schematics for floppy disk interfaces

[aalea]

This is the status of my work now:

The copper board match the picture, i hope 100%, and all the copper tracks i was able to see in the coponent side.

There is attached a schematic, in it you can see my guess about the Address line swap on the ROM.

obviously this do not work, the big work is on the address decode for the chips and in the 74LS174, hopefully with a bit of testing will be posible to determine it.

One interesting point is that I think that the interface work with the WD1773, wich is even cheap that the WD1770

[aalea]

Hi,
Here are some pictures of a Q-Disk 4 dated 2986, with a ROM v1.8
Here is a view without the heat Sink
Q-Disk_Top_NoHeatSink.jpg

View underneath
Q-Disk-4_Back.jpg

Funny Fact: Your PCB is wrong.

When I analize the pcb, there was a detail I can't understand , and is that they put a big square under the 7805 in the solder side, and there was some lines that pass without varnish under the disipator.

Today I see a interface on ebay, with ROM V1.19, unfortunatelly is a bit over-priced, more over with the brexit, but when examine in detail the pictures I realized that the have the sides reversed, and now the square is in the correct side, under de disipator.

So, in my opinion, the ebay's PCB is correct, and your PCB has the sides of copper swapped, luckly in both cases the interface work.

BTW, my advice is that put some kapton tape, mica sheet or any other heat-resistant isolator between the disipator and the PCB.

[Derek_Stewart]

Hi,
Here are some pictures of a Q-Disk 4 dated 2986, with a ROM v1.8
Here is a view without the heat Sink
Q-Disk_Top_NoHeatSink.jpg

View underneath
Q-Disk-4_Back.jpg

Funny Fact: Your PCB is wrong.

When I analize the pcb, there was a detail I can't understand , and is that they put a big square under the 7805 in the solder side, and there was some lines that pass without varnish under the disipator.

Today I see a interface on ebay, with ROM V1.19, unfortunatelly is a bit over-priced, more over with the brexit, but when examine in detail the pictures I realized that the have the sides reversed, and now the square is in the correct side, under de disipator.

So, in my opinion, the ebay's PCB is correct, and your PCB has the sides of copper swapped, luckly in both cases the interface work.

BTW, my advice is that put some kapton tape, mica sheet or any other heat-resistant isolator between the disipator and the PCB.
s-l1600_R1.jpg
s-l1600_R.jpg

Hi,

I am only looking at the board made from CST, if this is wrong, then CST are to blame.

If you PM your postage address, I can send you the Qdisk Interface for examination, as I think you better t this than I am.

I see in your photograph, you have ROM v1.19, can you copy the ROM to an image and maybe upload it to the QL Homepage for preservation.

[aalea]

Hi,
Here are some pictures of a Q-Disk 4 dated 2986, with a ROM v1.8
Here is a view without the heat Sink

Funny Fact: Your PCB is wrong.

I am only looking at the board made from CST, if this is wrong, then CST are to blame.

Yes, of course, I imagine that the swap the photolith in the factory.

It's also curious that in this board there is no silk-screen, cost-cut i imagine.

I see in your photograph, you have ROM v1.19, can you copy the ROM to an image and maybe upload it to the QL Homepage for preservation.

No, it's not mine, the picture is from ebay. I only have the clone that nikosdoykas did.

[Dave]

This was common practice in the 70s and early 80s. There’s nothing wrong with the solder resist layer on this board.

[aalea]

This was common practice in the 70s and early 80s. There’s nothing wrong with the solder resist layer on this board.

Well, I agree about the common practice, but I do not share this opinion of nothing wrong, because they use the same solder mask in both sides, and with the route used, there is a potential short-circuit of 2-3 Address lines of the CPU by the heat disipator.

[Dave]

Only if you assemble the board with the heatsink on the wrong side. In which case you've got bigger problems

[aalea]

Only if you assemble the board with the heatsink on the wrong side. In which case you've got bigger problems

Yes, nothing that a dremel can not solve.

but we are speaking about the V4 version as per the photos that Derek_Stewart posted here: viewtopic.php?f=2&t=3422&start=40#p46323

I can assume that the first photo is as factory, and in the second photo you can see tha tracks exposed.

[Derek_Stewart]

Only if you assemble the board with the heatsink on the wrong side. In which case you've got bigger problems

Yes, nothing that a dremel can not solve.

but we are speaking about the V4 version as per the photos that Derek_Stewart posted here: viewtopic.php?f=2&t=3422&start=40#p46323

I can assume that the first photo is as factory, and in the second photo you can see tha tracks exposed.

Hi,

All 3 photographs are the same board, I removed the heat sink, which had an insulating pad to stop the tracks under the heat sink from shorting out.

This a guess, but I would say, that the lack of solder mask on the tracks under the heat sink is a feature of the CST Interface. I would of thought the 2 tracks should of been routed around the heat sink.

But only CST will know this for certain.

[Derek_Stewart]

Hi,

Here is a copy of the CST QDISK v1.18 jumbled.

CSTQD118.zip

CST QDISK v1.18 Jumbled

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