Here is my C103225 REV.2 STFM board awaiting mandatory upgrades and 4 Meg upgrade.
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C103225 REV.2
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KD4CBM
- Posts: 1
- Joined: 05 May 2023 23:13
C103225 REV.2
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exxos
- Site Admin

- Posts: 28579
- Joined: 16 Aug 2017 23:19
- Location: UK
Re: C103225 REV.2
:thanksyellow:
One of those odd revisions I don't seem to see very often.
One of those odd revisions I don't seem to see very often.
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MacTech05
- Posts: 69
- Joined: 07 Jul 2022 01:21
- Location: USA
Re: C103225 REV.2
KD4CBM,
That is same motherboard I have in my 1040 STFM. You don't happen to have a schematic specific to the motherboard, do you? I am trying to locate the Reset circuit capacitors so I can replace them.
Thank you
Randy
That is same motherboard I have in my 1040 STFM. You don't happen to have a schematic specific to the motherboard, do you? I am trying to locate the Reset circuit capacitors so I can replace them.
Thank you
Randy
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rubber_jonnie
- Site Admin

- Posts: 15016
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- Location: Essex
Re: C103225 REV.2
From what I can see looking at a bunch of schematics, the reset circuit is much the same across all boards and uses a 556 IC labelled either U2 or U37, so you'll be looking at the electrolytic caps surrounding that and that are connected to it.MacTech05 wrote: 28 May 2024 08:05 KD4CBM,
That is same motherboard I have in my 1040 STFM. You don't happen to have a schematic specific to the motherboard, do you? I am trying to locate the Reset circuit capacitors so I can replace them.
Thank you
Randy
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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MacTech05
- Posts: 69
- Joined: 07 Jul 2022 01:21
- Location: USA
Re: C103225 REV.2
rubber_jonnie,
I will check that out.
Thank you.
Randy
I will check that out.
Thank you.
Randy
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MacTech05
- Posts: 69
- Joined: 07 Jul 2022 01:21
- Location: USA
Re: C103225 REV.2
rubber_jonnie,
Thank you for the info on finding the Reset Circuit capacitors on my 1040 STFM. While I still have not found a schematic for my 1040 STFM motherboard, I did find and download a different 1040 STFM motherboard schematic. Based on your information, I found the Reset Circuit capacitors immediately on the schematic and on my motherboard. I have replaced the capacitors.
Thank you!
Randy
Thank you for the info on finding the Reset Circuit capacitors on my 1040 STFM. While I still have not found a schematic for my 1040 STFM motherboard, I did find and download a different 1040 STFM motherboard schematic. Based on your information, I found the Reset Circuit capacitors immediately on the schematic and on my motherboard. I have replaced the capacitors.
Thank you!
Randy
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rubber_jonnie
- Site Admin

- Posts: 15016
- Joined: 17 Aug 2017 19:40
- Location: Essex
Re: C103225 REV.2
:girldance:MacTech05 wrote: 06 Jun 2024 13:34 rubber_jonnie,
Thank you for the info on finding the Reset Circuit capacitors on my 1040 STFM. While I still have not found a schematic for my 1040 STFM motherboard, I did find and download a different 1040 STFM motherboard schematic. Based on your information, I found the Reset Circuit capacitors immediately on the schematic and on my motherboard. I have replaced the capacitors.
Thank you!
Randy
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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