520 STFM C070789-001 Rev F2

Blogs & guides and tales of woo by forum members.
friijy2001
Posts: 77
Joined: Sun Jan 17, 2021 1:34 pm

520 STFM C070789-001 Rev F2

Post by friijy2001 »

Hi everyone,

Another one I am tinkering with and this one seems to boot but opened her up before I look at doing the fixes.

51200390919_5ba4bda106_z.jpg
51200390919_5ba4bda106_z.jpg (133.24 KiB) Viewed 3552 times

I have a couple of questions if someone on here who may have a similar board could answer?
  1. This is a 2 CHIP TOS version 1 so want to upgrade to TOS 1.4 and noticed some extra wires around the TOS chips, I was going to buy a set 6 chip TOS chips, remove the wires and just solder them in to the sockets. I am assuming the wires are to convert to a 2 chip version so just removing them will be fine?
  2. It looks like it has been upgraded to 1MB but seems to be missing the capacitors next to the chips, I was just going to add these in. Is there any reason they are not soldered on the board? any thoughts?
Hope that all makes sense :)
Call me Stephen :)
User avatar
PhilC
Moderator
Moderator
Posts: 7504
Joined: Fri Mar 23, 2018 8:22 pm

Re: 520 STFM C070789-001 Rev F2

Post by PhilC »

(Just moved this into the blog forum as its not really a hardware issue topic}
If it ain't broke, test it to Destruction.
friijy2001
Posts: 77
Joined: Sun Jan 17, 2021 1:34 pm

Re: 520 STFM C070789-001 Rev F2

Post by friijy2001 »

PhilC wrote: Mon May 24, 2021 11:47 am (Just moved this into the blog forum as its not really a hardware issue topic}
Thank you Phil, still finding my way around :)
Call me Stephen :)
User avatar
exxos
Site Admin
Site Admin
Posts: 28616
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: 520 STFM C070789-001 Rev F2

Post by exxos »

@friijy2001 could you upload the image onto the forum please, and upload a higher resolution as we cannot see where that wire is connected, but probably a track repair.
friijy2001
Posts: 77
Joined: Sun Jan 17, 2021 1:34 pm

Re: 520 STFM C070789-001 Rev F2

Post by friijy2001 »

exxos wrote: Mon May 24, 2021 11:49 am @friijy2001 could you upload the image onto the forum please, and upload a higher resolution as we cannot see where that wire is connected, but probably a track repair.
Please find attached, it may be larger than the forum but hope you can see it. If all else fails I will take a zoomed image later and make reference to the PIN numbers

Large image of mobo
Large image of mobo
834E2C76-0259-439B-A4C7-00548C168FA4.jpeg (981.41 KiB) Viewed 3536 times
Call me Stephen :)
User avatar
rubber_jonnie
Site Admin
Site Admin
Posts: 15027
Joined: Thu Aug 17, 2017 7:40 pm
Location: Essex
Contact:

Re: 520 STFM C070789-001 Rev F2

Post by rubber_jonnie »

friijy2001 wrote: Mon May 24, 2021 1:12 pm
exxos wrote: Mon May 24, 2021 11:49 am @friijy2001 could you upload the image onto the forum please, and upload a higher resolution as we cannot see where that wire is connected, but probably a track repair.
Please find attached, it may be larger than the forum but hope you can see it. If all else fails I will take a zoomed image later and make reference to the PIN numbers

834E2C76-0259-439B-A4C7-00548C168FA4.jpeg
I've edited to be an inline image rather than an attachment, as this is preferred.
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...
friijy2001
Posts: 77
Joined: Sun Jan 17, 2021 1:34 pm

Re: 520 STFM C070789-001 Rev F2

Post by friijy2001 »

It seems like the wires connect the lo TOS pins to various parts of the board.
Call me Stephen :)
Steve
Moderator
Moderator
Posts: 3334
Joined: Fri Sep 15, 2017 11:49 am

Re: 520 STFM C070789-001 Rev F2

Post by Steve »

1 - I would buy a TOS switcher. They look socketed, so super-easy job, why make work for yourself.
2 - I would install the caps, they are available on exxos store
User avatar
stephen_usher
Site sponsor
Site sponsor
Posts: 7454
Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
Contact:

Re: 520 STFM C070789-001 Rev F2

Post by stephen_usher »

Those bodge wires looks as though someone's removed the original sockets and broken some traces.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
friijy2001
Posts: 77
Joined: Sun Jan 17, 2021 1:34 pm

Re: 520 STFM C070789-001 Rev F2

Post by friijy2001 »

stephen_usher wrote: Mon May 24, 2021 2:37 pm Those bodge wires looks as though someone's removed the original sockets and broken some traces.
Thank you for this, I just noticed the 2 chip 1.4’s are out of stock at present. Can these be re-wrote on mine or shall I just wait for them to come back in stock?
Call me Stephen :)
Post Reply

Return to “MEMBER BLOGS”