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[Kumadoken]

Hello all,I have recently bought a game doctor sf 7 in Hong Kong. To relive my younger days when I used to have one! And maybe add a floppy drive emulator down the line.

Generally It seems to work ok, however I was not provided with the power supply.

Bios = 7.1
Ram = 32MB Slot 1 and 16MB Slot 2

Since then I have been having issues with finding the exact of a psu which will work with GD7. With just 9V 800mA it was not reading disks at all. (New Floppy drive and using new floppys).

After some more searching I have managed to find a 10V 1A PSU it now reads disks. But I have noticed that I have been getting some memory issues. After reading and writing various disks. And it seems that not all the memory is booting correctly on the get go. Despite what the self test is showing.

If I only have 32 MB or 16 MB in slot 1 the GD does not boot with with memory slots at all. no A,B,C,D slots

However if I have 32 or 16MB in slot 2 the GD does boot with all the available memory slots. But the 32MB module seems to be tempermental, it doesn't always load games correctly. I get corrupted text showing triangles after loading the 1st disk of games. Same with the 16Mb minus the triangles, I will get black screen when running the game.

If I insert all the memory in slot 1 and 2 on boot the self test will show 32 MB and 16MB but it is only showing 8X2. It won't show 8X6 unless I move the cursor down to E.

So after all these testing it seems I have a troubled slot 1 (could that be the PSU issue do I need one with more V and A so I need to get 12V wtih 1.2A is really hard to find one. I am using 110 V where I am.

Both pieces of ram is probably showing signs of age as they I am experiencing issues with consistently loading games.

Could there be an issue with bios 7.1 in the way it recognises the ram on boot?

This is really frustrating for me because I paid a bit more 980 HKD to get a working game doctor sf7. And I am having all sorts of issues.

I am thinking my next step is to get a fresh 64MB ram and swap the bios to 7.11. To see if that will help things.

If not I have to just rely on having adequate ram in slot 2 (64) and use the 16 in slot 1 or another buy another piece of 64MB for slot 2. So the issues I am experiencing will not be effected .

Appreciate this is a bit of a long one. But just wondering if anyone has experienced anything like this. Any advice appreciated. I think I have a good unit there some where. But before buying the 3rd PSU I like to hear some thoughts.

[Tomy]

Please upload the photo of your ram card. Seems, your ram card have problem. Mostly SF7 main board is very well.

[Kumadoken]

Hi There Tomy,

Thanks for your response here is a picture of the memory modules. After putting the unit back together again same thing happened. After doing a memory test I scroll down the memory slots and 8m*6 appeared where it only shows 8m*2 on boot.

I also managed to back up a 32 MB cart and was able to read the disks afterwards as well the game started up fine.

But this feels like a luck of the draw. I rarely can sucessfully back up and read disks after a boot. The performance just doesn't seem consistent.

Anyway here is a picture of the memory modules. the 1st one is the 16MB and the 2nd is the 32MB..

My unit actually has a slightly different sticker to the other SF7s it says "Upgrade Version"

[Tomy]

Look like both ram card are original BUNG. The 3 chips one is dead bits ram. Mean one of 4bits ram have dead bits. That need to combine two dead bits ram to be one good 4 bits ram.

"Upgrade Version" mean people want to trade in with their other copier (like pro fighter) for Doctor SF7. (so price will be cheaper). "Upgrade Version" also original BUNG.

So, your problem fixed ?

[Kumadoken]

I don’t think it’s fixed, but to make sure it loads properly I need to run the test and scroll down to line E and then it sees 8*6 memory slots every time. Otherwise is highly likely that it will not load the disks properly As it is showing 8*2 . I will just get a line of triangles on the 1st entry. I am going to get a 64 MB of ram upgrade the bios to see how it behaves. So dead bits mean it needs both of the modules for it to work properly? IE 32 and the 16 not with out of them ?

Sorry really new to the inner workings of this. I remember my gd7 only had a 32MB inside occasionally it had occasional memory issues.But it worked ok in general.

Interesting information about the upgrade version thanks for clearing that up !

[Tomy]

Dead bits mean :

Normally 32M ram come with 2pcs 32M 4 bits chips. Two chips form 32M 8 bits memory. e.g. one chip only have 3 bits good. Then you need one more chip at least have 1 bit good. Then you can form 4 bits good. So, there is 3 chips on the board. Sorry for my english. Hope you understand.

[Tomy]

I still have SF7 64M ram card if you need. Thanks.

[philjay]

is it possible to update the 32m ram card to 64? Is it just changing the ram on the board?

[Tomy]

Yes, you can. If you have a 32M ram with 2 chips. Then add 2 more ram to it. It will become 64M ram card. You need solder skill to do it.

[Kumadoken]

[Tomy]

I think I have SF7 cartridge cover. Need to check.
SF7 64M ram here :
https://www.tototek.com/store/index.php?main_page=product_info&cPath=1_8_11&products_id=18

[Kumadoken]