Wednesday January 26, 2011

Attendees: Bill Newman,  Bob Erickson,  Ed Thelen, Frank King, George Ahearn, Glenn Lea, Joe Preston, Ron Williams, Stan Paddock and Judith Haemmerle

Joe Preston has made the third IBM 727 tape drive on the German machine wake up and almost load tape. Getting close to trying to read and write tape.

The IBM 1403 printer on the Connecticut system will pause the ribbon while printing and thereby cut a row into the ribbon. The ribbon supply and take up on the IBM 1403 is simple so that very few IBM CEs have ever had to work on it. That is what Frank King said when he started to work on the IBM 1403 of the Connecticut system

Well if I take it apart, maybe it will look like an IBM 026 keypunch

Well if I can't see what is going on, maybe I need more people on my team.

Well maybe I can get the whole team to see what is going wrong.

OK, maybe I should look at the mechanical drawing to see if I have missed anything.

By the end of the day we think it may be fixed. Since it only fails every 3 to 6 weeks, we should know if it is fixed when we pay our taxes.

Bill Newman and most of the rest of the team have been working on the Connecticut IBM 1402 almost since it came in. It will generate random read checks with a good deck.

We narrowed it down to cards with a large number of punches in the same row. Like 60 or more '9' punches in one card.
At Ron Williams suggestion, a jumper was moved up to the next voltage level. This helped a lot but was not the final solution.

The problem was further traced to the first read station. When there were over 60 '9' punches in a row, the roller was not being drawn all the way to ground.

We examined the brush that is used to ground the roller and found it was worn and not in the proper place. Corrected that and things were better.


We suspected the transistor that is suppose to ground the roller. While we did not have a ready source for the transistor, we bought a silicon transistor and wired it in place of the original.
When we ran the test program, we had no errors.
We wired the original transistor back in place. 
Failures again.
Bill Newman wanted to make sure it was not the final transistor that was the problem.
He removed the first transistor in the pair and one of the spade lugs fell off in his hand. (See picture above.)
While trying to add a new spade the second and third wires fell off the transistor.
Luckily, we had a spare for this transistor.
We tried it again with the original power transistor and still had errors.
We put the silicon transistor back in the circuit and have ordered a true replacement for the original power transistor.
We believe the random read problem with the Connecticut system has been identified and will be soon corrected. Until the transistor is replaced, the system is usable.

That is if the IBM 1403 ribbon transport unit is fixed.

Stan

Saturday, January 23, 2011

Attendees: Ron Williams, Bob Erickson Jim Hunt and Stan Paddock.

Work continues on the problem with the Connecticut 1402 card reader. Bob Erickson and Ron   Williams examine the power transistor of the first read roll.

Now that Jim has a full time job, his only time he can spare for the CHM is Saturdays. Here he is finding and fixing a problem with a power supply.


Stan

Wednesday, January 19, 2011

Attendees: Ron Williams, Bob Erickson, Robert Garner,  George Ahearn, Stan Paddock,  Frank King, Don Luke,  Bill Newman, Joe Preston, Ed Thelen and Allen Palmer

 

 

Ron Williams, Bob Erickson, George Ahearn, Bill Williams and Don Luke continue working on the Connecticut IBM 1401. The common brush for the first read station was replaced and a test transistor was placed in the circuit. While the machine is doing better, it is still not fault proof.

 

Joe is continuing to bring the third IBM 729 tape drive on the German machine back to life.

 

 

Ed thalen and Frank King continue to do what they do best.

 

Wednesday January 15, 2011

Attendees: Ron Williams, Bob Erickson, Robert Garner,  Stan Paddock,  Frank King, Don Luke,  Bill Newman, Joe Preston, Ed Thelen and Allen Palmer

Allen Palmer worked with Joe Preston on the third tape drive of the German system. A problem with the head mechanism was fixed.

Joe went back working on other problems with that tape drive while Allen continued his work on the right reel brake on the second tape drive of the same system.

Ron Williams, Bob Erickson, Bill Newman and Stan Paddock continued to work on the card read problem of the Connecticut machine. 

At Ron's suggestion, the voltage of the -20 volt power supply was raised one tap. This made a significant difference in the performance. The errors at the second read station disappeared. 

We still had errors reported and they were every other line. Suspect X or Y plane errors. 
The two wires were switched to use the first read station to be switched with the second.
Now the characters were not being read into memory correct.

At Bob Erickson's suggestion, we checked the brushes that provide ground to the first read contact roller. It was worn and only one of the two brushes was in contact with the roller. 

We are in the process of installing new brushes and will finish the job next week.

Saturday, January 8, 2011

Attendees: Ron Williams, Bob Erickson and Stan Paddock.

Stan finished cleaning, lubing and re-assembly of the ribbon feed mechanism on the Connecticut machine.

Bob and Ron tried to identify the problem on the German machine. A fast continuous read of cards runs without error. If there is a print between the card reads, there is a read error on the 1402 card reader. To be continued.

Jim Hunt came in and looked into some of our failed cards. He also brought a power supply back to life.

(END)

Wednesday, January 6, 2011

Attendees: Ron Williams, Bob Erickson, Robert Garner, George Ahearn, Stan Paddock, Frank King, Don Luke, Douglas Martin, Bill Newman, Joe Preston, Ed Thelen, Allen Palmer and Ron Crane

Joe Preston gets up close and personal with the number three tape drive for the German Machine. 

Allan Palmer is rebuilding a brake assembly for the number two tape drive on the German machine.

Bob Erickson shows off his skills with the IBM 083 card sorter.

Ron Crane, Dough Martin and others are working on the long term problem with reading cards on the Connecticut machine. We have a program and deck that can cause the machine to fail on demand. We are now trying to identify what part of the circuits are causing the failure.

The IBM 1403 printer on the Connecticut machine has, in the past, stalled the printer ribbon. This puts a series of holes in the ribbon. This situation occurred on Wednesday. We believe it is a weak ribbon drive mechanism. Stan started taking the mechanism apart to find the problem.


(END)