Faults & Fixes - Common breakdowns, glitches & solutions

[Omega-TI]

Over the the past year, we've all read multiple threads on common hardware issues, faults and breakdowns. In starting this thread it's hoped that we can all have a "clearing house" of sorts for common solutions. This way if someone develops issues in the future, they'll know where to come to quickly pinpoint and diagnose the issue and possibly get an instant solution.

 

For easy search, the title should list the PROBLEM, and the DEVICE involved.

 

If possible please include photos, because as they say, a picture is worth a thousand words and may help someone confirm and diagnose their issue.

[Omega-TI]

BLUE SCREEN (TI will not boot up)

HDX Modification

GLITCH (Easy Fix)

 

The problem

 

When the TI-PEB is attached, all you get is a blue screen and nothing works.

 

One easy way to diagnose this is to look at the HDX/RS-232 light, if it's lit in a constant state, the memory on the card is corrupted, this can happen frequently when the battery is near death.

 

The cheapest solution is a quick trip down to Dollar Tree for a $1.00 pack of CR2032's (They cost more almost everywhere else)

 

Now just open up your PEB, remove the card and battery, wait a minute, install the new battery, re-install the card and close it up.

 

Turn on the computer....

The light looks normal and the system boots, so now all you have to do is reload the DSR into memory and you're back in business.

[dphirschler]

No sound from the console

 

One day my otherwise good console stopped producing sound. Two possible solutions were presented to me here on this forum (http://atariage.com/forums/topic/231542-no-sound-from-ti-console/).

 

1) Replace the sound chip, which might have gone bad. This solution fixed my issue. I just happened to have another TI motherboard which was bad. It powered on with an angry sound and glitchy video. The angry sound was enough to tell me that at least the sound chip worked. I swapped it out and my silent TI was again producing sound. It was an easy fix as the sound chip is in a socket. What I should have done before swapping the sound chip was to test speech. I am not certain, but I believe speech would have worked even with a bad sound chip. Am I correct? It would be an additional useful diagnostic step. PM me if you know the answer and I will correct this post.

 

2) Re-solder the back A/V connector which might have come loose through years of plugging/unplugging. One user reported that this was the problem and simply re-soldering the connection fixed it.

 

The sound chip is highlighted in blue in the following picture. The audio/video is shown in the upper left corner.

 

Darryl

Edited November 9, 2014 by dphirschler

[dphirschler]

Bad (currupt/garbled) video

 

When I first dug my TI's out of the basement and blew the dust off them, I powered up my beautiful beige console and the screen looked garbled, like this.

 

I asked the folks here and they quickly identified bad VDP RAM as the culprit (http://atariage.com/forums/topic/228756-diagnose-this-sick-ti/?p=3053085).

 

1) Modify my console by installing an F18A board. The F18A is a snap-in replacement to the 9918A video processor which gives VGA output from the TI. This board uses its own VDP RAM (baypassing the bad VDP RAM on the motherboard). The TMS 9918A chip is socketed, so it literally is a snap-in mod. The more difficult part of the mod is cutting a hole in your console casing to make a spot for the VGA connector. There are some photos of other people's case mods for the VGA connector here http://atariage.com/forums/topic/228626-who-has-vga-out-on-their-console/.

 

2) Identify and replace the defective VDP RAM chip(s). It seems the easiest way to identify the bad one is to stack a good one on top of the supposed bad one, making sure all pins make good contact, and look for the video to improve. The technique was mentioned in the first thread above (diagnose-this-sick-ti). There was one other thread which described how to possibly identify a bad VDP chip out of circuit (http://atariage.com/forums/topic/229064-testing-4116-ram-chips-out-of-circuit/).

 

I went with solution 1, and am happy about it. The TI never looked better than on this VGA screen.

 

Darryl

Edited November 9, 2014 by dphirschler

[dphirschler]

Joysticks that don't work right

 

I had a joystick that would not go up. And it was not the Alpha-lock key. I described my problem here in this thread (http://atariage.com/forums/topic/230818-joystick-horror-story-with-a-happy-ending/).

 

The solution is to clean the contacts on the flexible circuit board inside the joystick. I used 90% isoprohyl alcohol. Take care not to "clean" the silver pads painted inside the TI joystick. If you do, it will just rub away like a scratch-off lottery ticket. But even that can be saved by either painting it again with conductive paint, or applying a small square of conductive tape.

 

Darryl

[+mizapf]

If this is OK for you I'll copy these reports to ninerpedia. When I created the faulty screen outputs I already thought about setting up a troubleshooting section.

[dphirschler]

If this is OK for you I'll copy these reports to ninerpedia. When I created the faulty screen outputs I already thought about setting up a troubleshooting section.

Feel free to use any of my writings here.

 

Darryl

[Omega-TI]

If this is OK for you I'll copy these reports to ninerpedia.

 

Feel free to use any of my writings here.

 

Same here, we're all in this together. The point is to get the information out there for those who need it.

[Omega-TI]

If this is OK for you I'll copy these reports to ninerpedia. When I created the faulty screen outputs I already thought about setting up a troubleshooting section.

 

 

Did you ever get the troubleshooting section open?

[+RXB]

No sound from the console

 

One day my otherwise good console stopped producing sound. Two possible solutions were presented to me here on this forum (http://atariage.com/forums/topic/231542-no-sound-from-ti-console/).

 

1) Replace the sound chip, which might have gone bad. This solution fixed my issue. I just happened to have another TI motherboard which was bad. It powered on with an angry sound and glitchy video. The angry sound was enough to tell me that at least the sound chip worked. I swapped it out and my silent TI was again producing sound. It was an easy fix as the sound chip is in a socket. What I should have done before swapping the sound chip was to test speech. I am not certain, but I believe speech would have worked even with a bad sound chip. Am I correct? It would be an additional useful diagnostic step. PM me if you know the answer and I will correct this post.

 

2) Re-solder the back A/V connector which might have come loose through years of plugging/unplugging. One user reported that this was the problem and simply re-soldering the connection fixed it.

 

The sound chip is highlighted in blue in the following picture. The audio/video is shown in the upper left corner.

TI994a mobo_layout.png

 

Darryl

Has anyone every thought of bank switched 256 bytes RAM for 9900?

That is the Scratch pad RAM right?

16 pages of 256 bytes RAM would be 4K of 9900 Fast RAM right?

[+mizapf]

Did you ever get the troubleshooting section open?

 

Ehm ... thanks for reminding me ... just forgot about that

 

In fact, there is a Troubleshooting section in ninerpedia, so if anyone volunteers to fill it in ...?

[Omega-TI]

Bump - (there is a reason).

[+DuaneAL]

I recently picked up five 4a's on Ebay that had issues. Two were key board issues that were easily fixed. They were missing keys. One was fixed by taking a key from the other keyboard that was missing keys. The second one was fixed by replacing the keyboard from one of the non-functioning keyboards. I also had to replace the internal power supply in that one. One was listed as having a bad cartridge port. Cleaning the port was all that was needed. One of the other ones had a bad internal power supply. Replacement fixed that one. The two bad power supplies had different voltage readings. The first read -5v, 12v, gnd, +3.6v. The second read -5v, 12v, gnd, +11v. I also had a problem with the 32k sidecar working on 3 of the consoles but not on one. That ended up being operator error on my part. There is a switch on the sidecar that switches between the ti for power and an external power supply. I had it set to external but had no power supply going to it. Apparently there is enough voltage leakage to somehow power the sidecar regardless of switch position sometimes even through the speech synth. I am still working on fixing the last one from that lot but I ended up better than I had hoped to when I bought them. Hope this helps!