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techknight

Color Classic VGA Mod. the CORRECT way

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Techknight....

 

You say:

RF14 Changes from 236K to 216K 1% Precision resistor.

 

I can't find any resistors at Mouser that are 216K.  How about this one that is 215K?:

 

http://www.mouser.com/ProductDetail/IRC-TT-Electronics/RC55LF-D-215K-B-B/?qs=sGAEpiMZZMtlubZbdhIBIGXM%2fQECGO4o5HITMP02i0w%3d

 

I also found a 218K one rated @ 100 mW.  I am not sure of the power rating needed....

 

Also, looking at your list here:

 

RL62 Changes from 47Ohm to 100Ohm

RL70 changes from 33K to 22K. 

RL54 changes from 33Ohms to 15Ohms

RP8 Changes from 15K to 33K

RP23 Changes from 22K to 33K 

RP6 changes from 4.52K to 5.11K (SMD)

 

I could not figure out how many watts the resistors need to be.  Can you ball park a number for me?

 

Thanks

 

mraorid

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You need 216K there at RF14. Those are high precision resistors and you won't find those easily.

I put in two resistors in there that measured exactly 216K when put in series. Can't remember the exact values though.

For the other resistors I used mostly 2W. For the ones in the power section at RP8 and RP23 3-4W may be better but 2W works for me.

Edited by Bolle

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Thank you Bolle...  Depending on the price, I could buy 6/8 108K resisters and and then start matching them up.  I will use 2W resistors.  Thank you for your help.

 

mraroid

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@mraroid please post photos when you're done and share what you think of the mod :)

I will. I will post photos as I go along. 

 

mraroid

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"R" is for resistor, but....

 

​I am trying to buy some parts on Mosure for this 640 X 480 mod.  I know that "R" means resistor.  But what is:
 
RL----?
RP----?
RF----?
 
Can someone give me a little more information so I can buy the parts above?  I have the capacitors.  I am doing the mod to board rev "C".
 
Thanks you
 
mraoid


RL62 Changes from 47Ohm to 100Ohm

RP61 gets 7.5K 3Watt resistor added. 

J104 jumper gets removed and replaced with a 10 ohm resistor, 2 Watt. 

RL70 changes from 33K to 22K. 

RL54 changes from 33Ohms to 15Ohms

RP8 Changes from 15K to 33K

RP23 Changes from 22K to 33K 

RF14 Changes from 236K to 216K 1% Precision resistor. 

J78 moves to J79. (SMD)

RP6 changes from 4.52K to 5.11K (SMD)

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So they are all resistors then.  - R, RL, RP, RF, .    I wonder why they have different names.  Capacitors are usually all called "C".

 

Bolle said to buy 2 W resistors.  OK, I will place my order.  Thank you.

 

mraroid

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Because back in those days, the circuit boards were designed as grids. Letters on one side, numbers on the other. and each component has a number and letter associated with it in co-ordinance with the grid. 

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Ah, OK.  Got it.  So I am going to buy some 2 watt resistors from Mouser and call it good then.  I was confused by the lettering.  Thanks for clearing that up for me.

 

mraroid

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Hi Everybody,

glad to see that this topic is still alive ;) I did the VGA Mod as explained by techknight and it worked very well with my 575 Board. Now I decided to build up a Takky with a 6500 Board. Everything is done and it seems to work(start chime, HDD activity, and so on...) but the screen left black. In understanding what is the error I think that it could be the VGA Mod. Could it bee that this "new" VGA Mod operates not with a Takky? Or anyone has a idea what the problem could be?!

 

Thanks in advantage...

Edited by olwilli

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>Hi Everybody,

>glad to see that this topic is still alive ;) I did the VGA Mod as explained by techknight and it worked very well with my 575 Board.

 

I thought this mod was for the original analog board that came with the color classic.  Did you put a analog board from a 575 in your color classic?

 

 

 

>Now I decided to build up a Takky with a 6500 Board. Everything is done and it seems to work(start chime, HDD activity, and so on...) but the screen left black.

>In understanding what is the error I think that it could be the VGA Mod. Could it bee that this "new" VGA Mod operates not with a Takky? Or anyone has a idea

>what the problem could be?!

 

Again, I thought this mod was for the original analog board that was stock on the color classic.

What am I missing? Did you do any mods to the 575 logic board that you are using?  Or is it stock?

 

mraroid

 

 

 

 

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Sorry for the misunderstanding words ;) At the moment im using the original Color Classic Analogboard with the explained VGA Mod. My Logicboard was a 575 Board - so I hope you are understanding what I got.

 

I found out in the tutorial to build a Takky, that the "VGA Mod" is provided and the explained rewiring of the harness is designed for that. My opinion is that I have to change the sense wires to the Hi-Res Sense Line wiring. I hope you can follow me...?!

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Hey, tk. How is your application of the documentation on this hack going on your 12" RGB "640x480 conversion done right?"

 

I haven't had time to get back to those monitors. The B+ has to be raised, but I think it can be done without trace cuts, just as this one has. Then the horizontal output safety capacitors need adjustment just like this one did to compensate for the higher frequencies, and the requirement for a slightly higher HV requirement, and then the adjustment in the Sync circuitry and it should be fine. 

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Is anyone able and willing to do this VGA mod on an analog board that I send to them? I'm not confident enough to perform the surgery on my own machine, but I'd love to have the results.

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Bolle, sounds like you got very close, have you tweaked your mod successfully?

 

@tk: I imagine your 12" RGB 640x480 conversion is still on the back burner?

 

On 1/18/2017 at 9:04 PM, rsolberg said:

I've done the 60hz 640x480 mod to my CC Mystic. I get the option of 800x600 56Hz and it's pretty hard on the eyes. The 56Hz refresh isn't so bad since it's such a small monitor, but the UI text looks terrible as it's finer than the pixel pitch of the CRT.

Is that the original, "unauthorized" conversion done by the CC crowd back in the day?

 

Might some combination of the two methods yield better results?

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It is okay-ish for me now. Turned that little pot right under below the tube all the way up... might remove one of the capacitors I added at C26 again to see how things change with the increased voltage now.

All in all picture is a bit dark and seems to be a little bit out of focus sometimes. That usually clears up once the machine has warmed up. I have no old caps in there at all so no idea where the warm up thing is coming from.

It is not perfect but I am not going back either... it is running just so much more software with 640*480 now that it makes up for not being 100% (yet)

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@techknight I'm getting all the resistors, caps, & diodes to do the upgrade. I currently got my hands on 3 Color Classics for dirt cheap! All of them had bad Caps on the logic board. I did my first recapping of one and it boots in every one of the CCs! yay! (Although the startup chime has stopped or is so faint I can barely hear it) Thats for a different thread. Anyway, I have two questions for you. Am I reading that after this mod, the original CC Logic Board will still work or does is this only if you're looking to goto a 575 LB?  I'm thinking not, but just checking. 

 

My other question is about an AB from a Performa 550. I purchased a 550 on eBay because I got a box of old logic boards that I wanted to recap and check if they worked. One of the logic boards I'm looking to possibly put in a CC is from a Macintosh TV. (Probably the rarest of Logic Boards to find in a random box-O-boards purchased off eBay) However, it arrived with the casing in hundreds of pieces. I tried my CC board and when it didn't work I decided to strip the parts out of the 550 and send the rest for proper recycling. The it dawned on me that the CC logic board wouldn't work on a 550 because its not configured for VGA. Though in pieces, I still have the 550 tube and AB. I'm wondering if I should Mod the 550 AB instead of the CC because of the rareness of the CC. Is it possible to make a 550 AB drive a CC tube? I get that I'd have to cut the AB board down and get clever in fitting it in the CC casing because the "bump out". I'm fairly new to this level of Modding and want to make sure that I don't damage the CC tube or fry a logic board. Any advice? 

 

BTW this site is awesome!!!

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1 hour ago, Macdrone said:

the 550 and cc boards are directly interchangeable as the 550 was also the color classic II's board. no mods needed.

Oh... very cool!!! Thank you. I just recapped my Macintosh TV Logic Board and put it in a CC and I get video, though massively distorted. Need to create a new boot disk that the Mac TV will work on. I will have to go pull the AB from the 550 and see were it lands me!!  Thanks again!

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