herkamur Posted May 25, 2015 Share Posted May 25, 2015 I have an Intellivision II here that seems to be having problems with its graphics. See the attached photos. Does anybody know if this is repairable? The previous owner had a 22V AC power supply hooked up to it. Might that be the cause? Any assistance would be appreciated. Thanks. Quote Link to comment Share on other sites More sharing options...
+intvsteve Posted May 26, 2015 Share Posted May 26, 2015 Hmm... Since text from GROM looks fine, it could be the GRAM chips or connections related to them. Quote Link to comment Share on other sites More sharing options...
herkamur Posted May 26, 2015 Author Share Posted May 26, 2015 I opened it up a bit ago and had a look inside. It's a remarkably clean interior which is nice. I found a maintenance manual for the Intellivision II and had a look at the GRAM and related chips. All the solders look good. I couldn't see any breaks or obvious shorts on the top side. I haven't pulled out the board to check the bottom yet though. I tried reseating the socketed chips although I don't have an extractor handy to pull them and reset them. I have one somewhere, but I haven't used it since my Amiga upgrade days. I turned it back on and still have issues. Quote Link to comment Share on other sites More sharing options...
HunterZero Posted May 26, 2015 Share Posted May 26, 2015 Most likely a logic issue. Using the wrong power supply might have damaged the STIC or GRAM. I would suggest replacing the STIC then if that doesn't fix it replace GRAM. Quote Link to comment Share on other sites More sharing options...
herkamur Posted May 26, 2015 Author Share Posted May 26, 2015 Where might one purchase replacement chips? Quote Link to comment Share on other sites More sharing options...
HunterZero Posted May 27, 2015 Share Posted May 27, 2015 Long out of production I am afraid. If you are lucky someone here might have spare parts to offer. Watch eBay as chips sometimes come up for sale but your best option is to find another unit as a parts donor. Quote Link to comment Share on other sites More sharing options...
herkamur Posted May 27, 2015 Author Share Posted May 27, 2015 Thanks, eh? I'll have to see what I can unearth. I have an original Intellivision too which works well, so I'm not without a working console. Quote Link to comment Share on other sites More sharing options...
intvnut Posted June 2, 2015 Share Posted June 2, 2015 (edited) Wow, that's the most interesting corruption I've seen in a long time. Here's my guess what's going on: The output enable line going to the GRAMs is busted (or the output enable on the RAM itself is busted), and what you're seeing is the remaining charge on the shared address/data bus as data. The corruption mainly seems to affect the lower 4 bits of each GRAM word, which suggests that one of the two GRAM chips is at fault. If the RAM itself is the culprit, it's a single chip that needs to be replaced, and it should be a fairly common chip. As I just mentioned, there are two 2114 (or 9114) RAM chips that comprise the GRAM on the Intellivision 2, and these RAM chips were relatively common. 10 seconds in Google led me to this eBay auction: http://www.ebay.com/bhp/2114-ram You can probably do much better than that on price. So, if you feel up to the task of desoldering an 18-pin DIP and soldering a new one in, that may be all it takes.... You likely just need to replace the "low GRAM" chip. But, before you do: Clean the circuit board well, and look for places where a solder bridge might have formed and break those bridges. Lathe26 had an Intellivoice that was causing all sorts of weird issues that we eventually traced to a short that had formed due to... well, we were never quite sure. But we traced the symptoms to an enable line that was getting triggered when it shouldn't, and when he cleaned the board, it stopped happening. It could have been a solder bridge or dust or who knows... Edited June 2, 2015 by intvnut 2 Quote Link to comment Share on other sites More sharing options...
herkamur Posted June 2, 2015 Author Share Posted June 2, 2015 Thanks for the information intvnut. I'll pull the board from the console entirely and have a look at the backside. I didn't see anything on the front, but I didn't pull it to examine the back yet. Again, thanks. Quote Link to comment Share on other sites More sharing options...
herkamur Posted June 7, 2015 Author Share Posted June 7, 2015 OK, an update. I pulled the board and had a close look at it. I cannot see anything obviously wrong with it. All the solders look good on both sides. I cleaned it up and nothing has changed. <sigh> Quote Link to comment Share on other sites More sharing options...
HunterZero Posted June 8, 2015 Share Posted June 8, 2015 See if you can get replacement 2114 GRAM chips as recommended above. If you are handy with desoldering and you socket them you could swap them and see if the corruption changes. Then that confirms if one of the GRAM chips has an issue. Quote Link to comment Share on other sites More sharing options...
herkamur Posted June 10, 2015 Author Share Posted June 10, 2015 Regarding 2114 GRAM chips: Are there limitations to what chips will work? For example, would these ones work? http://www.ebay.ca/itm/NEC-2114-1024-x-4-1k-x-4-static-ram-2-pieces-/301654023499?pt=LH_DefaultDomain_0&hash=item463bfb1d4b I haven't played with ICs for at least two decades. I'm a bit rusty at this. Thanks, eh! Quote Link to comment Share on other sites More sharing options...
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