The Unofficial DPU-550 Hardware Installation Guide Version 2.1 By R. G. Sparber May 24, 2010 Copyleft1 protects this document. Disclaimer: Use these notes at your own risk. Although the author has made every effort to produce an accurate document, he assumes no responsibility for errors. Version description 1.0.0 Initial installation without new Flex and Tach cables 1.1.0 Flex and Tach cables added 1.1.1 Typos corrected 2.0 Changed to “unofficial” 2.
Table of Contents Overview...................................................................................................................................3 Scope.........................................................................................................................................4 Needed Tools and Materials......................................................................................................5 Preparing the DRO-350..........................................................
Overview When the DRO-350 is upgraded with the DPU-550, the resulting machine is called a DRO-550. The DRO-350 has been a very capable Digital Read Out system for many years. During this time processor technology has improved and scale data formats have grown from the original one to five at last count. Only the original format can be directly connected to the DRO. Additionally, users have asked for more features than can be crammed into the existing memory.
Some assembly might be required but only of through hole connectors. The Lite DPU-550 uses the same circuit board as the full DPU-550 but has fewer functions available. This document is long. Before you give up right now, understand that I have shown every step in detail and used lots of pictures. The work will go fast, unless, of course, you screw up as bad as I did on removing the PIC. Ah, but I get ahead of myself. The majority of the connections between DRO and DPU are through the old PIC connector.
Needed Tools and Materials • [ ] temperature controlled soldering iron • [ ] a means of cleaning the solder tip • [ ] thin, rosin core solder • [ ] Solder-Wick2 (the white spool with yellow print) and/or a solder vacuum tool • [ ] wrist strap connected to ground • [ ] conductive surface connected to ground • [ ] eye protection (If you get solder in your eyes, there isn't much reason to own a DRO since you won't be able to see it.) 2 See http://en.wikipedia.
• [ ] a pair of small diagonal cutters • [ ] a pair of small needle nose pliers • [ ] a small Phillips head screwdriver to fit the 4 screws on the back of the DRO case • [ ] a medium Phillips head screwdriver to fit the 6 screws holding the main circuit board in place • [ ] a small cup to hold loose screws • [ ] 1 square inch of double sided foam tape • [ ] two hard rubber washer (see text on page 14 for details) • [ ] 1” by 2” piece of masking tape or Avery label • [ ] a thin pointed instrument able to den
each step can be checked if you like: 1. [ ] Remove all cables from the DRO. 2. [ ] Using a small Phillips head screwdriver remove the four screws on the back of the DRO enclosure and place them in the cup. 3. [ ] Pull off the larger part of the enclosure. Here is the DRO with the top of the case removed. The tiny red LEDs across the top of the display ICs stick out a little and can easily be bent. I suggest if you do bend them, do not straighten the leads until you are done with the upgrade.
Our task is to carefully remove the PIC which is located on the left edge of the circuit board. It is a 28 pin IC with a few components around it that will not be needed after the upgrade. In order to improve access to the pins that must be cut, we will first remove these components. If you used a socket for the PIC, this next step may not be needed. 8. [ ] Locate the resonator. It is a shiny brown blob with three wires sticking out the bottom. See the arrow shown below. 9.
associated with the resonator. This is where the Solder Wick really pays for itself. Alternately, a solder vacuum can be equally effective. Leave the soldering iron on the board for as short a time as possible. Excessive heat will cause traces on the circuit board to lift. If you are unable to remove all of the solder, add fresh solder and then briefly heat the area and use the Solder Wick again. As the Solder Wick fills with solder, cut off the end to expose clean braid. The hole should be free of solder.
Final Assembly of the DPU-550 If you are installing the Lite version of the DPU-550, just skim over the next few steps. You only need to install the inter-board pins, the Edge 1 connector, the program pushbutton, and the USB connector. 1. [ ] As you look a the DPU-550, you may find Surface Mount Technology components5 locations without components. Don't panic. You are not missing parts and you will not be soldering any of these tiny components in place. 2.
I have completely soldered in one header and am about to do the next one. Solder in all of these headers. An alternative technique is to use a tiny dot of Super Glue on the bottom of the header. It will securely hold the part in place for soldering. The glue may complicate removal of the header if necessary later. I don't see that as an issue. Avoid applying any more heat to the board and pins than necessary to flow the solder. Excessive heat can cause damage to the board and to the header.
pin connectors, be sure that the pushbutton and USB connector are flat on the circuit board before soldering all pins. Inspect all solder connections and re-flow any that are not smooth and limited to the area around the pin. There must not be any solder bridges to adjacent paths. 5. [ ] The two female pin headers feed in from the back of the circuit board. It is an easy fit. Solder one end pin first and check that the header alignment. It must be squarely on surface.
Final Modifications to the DRO-350 Circuit Board 1. [ ] Bring back the DRO-350 circuit board. 2. [ ] The PIC pin blocks feed in from the front side of the board. The pins are square and will cut into the sides of the holes. As long as all holes are free of solder, you will be able to carefully push each pin block in place. Take care to push straight in so no pins are bent. The ends are sharp so you may find that the pliers help. An alternate method is to use a small block of wood as a pusher.
I started by putting down two pads of double sided foam tape. Then I found some used rubber washers out of an old faucet (What? Me throw anything away!). I thinned them on my belt sander taking care not to thin my finger.
Once I was satisfied that they fit right, I removed the top protective covering on the foam tape and pushed the washers down. 7. [ ] Reinstall the DPU onto the DRO and verify the two boards are parallel when the washers contact the DPU-550.
Final Fit to Enclosure There are two components on the DPU-550 that must pass through openings in the enclosure. One is the program pushbutton and the other is the USB connector. 1. [ ] Pick up the back of the enclosure which has the connectors mounted to it and move all cables out of the way.
2. [ ] place the tape or Avery label as shown. 3. [ ] trial fit the DRO plus DPU-550 circuit board assembly on its standoffs. Use the two long 6-32 screws to align the board on the standoffs yet permit the board assembly to float vertically. The pushbutton's rod will hit the bottom of the enclosure to prevent the board assembly from seating on the standoffs. 4. [ ] Steady the board assembly with one hand and verify that the pushbutton's rod and USB connector are both over the tape or label.
the pencil lines are aligned with the center of the pushbutton's rod. 10. [ ] Remove the two 6-32 screws and then the board assembly. 11. [ ] Drill a hole 9/64” or 5/32” through the case at the marked out location that just passes the tip of the pushbutton's rod. The goal is to have the hole large enough that it does not bind the pushbutton yet small enough so it does not flop around. Trial fit the board assembly to be sure there is no binding. 12.
Here you see the USB connector peaking through the back of the DRO enclosure. The probe is pointing to the program pushbutton. You can also see my separate electronic edge finder and tachometer jacks in the upper left hand corner. I chose to not add connectors for Edge 2 or Flex 1 at this time. Flex 1 used to be called Tach 1. 15. [ ] If you bought the Lite DPU-550 version, then put the existing cables back on the DRO-350 board in their original position.
18. [ ] Plug the two-pin female connector from the power plug located in step Black wire Red wire 16 into the “in” header. The red and black wires should be as shown above. You may want to use a red and black fine point marker on the header to indicate what color wires connects to which pin. If you are using the correct plug here, it will not let you plug it in backwards so this would not be an issue. 19. [ ] Plug one end of the new power cable into the “out” header.
connector. You should see the red and black wires as shown above. If these wires are reversed, you may blow up the DRO so be sure to check this twice. 20. [ ] Plug the other end of the new power cable into the power connector on the DRO board shown circled above. With the DRO power connector in the upper right corner, Red wire Black wire you should have the red wire on the right and the black wire on the left. 21.
of where the resonator was before you removed it back on page 8. Over on the DPU board, you can find ground at the “out” connector's left pin. This is the pin closest to the corner of the DPU board. You should see a dead short between these two points. If your meter initially shows it shorted but then an open, this implies that you are seeing filter capacitors which would mean one of the cable ends is on backwards. Fix this before moving on. 22.
page 26 for a picture of the installed piezo beeper. 25. [ ] Carefully reassemble the board assembly on the standoffs using the original short 6-32 screws. Do not force anything. I had some trouble with wires getting caught between a DPU feature and a DIN connector. It will all fit with the wires out of the way. I took the time to route the scale wires away from the display area as the proximity might cause an increase in noise pick up that can cause scales to jitter. 26.
Pictures of the Assembled Unit You can see the DPU-550 buried in there with many wires attached.
Note one of the two washers supporting the DPU-550 Page 25 of 27
Directly under the keypad is my piezo buzzer which plugs into the Flex 2 socket. This is an end view showing how the inter-board connector is fitted. You can also see how the piezo beeper connects to the main board's AUX connector. The new software calls the old AUX connector “Flex 2”.
Acknowledgments My thanks go out to J. Eric "jet" Townsend, Larry Gill, and Jim Fager for their insightful suggestions for making this document better. Thanks to Greg [g_end@email.com] for supplying the picture of the production DPU-550.
