Gradiente Expert 1.1 help needed

By LS120

Expert (99)

LS120's picture

20-05-2017, 06:38

does anyone have a schematic of the Gradiente Expert 1.1 i have got most off the net but none show where c68 goes as 1 side is earth but need to know what other side goes to...
oO

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By wernerkai

Champion (357)

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04-06-2017, 00:11

Hello,

You can download it from this page:

MSXPRO Schematics

In the section "Gradiente" there are 6 links regarding Expert 1.1. The last is a "big" file with 308Mb containing all 5 previous parts together.

Regards,

Werner

By wernerkai

Champion (357)

wernerkai's picture

04-06-2017, 00:37

Okay, I've checked directly at the PCB for you. This capacitor C68 is not shown at the schematic.

The terminal near the printer connector (CN10) is connected to GND.

The terminal near the RAM (U13) is connected to the pin 1 of the eight RAMs (U6-U13). This pins is NC at the chips.

If you trace this connection at underside of PCB, it ends in the Jumper J2, which is open.

So this point of the circuit isn't connected to anything.

By LS120

Expert (99)

LS120's picture

09-06-2017, 10:53

the doc's say to connect to these points..

has anyone doe this and have it working??

By LS120

Expert (99)

LS120's picture

09-06-2017, 10:59

what it says to connect is, Centure pin of Sub-1 with jumper removed, the inner contact of C68 and pin 1 of U23 (74ls157)

that's all i know

By wernerkai

Champion (357)

wernerkai's picture

22-06-2017, 05:30

Hello, please can you point your reference (the doc's) ?

At this complete schematic:

Gradiente Expert CPU PCB Schematic

You can see the pin 1 of eight RAMs are connected, but they aren't connected to anything. In the PCB they go to the outside pin of C68, which is at the PCB but is not shown in the schematic.

Pin 1 of U22 and U23 (74LS157) are connected and come from pin 1 of U36. This signal is called /M-SELECT.

Center pin (3) of SUB-1 is connected to pin 2 of same connector by J200. You can see this jumper as naked thick wire at the uppper side of the PCB. This signal comes from pin 12 of U23 and goes to pin 9 of eight RAMs.