Something popped in my ColecoVision. But what?

[Ace_1]

Well, I've just checked eBay and have not found a single ColecoVision power supply. I think I'm going to do this next:

 

-Use a 78L012 for a regulated 12V input into the ColecoVision.

-Use the Negatron

-Replace the RAM chips by the 4164(do none of the 4164 chips in the search correspond to the RAM chips needed by the ColecoVision?) - it doesn't matter if the procedure to adapt the RAM chips is time-consuming and tedious; if it'll make the machine more reliable, it's worth it.

 

Come to think of it, I'll be in Ontario next week. I'll see if any of the game shops that carry classic game consoles have a ColecoVision power supply(and maybe a ColecoVision console).

[GonzoCV-1]

do none of the 4164 chips in the search correspond to the RAM chips needed by the ColecoVision?

 

Let me look again.....

 

OK:

 

A 74164 is a shift register.

 

So is the M53364P.

 

 

The other two look like samsung's connotation for memory, but they're missing the KM at the front. Call and make sure. If they are Samsung part nubmers, then they'll be the right thing:

 

http://www.datasheetarchive.com/pdf-datash.../DSA-570564.pdf

 

 

ETA: I highly recommend that you replace your chips with sockets, and then for a "test" run (without changing anything else) just order a set of 4116 chips to drop in and see if anything else is blown.

 

It is POSSIBLE (though unlikely in this design) that if your +17 bridged something internal in one of those 4116 chips, that voltage may have crossed into the TMS9928 chip (the video chip with the heat sink) in which case, good luck.. those are harder and harder to find.

Edited July 12, 2009 by GonzoCV-1

[channelmaniac]

Try this from my repair logs site:

 

http://newlifegames.net/nlg/index.php?topi...g11121#msg11121

 

I wrote down what I did when I modified a CV for +5v only DRAM.

 

RJ

[Ace_1]

Is the -5V source only for those pesky 4116 RAM chips? If so, I guess I can use a regulated +12V and +5V power source after replacing the 4116s by 4516 or 4164 RAM chips?

[channelmaniac]

According to the schematic, you still need the -5v for the silly controller port logic.

 

I looked through the Mouser.com website and couldn't find a single output DC-DC converter that had an output of -5v. It looks like you'll need to get a dual output unit and put a simple resistor across the positive output to load it properly. Then you can use the negative output to power the port logic.

 

RJ

[+Yurkie]

If I understand you Gentlemen correctly, are the ICs your referring to VRAM. I have a very minor video glitch. I ran a test off my Multi-cart for VRAM I would love a source for these 4164 ( I hope I got the number right ) replacement ICs and sockets. I would glady removed those 8 ICs and put sockets in place and modify the replacements.

[Stephen Moss]

As GroovyBee said I would not worry to much about the angled IC as it was probably like that from the factory, it would need a significat explosive force to move it that far unless the solder had melted and it is doubtfull that any fault would be able to heat it upto at least 200 centigrade required.

If you look at your "close up of the array" picture the capacitor on the left hand side nearest the IC (processor?) with the heatsink on appears the have a line on that does not nornamally occur on those ceramic disc capacitors and may indicate damage to that capacitor so have a close look at it.

 

So you're saying the pop came from the RAM chips(are those the 8 chips in the array I show?)? It must have come from there because a cloud of smoke came from that particular area. All capacitors are fine; none are bulging or blown.

 

FYI, my power supply was giving 17V on the multimeter WITHOUT a load.

 

By the way, how should I wire up the -5V line using that over-powered brick? It seems the 7905 can only convert from negative voltage to negative voltage. Is there another regulator that can convert positive voltage to negative voltage?

 

EDIT: A search for "4164" turned up this at my local electronics shop: https://www.addison-electronique.com/catalo...amp;x=0&y=0

 

Which is the proper one?

 

If your +12 was really only +17 without a load, you may have lucked out on the LM1889 in the RF Modulator box. (My datasheet says 18v max).

 

Negative voltage circuits are touchy, and forgive me for saying, probably beyond your skill (that's OK, I screwed up a dozen before I figured it out). Permit me to suggest a shortcut: http://www.dimensionengineering.com/Negatron.htm Ben Heck used it in his Coleco portable, and I will as well unless I figure out a substitution in the controller circuitry that obviates the need for negative voltage swings.

GonzoCV-1, look back at my previous post, the circuit was probably getting closer to +12 than +17 when the power supply was a connected to the system, of course the only way to know that for certain is to connect it to the system and measrue the voltage on the PCB.

It is not for the faint hearted but you could try using all positive voltages provided that are relative as follows...

 

+12 becomes + 17

+5 becomes + 10

0 becomes +5

-5 becomes 0

 

as long as all the voltages are relative it should work (in theory) but you try it at you own risk. However it is not without its poblems, for example when trying to diagnose a problem with a logic analyser or oscilloscope anyone working on the system should realise that connecting the ground line of the test equipment to your consoles ground which is effecively floating at +5V using this solution could ground the +5V causing all sorts of problems and resulting damage to the system and/or power supply.

 

There are many IC's that do DC-DC voltage conversion such as the ICL7660 but puchasing a module like the one GonzoCV-1 mentioned may be easier for you as it appears to be a proven solution provided it can provide the corect amount of power.

Edited July 16, 2009 by Stephen Moss

[GonzoCV-1]

If I understand you Gentlemen correctly, are the ICs your referring to VRAM. I have a very minor video glitch. I ran a test off my Multi-cart for VRAM I would love a source for these 4164 ( I hope I got the number right ) replacement ICs and sockets. I would glady removed those 8 ICs and put sockets in place and modify the replacements.

 

Here's a link to the thread for the fist time I did the 4164 mod. I only had a short period of time, so I short cut it by piggy backing the 4164s on top of the 4116 chips and then depriving the 4116 chips of power. I tried pulling the choke coils to deprive the whole area of the board of +12 and -5, but as long as any of the power or ground pins of those 4116 chips were connected to anything it didn't work. So I came up with the result here. Not elegant, but it works great and wow its nice to not _ever_ have any issues with the power switch!

 

 

http://www.atariage.com/forums/index.php?s...=135183&hl=

 

I ordered my chips from an eBay vender.

 

Here's one selling original NOS chips, and they're even "real deal" Texas Instruments!

 

http://cgi.ebay.com/Nine-TMS4164-15NL-DRAM...p3286.m20.l1116

 

Good luck.

[Stephen Moss]

Sorry, I got so wrapped up in the whole standard DC power brick thing as that was the part originally purchased as a replacement that I forgot other power sources with multiple output voltages such as http://cpc.farnell.com/xp-power/pcm50ut04/...-50w/dp/PW01273 are available. Ok they are a lot more expencive than the basic single output DC brick and you may not be able to get one with the exact output voltages you require but with +/-12 or 15V you can sub regulate down from you should be able to get the voltages you want.

Assuming you can find one that directly provides the voltages and currents you need this type of supply is normally terminated in a circular "DIN" connector so all you need to do is cut at least the last six inches (including the connector) off the power cable from your consoles orginal power supply and correctly wire it to an appropriate DIN line (cable mounting) socket and connect the two together.

[GonzoCV-1]

Sorry, I got so wrapped up in the whole standard DC power brick thing as that was the part originally purchased as a replacement that I forgot other power sources with multiple output voltages such as http://cpc.farnell.com/xp-power/pcm50ut04/...-50w/dp/PW01273 are available. Ok they are a lot more expencive than the basic single output DC brick and you may not be able to get one with the exact output voltages you require but with +/-12 or 15V you can sub regulate down from you should be able to get the voltages you want.

Assuming you can find one that directly provides the voltages and currents you need this type of supply is normally terminated in a circular "DIN" connector so all you need to do is cut at least the last six inches (including the connector) off the power cable from your consoles orginal power supply and correctly wire it to an appropriate DIN line (cable mounting) socket and connect the two together.

 

Very sound suggestions.

[Ace_1]

Guys, you will NEVER believe this: I got my hands on an original ColecoVision power supply(that thing is MASSIVE!) and guess what? THE COLECOVISION WORKS! Seriously! I can't believe it that even after something popped in the console and after it was given incorrect voltages, the ColecoVision still lives. And I was expecting the RAM chips to have been fried from not having a -5V source.