ALPHA MODIFICATIONS

[exxos]

i can see all the chips have a decoupling capacitor,,, but what about BAD DMA ? is there one and where? or is it not necessary?

Theres 4 caps around the DMA already.. no need to add a 5th.. :)

[PhilC]

For the sync fix I pulled both pins 8 and 9 out of the U51 socket and then jumpered the socket.

[kodak80]

For the sync fix I pulled both pins 8 and 9 out of the U51 socket and then jumpered the socket.

Do you have a photos of the change for us less technical builders? And did this resolve the sync problem?

[PhilC]

Hopefully you can see it on here.

It didn't sort my sync problem but will work on that.

[exxos]

For the sync fix I pulled both pins 8 and 9 out of the U51 socket and then jumpered the socket.

You shouldn't pull pin 9 because you will have 2 floating gates in the chip then due to disconnected inputs.

[PhilC]

Ok will put 9 back in, good point

[exxos]

BR PULL UP FIX

Bodge wire 1... Wire the thick yellow drawn wire as shown on the back of the pcb...

(Fixing missing pull up resistor on BR).

bw1.jpg

[exxos]

BGACK PULL UP FIX

Bodge resistor 1..... 2.2K between the 2 circled points on back of CPU socket...

(fixes missing pull up on BGACK)

f2.jpg

[troed]

Bodge resistor 1..... 2.2K between the 2 circled points on back of CPU socket...

I'm confused by this being connected to BR.

[exxos]

I'm confused by this being connected to BR.

Its a missing pull up resistor on BR & BGACK.