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About vans1932

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    Combat Commando
  1. Oh, so sorry. I was in a hurry yesterday to test and it takes a little while to get an account activated here. I retested the voltages in DC mode and you are correct. Ok, so do you think with the circumstances (black screen and continuous noise) that it could be a vram chip? dram chip? ROM? If so where would you recommend buying one. Amazon or eBay would be best. Also what does the chip look like? I see these chips (picture below). Once again I had this as a kid but never opened it, and this is my first motherboard repair. Most of the time I try to get working items, but I got a good deal on this.
  2. Another thing of note is that some of the RAM chips (TMS4116) report 4V and some report 1.5V
  3. Hello I am new to AtariAge. I recently picked up a TI 99/4a computer off of ebay and expected to turn it on and relive my childhood. However it shows a black screen or a black screen with lines and a loud continuous beep from the TV. I've done my normal troubleshooting steps, 1. Reseated and cleaned all the chips. (their aren't that many to reseat) 2. Checked the TIM9904 Clock Generator (for voltages) 3. Taken the grom connector out (cart connector) 4. As far as I am aware the video chip gets very warm but don't know what the temp is actually supposed to be. (TMS9918A) 5. Checked for cracked traces, etc etc. I've read other forms online including these from AtariAge: https://atariage.com/forums/topic/270436-ti994a-black-screen-and-continuous-beep-sound/ https://atariage.com/forums/topic/172939-ti-994a-console-not-working-anymore/ And many others including this one: http://www.vcfed.org/forum/showthread.php?65903-TI-99-4a-black-screen Now here's the interesting thing, when I check the voltage coming directly from the Power supply (AC 9500) It only shows between 2-8 volts on all wires. Not the -5 volts on pin 1, 12V that should be coming out of pin 2, (ground on pin 3 is even 3-4V) and pin 4 which is the only one that seems to be closer to the 5V but still at 2.5V. http://www.mainbyte.com/ti99/hardware/power_supply.html Now from the info I've seen it could be a ram chip but I don't want to desolder anything until I have some evidence otherwise. Could it be a power supply issue or is it a ram chip (or something else) Note: The power is changing a lot sometimes it will jump from 4-7V and sometimes it will go down as well.
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