, BITD I cleaned my mouse every couple of weeks...those things get nasty.

September 29, 2011

Hey guys, I just got an A500 (cool machine!) and the mouse only goes up/down. I don't have another mouse to test it with so I don't know if it's the mouse or the port. Is there something I can look for on the port? Is there a way that I can test for voltage to see if I have a bad port or anything?

I'm going to open it up and start digging around, but I figured I'd ask you guys first.

BTW, each joystick port has a pin pushed in...in the same position. Is this normal? I attached a lo-res pic...hope you can see it. I wonder if this or some other mouse/controller pushed these pins in and is screwing it up. BTW, a joystick in Port 2 works fine. still have to test one in port 1...no games that support it yet.

Thanks!

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