Exxos's H5C5B Build

[exxos]

This is the board as sold in the store currently.

NOTE - 2 resets switches may be included.. One is the wrong type (6 pins, not 3 pin) I couldn't be bothered to remove the 6 pins ones, so the correct 3 pin were just slotted inside the box..

The 2 oscillators & MFP are included. Most other parts can come from the store (sockets etc) and main chips, but I suggest using a old (broke) ST to use as donor chips etc

Let's get building

This is the minimal steps to get it booting rather than a complete assembly guide... Maybe someone else can do a more comprehensive guide..

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Firstly fitting the two oscillators..

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[exxos]

The reset switch has pi$$ed me off. As for some reason the holes are the wrong size for the switch frame

My only solution is to bend the front metal tab sideways and scratch a bit of the resist of the PCB to make a solder point.
The other back pin I did not bother with I just cut it off.

I also noticed that the left back pin could actually wear through the solder resist and short out on the track so I have bent that rear pin upwards to miss it and I will update the PCB files to correct that problem. That problem must of been there for a while and went unnoticed until just

I think the hole size thing might have happened because the holes were not part of the switch template actually just on the PCB.. I think at some point I moved all the holes to 0.3mm instead of 0.2mm (which involved a fair bit of re-routing as well) as larger holes will be stronger and can be a bit cheaper in some fab houses. Though the switch holes must have got "caught" in the resize

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Also noticed the PLCC location dots on the silkscreen also seem to have fallen victim to the hole resizing

[exxos]

Bit more progress...

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[exxos]

First power up - smell of burning

It seems the amp chip was soldered in upside down and it let the magic smoke out

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[exxos]

TOS104 booted from floppy fine

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[exxos]

NEW FEATURE - Built in TOS206 decoding.


To enabled it, solder the jumper pad as shown...

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Move the ROM select jumper to the 104&206 decoding location.

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Move the ROM bank select jumper (open for upper bank select)

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Done

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You can now just simply alter the ROM bank jumper to select TOS versions.


Not bad if there are only two relatively minor screw ups this time I guess

[stephen_usher]

First power up - smell of burning

It seems the amp chip was soldered in upside down and it let the magic smoke out

Oops! Just this board or all of them? Is it obvious on the silkscreen which is pin 1?

At least it's booting otherwise!

[exxos]

Oops! Just this board or all of them?

I assume all of them, I don't really fancy unpacking and repackaging the whole lot to find out

[stephen_usher]

Oops! Just this board or all of them?

I assume all of them, I don't really fancy unpacking and repackaging the whole lot to find out

OK, so there's a mandatory fix for all the purchasers to do... Either use hot air on the amp or let the magic smoke out.... their choice.

[exxos]

OK, so there's a mandatory fix for all the purchasers to do... Either use hot air on the amp or let the magic smoke out.... their choice.

Yep, nobody will read instructions anyway, so i will just put a sticker on it to warn people about it.

The problem is that chip is a Chinese one, I don't have any stock of them here