Super agnus adapter fur a500 rev 6

rjd324 · 14 September 2021, 09:33

So for the rj1307 (2mb agnus) [https://www.amibay.com/showthread.ph...00-Amiga-CDTV] I used the following memory: HM514260AJ8 (262, 144-Word x 16-Bit Dynamic Random Access Memory)

And I bought cheap 74f00 and 74F139 from ebay. China/HK.

This is for my rev 6. Other than the difference in memory the components are all in place.

I have soldered the module in place and in the correct orientation. When I boot, I see only 0.5 chip.

I made sure jp2 was bridged across the top and the trace is cut from bottom to mid. Jp7a also has had bottom two trace cut.

I guess it is either

. The memory is not compatible or not working
. The Chinese chips are all lies
. Bad soldering

I doubt it's the mem because I bought that here from a seller. It was originally intended for back up a1200 2b memory but I assumed it would work.

Regards.

jasonsbeer · 15 September 2021, 02:57

Just random thoughts. I am not familiar with that adapter. Have you contacted the seller?

Make sure you are using the correct 8375. They are not all pin compatible. I did not see the Agnus part number mentioned in the BOM. Maybe its shown on the board. Near as I can tell, the project is not documented in a useful way. Did you get any documentation with your purchase?

Quote:

The memory is not compatible or not working

You need to check the data sheets to see if they are compatible with the defined parts.

Quote:

The Chinese chips are all lies

Unlikely. Those are very common logic ICs. They could be defective, though.

Quote:

Bad soldering

Likely if you are not proficient at SMD technique. You need review the schematics and check continuity with a multimeter. Bad solder joints can be tough to spot or intermittent.

8 Bit Dreams · 17 September 2021, 22:28

You need to be careful, there are some SOJ RAM chips that have same footprint but are 3.3v - these will not work, You need 5V, beside of that, check SMD Pins under the microscopescope, a mistake can be done easily at this stage of assembly.... Have built a lot of them in the past:
https://www.amibay.com/showthread.ph...light=Megachip

14 September 2021, 09:33	#1
rjd324 Registered User Join Date: May 2020 Location: NE / UK Posts: 227	Super agnus adapter fur a500 rev 6 So for the rj1307 (2mb agnus) [https://www.amibay.com/showthread.ph...00-Amiga-CDTV] I used the following memory: HM514260AJ8 (262, 144-Word x 16-Bit Dynamic Random Access Memory) And I bought cheap 74f00 and 74F139 from ebay. China/HK. This is for my rev 6. Other than the difference in memory the components are all in place. I have soldered the module in place and in the correct orientation. When I boot, I see only 0.5 chip. I made sure jp2 was bridged across the top and the trace is cut from bottom to mid. Jp7a also has had bottom two trace cut. I guess it is either . The memory is not compatible or not working . The Chinese chips are all lies . Bad soldering I doubt it's the mem because I bought that here from a seller. It was originally intended for back up a1200 2b memory but I assumed it would work. Regards.

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17 September 2021, 22:28	#3
8 Bit Dreams Retro maniac Join Date: Feb 2017 Location: near Munich / Germany Posts: 485	You need to be careful, there are some SOJ RAM chips that have same footprint but are 3.3v - these will not work, You need 5V, beside of that, check SMD Pins under the microscopescope, a mistake can be done easily at this stage of assembly.... Have built a lot of them in the past: https://www.amibay.com/showthread.ph...light=Megachip

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