[vcf-midatlantic] TDL SMB Repair Writeup

Douglas Crawford touchetek at gmail.com
Tue Jul 31 22:35:26 EDT 2018

On 7/31/2018 10:32 PM, systems_glitch via vcf-midatlantic wrote:
> Last October, I traded Herb Johnson for two TDL SMB boards that had been
> stripped of all socketed parts, and even some of the soldered-down ones!
> Here's my writeup on the repair process:
> http://www.glitchwrks.com/2018/07/31/tdl-smb
> Both boards had an etch error that shorted the +5V rail to ground! This is
> presumably why they ended up in the TDL boneyard. Herb had acquired them
> stripped of all parts from a former TDL employee, presumably someone
> plugged it in, noticed the power draw, and moved on to the next board. I
> found the short by stripping one board of its sockets and bisecting the +5V
> rail with trace cuts. The short was hidden under silkscreen, making it
> invisible.
> In the process, I did two things that will probably be useful to other
> people here: I designed a replacement board for the SEMI 4804 SRAMs, which
> are unobtainium, and I reproduced the Interface One and Interface 2 I/O
> breakout boards. All will be available through my Tindie store as I get
> time to photograph and list them, but if you're in need of them now, send
> me an email!
> The writeup also covers the cuts and jumps necessary to use 2716 EPROMs
> instead of the mask ROM that TDL originally supplied with the SMB. There
> are pictures of my modifications, with the cut areas circled for clarity.
> Thanks,
> Jonathan
As usual, awesome job there, Jonathan!

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