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Faulty Microdisc?

Posted: Fri Mar 02, 2012 8:42 pm
by 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. :-)

Re: Microdisc faulty?

Posted: Fri Mar 02, 2012 9:07 pm
by 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.

Re: Microdisc faulty?

Posted: Fri Mar 02, 2012 9:36 pm
by 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.

Re: Microdisc faulty?

Posted: Sat Mar 03, 2012 12:12 am
by 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 :)

Re: Microdisc faulty?

Posted: Sat Mar 03, 2012 12:16 am
by 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

Re: Microdisc faulty?

Posted: Sat Mar 03, 2012 10:24 am
by 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.

Re: Microdisc faulty?

Posted: Sat Mar 03, 2012 1:04 pm
by Godzil
I really don't like the hole that was made on the microdisk board to access the floppy jumpers...

Image

Re: Microdisc faulty?

Posted: Sat Mar 03, 2012 2:49 pm
by Silicebit.
I think that is a good idea, you can change the number of drive without dismantle all Microdisc.

Re: Microdisc faulty?

Posted: Sat Mar 03, 2012 5:35 pm
by 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.

Re: Microdisc faulty?

Posted: Sat Mar 03, 2012 7:07 pm
by 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
IMG_0859.JPG (174.35 KiB) Viewed 17000 times
IMG_0861.JPG
IMG_0861.JPG (210.17 KiB) Viewed 17000 times

Input of IC5 pin 2.
IMG_0860.JPG
IMG_0860.JPG (164.11 KiB) Viewed 17000 times

Re: Microdisc faulty?

Posted: Sun Mar 04, 2012 11:22 am
by Dbug
I did not realize that phpBB3 came with a built-in attach pictures feature. Cool :)

Re: Microdisc faulty?

Posted: Sun Mar 04, 2012 4:25 pm
by 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.

Re: Microdisc faulty?

Posted: Mon Mar 05, 2012 1:10 pm
by Silicebit.
Dbug wrote:I did not realize that phpBB3 came with a built-in attach pictures feature. Cool :)
Trick, trick. :wink: :D

Re: Microdisc faulty?

Posted: Mon Mar 05, 2012 1:18 pm
by Silicebit.
kenneth wrote: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.

Re: Microdisc faulty?

Posted: Mon Mar 05, 2012 7:26 pm
by 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 ! :wink: