Search found 24 matches

by Equinoxe
Tue Mar 19, 2019 5:48 am
Forum: Technical questions
Topic: Oric Atmos Won't Initialise
Replies: 18
Views: 4277

Re: Oric Atmos Won't Initialise

I have access to oscilloscopes at work (or rather, the people I work with have access to them) so I could probably ask one of our techs to have a look at the Oric (which I'm sure would generate some curiosity since they were never sold in North America) I was first trying to do it myself with my lim...
by Equinoxe
Mon Mar 18, 2019 5:29 am
Forum: Technical questions
Topic: Oric Atmos Won't Initialise
Replies: 18
Views: 4277

Re: Oric Atmos Won't Initialise

Thanks so much to everyone for the help so far - I was hoping there were some easy tests that would avoid putting this machine 'under the knife' by way of cutting traces but if that's what's needed to give another 35 years of life I'm willing to do so. Before I go down that route, on the topic of RA...
by Equinoxe
Sat Mar 16, 2019 5:00 pm
Forum: Technical questions
Topic: Oric Atmos Won't Initialise
Replies: 18
Views: 4277

Re: Oric Atmos Won't Initialise

I checked the reset switch and that's good. I also checked the voltage for the 6502 IRQ and NMI lines and read 4.85v and 4.75v respectively. I also checked the resistance across the 5v rail and read 160 Ohms. I also did a memory chip piggy back test with no change on the display. I have spare ICs on...
by Equinoxe
Sat Mar 16, 2019 3:24 am
Forum: Technical questions
Topic: Oric Atmos Won't Initialise
Replies: 18
Views: 4277

Re: Oric Atmos Won't Initialise

None of the chips are getting hot - just the 6502 and 6522 get slightly warm after a few minutes - any suggestions on how I might be able to determine which chip may be at fault?
by Equinoxe
Sat Mar 16, 2019 1:17 am
Forum: Technical questions
Topic: Oric Atmos Won't Initialise
Replies: 18
Views: 4277

Oric Atmos Won't Initialise

I have another eBay special (i.e. project Lazarus) that I'm hoping to resurrect - It's showing the usual memory initialisation pattern at startup (see pic) but goes no further. Voltage at output of 7905 is 4.85v (Input is 9.15v using a 2a modern PSU). The regulator heatsink is too hot to touch withi...
by Equinoxe
Thu Mar 14, 2019 5:10 am
Forum: Technical questions
Topic: Replace XT1 and XT2 crystals
Replies: 12
Views: 3019

Re: Replace XT1 and XT2 crystals

That sounds about right. This machine had a repair sticker from a radio shop so I'm wondering if the XTAL was harvested for another project (im hoping that's the most significant fault) incidentally do you have a similar diagram showing the 5v rail by any chance so that I can check continuity while ...
by Equinoxe
Tue Mar 12, 2019 7:06 pm
Forum: Technical questions
Topic: Replace XT1 and XT2 crystals
Replies: 12
Views: 3019

Re: Replace XT1 and XT2 crystals

Many thanks I've ordered the crystal and will post updates on progress as it's made. In the meantime I've attached pictures of the mobo in question and I'm curious if anyone has any thoughts on why the underside of XTAL2 looks in bad shape and also what the two extraneous solder additions might have...
by Equinoxe
Mon Mar 11, 2019 1:59 am
Forum: Technical questions
Topic: Replace XT1 and XT2 crystals
Replies: 12
Views: 3019

Re: Replace XT1 and XT2 crystals

Thanks very much for the quick reply - You mention different types but the service manual simply states 'XTAL 12MHz' so I'm guessing it would be the most common option (most places I'm looking for these don't seem to state the type - simply '12Mhz Crystal 'x' package and 'x' tolerance') - Do you thi...
by Equinoxe
Sun Mar 10, 2019 8:07 pm
Forum: Technical questions
Topic: Replace XT1 and XT2 crystals
Replies: 12
Views: 3019

Replace XT1 and XT2 crystals

First I have to say thanks to Dbug and the Oric community for creating such an amazing Oric resource - I never would have imagined my first computer from 1984 would still be so enthusiastically supported in 2019! On that topic I imported a couple of dead Orics recently to Canada both of which were d...