If your Model 309 has failed even though it hasn't been physically abused and it's Operating Software is current, the problem probably lies with one of these three components:
100 nF MLC (multi-layer ceramic) capacitors
Removing circuit boards for service
Although no longer significant, in 2001 a surge of clock crystal failures occurred in earlier Model 309 instruments. Such failures are covered under warranty regardless of the age of your instrument. Specifics follow:
Last update: 24 July 2002
The problem: Hardware version four Model 309s shipped before about November 2001 experienced what we think was a component batch related flaw which caused a relatively high hardware failure rate in this otherwise very reliable instrument. Since we have not observed any further failures in the last few months, we think that most or possibly all of the flawed components have failed and been cleared from the field. But we can't be certain of that.
The component involved is a subminiature 32.768 KHz watch crystal. When that crystal fails, the instrument will never boot or otherwise function in any useful manner. If your instrument is malfunctioning, but does boot, even if repeated power cycling is required to do so, you almost certainly have an Operating Software flaw. In this case the problem is resolved by installing the latest Operating Software, which you should do yourself. If you're not certain which problem you have, you can use a frequency counter or oscilloscope to check the clock port on the bottom of the instrument (use the left probe sense line as reference - click here and refer to step 16 for specifics). If the frequency is either 16.77 MHz or 8.39 MHz, your crystal is good, and you need to install the latest Operating Software in order to correct the malfunction. You can also check your Operating Software version range. If your instrument uses either version 1.xx or 3.xx, it belongs to a hardware version group of instruments in which no crystal failures have occurred to the best of our knowledge, so it's very unlikely that your crystal has failed. The same is true for all instruments shipped after November 2001.
What you need to do: If your instrument's crystal has failed (will not boot even on repeated attempts), refer to the packing instructions (very important) and return it to us for warranty repair. Please ship only the instrument itself - please do not include any probes, network cables, power cords, or other accessories. You don't need an RMA number, but you do need to provide your return shipping address. The instrument will be repaired, calibrated and recertified, and returned promptly via FedEx Ground, all without charge. If you need premium freight, please provide your carrier's account number or a PO number so that we can invoice the premium freight charge. (If you provide a PO number to cover premium freight, your account must be in good standing, or the instrument will be returned via COD.)
What we did: We worked with the component vendor in an effort to try to uncover the underlying cause of these failures. Our circuit design appears to be fully proper and nominal, and there is evidence that at least some of the failures are not related to physical shock. While it's impossible to confirm in absolute terms, our conclusion is that we acquired two bad batches of the crystal, even though they were purchased over a broad date span. There are multiple manufacturing facilities for the component, but both of the batches that we acquired appear to be related in certain ways.
We now utilize a larger style crystal in new instruments and for repairs. This crystal was used in the Models 306 and 307, and in hardware versions one and three of the Models 308 and 309 (those running Operating Software version 1.xx or 3.xx). Our experience with this crystal has been excellent - our records indicate that none of them have ever failed.
Our investigation is complete, and we have made a global design decision in order to avoid the possibility of experiencing this problem in future designs. We will utilize a fully silicon strategy to generate a precision clock in all future hardware versions of our products so as to eliminate the crystal altogether.
Conclusions: If your instrument's clock crystal has failed, please accept our apologies and return it to us for warranty repair. Remember to consider your Operating Software first though. If you're running version x.64 or earlier you should install version x.65 now. It is not appropriate to return your instrument to us for Operating Software upgrades, and if you do so a standard calibration service charge will apply.
Click
here to go to the Operating Software update page.
Click here to go to the quick Operating Software installation guide.
An earlier 390 uH Power inductor on the Power Management circuit board was underrated, and can fail due to shorted turns. Such failures are covered under warranty regardless of the age of your instrument. Specifics follow:
Last update: 6 October 2006
The problem: Earlier hardware version four Model 309s utilized an inductor on the Power Management circuit board, which is mounted in the nylon guides just forward of the variable transformer, that was rated below the average current that can flow through the component in some instruments. (We failed to update this component as power consumption grew from previous hardware versions of the Model 309.) While typical inductors are able to withstand the overload long term, some eventually fail due to overheating which can lead to shorted turns. When this happens the + 5 Volt power rail collapses in a limit protected mode, causing the instrument to fail to boot, or to freeze during operation.
When a 390 µH inductor fails, or anytime a Power Management circuit board equipped with one is removed for other service, we replace the 390 µH inductor with a much higher current capacity 820 µH toroidal inductor. For older instruments with a 390 µH inductor that has never failed, if we remove the cabinet cover for other service, but need not remove the Power Management circuit board for other service, we remove the outer jacket from the 390 µH inductor to reduce its operating temperature, which reduces the already low possibility that it might fail at a later time.
100 nF MLC capacitors. Most failures of this component are covered under warranty regardless of the age of your instrument. Specifics follow:
Last update: 1 September 2005
The problem: We've noted a higher than normal 100 nF MLC capacitor failure rate in hardware version four Model 309s. It's not clear why, although some may trace to thermal gradients during circuit board assembly. Most of these appear as infant failures, and most are detected during burn-in and corrected before a new instrument ships. But a few have failed after shipment, in some cases years later. When they fail, they become electrically leaky or short, and are thus usually easy to locate during electrical troubleshooting, although in rare cases they become intermittently leaky, which can make troubleshooting difficult.
Careful replacement of failed components is the only known solution as we seek vendors with evidence of higher reliability components.
Removing circuit boards for service:
Preliminary Notes and cabinet top removal
Preliminary notes: The Model 309 is easy to service when the correct procedures are followed. It is never necessary to cause any damage to any components or hardware when servicing this instrument. So if you find that you need to cut, bend, or otherwise harm any part of the instrument, you're using an incorrect procedure. Always utilize static protection procedure, and work in a clean environment, since small contaminants might cause short circuits in fine pitch components or circuit boards.
"CB" Stands for circuit board. "µC" Stands for Microcontroller. "C&R" Stands for Controls and Readouts. PM stands for Power Management.
Cabinet top removal: Remove the cabinet top by removing the twelve torx bolts, six on each side, which secure it to the cabinet bottom. Two #6 lockwashers are located between the cabinet halves associated with the lower rear two bolts. These will fall out or may adhere to one side of the cabinet or the other.
Cabinet top replacement: Place two new #6 lockwashers between the cabinet halves before you replace the lower rear cabinet bolts to insure that the cabinet top is well grounded electrically.
µC (Microcontroller) and C&R (Controls and Readouts) CBs, removal procedure:
There are two identical white flat ribbon cables which connect from the µC CB to the Power Management CB. Remove both of them from the instrument by pulling them straight out from their connectors.
There is a two conductor ribbon cable which connects from the µC CB to the current sense resistor. Remove the front end of that cable from the µC CB. Leave the other end in place.
Remove the small knob from the rotary actuator. You must protect the lexan front panel with a barrier such as a thin steel ruler, allowing you to pry the knob off of the shaft. There is a spacer in the knob's shaft hole - keep it there.
Locate the shaft coupler on the Current Adjust control shaft. Loosen the front set bolt in that shaft coupler with an Allen driver (don't loosen the rear set bolt). Pull on the Current Adjust knob, turning it if helpful, until the knob and shaft are pulled free from the instrument.
Read this entire paragraph before performing this task: There are three flat head torx bolts in the cabinet flange above the µC CB which are secured with nylon snug nuts on the opposite side of the upper flange. Holding the snug nuts so that they can't rotate, remove those three flat head bolts. Important: Do not attempt to remove the three snug nuts or their associated bolts located on the bottom portion of the cabinet - those bolts are permanent and you must not attempt to remove or adjust them.
The µC and C&R CBs must be removed as a set - don't attempt to remove them one at a time.
Working on the top side of the µC CB, in the area of the rotary actuator, pull the µC CB slightly away from the C&R CB. Separate them only modestly, until the connector pins for the rotary actuator almost disengage, and no further.
Then push forward, toward the front of the instrument, on the bottom center of the µC CB, next to the red or white connector, a short distance, squeezing the bottom of the µC CB toward the C&R CB. These two adjustments help to provide clearance so that the boards can be rotated out and away from the cabinet.
The CB pair should now be rather loose. Pull the top edges of the CBs backward, and jiggle them slightly if necessary to help clear obstructions, until they clear the top cabinet flange. You may need to push down slightly on the audio annunciator (the white plastic device next to the timer readout) in order to free it from its clearance notch in the cabinet flange. Then rotate the CBs out and away from the instrument - as the bar graph leds and the other parts clear their areas, the pair of circuit boards will rotate out and completely clear the instrument.
µC and C&R CBs, reassembly procedure:
Reassembly is basically the reverse of the procedure above. When reinstalling the µC and C&R CB into the cabinet, remember to keep the bottom edges of the CBs squeezed together and the top edges pried slightly apart as you rotate them into position. Finesse the boards until they drop into place. Do not attempt to force the boards into position - if you do, you will probably damage the bottom bar graph led. Once the boards are in place, push the top edge of the µC CB forward until the boards are parallel to each other.
Special reassembly notes:
Align the red button housing in it's cabinet hole: As you reinstall the circuit boards, be certain that the square red push to test button housing clears the edges of its front panel hole. Sometimes the button's black housing can snag on one side as the boards are installed. If so, finesse the boards until the snag is cleared and the button housing clears the edges of the square cabinet hole on all sides. The button does not extend fully through the hole - the black edges should extend about half way through the thickness of the cabinet metal. But it must not be allowed to remain snagged on an edge of the cabinet hole.
Align each of the snug nuts so that a flat side rests against the µC CB. When correctly installed, there is only a small amount of pressure holding the CBs in place.
Align the Current Adjust knob precisely, so that the knob's index line exactly aligns with the first graticule line on the lexan panel when the knob is turned fully counterclockwise, and so that the back edge of the knob just barely clears the surface of the lexan panel. It is best by far to align the knob so that the shaft coupler's set bolt falls exactly back into it's original indentation in the shaft. Tighten the set bolt firmly, but don't over-tighten it since it's possible to strip the threads in the shaft coupler.
Rotary encoder knob replacement: The knob has a spacer in the bottom. Don't remove it - it's necessary to prevent the knob from sliding too far onto the shaft. Important: You must support the back of the rotary encoder when you push the knob onto the encoder shaft. Otherwise you may damage or break one or both of the circuit boards.
PM (Power Management) CB, removal procedure:
There are two types of brackets which hold the variable transformer, Network Card, and Power Management CB, an early version and a current version. The current version utilizes three bolts and nuts on the vertical flange toward the center of the instrument to secure one edge of the PM CB. If there are no bolts on this flange, and the nylon card guide on that specific flange is fixed in position by nylon pins, you have an early version bracket, which is more cumbersome to service.
Current version:
Remove the network card.
Remove the two safety tie wraps which secure the PM CB to the bracket flanges by cutting them.
Disconnect the small fan power connector.
Disconnect the two ribbon cables from both the PM CB and the µC CB.
Carefully note their correct locations, then disconnect the four spade connectors on the wires which lead from the PM CB to the power switch / circuit breaker and the variable transformer.
Loosen the aft set bolt on the aft end of the shaft coupler, and then move the shaft with the coupler forward to clear the PM CB. Remove the nylon shaft washer (be sure to replace it when reassembling).
Remove the three bolts and nuts on the vertical flange toward the center of the instrument which secure that edge of the card guide and PM CB.
Rotate that edge of the PM CB toward the front of the instrument. The nylon card guide on that side will fall free (be sure to replace it when reassembling), and the PM CB can be pulled completely away.
Early version:
Remove the network card.
Remove the two safety tie wraps which secure the PM CB to the bracket flanges by cutting them.
Disconnect the small fan power connector.
Disconnect the two ribbon cables from both the PM CB and the µC CB.
Carefully note their correct locations, then disconnect the four spade connectors on the wires which lead from the PM CB to the power switch / circuit breaker and the variable transformer.
Loosen the aft set bolt on the aft end of the shaft coupler, and then move the shaft with the coupler forward to clear the PM CB. Remove the nylon shaft washer (be sure to replace it when reassembling).
Use a thin open end 1/2" wrench to fully loosen the nut which holds the variable transformer to the front of the bracket, turning the nut completely off of the threads. Access the nut between the back of the PM CB and the front of the bracket. Access space is minimal, and it's a tedious process since only a partial turn can be made for each reposition of the wrench.
Perform the following steps only if you have a clear plastic guard mounted on the interior side of the fan, between the fan and the variable transformer (otherwise skip to the last step below): Remove the two bolts and four lockwashers which hold the top rear of the bracket to the back of the cabinet. Insert a thin sheet of protective material such as heavy paper between the fan guard and the variable transformer to protect the variable transformer windings. Pry the cabinet back about a centimeter from the rear of the bracket and insert an object to keep the two separated.
Move the variable transformer back to allow the PM CB to slide up and off of the nylon card guides on the bracket. Clearance is minimal.
PM CB, reassembly procedure:
Reassembly is basically the reverse of the procedure above. Be careful to insure that you do not damage the variable transformer windings. With the current version bracket, prepositioning new safety nylon tie wraps before fully reinstalling the PM CB makes their installation much easier.
Special reassembly notes:
Don't forget to install the nylon insulating washer on the variable transformer shaft before reinstalling the shaft coupler - the nylon washer is a required component for electrical isolation.
Install two new safety tie wraps through the bracket and the PM CB, threading them through the oval holes in the bracket and the CB, securing them tightly and trimming them neatly. These are required safety components. Hemostats or tweezers are useful to thread the tie wraps through the oval holes.
Be sure the line wires are located correctly. The shorter brown line wire connects to the outer top terminal of the power switch / circuit breaker, and the longer brown line wire connects to the uppermost spade terminal of the variable transformer. The shorter blue line wire connects to the inner top terminal of the power switch / circuit breaker, and the longer blue line wire connects to the lowermost spade terminal of the variable transformer.
Align the Current Adjust knob precisely, so that the knob's index line exactly aligns with the first graticule line on the lexan panel when the knob is turned fully counterclockwise, and so that the back edge of the knob just barely clears the surface of the lexan panel. It is best by far to align the knob so that the shaft coupler's set bolt falls exactly back into it's original indentation in the shaft. Tighten the set bolt firmly, but don't over-tighten it since it's possible to strip the threads in the shaft coupler.
Hypatia Inc. Contact Information ucecage@Hypatia.com. Report mail misconduct to uce@ftc.gov.