Faulty Microdisc?

[Silicebit.]

Hi all!

I have two Microdisc and three Atmos. Recently I built a power supply for them, with one jack and two 4 pin DIN connectors (Microdisc style), the PS go out 7.5V 2A and 15V 1A. When I connect Atmos, Microdisc and PS, the Atmos don't boot, all I can see is a screen full of trash.

Photos here: http://www.retrowiki.es/e107_plugins/fo ... 16006.last in spanish only, sorry.

Please, can someone help me? I could solve the problem with ampli-bus perhaps?

Thanks in advance.

[Symoon]

I'm no expert but have you tried without the Atmos' PSU?
The Microdisc is supposed to power the Atmos thru the expansion port.

[Silicebit.]

Thanks Symoon, for the fast reply.

Yes, i tried without the Atmos' PSU too and the Microdisc power the Atmos thru the expansion port, but same results. I forget to say that the two Microdisc don´t work on the three Atmos.

[nobbysnuts]

Hi
I had problems when I rebuilt a couple of drives a few years back and steve marshall sorted me out so you could drop him an email ,from memory your dil switches look in the wrong position on your controller I maybe wrong but its worth a try on row 'A' mine had to be set to 1 on,2 off 3 off 4 off 5 on or off depending on version.
row 'B' 1 off ,2 on 3 off ,4 off others not used

maybe somone still with a drive could confirm this

[nobbysnuts]

also what happens when you hit the red reset button on back of microdisc it should revert to atmos rom as opposed to microdisc

[Silicebit.]

Hi nobbysnuts!

When i press the reset button nothing happen, some times the pattern on screen change, other times no. I tested the flat cables and all ok, i think the problem can be with signal integrity (Phi2) and others, and a unshielded flat cable.

[Godzil]

I really don't like the hole that was made on the microdisk board to access the floppy jumpers...

[Silicebit.]

I think that is a good idea, you can change the number of drive without dismantle all Microdisc.

[Silicebit.]

Hi!

In the article, Réalisez un contrôleur de disquettes pour votre Oric (type Microdisc) part 2/3, from Thierry Bestel, is mentioned a disquette issued quarterly with the Microdisc chronogrammes. Someone has the above mentioned disquette? Please, i'll be very grateful if the holder send me a private message.

Have a nice day.

[Silicebit.]

Hi again!

A pics of Phi2 signal on my oscilloscope:

Output of IC5 pin 18 and input of IC20 pin 1.

IMG_0859.JPG (174.35 KiB) Viewed 17004 times

IMG_0861.JPG (210.17 KiB) Viewed 17004 times

Input of IC5 pin 2.

IMG_0860.JPG (164.11 KiB) Viewed 17004 times

[Dbug]

I did not realize that phpBB3 came with a built-in attach pictures feature. Cool

[kenneth]

the IC5 pin 2 signal has a strange shape.. Normally phi2 provides a square signal shape and a "pull up" resistor of 3.3k is there for that.

[Silicebit.]

I did not realize that phpBB3 came with a built-in attach pictures feature. Cool

Trick, trick.

[Silicebit.]

the IC5 pin 2 signal has a strange shape.. Normally phi2 provides a square signal shape and a "pull up" resistor of 3.3k is there for that.

The 3K3 pull up resistor is lost in my two Microdisc, i'll put them and i'll see the wave again. Also, the IC5 pin 2 signal has a level of, 3 squares * 2 volts per square = 6 Volts???? Mmmm strange.

[kenneth]

The voltage can go beyond 5v if there is a floating potential ( command by a transistor with an "open collector" ) and add a capacitor... the oscilloscope for example !