![]() |
![]() |
#21 |
Registered User
Join Date: Dec 2018
Location: UK
Posts: 1,716
|
And yes, I also think that information out there is being mixed with the onboard chip ram mod, which requires a change to JP7A to prevent any expansion ram conflicting with it.
|
![]() |
![]() |
#22 | |
Registered User
Join Date: Oct 2020
Location: Brighton England
Posts: 15
|
Quote:
Instead of using the amiga power unit to ground the board which might not have been working as desired I should clip a wire on a ground section of the MB and have that run directly into the mains ground pin. All elementary stuff but I guess I've just gotten slap dash with an 'ah it'll be alright' attitude. On a side note, my new populated motherboard came wrapped in just bubble wrap yesterday!!! It worked but you'd think that would have been a recipe of disaster. |
|
![]() |
![]() |
#23 | |
Registered User
Join Date: Oct 2020
Location: Brighton England
Posts: 15
|
Quote:
If I've understood this correctly then I think I'm done here! Even if I don't get this mod working, I was keenly seeking the knowledge over the result. The result would be DEAD handy and is what I want but now I'm spooked. Thank you so much for you help with this and your replies. I know that I went VERY VERY long with my explanations but I really want to gain 100% knowlege of the Amiga one day both HW and SW and although my questions may seem tedious to the very much indoctrinated Amiga modder, this stuff really helps me on the path. I will be sure to properly read the Amiga Hardware manual along with the schematics and hopefully some day 100% know this system's every knook and cranny. Thanks! |
|
![]() |
![]() |
#24 | |
-
Join Date: Jul 2003
Location: Helsinki / Finland
Age: 43
Posts: 9,923
|
Quote:
Yes, it has a pullup near the gary socket. |
|
![]() |
![]() |
#25 | |
Registered User
Join Date: Dec 2018
Location: UK
Posts: 1,716
|
Quote:
|
|
![]() |
![]() |
#26 | |
Registered User
Join Date: Dec 2018
Location: UK
Posts: 1,716
|
Quote:
Apologies. I was was testing with a memory expansion that has an on/off switch, and it was on the off position, which effectively made the _EXTICK/_EXRAM signal floating, which means it is HIGH. So JP7A doesn't need to be cut ONLY if the expansion ram does have an on/off switch (which needs to be OFF, to make _EXTICK/_EXRAM go HIGH). Otherwise, yes, it needs to be cut to make _EXTICK/_EXRAM float and go HIGH). |
|
![]() |
![]() |
#27 | |
Registered User
Join Date: Oct 2020
Location: Brighton England
Posts: 15
|
Quote:
Funny this whole modding thing, I had planned that it was going to be a 30 min job max and it's cost me a week BUT it has meant that I have finally engaged in this forum despite being a lurker for what could easily be 15 years! (I would have definitely visited here in 2005 if not earlier). So in some strange way I'm glad I bollocksed this up and got to meet you all. Once again, thank you ALL for engaging in this mod. I have learnt a lot even though the end result wasn't in my favour. |
|
![]() |
![]() |
#28 |
Registered User
Join Date: Oct 2020
Location: Brighton England
Posts: 15
|
The latest update on this:
Measured voltage of my soldering iron tip to mains ground and got a fluctuating reading of 0.03V. That's perhaps enough to zap something. After connecting the ground pin of my iron to mains ground the voltage reading of the tip to mains ground was 0V. So I undid the bodge wires on JP7A, jumpered the top two pins, repopulated the board (but missing even CIA), connected the trapdoor expansion. * Boots up and flashes dark grey light grey repeatedly. I think that's what happens when Agnus cannot see the expansion... Jumpered the lower two pins of JP2, removed expansion. * Boots up to light grey and screen flickers slightly every second. Although JP7A is floating therefore in a expansion disabled state, without an expansion board I'd expect it to boot at least. Also I managed to get my unmodded REV6 board to boot with the same set of chips before repopulating the modded one so it's possible I've zapped something on the motherboard itself. I've just received two good CIAs in the post and I put them in my 3rd Rev6 board along with the expansion and I'm seeing 512k / 512k with all systems working so I can confirm the expansion is fine. I guess if I repopulate my 2nd Rev6 with everthing from my modded Rev6 and it still boots then assume something on MB is zapped and either attempt the mod on my 2nd Rev6 or just give up because I'm spooked. |
![]() |
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
Thread Tools | |
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
a500 rev 5 1mb chipmem mod... confused | kipper2k | Hardware mods | 104 | 18 August 2023 09:33 |
A500 Rev5 1Mb Chip Ram Mod | gurth | Hardware mods | 13 | 07 July 2023 13:46 |
A500 rev 8a no boot after 1mb mod | timmyotool | support.Hardware | 0 | 03 March 2019 17:25 |
A500 plus 2MB mod, what am I doing wrong? | avinitlarge | support.Hardware | 15 | 18 June 2016 09:58 |
A500 1mb upgrade chips available | kipper2k | support.Hardware | 7 | 13 August 2012 20:05 |
|
|