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#1 2014-08-24 03:57:48

Scott Baret
Member
Registered: 2014-05-21
Posts: 181

The Compact Mac CRT Guide

This is a quick reference guide I originally wrote on May 29, 2007 regarding the different CRTs in compact Macs. I am posting it here so it can bolster our knowledge base. Having worked inside of dozens of compacts, I became quite familiar with the CRTs used and the variations between the tubes and boards used in the 1984-1993 black and white machines. I have done some updates to the original post.

CRTs IN THE EARLIEST MACS

The Macintosh 128K, 512K, Plus, and variations of those machines used the same CRT, which was typically manufactured by Clinton (a Taiwan-based company), although LCGuy found a Samsung in a 128K a few years back. Samsungs seem to be the definite minority here. Early Macs use Connector Type A (see below).

CRTs IN THE MAC SE SERIES

The SE, SE/30, and variations of those machines used the same CRT. Many were manufactured by Clinton but Samsung (based in Korea) made a number of CRTs for these machines as well. There has also been one example of a Toshiba CRT found in an SE manufactured in late 1987. SEs use Connector Type A (see below).

ANALOG BOARDS IN MAC CLASSICS

The analog board design for the Macintosh Classic changed sometime in the first half of 1991. The original is referred to as Revision A on most parts lists. It used Connector Type A (see below). Sometime around the spring of 1991, Classics began to roll off the assembly line with Revision B boards installed. These persisted throughout the Classic II series and were produced until the demise of the line in 1993.

OTHER MAC CLASSIC CRT NOTES

Classics manufactured in 1990 should have Revision A boards. The exact time in 1991 when the Revision B board was introduced is unknown, but it seems to have been introduced first in Singapore. I've seen May 1991 Singapore-produced Classics with Revision B yet I've also seen June 1991 Classics from Ireland with Revision A. Any Classic made from later in 1991 or during anytime in 1992 has Revision B. All Classic IIs have Revision B.

Of the CRTs with a Type B connector, the vast majority are Clinton-produced. Samsungs are less common and, for some reason, seem more prevalent in Classic IIs.

The anode caps changed color for all CRTs, not just Samsungs (which had used darker anode caps in the SE series) sometime in late 1991 or early 1992. They are a darker red in the later Classics as opposed to a pale reddish-purple color in the earlier models.

CONNECTOR TYPE A vs CONNECTOR TYPE B

I term the connectors Type A and Type B after the analog boards they are used with. Connector Type A is clear and relatively boxy. It fits itself into another clear plastic connector on the analog board. To remove it, one must hold in on a tab on the side of the connector. Connector Type B, on the other hand, is white and significantly smaller. The connector isn't bulky and is slightly rounded around the edges. It has four holes on its end and fits over four pins. Type A connectors are the same as those found in pre-Classic Macs.

These two display types are NOT INTERCHANGEABLE.

SWAPPING A AND B (ADDED AUGUST 23, 2014)

It is entirely possible to swap out the analog board and CRT between older and newer Classics. A Classic II will work fine with a donor board and CRT from a Type A Classic.

Since many good machines these days are built from combining other computers, be sure to actually open the Mac to check the analog board, even on a Classic II.

COMPATIBILITY SUMMARY

TYPE A: 128K, 512K, Plus, SE, SE/30, Early Classics

TYPE B: Later Classics, Classic II

NOTE: All Classic notes assume original CRT and analog board.

CLINTON VS SAMSUNG

There is no functional difference between the two, although Samsungs tend to have a different hue of white to them than their Clinton counterparts; it seems the slightest bit bluer to the very observant human eye if put side by side. Clintons were made in Taiwan, Samsungs in Korea.

THE TOSHIBA CRT (ADDED AUGUST 23, 2014)

In April 2013, I bought a Macintosh SE which appeared extremely ordinary on the outside. Inside, I was in for a surprise. The CRT was neither a Clinton nor a Samsung, but a Toshiba. The circle of red paint around the anode cap was far greater in diameter than either a Clinton or a Samsung. The CRT had model number E2728B4-TCOISDHT and was manufactured in Japan.

I believe this CRT to be either a replacement or a short-lived deal if supplies from Clinton or Samsung were low. Functionally, the Toshiba CRT is identical to the Clinton/Samsung in every aspect.

WHY THE SWITCH BETWEEN ANALOG BOARDS?

Apple usually has good reason for changing designs of components. The switch from squirrel cage to rotary fans in the SE is an example of this--those who have been with Macs long enough know of the noise and screen interference problems caused by those fans.

In the case of the analog board, I have a few theories. One is that Revision A boards tend to be less reliable, especially in the long run. I've seen more of these with some sort of screen problem (jittering, lines, etc) than of Revision B boards (which seem to be pretty sturdy).

Another theory is that Apple wanted to use up older connectors from Pluses and SEs. The SE was actually still in production through the first few weeks of 1991 despite having been formally discontinued (I once had an SE with a 1991 date to verify this and have seen several other SEs from January 1991). They may have been in production to use up older parts. At the same time, Apple was still producing the SE/30. Since the SE/30 was going to be on its way out and replaced by a more cost-effective machine (the Classic II), Apple may have been using up parts like the CRT connectors on the SE with the eventual intent to switch to the newer design, which is believed to have been cheaper.

There is also the theory that they switched due to cost reasons but the SE had nothing to do with it. The SE/30 was stlll alive and well in May-June 1991 and was never produced with a Type B connector.

CAN I MODIFY A TYPE A FOR A TYPE B BOARD?

I've heard it's possible but is supposed to be tricky. Good luck if you try to pull it off. I don't have any directions for this.

WHO OR WHAT IS CLINTON? (UPDATED AUGUST 23, 2014)

Clinton is an electronics company specializing in applied display technologies. It's interesting to note they have, as of August 2014, a 9" CRT monitor available on their website: http://www.clintonelectronics.com/store/CE-MM9.html

CAN I PUT A COLOR CLASSIC CRT INSIDE A CLASSIC, PLUS, SE, OR EARLIER CASE? (UPDATED AUGUST 23, 2014)

The short answer: it won't fit.

The long answer: modify like none other.

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#2 2014-08-24 04:57:21

LCGuy
Administrator
From: Sydney, Australia
Registered: 2014-05-13
Posts: 821

Re: The Compact Mac CRT Guide

Good to have this here as well. smile But yeah - my 128k is back at my parents place up in Queensland, provided I fly home for Christmas this year I'll pull the back off and get a pic. smile

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#3 2014-08-25 02:06:40

jt
Member
From: Bermuda Triangle, NC USA
Registered: 2014-05-21
Posts: 1,408

Re: The Compact Mac CRT Guide

Very nice, love the write-up. I try to learn new stuff every day, it's great to start doing it more here! wink

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#4 2014-08-25 03:44:00

Scott Baret
Member
Registered: 2014-05-21
Posts: 181

Re: The Compact Mac CRT Guide

I'll snap some pics of that Toshiba CRT next time I'm at my mom's place where it's currently being stored.

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