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Black screen, no beep with boyfriend's TI


xabin

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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).

Good Luck on finding a balun locally..... As far as the input setting on the TV it probably says Antenna, Cable, or TV, etc. On the Modulator set that to modulator and the channel to 3 or 4. You'll also have to set the TV to channel to 3 or 4.

 

If you already knew this... just thought I'd cover it anyway.

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The one time I've ever had a black screen and no sound (as opposed to the normal cacophony) was due to a power supply issue (the internal PSU, not the transformer). It was a pretty easy fix: the contacts in the switch were oxidized and needed to be sanded. When/if you're able to open the computer, check the voltages from the power supply. They're labeled on the board silkscreen.

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The one time I've ever had a black screen and no sound (as opposed to the normal cacophony) was due to a power supply issue (the internal PSU, not the transformer). It was a pretty easy fix: the contacts in the switch were oxidized and needed to be sanded. When/if you're able to open the computer, check the voltages from the power supply. They're labeled on the board silkscreen.

That's possible; the light comes on red on the TI, but the light on the RF box doesn't come on when it's on and working, so...

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https://translate.google.com/translate?hl=en&sl=auto&tl=en&u=http%3A%2F%2Fwww.ti99.com%2Fti%2Findex.php%3Fcategorie5%2Fhomecomputerti994a

 

I found this French link to a TI-99 site that seems to have schematics for the 4A, but I dunno if that's different from the American ones. Anyone familiar with it? It seems to have what we need to test out the various parts of it.

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We don't know how to test the voltage, sadly, but we may have found something; when trying to clean the back of the circuit board, we found that one of the traces right near where the switch is (right next to where the red line connects to the circuit board) is corroded to almost nothing. We're thinking that's the issue, but we don't have the tools with us to get it fixed. We may have to take it down to my boyfriend's dad and have him reconnect it with some solder or something.

Edited by xabin
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Yeah, but he lives about a half-hour away from us. Right now, we are stuck with no way of proceeding until we get someone more knowledgeable with electronics to help out.

 

Also, RickyDean, please don't treat us like idiots; we're trying our hardest to get this fixed, but we have no real clue what we're doing, besides turning it on to see what works, and cleaning the boards of corrosion.

Edited by xabin
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Yeah, but he lives about a half-hour away from us. Right now, we are stuck with no way of proceeding until we get someone more knowledgeable with electronics to help out.

 

Also, RickyDean, please don't treat us like idiots; we're trying our hardest to get this fixed, but we have no real clue what we're doing, besides turning it on to see what works, and cleaning the boards of corrosion.

I am so sorry I came across like that, I am at work and peer though here from time to time. Please forgive me if I offended you, I definitely don't believe you are idiots, sorry.

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I am so sorry I came across like that, I am at work and peer though here from time to time. Please forgive me if I offended you, I definitely don't believe you are idiots, sorry.

It's fine, we're just learning about this.

 

After cleaning the power board, we did notice two changes: the light, when the power is off but not unplugged, will still be on but dim, and when it is on, we get a more fuzzy signal than pure black, with the fuzz being reddish in color.

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I am so sorry I came across like that, I am at work and peer though here from time to time. Please forgive me if I offended you, I definitely don't believe you are idiots, sorry.

 

I didn't see the reply as offensive. Perhaps it's the vacuum of text-based-communication that sometimes causes confusion.

 

To the OP--- it sounds like you've got some stuff fried in there. We used to have people around who would take your computer and fix it up... but I don't know of anyone offering console repair services right now. I know this particular one is special to you guys, but as a consideration, these computers are usually less than $40 on eBay. Might be worth buying a good one and parting it out to fix your boyfriend's... or perhaps put his on display and use the second machine.

 

That is--if you are unsuccessful in your restoration efforts.

 

Just food for thought.

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I didn't see the reply as offensive. Perhaps it's the vacuum of text-based-communication that sometimes causes confusion.

 

To the OP--- it sounds like you've got some stuff fried in there. We used to have people around who would take your computer and fix it up... but I don't know of anyone offering console repair services right now. I know this particular one is special to you guys, but as a consideration, these computers are usually less than $40 on eBay. Might be worth buying a good one and parting it out to fix your boyfriend's... or perhaps put his on display and use the second machine.

 

That is--if you are unsuccessful in your restoration efforts.

 

Just food for thought.

That is a possibility. We'll just have to see.

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The PSU is in pretty rough shape but I wouldn't write it off as unrepairable. If the LED is on when the computer is off but plugged in, I'd definitely assume a switch issue since the anode of the diode is connected directly to the switch (and it's not surprising given the condition of the surrounding area). The corroded traces can be patched with wire. As others have stated already though, a new PSU isn't too expensive if you can't get that one fixed.

Edited by AwkwardPotato
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The PSU is in pretty rough shape but I wouldn't write it off as unrepairable. If the LED is on when the computer is off but plugged in, I'd definitely assume a switch issue since the anode of the diode is connected directly to the switch (and it's not surprising given the condition of the surrounding area). The corroded traces can be patched with wire. As others have stated already though, a new PSU isn't too expensive if you can't get that one fixed.

We fixed that problem, while I was testing out how to use the multimeter to read the circuits; there was still a lot of residue on the PSU from where we scrubbed it, so another dry scrubbing took care of that. But yeah, with near no knowledge of how to diagnose let alone fix this, we're going to wait until we can get back with my boyfriend's dad and see what he can do with it. If he can't fix it, we may have to buy a new PSU, as you guys suggested.

Edited by xabin
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  • 1 month later...

We managed to find this item, here, that we think will work, but we're tight on money, right now. I'm hoping I can get the money to buy it, by the end of the month, if it hasn't been sold out, by then. https://www.ebay.com/itm/Texas-Instruments-Internal-Power-Supply-1049689-3-for-TI-99-4A/382803490693?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

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That will work--just make sure your board has the four prong white connector (at the edge of the board next to the end of the huge black capacitor). Some boards have a short cable with a connector there instead. The boards are electrically compatible, but you'd need to build an adapter to connect one that doesn't match--and the parts for the connectors on that adapter cable are difficult (but not impossible) to find.

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I'm pretty sure it does have that, it's been a little while since we cracked it open to see, but I'm pretty sure I remember it having that.

 

A funny little anecdote from today: my boyfriend and I went to one of our local used game shops, and noticed that they had an Atari 800 computer. So, I asked them how far back of computer tech they are able to sell and fix (they do fixes, too). When we mentioned that we had a TI-99, one of the store owners said his dad had one, and they'll take a look at it, once we get the power board for it.

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