Re: G201 death/repair/questions/problems (long post)

Hi MAriss,

Thanks for the detailed explanation.


and of course, that brings up the question as to any projected
release of the 'bullet proof' 210 's ?

Dave




--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mariss Freimanis"
<mariss92705@y...> wrote:

> Hi,
>
> This is a long post. For trobleshooting non-supported drives, see
> immediately below. To set the record straight about these drives,

see

> the "P.S" at the end of this post.
>
> Trouble-shooting non-supported drives:
>
> 1) Inspect the PCB for charring. If a fuse has not been used,

enough

> current can flow thru the drive after a fault to char (burn) the
> board. If any burned or carbonized areas are noted, the drive

cannot

> be repaired. Carbon conducts electricity.
>
> 2) If it passes test (1) then test the power MOSFETS. Set a
> multimeter to "Ohms" and measure each of the 4 phase output
> resistance to ground terminal and then to the power supply

terminal.

> This requires 8 measurements, (1 to 3, 1 to 4, 1 to 5, 1 to 6, 2 to
> 3, 2 to 4, 2 to 5 and 2 to 6).
>
> Good readings will be megohms, bad readings are less than 100 ohms,
> usually a dead short.
>
> 3) If it passes test (2) then connect ONLY the power supply to the
> drive, nothing else. Measure the DC power supply current flowing

into

> the drive. A good reading will be less than 0.03A, a bad reading

will

> be 100mA or more.
>
> 4) If it passes test (3) then measure the DC voltage across the
> CURRENT SET terminals. A good reading will be 17.5VDC +/- 0.5V. Bad
> readings will be above or below those limits.
>
> What to do if it fails a test:
> ------------------------------
> Fails test (1): Cannot be repaired.
> -----------------------------------
> Fails test (2): Remove the 4-40 cap-head screws and remove the

board.

> Turn it upside down. The MOSFET pair closest to the main connector

go

> to PHASE D, the next pair to PHASE C and so on.
>
> Identify the dead MOSFET / MOSFETs and clip the 3 leads going to

the

> part. Use a pair of tweezers and a medium soldering iron with a

wedge

> tip and carefully remove each remaining lead from the PCB. Use

solder-

> wick to clear the 3 holes of solder.
>
> Apply ONLY the power supply (24VDC) and a STEP pulse source to the
> drive. Measure the power supply DC amps going to the drive. A good
> reading will be 0.03A or less and makes the drive a good candidate
> for repair.
>
> (1) If so, use a non-hydroscopic solvent like xylene (do not use
> acetone) on a Q-tip to clean the board of rosin flux residue. Take
> the replacement IRF530 and bend its leads back at the natural bend
> location 45 degrees past 90 degrees. Press-fit the MOSFET into

place

> taking care its body seats directly onto the PCB.
>
> (2) Re-apply power to the drive and measure the current draw. If it
> stays below 0.03A then the drive may be repaired. Solder the MOSFET
> into place AFTER the board has been re-seated with the 4-40 screws.
> Clip the excess lead lenght and re-try the drive with a motor.
>
> (3) If it does not work, the damage has propogated past the dead
> MOSFET and has killed the IR2104S half-bridge driver. This requires
> SMT rework equipment (hot air soldering).
> ---------------
> Fails test (3):
> ---------------
> This means one of about 50 components connected across the internal
> 12VDC supply has shorted.
>
> (1) You need a variable voltage, variable current limit lab-type
> power supply. Set the supply to +12VDC and turn the current limit

to

> zero. Clip the "+" supply lead to the opto pin 8 and the gnd lead

to

> the opto pin 5.
>
> (2) Slowly turn up the current limit until at least 6VDC is

indicated

> on the supply. Use your fingertip to search out a part on the board
> that will be hot, usually an IC. If it is hot, replace it and try

the

> test again. When you see only 0.03A or less, the drive may be
> repaired.
>
> -------------
> Fails test 4:
> -------------
>
> If the voltage is below limit, go to "Fails test 3:" above. If it

is

> above the limit then the main TL783C voltage regulator has failed

and

> the drive is probably unrepairable due to multiple/all ICs being
> destroyed.
>
> Mariss
>
> P.S. About these drives:
>
> On our very first production run of the G201s the sheetmetal vendor
> supplied soft anodized plates instead of the specified hard
> anodizing. Our options were to rework the first revision drives or
> sell the the second revision (auto standby) with the proper plates.
> We opted for door #2 because it was quicker; we had to meet orders.
>
> The choice now was to junk the first 1,000 drives or to rework them
> as time allowed.
>
> Again we chose door #2; all of the first revision drives had their
> plates replaced with the hard anodized ones but now they were one
> generation behind and thus rendered unsaleable at the list price.
>
> Because they were one generation behind, we sold them off to
> resellers at cost ($49) and licked our wounds; hundreds of hours of
> hard work with nothing to show for it.
>
> Main point: No drives were ever sold with the soft plates; I would
> never sell anything I knew was junk or flawed in any way. I have a
> large box filled with 1,000 plates to remind me we did the right
> thing.
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Steven Ciciora
> <sciciora@A...> wrote:
> > I thought someone told me that the Geckos that were sold without
> lids
> > initially had the heat sink/base plate 'soft' anodized, not 'hard'
> > anodized. Small scratches in the heat sink/base plate would

cause

> the case
> > of the FETS to conduct/short out to the base plate. This is a

bad

> thing.