Re: New small sized MOS8701 replacement

From: Jim Brain <brain_at_jbrain.com>
Date: Fri, 10 Jul 2020 15:02:18 -0500
Message-ID: <1a7291ed-746d-4e97-41e9-936f5448e9b1_at_jbrain.com>
On 7/10/2020 1:17 PM, Jeffrey Birt wrote:
>
> I have been working on a MOS 8701 clock chip replacement that is just 
> a bit bigger than the original so it will fit into a C128 with the RF 
> shield cover in place.
>
> The design is based on Frank IZ8DWF's design from one of his videos. 
> The PCB size is about 0.5"x0.9" with the holes on 0.4" centers. This 
> was needed to make room for the SSOP28 clock chip.
>
> The 0.4" spacing required making a fixture to custom bend some leads 
> into a 'Z' shape. And another fixture is used to align the leads for 
> soldering. To make it even more fun the resistors and caps are 0603 
> size which is about as small as I care to do without a proper 
> microscope. I built the first board this morning and it works!! It 
> takes a fair amount of time to build one of them, and you need the 
> special fixtures for the leads, but it was an interesting challenge.
>
> This version of the PCB uses cut pads to configure NTSC or PAL. I have 
> a new design that should do this automagically. I should have some of 
> those PCBs in a few weeks for testing.
>
> _at_IZ8DWF – Frank when I am able to confirm that PAL works, I will send 
> you some completed units, gratis.
>
> Links to images
>
> https://1drv.ms/u/s!AtH4vpaZnzX7kvswntJpVdEm6W-OrQ?e=4wnmac
> https://1drv.ms/u/s!AtH4vpaZnzX7kvsts_rsv_eTHoKL7w?e=TlqTnX
> https://1drv.ms/u/s!AtH4vpaZnzX7kvsuRF1lVXL5UNJLgA?e=NjEhZa
>
> Jeff Birt (Hey Birt!)
>
I can't find a picture at present, but I buy surface mount IC headers 
from a source in Asia that has a DIP 16 footprint.  If you are 
interested, I can get some more information.


-- 
Jim Brain
brain_at_jbrain.com
www.jbrain.com
Received on 2020-07-10 23:00:03

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