Good luck with that :)JezC wrote: 13 Mar 2025 15:51The working one doesn't have space for a battery, jut the 4x RAM chips, a switch and some resistor packs...rubber_jonnie wrote: 13 Mar 2025 15:47 Well mine had green goo on the pins, and though I ended up removing the connector to clean in my ultrasonic bath and resoldering, but there was nothing I'd class as bad corrosion and as you know it turned out to be a bad RAM IC on the expansion board.
I'm sure it'll be fine. My clock/RAM board has a CR2032 so should be relatively immune from leakage now.
The other one I'm about to test did have a Varta but has allegedly been repaired...we will see...
:waiting:
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A500 - resurrection or pit of despair?
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rubber_jonnie
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- Posts: 15022
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Re: A500 - resurrection or pit of despair?
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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JezC
- Posts: 2815
- Joined: 28 Aug 2017 23:44
Re: A500 - resurrection or pit of despair?
Thanks @rubber_jonnie
I've removed the metal shield from the other trapdoor RAM and it's now being tested...detected OK as 1/2 MEG slow RAM...
It's up to round 10 of testing already so I'll leave it running for a while to see the results!
:crossed1: :hide1: :waiting:
I've removed the metal shield from the other trapdoor RAM and it's now being tested...detected OK as 1/2 MEG slow RAM...
It's up to round 10 of testing already so I'll leave it running for a while to see the results!
:crossed1: :hide1: :waiting:
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rubber_jonnie
- Site Admin

- Posts: 15022
- Joined: 17 Aug 2017 19:40
- Location: Essex
Re: A500 - resurrection or pit of despair?
Good stuff. Is it an issue 6? If so you can boost the chipram with a trapdoor expansion quite easily.JezC wrote: 13 Mar 2025 16:29 Thanks @rubber_jonnie
I've removed the metal shield from the other trapdoor RAM and it's now being tested...detected OK as 1/2 MEG slow RAM...
It's up to round 10 of testing already so I'll leave it running for a while to see the results!
:crossed1: :hide1: :waiting:
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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JezC
- Posts: 2815
- Joined: 28 Aug 2017 23:44
Re: A500 - resurrection or pit of despair?
Nope Issue 5 B52 Rock Lobster, same as you bought from me.rubber_jonnie wrote: 13 Mar 2025 16:49 Good stuff. Is it an issue 6? If so you can boost the chipram with a trapdoor expansion quite easily.
The other RAM card has now gone through more than 150 cycles (testing both 0.5 Meg blocks) so might be OK...can I be bothered to fit a battery for the RTC on it though?....
I might even get the last A500 out of its box to check if that can be resurrected as well...especially now I appear to have two working trapdoor RAM cards :D
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rubber_jonnie
- Site Admin

- Posts: 15022
- Joined: 17 Aug 2017 19:40
- Location: Essex
Re: A500 - resurrection or pit of despair?
Well mine is a Rock Lobster, but I could have sworn it was issue 6. Will look next time I'm in it.JezC wrote: 13 Mar 2025 17:06Nope Issue 5 B52 Rock Lobster, same as you bought from me.rubber_jonnie wrote: 13 Mar 2025 16:49 Good stuff. Is it an issue 6? If so you can boost the chipram with a trapdoor expansion quite easily.
The other RAM card has now gone through more than 150 cycles (testing both 0.5 Meg blocks) so might be OK...can I be bothered to fit a battery for the RTC on it though?....
I might even get the last A500 out of its box to check if that can be resurrected as well...especially now I appear to have two working trapdoor RAM cards :D
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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rubber_jonnie
- Site Admin

- Posts: 15022
- Joined: 17 Aug 2017 19:40
- Location: Essex
Re: A500 - resurrection or pit of despair?
Good stuff :)JezC wrote: 13 Mar 2025 17:06Nope Issue 5 B52 Rock Lobster, same as you bought from me.rubber_jonnie wrote: 13 Mar 2025 16:49 Good stuff. Is it an issue 6? If so you can boost the chipram with a trapdoor expansion quite easily.
The other RAM card has now gone through more than 150 cycles (testing both 0.5 Meg blocks) so might be OK...can I be bothered to fit a battery for the RTC on it though?....
I might even get the last A500 out of its box to check if that can be resurrected as well...especially now I appear to have two working trapdoor RAM cards :D
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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JezC
- Posts: 2815
- Joined: 28 Aug 2017 23:44
Re: A500 - resurrection or pit of despair?
Maybe I'm struggling to read it properly under the label...but there are 16 RAM chips on the motherboardrubber_jonnie wrote: 13 Mar 2025 17:13 Well mine is a Rock Lobster, but I could have sworn it was issue 6. Will look next time I'm in it.
And I am definitely not an Amiga expert by any means! ;)
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rubber_jonnie
- Site Admin

- Posts: 15022
- Joined: 17 Aug 2017 19:40
- Location: Essex
Re: A500 - resurrection or pit of despair?
Oh, mine has 4 with space for another 4, Typical, I have no photos of that part of the board.JezC wrote: 13 Mar 2025 17:18Maybe I'm struggling to read it properly under the label...but there are 16 RAM chips on the motherboardrubber_jonnie wrote: 13 Mar 2025 17:13 Well mine is a Rock Lobster, but I could have sworn it was issue 6. Will look next time I'm in it.
And I am definitely not an Amiga expert by any means! ;)
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
-
JezC
- Posts: 2815
- Joined: 28 Aug 2017 23:44
Re: A500 - resurrection or pit of despair?
Sounds like I passed you the better one then :)
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rubber_jonnie
- Site Admin

- Posts: 15022
- Joined: 17 Aug 2017 19:40
- Location: Essex
Re: A500 - resurrection or pit of despair?
It's certainly possible.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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