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hyuma

Trying to fix Colecovision PAL rev. D

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Hi guys, i need some help, I got a rev D PAL Colecovision and I would like to know if someone have same board revision, because I have to replace some parts that I presume are cooked. The console doesn't work, I got black screen. I powered up by using modern ATX psu for -5v, +5v, 12v, GND. I checked the 8 RAMs and there are good -5v, 12v and 5v. I checked cpu clock with a logic analyzer and seems aroune 3.3mhz. Then i checked the VDP on pin 36, 38 and 35 if i remember but with logic analyzer i don't know the normal values.. I inspected a bit and there are some inductors that need to be replaced, but on schematics I found there aren't same label inductors (my coleco have L28, L19, L18 for example), so i don't know the correct value odlf them. I love repair old vintage stuff and study and learn how they works and how to search the issues. If anyone could help me, it will be really appreciated. 

 

Thanks guys!! 

 

IMG_20201113_122233.jpg

IMG_20210113_121644.jpg

IMG_20210113_121628.jpg

IMG_20210113_121614.jpg

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First of all, make sure you're using the PAL schematics.  I recently reverse-engineered that rev of board.

Coleco.zip

 

You should find PDFs for the PAL version.

 

The main clock should be 3.58MHz.

 

VDP 35, 36, and 38 are all analog outputs, so your logic analyzer won't be of use.  You'll need an oscilloscope to see if they are giving you proper outputs.

 

How do you know the inductors need to be replaced?  L18 provides power for the input controller ICs.  L28 provides power for the video modulation.  L19 is part of the resonant circuit that clocks the VDP at around 10MHz.

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Also, interestingly, my board is missing the channel selector switch.  Don't know if it's a different country or if it just got removed along the way.

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I just presumed that because of their aspect. L28 as you can see in the picture has the back part missing, and also they seems to be "dry".. so for now I can't do nothing without a scope, right? Yes this is PAL version and I live in Italy 😄😄 Thanks a lot for your schematics!!! 

 

@ChildOfCv Just for safety i will change all of them, I have to consider some other parameters other than microHenry?

 

L18 - 10uH

L19 - 2.7uH

L28 - 3.7uH

L25 - 42uH

L17 - 32uH

L2 - 10uH

L3 - 10uH

L4 - 10uH

 

Edited by hyuma

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34 minutes ago, hyuma said:

I just presumed that because of their aspect. L28 as you can see in the picture has the back part missing, and also they seems to be "dry".. so for now I can't do nothing without a scope, right? Yes this is PAL version and I live in Italy 😄😄 Thanks a lot for your schematics!!! 

 

@ChildOfCv Just for safety i will change all of them, I have to consider some other parameters other than microHenry?

 

L18 - 10uH

L19 - 2.7uH

L28 - 3.7uH

L25 - 42uH

L17 - 32uH

L2 - 10uH

L3 - 10uH

L4 - 10uH

 

They are standard inductors which seem to be soldered to mounting pins and then dipped in epoxy.  There is nothing wrong with them as far as eyeballing can see.  This style was popular in the 80's for some reason.  The main thing to check is that there is continuity through them.

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6 minutes ago, ChildOfCv said:

They are standard inductors which seem to be soldered to mounting pins and then dipped in epoxy.  There is nothing wrong with them as far as eyeballing can see.  This style was popular in the 80's for some reason.  The main thing to check is that there is continuity through them.

Yeah, checked now all of them, and they have continuity 

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12 hours ago, ChildOfCv said:

Also, interestingly, my board is missing the channel selector switch.  Don't know if it's a different country or if it just got removed along the way.

At least in the UK, RF channel select switches were not a thing and consoles like the Atari2600, IntelliVision and ColecoVision didn't come with them.  UK TV sets didn't have the predefined frequency channel numbers (1, 2, 3....) that US sets did.

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9 hours ago, hyuma said:

Yeah, checked now all of them, and they have continuity 

So next question is whether or not there is activity on the data and address lines.  Did you probe them yet?

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18 hours ago, ChildOfCv said:

So next question is whether or not there is activity on the data and address lines.  Did you probe them yet?

I checked the address line of the TMS9929 with logic analyzer and seems there is activity 

http://imgur.com/a/jCJzYDc

Edited by hyuma

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I noticed just now a thing: the 12v rail when I power on the console goes down to 1.11v... so there are part of board that doesn't receive the 12v... so that should be the issue! 

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1 hour ago, hyuma said:

I noticed just now a thing: the 12v rail when I power on the console goes down to 1.11v... so there are part of board that doesn't receive the 12v... so that should be the issue! 

Fixed the 1.1v issue, it was related to atx wiring to the coleco connector. Now the console have 12.08v but when i power on it draws to 8.90v 

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4 hours ago, hyuma said:

I checked the address line of the TMS9929 with logic analyzer and seems there is activity 

http://imgur.com/a/jCJzYDc

I was talking about ALL address lines, but that's a start.

 

48 minutes ago, hyuma said:

Fixed the 1.1v issue, it was related to atx wiring to the coleco connector. Now the console have 12.08v but when i power on it draws to 8.90v 

Make sure your connections from the power supply have clean pins.  Then start feeling around on the memory chips to see if any are getting hot.

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11 minutes ago, ChildOfCv said:

I was talking about ALL address lines, but that's a start.

 

Make sure your connections from the power supply have clean pins.  Then start feeling around on the memory chips to see if any are getting hot.

Yes the problem came back, now I have 1.11V again... tomorrow I will check better the connection with PSU

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Ok, no more voltage drop now, it was a wiring issue between ATX and console. Now I'm at starting point again, but i want to check on 12v rails if all components get the correct voltages.

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I measured transistor voltages on the +12v rails:

 

Q16 - 2N3904 = pin1(0.87v) pin2(1.58v) pin3(9.57v)

Q19 - 2N3904 = pin1(1.36v) pin2(2v) pin3(11,89v)

Q20 - 2N3906 = pin1(11.87v) pin2(11.86v) pin3(8.58v)

Q21 - 2N3904 = pin1(5.36v) pin2(6v) pin3(8.83v)

Q22 - 2N3906 = pin1(11.87) pin2(11.17) pin3(11.86v)

Q23 - 2N3904 = pin1(7.80v) pin2(4.21v) pin3(3.47v)

Q24 - 2N3904 = pin1(0.07v) pin2(0.68v) pin3(0.12v)

 

I think those values are normal, no? I'm not sure on Q24..

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On 1/17/2021 at 10:18 AM, ChildOfCv said:

Q24 is the composite output.  It should have voltage from the RF module.  Is that still connected?

Ah no, The RF module is not connected!

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Hey again, I still not fixed yet but I've some updates, I got hot air station and started some working. I've desoldered some logic ICs: U5-U6-U7-U8-U22 and tested with the TL866II plus programmer and they are good, no error at any ports! On next days i will continue my work by focusing on desolder the BIOS U2 and dump the content and check with some checksum if it's good. Sadly i don't have any oscilloscope so i have to proceed with this "brute forcing" method. Next step could be focusing on CPU and VDP? If you have any tips I appreciate a lot!

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Did you reconnect the modulator?

 

If you have an old VCR, it might be useful to try to inject its video output into the RF modulator video input to see if you can get a picture.  You could do that by patching to the blue wire that goes from the top of the board to the modulator and connecting VCR ground to ground.

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7 hours ago, ChildOfCv said:

Did you reconnect the modulator?

 

If you have an old VCR, it might be useful to try to inject its video output into the RF modulator video input to see if you can get a picture.  You could do that by patching to the blue wire that goes from the top of the board to the modulator and connecting VCR ground to ground.

Yes I have an old one, but I didn't quite understand how to connect VCR.. 

 

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Posted (edited)

I think I got something! I've desoldered all 8 4116 DRAM and tested with arduino code and seems that all 8 are bad. Voltages of these rams was good but there must be something else...? Can I replace the 4116 with 4164 on PAL Colecovision, the guide founded on console5 seems like for NTSC Colecovision, so by removing L2 and L3 coil is the same on PAL version, or I have to consider something else? 

 

IMG_20210303_132130.jpg

4116_tester_code.ino

 

I've added Arduino code that i got from the guy on youtube that made the DRAM tester for 4164, I hope this will be useful for someone else!

Edited by hyuma
Adding arduino code

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All versions of CV use the same video memory technology, so any solution you find for NTSC should work for PAL too.  Console5 has a chip replacement kit specifically for CV.  It uses a different type of 16K memory chips, rather than 64K chips.

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just a note that console 5's installation guide for the 5v ram is for ntsc boards, and although can e done on pal boards you cant blindly go and do the same wireing because the components are different / different places.  i have done a 5v ram mod on a pal machine so i may be able to help if needed

 

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just a note that console 5's installation guide for the 5v ram is for ntsc boards, and although can e done on pal boards you cant blindly go and do the same wireing because the components are different / different places.  i have done a 5v ram mod on a pal machine so i may be able to help if needed
 
I noticed that on console5 page wiki there are instructions also for board like mine rev D. I soldered a jumper wire and now I have 5v on pin8, 5v on pin9, 0v on pin 16 and on pin1 I have more about 1v. I think are good, right?

Inviato dal mio CLT-L09 utilizzando Tapatalk

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