A604n not working

[Doppie1200]

Hi all,

I received my A604n with Indy ECS today. However, the A604n is not working.
When inserted the A600 just hangs. Nothing happens. The power LED comes on, the capslock LED comes on.
That is it. No video, no diskdrive activity. The Indie ECS is not mounted yet.

When I mount a different memory expansion the A600 works fine.

It seems something is wrong with my A604n.

I am using it on a rev 1.1 A600 with an ACA 600 on ROM 3.1

Is there some common issue you guys know of or have I just received a dodgy one?

Thanks.

[Doppie1200]

Did you mean ACA620?

No the ACA620 is fine. Trouble sets in when the A604n is connected.

 It's unlikely but not impossible that your A604 is faulty. If you don't have a spare 600 then I suppose you have no choice other than to return it.

No spare A600 sadly. I may get one if it pops up for a reasonable price.

Before you return it though, are you absolutely sure there's no shorts anywhere? The floppy drive screw can get awfully close to the motherboard chip ram IC...worth checking if you've fitted the Subway clock port PCB to the A604.

When I remove the A604n the A600 boots just fine. Also when I have my old 1M expansion in there are no issues.

I took a look at the diagram
It is for a rev 1.5 but so far I have been able to find every component I wanted.

The reset signal is held low. This signal comes from the rst signal which is basically driven by the cpu. So it seems the cpu is holding everything in reset.
I measured the keyboard reset chip (ne555) and that makes a nice pulse. However, since the rst remains asserted nothing happens from there on.

Tonight I'll do some measurements on the clocks and check for shorts. Tomorrow I reserved the microscope at work so I can have a look for dodgy solder joints on the A604n.

Keep your ideas coming. It is much appreciated.

[Doppie1200]

Hi,

In the meantime Jens is on the case. It seems there is an incompatibility with the new batch and the A300 boards (A600 marked A300 rev 1.0 - 1.1).

See here: http://eab.abime.net/showthread.php?t=82759

First I waited for the A604n to be in stock and now this.... This is all taking too long for my taste as all I wanted was to fit an indivision.......



So, I decided just to hack it in wirewrapping style. After getting a solid ground and protection for the CCK signal it works like a charm. Who needs an A604n anyway

[Doppie1200]

Impressive stuff. Thanks for the link too. Of particilar interest was the age related Blitter problems (15 years or more of heavy use, applies to all Amiga's from what I can gather).

Is Jens going to remove C4 from the A604N designs I wonder? I don't think he has much choice except to remove the capacitor, but perhaps leave the pads on the board to solder your own in if required. Maybe a toggle switch for C4 would be a good idea so that both cases are covered for when our Amiga's do start to exhibit Blitter ageing.

The capacitor is only a problem when you have an early revision A300 board. These boards have a slightly incompatible memory expansion port as they provide a clock signal where on the later boards the vbb power is.

Since these boards are not as common as later boards I don't think Jens should change anything. A mention of this problem in the product manual would be nice.

Really, this capacitor can be dealt with in a matter of seconds with a pair of pliers or a hot soldering iron