![[SE video board]](sevideo_2.jpg)
This page was most recent revised date Nov 26 2023.To contact me or to order, please follow this link for ordering information, terms and conditions, and info about orders outside the USA.
Due to customer requests, I've done some research on Mac SE and SE/30 video boards. The video board is a PC board on the end of the CRT, cabled to the
analog card. It provides the video signal to the CRT, routed from the CPU board. The construction of the video board has changed over the
time the SE and SE/30 was produced. This note describes different models and those changes. To obtain these boards, check my Compact Macs Web page, SE and SE/30 section.
The 820-0205 630-0146 video board, sits "horizontal", that is the long side of the board is horizontal. That means the edge is closer to the fan assembly on the Mac SE analog card. The original SE fan was a "squirrel cage" or cylindrical fan.
The 820-0207-A (and -C) 630-0169 video board sits "vertically" in the SE chassis. Again, the long side mount vertically. When Apple changed the analog card fan to an "axial" or five-blade fan, there was little clearance to the horizontal video board. So Apple redesigned the video card to mount vertically. The SE/30 has the same axial fan analog card, and same vertical video card.
Here's photos of these SE, SE/30 video cards and how they mount.
The pin end of the CRT on the SE shows the CRT pin orientation, with the top of the photo as the top of the SE CRT from the back.
Shows the two video boards I describe above. One used, one apparently unused in an antistat bag. They are oriented one vertical, one horizontal. Look at the CRT socket, the orientation of its pin-sockets. They mirror the pin end of the CRT in the previous photo.
The back of the "0205" card as mounted shows its horizontal mount. Observe how close it is to the axial fan.
The back of the "0207" card as mounted shows its vertical mount.
One Apple Service Manual for the Mac SE, mentions the SE "vertical" video board as providing "adequate vibration clearance" from the axial fan. The photos above show that clearance.
The SE Service Manual also mentions replacement video boards have a "ferrite bead" on the cable. Apple recommends updating the SE video card to a card with that ferrite bead. Ferrite (a hard grey ceramic) is used around cables to act as a high-frequency filter (by inductance, like a coil) wherever there's RF signals. Such signals are generated by the high-voltage flyback and the switching analog power supply.
On inspection, my used vertical boards are either "820-0207-C" models with one-piece ferrite bead on each cable; or "820-0207-A" models without that ferrite. The bead is a ceramic grey cylinder about 1" long, 1/2" diameter.
I have one "unused old stock" 820-0205 horizontal board. It has a ferrite bead in the form of a clamp-on model. Also, one *used* horizontal 820-0205 board, in my test SE, does *not have* a ferrite bead on its cable. Apparently, Apple added the ferrite as a mod for the older video board cable, and on later boards assembled the bead on the cable at the factory.
As far as circuit differences between the two video boards? Visual inspection suggests they have the same parts, same values, but rearranged. Schematics are very hard to find. I found two, one produced by Apple, by Web search.
This linked site has a SE schematic set, under the title: "MacSE_Schematics.zip, (3.2 MiB / 3.36 MB) / Zipped"
The two schematics appear by my inspection to show the same parts, same values, same connections and wiring. I've snipped out the video board schematic in this image. The ferrite bead is not shown in the schematic, the cable is described by colors of wires.
- Herb Johnson
When ordering, please follow this link for
ordering information, terms and conditions, and info about
orders outside the USA.
Copyright © 2023 Herb Johnson
Herb Johnson
New Jersey, USA
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