Help with two Orics

If you want to ask questions about how the machine works, peculiar details, the differences between models, here it is !
How to program the oric hardware (VIA, FDC, ...) is also welcome.
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protek
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Help with two Orics

Post by protek » Tue May 29, 2018 6:54 pm

Greetings! A fresh Oric owner and a new member reporting for duty! I recently acquired one Oric and a spare mainboard. Both were fixer-uppers.

First board had no RAM, CPU, ULA, ROM or VIA, but there were sockets for all the missing chips. I got new ULA, CPU and VIA and borrowed 4164 RAM chips from my spare Spectrum, and the ROM from the other Oric mainboard. I checked the 5V line to be within tolerances. The image I’m getting on my Amstrad GT65 is as below. It is also buzzing.
Image

The other one had all the chips accounted for, although I knew it was not working. I got a set of new 4164 RAMs and installed those on sockets. Also removed the ULA, put a socket and tried the new ULA. This one makes a chime (relay click?) upon startup. Picture is as below. 5V line is all right.
Image

Which of the two boards is a better canditate for revival, and what would be the next thing to check out? I have a multimeter and logic probe that I can use.

Thank you in advance!

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iss
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Re: Help with two Orics

Post by iss » Tue May 29, 2018 8:39 pm

Welcome, protek!
I would start with the first one (which has sockets) - at least good text chars are visible.
I tried my crystal ball but no insights... ;)
Can you post pictures of the PCB and your power adapter (mainly its label with data about voltage and current).
You measured 5V line and it's good - you mean the thick track on the PCB, right?

protek
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Re: Help with two Orics

Post by protek » Tue May 29, 2018 9:24 pm

The PSU is a modern, switching multi-voltage adapter that outputs 9 V at 1 amp at least. I’ll provide pics of the board and the PSU. Can’t remember exactly where I measured the voltage but can do it again from the 5V rail.

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ibisum
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Re: Help with two Orics

Post by ibisum » Wed May 30, 2018 1:46 pm

More amps required! I use 1.5A ..

protek
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Re: Help with two Orics

Post by protek » Wed May 30, 2018 9:46 pm

No worries. It outputs 1.7 A at 9V

protek
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Re: Help with two Orics

Post by protek » Wed May 30, 2018 9:51 pm

Here are the pics:

Image
Don’t mind the missing ROM. It’s on the other mainboard atm

Image

Image

The 5V line reads -4.96 V, and in case you’re wondering, the PSU is positive center.

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iss
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Re: Help with two Orics

Post by iss » Wed May 30, 2018 10:46 pm

IMO everything looks nice and nothing suspicious.
Are this tracks OK or it's because the low resolution of picture:
Tiedosto_002.png
Tiedosto_002.png (93.69 KiB) Viewed 530 times
You can check also if the insulator under the 7905 is firmly placed and doesn't short tracks.

protek
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Re: Help with two Orics

Post by protek » Thu May 31, 2018 7:35 am

The traces are all right. It’s just some grime on top of them.

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