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mjnurney
April 20th, 2018, 08:57 AM
Hi guys

my ti99 disk controller seems dead - light on but no response.

However it has a 3.5 inch disk connected...is there anything special about adding a 3.5 rather than the 5.25 of old?

cheers
mike

SomeGuy
April 20th, 2018, 09:31 AM
Slightly, yes. The TI-99/4a uses a traditional "Sugart" style interface that permits addressing up to four drives, has a single motor enable, and connects via a flat cable.

Most 3.5" drives expect an IBM PC style FDC with twisted cable. If the drive does not have a "0", "1" (first, second) drive switch then you will probably have to wire a special cable. Look up the "Sugart" vs "IBM PC" floppy controller pinouts to see the difference.

Other than that, a 3.5" drive with low density disks will work just fine as a substitute.

mjnurney
April 20th, 2018, 09:59 AM
thanks for the reminder its been a long time...

Hi yes isn't it the drive 1,2 or 3 pin thats different or something. as i recall a standard non twisted pc floppy cable makes it DSK2

however mine does nothing ,no drive light or anything. i can see someones been at it at some point with a soldering iron...



Slightly, yes. The TI-99/4a uses a traditional "Sugart" style interface that permits addressing up to four drives, has a single motor enable, and connects via a flat cable.

Most 3.5" drives expect an IBM PC style FDC with twisted cable. If the drive does not have a "0", "1" (first, second) drive switch then you will probably have to wire a special cable. Look up the "Sugart" vs "IBM PC" floppy controller pinouts to see the difference.

Other than that, a 3.5" drive with low density disks will work just fine as a substitute.

krebizfan
April 20th, 2018, 10:39 AM
Which disk controller do you have? Could make for a difference in terms of what formats are on disk. I think the PEB controller would create disks double sided, single density, 40 track (90 kB a side) which will look weird to any other 3.5" system.
Soldering iron may mean you have an upgraded controller making it more interesting but also harder to troubleshoot. I suggest checking that the user soldered components didn't break loose.

Check some TI-99 related web pages. There were instructions to create twisted cables used for 3.5" drives that lacked DS jumpers. Different from PC twisted cables because only drive select wires need swapping.

barryp
April 20th, 2018, 01:22 PM
Hi yes isn't it the drive 1,2 or 3 pin that's different or something.
Some drives are numbered 0,1,2,3 and others are numbered 1,2,3,4.
IBM chose to always use the second jumper and make the A: or B: selection by putting a twist in the cable.
TI chose to use a straight-through cable and do the drive selection (DSK1 or DSK2 or DSK3) with jumpers.

What you describe is exactly what you'd see if you took a drive from a PC to TI without changing the jumper; the controller looks for DSK1 but the drive is set for DSK2.
If you're using a Disk Manager module, try selecting DSK2.

mjnurney
April 20th, 2018, 11:57 PM
I’ve just tried the cor comp peripheral test and it says no controller found... maybe it’s a dud.

Is there and diag software to recognise the card regardless of wether a disk drive is fitted?

thanks guys.

mjnurney
April 22nd, 2018, 11:31 AM
Should the LED be on all the time > mine is...

ive run an extended basic program to test the card but it shows nothing sadly.





Iíve just tried the cor comp peripheral test and it says no controller found... maybe itís a dud.

Is there and diag software to recognise the card regardless of wether a disk drive is fitted?

thanks guys.

krebizfan
April 22nd, 2018, 11:55 AM
If the LED is on all the time, that tends to mean one cable is installed incorrectly.

You might consider taking pictures of the modifications to the controller to check if anyone remembers information about the specific setup you have.

mjnurney
April 22nd, 2018, 09:49 PM
Hi

The LEd is on all the time without a cable or drive connected. I did try to add pics but the process seems a bit archaic. Iíll have another go.

The LED should only light up when the drive is accessed ?



If the LED is on all the time, that tends to mean one cable is installed incorrectly.

You might consider taking pictures of the modifications to the controller to check if anyone remembers information about the specific setup you have.

mjnurney
April 22nd, 2018, 09:52 PM
Great ... the 32k card has packed up now..

No 32k found and disk controller led always on.

Could this be a bad flex cable and board I wonder...

Ksarul
April 24th, 2018, 03:05 AM
Since the light is on all the time for the controller, remove it and test your 32K again. If the 32K works, you can try again with the disk controller in the box--but try it in the seventh slot instead of the last one. Sometimes, the problem is in the backplane, and that helps find it. If the 32K still fails, check the Flex Cable card and the side connector on the TI. Sometimes one or both sides of that connection gets gunky and needs to be cleaned, other times, there will be some damage in the Flex cable connector that allows it to short some pins. Lastly, one of the buffer chips in the Foot of the Flex cable may be blown. These are easy enough to replace if you have some soldering skills. Note that it is a good idea to remove and reseat all of the cards in the PEB if it has been sitting for a long time too, as that helps clean the connections.

mjnurney
April 24th, 2018, 05:15 AM
Hi

I’m going to have a look at the flex card tonight. I’ve stripped the peb to fit an ATX power supply. I have a feeling it’s the flex card to be honest.

Thanks

mjnurney
April 24th, 2018, 11:19 AM
well , i don't know...

ive replaced the buffers and voltage reg on the flex cable it looks good. lights up but the PEB finds no cards.

So ive ordered another flex card from eBay , i have an RS232 on its way from the states too so hopefully something will work soon.

Ksarul
April 25th, 2018, 03:29 AM
Have you put the Flex Card in a different slot in the PEB? Sometimes changing the slot helps. Also, check with a different console if you have one. Sometimes the buffers in the console go bad too. . .

mjnurney
April 25th, 2018, 12:34 PM
hi thanks

no other console but i'll investigate further when i have known working cards :-)

thanks

mjnurney
May 7th, 2018, 05:53 AM
Ok some news on the PEB.

An RS232 and a tested flex cable have come and both function perfectly...so the 32k and disk controller must be faulty.

The disk controller has a solid blue led all the time and freezes the ti99, the 32k is not detected at all.

I have ordered another 32k and a disk controller so i can return to fixing these at a later date...

:-)