Mark IV Troubleshooting 1: RA drive problems

Correspondence between Arne Henden and Tom Droege

Date: Wed, 24 Jan 2001 19:32:39 -0600
To: Arne Henden
From: Tom Droege 

>Tom,
>   I've made the mods to the motor board, but am having trouble
>with the cabling.  I think I have the limit switches hooked right,
>as well as the steppers.  The power connector can go in either
>of the 9pin headers, right?

Yes, either one.

There is a set of 4 pages in the documentation that I left. These are xeroxed pages out of my log book and are numbered (log book pages 148 to 151. These show the colored wire used for most of the little push on connectors. There is a drawing on p-149 that lets you get oriented.

>   The temperature sensor headers are confusing.  They are labelled
>0-3.  We have a sensor hooked to #2 that is 'available', with
>the thought to use it for outside temp or tube temp.  I see one
>cable that looks like it is attached to a sensor, mounted on the
>back, on a block that the cooling water passes through.  I assume
>that reads the cooling water temp, right?  which position does
>it go to?  I seem to recall there was one of the 4 that caused
>a short or loading.

The water temperature goes to the temp 0 connector. This is the top one looking at page 149. That is toward the limit switch connectors.

It may be that the extra temperature sensor positions do not work. I will have to work on them here to see if there is any wiring error. At least the water temperature position (0) is known to work.

This wire seems to have evaded the wiring list.

>   There is a 6 pin header with two wires: a white one with red bands,
>and a green one with black bands.  Where does it go?

This the second wire that seems to have evaded the wiring list.

This goes to a register and can be used to control something external. This is shown on p-149 as a "Chiller Temp Control". The Green Black is the common, and the Red White is the TTL 0-5 volt signal. I use this to turn on the TEC chiller through a Crydom switch. You don't need to use it, but it is there for external control of something. With the right Crydom switch (or any other brand of SCR switch that uses TTL control signals), you could drive anything. I am using this on TOM to turn on a de-humidifier that chills the water. It is programmed in the code to hold the water temperature at (I recall 10 C) a set value. While I was there, I used this to control the TEC chiller.

The other end of this wire has a DB9 connector on it.

>   There is a 4 pin header with three wires: basically green, blue
>and red.  Where does it go?

The devil is in the details. There is a:

green/white  (pin 1)
red/white
blue

That goes to sense 2 (RA Limit)

green/black/white
red/black
blue/black

that goes to Sense 3 (Dec Limit)

But look at the wiring pages, 150, and 151.

>   Is there a sheet that shows the wiring to the RA drive itself
>(that is, which cable goes to the stepper, which goes to the limit
>switch, etc.)?

Easy, the stepper has 4 wires and the limit switch has three.

The RA Stepper is:

black/red  (pin 1)
white/red/black
orange/black
white/black

You can put this connector on two ways. If you reverse it, the direction will reverse. In general, pin 1 of the connector goes to the socket pin marked with double lines.

The RA limit sense is:

green/white   (1)
red/green
blue

It should be obvious which way it goes on. In general pin 1 goes to the connector end marked with stripes. If not sure look at one of the others. They all go on the same way. We painted one side of both connectors in most cases to show which way they go on. Some of this was lost when we exchanged boards there. OK, looking at my drawing, pin 1 is on the side with the 470 ohm reisitor. This is yellow-violet-brown resistor color code.

The limit switches on the motor board end plug in with the blank pin toward the center of the board. It should be hard to plug them in wrong as they are all cable tied together which helps guide them.

In general look at the log book pages to decode wiring color code.

Not to crow too much about my documentation, but from my experience at Fermilab, there is not one experiment there where the builders could answer such questions remotely. ;^) I don't know how things are done in astronomy.

Hope this helps.