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ralphb

The FinalGROM 99

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I often have to go through several rounds of pressing the reset switches, turning the computer off and on, removing the cartridge and reinserting it, removing the SD card and reinserting it, and whatever else I can think of, before I can get my FinalGROM to load anything. I think it's worse on my F18A console than on my other console, and I believe other carts work fine, but I haven't done any systematic testing. Every time it fails I get a new result. Sometimes it fails on the opening screen, sometimes there is no menu, sometimes it seems to work but then loaded program fails - it seems completely random. In then end it suddenly works, and then I can often load other programs if I just press reset.

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I often have to go through several rounds of pressing the reset switches, turning the computer off and on, removing the cartridge and reinserting it, removing the SD card and reinserting it, and whatever else I can think of, before I can get my FinalGROM to load anything. I think it's worse on my F18A console than on my other console, and I believe other carts work fine, but I haven't done any systematic testing. Every time it fails I get a new result. Sometimes it fails on the opening screen, sometimes there is no menu, sometimes it seems to work but then loaded program fails - it seems completely random. In then end it suddenly works, and then I can often load other programs if I just press reset.
Just curious if you have rebuilt your power supply?

Sent from my LM-V600 using Tapatalk

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1 hour ago, Asmusr said:

I often have to go through several rounds of pressing the reset switches, turning the computer off and on, removing the cartridge and reinserting it, removing the SD card and reinserting it, and whatever else I can think of, before I can get my FinalGROM to load anything. I think it's worse on my F18A console than on my other console, and I believe other carts work fine, but I haven't done any systematic testing. Every time it fails I get a new result. Sometimes it fails on the opening screen, sometimes there is no menu, sometimes it seems to work but then loaded program fails - it seems completely random. In then end it suddenly works, and then I can often load other programs if I just press reset.

Exactly the same, I'm glad you raised this as I was wondering if I was alone with this or if it's just the norm.

 

I've read about people testing power supplies, I've no idea how to do this? I'm using my original power supply and also have a spare original.

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34 minutes ago, arcadeshopper said:

Just curious if you have rebuilt your power supply?

No I haven't.

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I have seen issues when the 5v is not up to snuff there's a 3.3 volt regulator on there and I think there are issues with some power supplies..

Sent from my LM-V600 using Tapatalk

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1 hour ago, arcadeshopper said:

I have seen issues when the 5v is not up to snuff there's a 3.3 volt regulator on there and I think there are issues with some power supplies..

Sent from my LM-V600 using Tapatalk
 

Is this a case of testing the part that plugs into the back of the computer with a multimeter? I think I will have to get one of those and test both my power units if so.

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No the internal power supply is the issue

The external is an ac supply its the internal supply that provides 5v -5v and 12v DC



Sent from my LM-V600 using Tapatalk

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Posted (edited)

I would be surprised if a defective power supply was the problem in all cases. I have FG99 troubles with several TI-99/4A, all of their power supplies are verified OK and regularly maintained. The TIny99/4A v3 computers (two have now been built), where the FG99 issue is also observed, are powered by a brand new Astec professional PSU.

I could tend to think that I'm not as unlucky as I thought and I am near reassured to see that I'm not alone to have some issues with the FG99. Yes, the  problems are erratic, that causes some difficulties to point on the fault. So, I will control FG99 data, clock and power signals during each step of a program launch (Computer startup /FG99 selection in the TI main menu / a sub-dir selection / Program launch) with my logic analyzer to understand what's wrong with it.

 

Edited by fabrice montupet
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Fabrice,

 I'm glad you are willing to take on this debugging task, I have a similar problem with a John Guion modified Super Extended Basic.

 Sometimes it's seen, sometimes it is not. Sometimes, just a power on / power off is need, other times a reset.

 I believe it to be, one of those very hard to debug, for mortal men, timing issue.

 

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Count me amongst those experiencing intermittent FG99 glitches. It usually works, but not always. Sometimes the console doesn't recognise it is plugged in, sometimes reset causes issues. Sometimes it just crashes. or refuses to load. Usually a power cycle solves the problem, but sometimes I have to reseat the cartridge or the SD card. It is random enough that I don't see a pattern other than a reset is more likely to cause havoc than anything else. I don't have problems with any other cartridge. The FG99 glitches are more of a nuisance than anything else as the utility of the cartridge outweighs the problems.

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Although I haven't had problems with my FG99, I worried about all that heat rising through the mug-warmer and into the cartridge. So I installed a 5v laptop fan directly below the power supply after cutting out the right-bottom ventilation grill. Just fits, without raising the console. I supply it 3v from an adjustable external power supply (a bit noisy at 5 volts - needless to say I've installed a quieter fan in my PEB). I covered the other two bottom grills to encourage circulation from the back of the console over the logic board clamshell. At 3v the fan exhausts a lot of air and very effectively keeps the mug-warmer cool. Lastly, it so happens that the cartridge into which I installed the FG99 has an open front. Here's hoping this all extends its life. 

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My FinalGROM99 works fine, again  🙂
The issue was due to defective 104 capacitor causing power instability on the Xilinx CPLD.

I also eliminated the FG99 recognition problem after a reset by replacing some ICs.  A very quick operation on the TIny-99/4A v3 as all the ICs are socketed, a little lesser one on the 99/4A as all of them are soldered.
Some months ago, I had to replace two LS138 ( U504 and U505) by HCT ones on the two computers to resolve the Tutankham timing issue (the game on the FG99 crashed with after the player number selection). Now, to make the FG99 always here after a reset,  I also replaced three LS04 (U508, U602 and U604).  I made this modification 3 days ago and  used intensively the Tiny-99/4A v3 and the TI-99/4A with the HCT ICs installed, since I haven't encountered the issue anymore.  

I have not enough time to explore further the FG99. The strange thing is that some people seems to haven't any trouble with it while other people have some.  I would have liked to understand why while all the TI-99/4A motherboards seems to have the same TTL components (same brand and livery), finally maybe not?  The FG99 has ended is development. I think that no modification on it can be expected.  That said, this is a great device with a very little annoyance compare to all its great advantages.   My solution is a just a bypass solution, it works and that's enough for me 🙂

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Low power consumption is one of the characteristic of the HCT series.  Among other things, we can also list a very high impedance inputs and outputs that can source more current. 

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11 hours ago, fabrice montupet said:

The FG99 has ended is development. I think that no modification on it can be expected.  That said, this is a great device with a very little annoyance compare to all its great advantages.   My solution is a just a bypass solution, it works and that's enough for me 🙂

First of all, great find!  So basically it wasn't a mechanical problem, but an electrical one?

 

Even if development on the FinalGROM is done, I could still update the instructions and add a section on how to fix your cartridge if anyone should experience similar issues.  But you said that it wasn't just the FinalGROM, but also your TIny console?  Does the cart now work in the stock console as well?

 

(I've actually learned a lot about capacitors for the SDD 99, so it might be possible that some earlier chosen capacitors on the FinalGROM might "wear out".)

 

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The chaotic behavior of my FG99 led me to a first wrong diagnostic, I think now that the SDCard slot was OK (I just had some luck after changing it), the real guilty was the capacitor.

The TIny-99/4A v3 reacts as a real 99/4A and the same problems were observed to each of one. Since a replaced the TTL ICs I haven't notice FG99 problem after a reset on each computer. It could be very interesting that someone also modifies its 99/4A as I have done and that he sends us the result. The goal is to have the more feedback as possible. After, yes, putting the information on the FG99 documentation would be fine.

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1 hour ago, fabrice montupet said:

The chaotic behavior of my FG99 led me to a first wrong diagnostic, I think now that the SDCard slot was OK (I just had some luck after changing it), the real guilty was the capacitor.

The TIny-99/4A v3 reacts as a real 99/4A and the same problems were observed to each of one. Since a replaced the TTL ICs I haven't notice FG99 problem after a reset on each computer. It could be very interesting that someone also modifies its 99/4A as I have done and that he sends us the result. The goal is to have the more feedback as possible. After, yes, putting the information on the FG99 documentation would be fine.

Can you tell us which capacitor from C3 to C14 it was? Or are all capacitors around the Xilinx CPLD suspicious !?

 

Fred

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20 minutes ago, fabrice montupet said:

Just only one was defective, the C10.

Quite weird -- I don't see anything special about that capacitor.

 

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On 5/8/2021 at 11:10 PM, Schmitzi said:

 

Do you use any shell/housing for the FinalGROM99 ? Try and take it out of  the shell and plug the bare board into the TI.

I have this problem with my 2 FlashROM99´s, when inside their Romox-housings. Very strange behaviour.

Somehow like a short circuit, or a open contact... As if closing the shell bends the board...

Removing the board from the shell may have solved the problem for me. 

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@Ralphb: A simple dead capacitor, these are things that can happen, nothing serious, easy to replace and at no cost 🙂

@Rasmus:  Maybe some shells cause a mechanical stress to the PCB? That could explain your problem and for some other users.

 

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18 minutes ago, Asmusr said:

Removing the board from the shell may have solved the problem for me. 

 

Do you also have a Romox-shell, coming from UK ?

 

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1 hour ago, Schmitzi said:

 

Do you also have a Romox-shell, coming from UK ?

No it was sitting in an ordinary shell with part of the top removed. But it's a little too early to say that the shell was definitely the problem.

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