[vcf-midatlantic] TDL SMB Repair Writeup

systems_glitch systems.glitch at gmail.com
Wed Aug 1 10:43:17 EDT 2018

Thanks! I was glad to be able to bring this one back from the boneyard,
hopefully my experience helps others along the way, too.


On Tue, Jul 31, 2018 at 10:35 PM, Douglas Crawford via vcf-midatlantic <
vcf-midatlantic at lists.vcfed.org> wrote:

> 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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