notes from Colecovison VGA card install

[+grips03]

I have rev H Colecovision (Canadian CV) and the C3 cap was labeled Tracon 1/50 T8302a. On a rev H schematic C3 is labeled 1uf, page 4 upper right. I'm thinking 1/50 means 1uf and 50V.

 

I replaced C3 electrolytic cap with a 10uf 16v electrolytic cap (10v would have been fine) and now no more garbled boot graphics for Frogger.

 

I did notice my other Colecovisions all had a 10uf cap in location C3 (near reset button in front right). These are all Rev F if I remember right.

Edited September 9, 2012 by grips03

[matthew180]

I have never seen a cap designation use anything like "1/50". 50V would be way overkill for something like a home computer. The schematics I found, and that I assume everyone else is using, show a 1uf cap for C3, but both of my CV's have a 10uf electrolytic cap.

 

Anyway, it is good to know that slowing down the power-on-reset resolves the start-up issues for the games. The CV is just one of those machines that likes to start up fast.

[+grips03]

Thought I would bump this old thread to show how F18A is installed.

 

Also I have pre-modded F18a CV console for sale if someone wants one. Send me a PM.

[+grips03]

Hakko 808 helps to remove VDP with no damage

 

You can see C3 1uf cap is replaced with 10uf cap.

 

You will need to push down some of the caps under the F18A in order for it to fit.

 

There are (4) jumpers on the F18A, these can all be left on for install into Colecovision

[matthew180]

Very nice!

 

A few comments come to mind as I look through the photos:

 

* The "tall-pins" version of the F18A exists specifically because of the tall capacitors used in the CV around the DRAM ICs. When I went to install an F18A in my CV I realized people would have to either bend the hell out of the caps, remove them, or the F18A had to get taller. You still have to bend them a little with a tall-pins F18A, but not much. Also, if you don't care about using the CV with the original VDP again, you can remove (cut or desolder) the caps around the DRAM ICs and use a low-pins version if you want.

 

* I noticed you cur the VGA cable to length and re-crimped the IDC connection. Very clean! However, for anyone following this install please note the the connector is now installed upside-down from how you would install the "stock" ribbon connector. The "bump" on the connector is typically *down*, however after this modification it is *up*. Just a detail you need to pay attention to if you are modding.

 

* The HAKKO certainly does make IC removal easier! I finally broke down and bought one myself. Also, "ChipQuik" can make IC removal much easier too.

 

* The CV motherboard is very fragile, so you have to be very careful. It is really easy to lift a pad or a trace.

[Jinks]

Does it still use the stock vram and power supply?

 

I noticed there are other parts mentioned for install. Is the kit complete With everything you need to get running without ordering various parts from china?

 

You say the stock ribbon cable is in backwards in that pic. Is there a picture of the normal install?

 

The complete rf daughterboard can be removed and this will work as bypasses it completely?

 

For sound do you go off c88 and ground?

[Jinks]

Any answers to these questions? Or any product support for installation? Just wondering before I buy as it is a bit of money to throw down and don't want to waste much more time and money on coleco stuff.

Is there a short and tall pin option to order?

[Tursi]

Matthew180 is the creator, you could ping him directly.

It does use the stock power supply, it does not use the VRAM (it has its own).

There are a number of other install threads with lots of pics in the TI-99/4A forum... the main challenge on the ColecoVision is the VDP is soldered in,

you have to be able to desolder it.

[Jinks]

Matthew180 is the creator, you could ping him directly.

It does use the stock power supply, it does not use the VRAM (it has its own).

There are a number of other install threads with lots of pics in the TI-99/4A forum... the main challenge on the ColecoVision is the VDP is soldered in,

you have to be able to desolder it.

Thats easy. the tricky part is the coleco boards are flakey and traces can easily be lifted out. I already replaced all my ram so the vdp is a 5 minute job compared to that nightmare.

[matthew180]

Does it still use the stock vram and power supply?

The DRAM ICs that make up the VRAM are not used when the F18A is installed. In my development 99/4A computer I completely removed the DRAM chips, which relieves the power supply a little. I *think* in the CV, only the DRAMs require the -5V and 12V, which means with the F18A you can replace the power supply with a single 5V supply (you will want to confirm this though). Yes, the F18A uses the system's 5V power via the same pins as the original 9928 VDP.

 

I noticed there are other parts mentioned for install. Is the kit complete With everything you need to get running without ordering various parts from china?

The F18A comes with a VGA pigtail and "PC" back-plate that you should modify and mount in your case to provide strain relief for the 15-pin VGA connector. For systems that have the original VDP soldered to the PCB, you will need to remove the VDP and add a socket yourself (the F18A does not come with a socket). No need to order a socket from China, they are easily available from suppliers in just about every country. In the US you can get them from Frys, Radio Shack (if you still have one in your area), Digikey, Mouser, JameCo, AdaFruit, SparkFun, etc.

 

You say the stock ribbon cable is in backwards in that pic. Is there a picture of the normal install?

 

grips modified the pigtail that comes with the F18A for a more custom fit. In the modification, the original 16-pin header was removed and flipped over, so it had to be plugged in upside-down from what would be "normal". I think grips made that comment to prevent confusion for anyone installing an F18A but not modifying their pigtail. The F18A comes with an instruction sheet that shows the proper orientation to plug in the pigtail.

 

The complete rf daughterboard can be removed and this will work as bypasses it completely?

 

With the F18A installed, the original video output will be dead. If you do not care about being able to reinstall the original 9928, then yes, the entire RF section could be removed from the motherboard.

 

For sound do you go off c88 and ground?

On my test CV I picked up sound from C88 and ground, and ran the wires to a standard "RCA" style audio jack. If worked fine, but there are probably other ways as well.

 

[matthew180]

Any answers to these questions? Or any product support for installation? Just wondering before I buy as it is a bit of money to throw down and don't want to waste much more time and money on coleco stuff.

Is there a short and tall pin option to order?

 

This is a hobby project, I assume people taking on a modification of their computers are aware of the risks. Product support is via the forum or email. All F18A boards are programmed and tested in a real 99/4A computer prior to shipping, and there are photos of the short and tall pin options on my F18A order page (see my web store). You choose short or tall pins when you add the F18A to your cart.

 

I added the tall pin option when I installed an F18A into a CV and realized the caps used around the DRAM chips in the CV are taller disc-type caps. The tall-pins option helps get the F18A up and over those caps with minimal bending of the caps. If you remove the DRAM caps from your CV then you could use the short-pins option if you like.

 

EDIT: If your DRAM chips are in sockets and you leave them installed, then you will need the tall-pins option.

Edited March 28, 2016 by matthew180

[Jinks]

All I can say is I am very impressed with your answers. I will order when I get some hobby money freed up. Thank you very much!

[+grips03]

Thought I would post these notes from the TI forum, in case one needs to change F18a version

 

 

0. Make sure your system is powered OFF to begin
1. Open your system to get physical access to the F18A
2. Plug the JTAG programmer in to your PC (via USB) and the F18A (via JTAG)
3. Power ON your system
4. Launch the Xilinx IMPACT tool
5. Double-click on "Boundary Scan", then right-click in the main area and select "initialize chain"
6. The FPGA should be detected and show up in the big area. A window will open with device properties, just click "ok"
7. Above the FPGA icon should be a dotted line with "SPI/BPI ?" in it. Right-click on that box and select "Add SPI/BPI Flash..."
8. Navigate to the f18a_250k_vXX.mcs file you extracted from the .zip file and choose "Open"
9. Select "SPI PROM" and "M25P80" from the two drop-down selections and click "OK"
10. The box above the FPGA should now say "FLASH" in it. Right-click the box and select "Program"

Once the programming is finished, cycle power on your system and make sure it comes up.

[Tursi]

Please also remember that there is a software-only updater for the Coleco available, if you have a flash cart that can load a 256k image like AtariMax: http://atariage.com/forums/topic/262086-f18a-firmware-update/?p=3726315

 

However, this is an upgrade-only path and takes you to v1.8. You can't down-rev (although source is available on Github as well as notes on how to change the firmware it loads.)