Super turbo PCB layout

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By Gregory

Master (163)

Gregory's picture

08-06-2021, 20:56

jltursan wrote:

Brilliant!

I don't have a 8250; but is it so tight under the floppies?, if so and you can't fit the new CPU PCB, I would try with pin headers instead a standard socket (of course you can use a low-profile one; but they're hard to find). There're low-profile pins that make the build ultra-short, like these
Anyway, beware, the above pins are too big for a standard pad size; so something smaller is needed, I think you got the idea...

Btw, how many flying wires have you connected and where?, why to another IC socket?

I have the other IC sockect so I can test the various boards I have. If I would mount ut definetely in a computer I would lose one of the sockets, then it would be as high as a normal socketed z80. Then height wouldn't be a problem. About those low profile pin, remember there are also parts on the underside of the PCB, so I don't know if they would hit the main board. Those flying wires, I just connected all diodes, because its difficult to solder the extra wires when the circuit is in its place (in my opinion), but sure, you could do whitout the extra wires.

By SkalTura

Champion (325)

SkalTura's picture

09-06-2021, 07:23

Looks great Gregory, congrats !! Cool

One note though... You should clean the PCB with alcohol (Isopropanol) after soldering.
Not only looks better, but some solder flux can eventually corrode the PCB traces.
Even "no clean" fluxes like I use at work will affect the traces, and even some components, after a few years...

By Gregory

Master (163)

Gregory's picture

09-06-2021, 08:07

SkalTura wrote:

Looks great Gregory, congrats !! Cool

One note though... You should clean the PCB with alcohol (Isopropanol) after soldering.
Not only looks better, but some solder flux can eventually corrode the PCB traces.
Even "no clean" fluxes like I use at work will affect the traces, and even some components, after a few years...

I use a cuetip with isopropol after each part to clean the flux up but it's stubborn stuff.

By SkalTura

Champion (325)

SkalTura's picture

09-06-2021, 09:03

Gregory wrote:

I use a cuetip with isopropol after each part to clean the flux up but it's stubborn stuff.

Yes it is stubborn stuff indeed Wink
At work we have special brushes for this sort of work, but at home I just use an old (soft) toothbrush and gently scrub my PCB's several times until all the residue is gone.

By Gregory

Master (163)

Gregory's picture

09-06-2021, 09:35

SkalTura wrote:
Gregory wrote:

I use a cuetip with isopropol after each part to clean the flux up but it's stubborn stuff.

Yes it is stubborn stuff indeed Wink
At work we have special brushes for this sort of work, but at home I just use an old (soft) toothbrush and gently scrub my PCB's several times until all the residue is gone.

Okay, thanks for the tip Big smile

By rigues

Supporter (4)

rigues's picture

10-07-2021, 16:58

Quick question, is the bill of materials (BOM) the same as on Hans Otten's circuit? I see there are less diodes in this version, any other difference?

Also, would it work with 4 MHz and 8 MHz crystals? Those are MUCH easier to find here in Brazil.

Regards,

By Gregory

Master (163)

Gregory's picture

10-07-2021, 18:17

rigues wrote:

Quick question, is the bill of materials (BOM) the same as on Hans Otten's circuit? I see there are less diodes in this version, any other difference?

Also, would it work with 4 MHz and 8 MHz crystals? Those are MUCH easier to find here in Brazil.

Regards,

I can only answer your question for the diodes. In this version there are two diodes in 1 package, that's the reason there are less of them on the board.

By SkalTura

Champion (325)

SkalTura's picture

15-07-2021, 07:18

rigues wrote:

Also, would it work with 4 MHz and 8 MHz crystals? Those are MUCH easier to find here in Brazil.

At work, we order most of our parts from Farnell (Newark) or Mouser
And both have an office in Brazil, so you should be able to order the original crystals from Mouser...

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