Jump to content

Looking to buy a Colecovision Component (YPbPr) Cable Mod.

Recommended Posts

Hi, I recently came into possession of a working Colecovision, and I've been looking all over for someone who can do a mod that allows it to work with Component (YPbPr) Cables.


Is there anyone on this forum who can do it, or at least point me in the right direction? I can't seem to find any available services that offer a component upgrade, just composite/RCA.


Obviously I'm willing to pay for the mod and its installation, as well as shipping.


I saw a video of a component modded Coleco, so I know it CAN be done, but I can't currently find the means to do so.




Edited by lapinbeau

Share this post

Link to post
Share on other sites

The mod in the video is one that 5-11under designed and sold for a limited time at the end of 2009 and into 2010.  Unfortunately it's no longer available.  Checkout this thread for more information.  One of my CVs has this mod and it works great apart from a blue tinge to black backgrounds.



Also, the_crayon_king started to design a new component video mod but there have been no updates since early 2018.



Share this post

Link to post
Share on other sites

My o-scope is iffy. I got component to work with just sending the outputs of the TMS9928A through a 75 ohm resistor and 220uf capacitor.

That kinda stuff will only work on a old school CRT and is not at all correct.


another way to write this would be to look at the range

0.9v black to white min; 0.7v black to white nominal; 1.1v black to white max.

0.4v black to sync min;  0.5 black to sync nominal; 0.5 black to sync max.

1.3 white to sync min; 1.2 white to sync nominal; 1.6 white to sync max


I do not think the input can be divided before going into the amp (I did not consider this earlier)., instead block the DC with 0.1uf capacitors

if sync is present on R-Y and B-Y then you probably don't need pull up resistors.

I will draw up what I am talking about later I have to backtrack a bit because I wasn't thinking about the offset.

Edited by the_crayon_king

Share this post

Link to post
Share on other sites
On 11/11/2019 at 10:30 AM, grips03 said:

best to use citrus3000psi RGB mod and then convert to what you want.

You mean the baby PAC man thing correct ?

If you have an old CRT and wanted only YPbPr then most likely you do not need to convert to RGB.

Converting from wonky YPbPr to RGB then back to a corrected YPbPr seems like overkill if you just wanted YPbPr.

Just divide the inputs to acceptable levels 0.7v p-p or 1v p-p if sync is present then 6db amp and use.

My crappy o-scope actually died so I haven't been able to actually test this stuff.

There is alot of variance in the data sheet so the only way I see to do it with minimum parts is with potentiometers and measuring the outputs with a scope per console.

as a note I am out of practice with this stuff; further note this should only be used with an old CRT TV or possibly a scaler. It is wildly unlikely it would work with a newer TV.

just replace r1,r2,and r3 with pots and adjust . If the voltages are the same across many systems (which I doubt) then the pots could be substituted for resistors.


To be clear

for Y you need 0.7v p-p difference on Y from BLACK to WHITE (ignore sync) as in 0 0 0 to 255 255 255

for R-Y you need a 0.7v p-p difference from RED to CYAN as in 255 0 0 to 0 255 255

for B-Y you need a 0.7v p-p difference from Blue to YELLOW as in 0 0 255 to 255 255 0


If looking at a black and white screen and viewing Y you should see three distinct voltages the lowest one is sync.

I have heard that R-Y and B-Y may or may not have sync (not sure) but the same would be true for them if sync is present otherwise:

when looking at a red and cyan screen and viewing R-Y you should see two distinct voltages

when looking at a blue and yellow screen and viewing B-Y you should see two distinct voltages

if there were a third lower voltage it would be the aforementioned sync.

These elements are what I am referring to when I say to adjust to 0.7v p-p and ignore sync.


The best way to do this would be with a color test screen or something, a scope, and the rough schematic shown below with the substitution of R1, R2, and R3


I may be wrong on all that do your own due diligence.



Edited by the_crayon_king

Share this post

Link to post
Share on other sites

Ooookay so, I really don't know anything about soldering, or circuit boards or the like, so all of this is basically moonspeak for me. I don't know what I actually physically need.


I'm mostly just looking to see if there's anyone who can actually do the modifications for me. I have money, so of course I'm willing to pay for it!

Share this post

Link to post
Share on other sites

The PAL version of the Citrus3000 almost does what you want.  In fact, after reverse engineering it to help out another installer, I decided that everybody ought to be using the PAL version for their RGB mod needs.  Anyway, with only half of the circuit, it is a YPbPr output buffer that also uses a sync circuit to suppress the blue tint.


It wouldn't be too hard to "undesign" the RGB converter part from the circuit and leave it with just the YPbPr output.

Share this post

Link to post
Share on other sites

Personally I didn't think my ColecoVision looked too bad with just a composite A/V mod...


That said, I'd be remiss if I didn't also mention this.  (Think High Def ColecoVision W/ built in SGM and homebrews!)   I have one and I love it! 




And if you do happen to order one, you'll want to follow this thread:



  • Like 2

Share this post

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

  • Create New...