xabin Posted January 17, 2019 Share Posted January 17, 2019 I recently got a 5-pin, 4-line composite cable for my boyfriend to test his TI-99/4a from his childhood that he tried cleaning up. We get a blank screen when booting it up, no beep or other sounds, and we don't know what needs to be cleaned or fixed. Anyone have any ideas? Thanks. Quote Link to comment Share on other sites More sharing options...
jaybird3rd Posted January 17, 2019 Share Posted January 17, 2019 Welcome to AtariAge!Be careful with the generic DIN5-to-RCA cables that are out there for the 99/4A and other classic computers. You only need two of the four lines, one for composite video and the other for audio, and depending on the cable, the lines you end up using may not match the standard yellow and white connector colors. Also, one of the lines will output 12V (this was intended to power an external RF switchbox), so you do NOT want to plug this into your TV by mistake! I recommend that you connect the cable to the computer, turn on the computer WITHOUT connecting the cable to the TV, and use a voltmeter to test the tip on each line. Once you find the 12V line, mark it or wrap it in tape so you don't accidentally use it in the future; then, try the remaining three in different combinations until you find the correct ones for video and audio. (If I remember correctly, the extra line you'll end up with is not connected to anything on the TI side, so it shouldn't hurt your TV.) Quote Link to comment Share on other sites More sharing options...
xabin Posted January 17, 2019 Author Share Posted January 17, 2019 (edited) Welcome to AtariAge! Be careful with the generic DIN5-to-RCA cables that are out there for the 99/4A and other classic computers. You only need two of the four lines, one for composite video and the other for audio, and depending on the cable, the lines you end up using may not match the standard yellow and white connector colors. Also, one of the lines will output 12V (this was intended to power an external RF switchbox), so you do NOT want to plug this into your TV by mistake! I recommend that you connect the cable to the computer, turn on the computer WITHOUT connecting the cable to the TV, and use a voltmeter to test the tip on each line. Once you find the 12V line, mark it or wrap it in tape so you don't accidentally use it in the future; then, try the remaining three in different combinations until you find the correct ones for video and audio. (If I remember correctly, the extra line you'll end up with is not connected to anything on the TI side, so it shouldn't hurt your TV.) We don't have the equipment, here, to do that, but I've tested multiple configurations. The yellow line gives the black screen, the white and/or red ones gives us audio (either/or, we're still not sure which), and the black one gives us sometimes a lighter blue screen without a "no signal" indicator, and sometimes graphical corruption. Still no beeps at all. EDIT: I checked the two reviews for the cable on Amazon that mention using it for the TI-99/4A, and one said that the yellow was composite video and the black was the mono audio. So I tried that combination, and still got nothing but a black screen. Edited January 17, 2019 by xabin Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted January 17, 2019 Share Posted January 17, 2019 I assume you are connecting this to a modern (LCD/Plasma) TV. If so, many of those TV's don't like the composite signal from older hardware like the TI. The fact you are getting a black screen (instead of the no-signal blue screen) tells me "something" is being sent to the TV and it's attempting to lock on. Without any testing equipment or a spare, confirmed working TI, to test, it's hard to determine the issue. So a few suggestions would be: 1) Try to locate the original RF modulator and skip composite. You may have to find an older (preferably CRT) TV to test it on. The picture will be fuzzy but should be legible. This will tell you if your composite cable is good and if the TI is OK. 2) Try to locate an older TV. Especially a CRT TV that has composite inputs. This will rule out your modern TV. 3) Finally, it might be worth sending it in to someone on the forums for some troubleshooting. I'm sure there are people in here that would be glad to help. I've had some hardware experience so I might be able to do it. But it would take me some time as I am currently moving my office downstairs and things are a mess right now. 4) Buy a working TI off eBay or CL. The good news is that TI's are still affordable and haven't skyrocketed in price like Apple's and Commodores. Keep us informed. It's awesome that you are trying to revive a TI for your boyfriend. Quote Link to comment Share on other sites More sharing options...
xabin Posted January 17, 2019 Author Share Posted January 17, 2019 I assume you are connecting this to a modern (LCD/Plasma) TV. If so, many of those TV's don't like the composite signal from older hardware like the TI. The fact you are getting a black screen (instead of the no-signal blue screen) tells me "something" is being sent to the TV and it's attempting to lock on. Without any testing equipment or a spare, confirmed working TI, to test, it's hard to determine the issue. So a few suggestions would be: 1) Try to locate the original RF modulator and skip composite. You may have to find an older (preferably CRT) TV to test it on. The picture will be fuzzy but should be legible. This will tell you if your composite cable is good and if the TI is OK. 2) Try to locate an older TV. Especially a CRT TV that has composite inputs. This will rule out your modern TV. 3) Finally, it might be worth sending it in to someone on the forums for some troubleshooting. I'm sure there are people in here that would be glad to help. I've had some hardware experience so I might be able to do it. But it would take me some time as I am currently moving my office downstairs and things are a mess right now. 4) Buy a working TI off eBay or CL. The good news is that TI's are still affordable and haven't skyrocketed in price like Apple's and Commodores. Keep us informed. It's awesome that you are trying to revive a TI for your boyfriend. Thanks. It's his old TI that he had as a kid; apparently, he was programming on it when he was 3, so he has very fond memories of it. He's got several cartridges for it and the speech synthesizer that we want to test, as well. We'll see about getting an old CRT TV/Monitor that we can plug it into; for the most part, the instances I've read of a black screen coming from it also accompanies a loud beeping sound, and there isn't that here, so I'm not sure if that makes a difference. It was pretty beat up and weathered (been in a barn for years), but thanks to watching the 8-Bit Guy restore stuff on Youtube, my boyfriend figured out how to dismantle the thing and clean up the rust on it. We dunno if any of the contacts are broken on it, but it doesn't look like it, so... Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted January 17, 2019 Share Posted January 17, 2019 Ah, I didn't realize it's been exposed to outside elements. Yeah, if there are lots of rust and debris inside that thing, that could be a real issue. If the chips and pins aren't corroded, it's possible the fix will be easy. But other than cleaning it, you may need more tools to test conductivity, etc. Oh, I like the 8-Bit Guy, but I wouldn't take his teachings as the best way to do anything. He's a little too quick to retro-bright things IMHO and some of the technical information he gives is wrong. But he's entertaining at any rate. That "worst VIC-20" episode he did (along with the Osborne) makes my skin crawl the way he left them. :-) Quote Link to comment Share on other sites More sharing options...
xabin Posted January 17, 2019 Author Share Posted January 17, 2019 Well, it was mostly the basics that he learned from the guy, like looking for cracks in circuits, how to clean off rust and debris, etc. Plus, as far as I know, he hasn't tackled a TI, yet, so we didn't have much in the way of his videos to work with. We did find a diagram for how to dismantle it for cleaning and repair, though. Quote Link to comment Share on other sites More sharing options...
RickyDean Posted January 17, 2019 Share Posted January 17, 2019 Also, I have a couple of sets of those generic cables, and I have to plug in the white cable to the yellow video jack on the TV, due to the fact that they are not set up right for the TI. Quote Link to comment Share on other sites More sharing options...
xabin Posted January 17, 2019 Author Share Posted January 17, 2019 We tried every combination. The best we can get is that Yellow in the Yellow jack gives us a black screen, and sometimes with it and the black one plugged into the white or red jacks gives a high-pitched whine or repeated beeping sound. It doesn't do it all the time, though, with the sounds. Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted January 17, 2019 Share Posted January 17, 2019 OK, the standard color codes for composite cables are yellow for video, red and white for audio. But, those are just standard. Nothing stopping anyone from building a cable with non-standard colors. From what you're telling me, it sounds like the yellow cable gives the black screen. You are plugging yellow to yellow on the TV right? TV's are more consistent with their coloring. Yellow on the TV is more than likely composite video. If you're still getting a black screen then it could be any number of issues. From a bad VDP to bad (cold) solder joints. Do you get any activity if you wiggle the cable on the back of the TI? Does the screen jump any then? Also, if you managed to take it apart....maybe you could post some pictures of the unit so we can take a look. Quote Link to comment Share on other sites More sharing options...
xabin Posted January 17, 2019 Author Share Posted January 17, 2019 We don't have access to a screwdriver long enough to get to the deep screws on it, right now, and our car is in the shop, but his dad works on electronics, so when he gets the chance, we can ask him to try and find an old CRT TV for us and bring his tool kit so we can disassemble it and take pictures. Quote Link to comment Share on other sites More sharing options...
RickyDean Posted January 17, 2019 Share Posted January 17, 2019 Try plugging just the white into the yellow, leaving the audio alone. I cannot get audio to work with mine. If you get a picture, then at least you have something to work with. I believe one of the lines coming out of the ti is 12v and that can cause problems. I am not at home to verify anything, but will be after 6pm EST. Quote Link to comment Share on other sites More sharing options...
xabin Posted January 17, 2019 Author Share Posted January 17, 2019 (edited) I know of that. We've tried the white into yellow, and got no signal. only the yellow one changes the signal, and it's changed to a black screen. Believe me, once we get the screwdrivers needed to dismantle it, we'll take pictures of the insides for you guys to look over. Edited January 18, 2019 by xabin Quote Link to comment Share on other sites More sharing options...
xabin Posted January 22, 2019 Author Share Posted January 22, 2019 We'll be getting the means to open the computer tomorrow, so I'll have close-up photos of the insides then. Hopefully, you guys will be able to help us out. The thing that bothers me is that there's no sound when the cable is plugged in to accompany the black screen that appears, like the other examples of this issue I've seen on here and other sites. Is that significant? Quote Link to comment Share on other sites More sharing options...
Opry99er Posted January 22, 2019 Share Posted January 22, 2019 To be honest with you... if you don't have a multimeter, the only way we will be able to help diagnose is if you have a tested-working AV cable. Without that, no matter what you do, the cable will still be suspect. They're pretty cheap--and it would really decrease your future headaches to have a verified and validated AV cable. Quote Link to comment Share on other sites More sharing options...
xabin Posted January 22, 2019 Author Share Posted January 22, 2019 I don't want to shell out more for another AV cable, but I guess it can't be helped. I found one on Etsy that I can get for $15, and it's specifically listed for TI-99, so I hope it works out. Quote Link to comment Share on other sites More sharing options...
RickyDean Posted January 22, 2019 Share Posted January 22, 2019 If you could get a cheap multimeter from Walmart, you could map the pins, where the cable assembly plugs into the TI and to the tip of each colored RCA jack, as well as the outside of the jack which would be for ground purposes. If you map that on paper, or computer, it would be easier for diagnoses. Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted January 22, 2019 Share Posted January 22, 2019 I can make one for you. But it would be this weekend. If you're interested, let me know. Quote Link to comment Share on other sites More sharing options...
xabin Posted January 22, 2019 Author Share Posted January 22, 2019 If you could get a cheap multimeter from Walmart, you could map the pins, where the cable assembly plugs into the TI and to the tip of each colored RCA jack, as well as the outside of the jack which would be for ground purposes. If you map that on paper, or computer, it would be easier for diagnoses. Fortunately, my boyfriend's dad messes around with electronics as a hobby (mainly CB radios), so he has a few multimeters he can bring over for the mapping. We can do that tomorrow. I can make one for you. But it would be this weekend. If you're interested, let me know. That's alright, I'm not sure how much it would cost me to have you make it, and I'd like to test to make sure the one I paid for is the issue, first, before we go ahead with getting another one. Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted January 22, 2019 Share Posted January 22, 2019 That's alright, I'm not sure how much it would cost me to have you make it, and I'd like to test to make sure the one I paid for is the issue, first, before we go ahead with getting another one. Definitely get the multi-meter and test your cable. You need to know if it's good or not for a refund if needed. I wouldn't charge you anything for the cable. I can make it for you and mail it for free. Just my way of helping the TI community. Just let me know. Quote Link to comment Share on other sites More sharing options...
retiredqwest Posted January 22, 2019 Share Posted January 22, 2019 You never mentioned what type of display unit you are trying to use for the console. If you still have the RF Modulator unit and can find a TV with an NTSC coax input you could buy a 75-300 ohm balun. https://www.amazon.com/Matching-Transformer-Off-Air-Antenna-Adapter/dp/B01H8Z2DXG/ref=sr_1_9?ie=UTF8&qid=1548194719&sr=8-9&keywords=75+to+300+ohm+matching+transformerThe spade tips from the RF could be attached to the balun could then be connected to the coax input on the tv. This would be a way to test and see if the console works without taking it apart. AS far as the Amazon purchase.... comparing the pinout that was provided for the cable against the console, the video is yellow and the audio is black. The white plug is not connected to anything in the console. https://justinpaulin.com/2014/04/21/testing-a-texas-instruments-ti-994a-without-power-or-video-cables/is a site that has the pinouts that correspond to the cable you bought and the 4A pinouts. (scroll down the page) The problem is the RED plug has the 12VDC out of the console and if you plugged that into any RCA port of the "display unit" you may have burned it out as they are not expecting that type of voltage. If you have another device that uses a composite cable you might want to try that on the "display unit" and make sure it still works. Quote Link to comment Share on other sites More sharing options...
xabin Posted January 22, 2019 Author Share Posted January 22, 2019 You never mentioned what type of display unit you are trying to use for the console. If you still have the RF Modulator unit and can find a TV with an NTSC coax input you could buy a 75-300 ohm balun. https://www.amazon.com/Matching-Transformer-Off-Air-Antenna-Adapter/dp/B01H8Z2DXG/ref=sr_1_9?ie=UTF8&qid=1548194719&sr=8-9&keywords=75+to+300+ohm+matching+transformerThe spade tips from the RF could be attached to the balun could then be connected to the coax input on the tv. This would be a way to test and see if the console works without taking it apart. AS far as the Amazon purchase.... comparing the pinout that was provided for the cable against the console, the video is yellow and the audio is black. The white plug is not connected to anything in the console. https://justinpaulin.com/2014/04/21/testing-a-texas-instruments-ti-994a-without-power-or-video-cables/is a site that has the pinouts that correspond to the cable you bought and the 4A pinouts. (scroll down the page) The problem is the RED plug has the 12VDC out of the console and if you plugged that into any RCA port of the "display unit" you may have burned it out as they are not expecting that type of voltage. If you have another device that uses a composite cable you might want to try that on the "display unit" and make sure it still works. We do have the RF modulator, but not any screen that can take them. The screen we have is a flatscreen TV with HDMI and composite inputs, an old 28" Visio. Just tried my boyfriend's PS2 with composite on the TV, and it still works, so the RCA ports are fine. Quote Link to comment Share on other sites More sharing options...
xabin Posted January 22, 2019 Author Share Posted January 22, 2019 https://www.amazon.com/gp/product/B008N29OSG/ref=ppx_yo_dt_b_asin_title_o00__o00_s00?ie=UTF8&psc=1 Also, this is the cable I had bought. It has 2 reviews on it that mention it being used for TI-99/4a computers, and both said they work well, so... Quote Link to comment Share on other sites More sharing options...
retiredqwest Posted January 22, 2019 Share Posted January 22, 2019 https://www.amazon.com/gp/product/B008N29OSG/ref=ppx_yo_dt_b_asin_title_o00__o00_s00?ie=UTF8&psc=1 Also, this is the cable I had bought. It has 2 reviews on it that mention it being used for TI-99/4a computers, and both said they work well, so... I figured out that was the cable you bought. So, you have eliminated the TV as a problem and I doubt the cable is a problem so that leaves...... Quote Link to comment Share on other sites More sharing options...
xabin Posted January 22, 2019 Author Share Posted January 22, 2019 There's something wrong with the TI itself. Great. I'll be in town, tomorrow, and I'll be passing by Walmart, so I can pick up a balun of the type you mentioned, if they have one. If not, there's a Lowes next door, so we can try that. Fortunately, the TV does have a coaxil port, just don't know which setting on the thing we'd need to put it on to test it out (probably cable). Quote Link to comment Share on other sites More sharing options...
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