> On 29 Oct, 2018, at 11:05 pm, dlewis1...@gmail.com wrote: > > Would there a chime at boot if the onboard video was fried?
There are several reasons why the video might not work, and not all of them are detectable by software. The chime mainly means we can eliminate faulty memory or interrupt handling as a potential cause. A completely detached video cable would simply cause the Mac to default to producing a low-resolution, monochrome video signal. The fault may lie in the CRT unit. Powering up simply means that it's receiving power - there is a mains-voltage switch in the IIci's PSU which handles that. If possible, we should verify that correct signals are coming out of the Mac before opening the CRT, but if there is a test mode or an alternative source of compatible video signals, we can use that to isolate whether any faults exist in the CRT. Likewise, there may be a fault in the video signal generator circuitry, more technically known as the RAMDAC. It's possible for the RGB signals to be correctly produced but the sync signals to be missing, and vice versa, and both would result in a blank screen. This mostly consists of a relatively large chip which should be near the video output. Look for circuit board damage or contamination in this area, as well as any faulty capacitors which may previously have been missed. - Jonathan Morton -- -- ----- You received this message because you are a member of the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to vintage-macs@googlegroups.com To leave this group, send email to vintage-macs+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/vintage-macs Support for older Macs: http://lowendmac.com/services/ --- You received this message because you are subscribed to the Google Groups "Vintage Macs" group. To unsubscribe from this group and stop receiving emails from it, send an email to vintage-macs+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
