How to use Extron sync hardware with the X68000

[TD-Linux]

The X68000 sync lines are a bit strange - they are open collector, with a 1k pull up resistor. This is too weak for some hardware, including Extron sync combiners like the 192. These use a 510K pull down resistor. Luckily, this can be easily fixed. Remove the 5 body screws, plus BNC and VGA nuts, and pull out the PCB. Look for two resistors labeled 511 - R84 and R85 in this case - and remove them. This won't affect using the Extron with other sources.

When shopping for Extron boxes, make sure to find ones that go down to 15Khz. The 192/198/etc are fine, avoid the SS 200 and similar.

[hyrulebr]

Hi, I use now a Extron 580xi to joint sync to a bvm (15khz) but in the past used a couple of others extron models with sucess. Do you think that only model 192 requires this mod?

What happens when you use the 192 without modification? No signal at all?

[TD-Linux]

It's possible that later Extron models improved the sync sensitivity, or changed their internal termination.

An unmodified 192 will fail to see the sync signals (orange LED). A SS 200 doesn't have an indicator but will likewise not output any sync signals.

[Jehuty]

Could this be used on an Extron VSC500 ? The VSC500 doesn´t sync with the X68000 while it does with an FM TOwns.

[hiker]

VSC500 spec sheet mentions sync input impedance of 600 Ohm, so might work.
I recently replaced 510 Ohm resistors of a 203 Rxi with 10k Ohm because it didn't sync with X68k and I saw in the manual of other Extron devices that some have a switch to toggle between 510 Ohm and 10 kOhm.

[incrediblehark]

Interesting if it does work with the VSC500... I  have a VSC700 that I may need to try this with