
is there a schematic for A5000 iss 1 ? , i have the one with IOEB chip
are there any scoop pictures ?
i have a clk signal but amplitude 1 volt ?? on the vidc chip freq looks good 20 ns high, 20ns low but 1 volt ??






TimoHartong wrote: βThu May 30, 2019 4:31 pm
Would it be possible to make a picture of the whole motherboard I can then have a look at the A5000's I have if I have a Issue 1 board. And I would say scoop is a Dutch spelled.
Yes, I have a cathoderay oscilloscope ( actually 3 )
There is a schematic for this PCB. There are two versions of the A5000 TRM, the first version contains the circuit diagram for the early machine, that you have. Both TRMs are available online, although not clearly labelled as to which diagram they contain.
Hi Daniel,
Well I never heard of it being referred to as a scoop before. So I guess so. That or I have lived a sheltered life. As you say in a later post, scope would be more usual. But now I know!
steve3000 wrote: βThu May 30, 2019 5:55 pmThere is a schematic for this PCB. There are two versions of the A5000 TRM, the first version contains the circuit diagram for the early machine, that you have. Both TRMs are available online, although not clearly labelled as to which diagram they contain.
I think I posted up some links to these a few years ago?
Unfortunately on holiday right now with only my phone and nearly no data signal, so I can't easily locate these.
steve3000 wrote: βFri May 31, 2019 6:19 pmTurned out to be easier than I thought to locate. TRM and PCB diagrams linked from my previous postings below. The A5000 PCB diagrams are from Chris' Acorns, and include the pre-IOEB circuits on page 4 of the diagrams "Acorn_A5000TRM_MainPCBCircuitDiagram4of4.pdf"
Hi duikkie,
TimoHartong wrote: βMon Jun 10, 2019 8:32 amHi,
Do you remember on which pin you measured the clk to the VIDC ( LK6 ) ?
Hopefully @duikkie has no more relevant postsElminster wrote: βThu May 30, 2019 6:22 pmWell I never heard of it being referred to as a scoop before. So I guess so. That or I have lived a sheltered life. As you say in a later post, scope would be more usual. But now I know!
And you have loads of responses now. Just most not relevant to your issue![]()
TimoHartong wrote: βMon Jun 10, 2019 2:24 pmOK,
Here some pictures:
The HAMEG used to do the measurements. I didn't feel in that good health to get the tektronix from the shed.
Picture of the probe near the VIDC link. I got the ground from a link nearby. Yes I know that at these frequency the shorter the better, but this was an indicative measurement![]()
The prope is at 10:1 so the voltage is nicely 5 Volts top top.
24 MHz![]()
And the screen.As I said this board has other problems
P.S. I do like the scopes with a real CRT.
The VIDC must be programmed by the ARM before HS/VS will appear.