Home Forums General Discussion Technical Questions Dead Miprom?

Have a 2 stop Montgomery miprom that won't come to life. Originally the elevator stopped working but had some I/Os lit up. We sent the motherboard/backplane in to World Electronics and they found a bad capacitor in the power supply and replaced all caps, regulators and logic. When we got everything put back together, no I/Os were lit up and the PSU has both leds on.
When the prom and cpu are pulled out of the rack the reset light on the PSU flashes but when either of these are plugged in, the brownout and reset light stay illuminated and won't reset. Also, the CPU led stays steady on when plugged in.
We don't have a extender/test board but when I put my meter leads on terminals 6-7 in the CPU slot, I have 5.21 VDC but between 6-8/8-9 I have 0 volts. I believe that 6-8 should be 14 VDC but I don't have enough experience with Miproms to know for sure.

Any suggestions are appreciated.

Thanks

Usually when both LED'S are high on the power supply board that indicates that the Power Supply Board is bad. I would start there. With all the I/O and Smart Boards pulled, you should have, 120vac from L1A to L2B, 17 to 27vdc from V+ to V- on the Power Board. 5vdc is measured across the 4000mfd on the Power Board.A bad Power Supply Board was most likely the original problem if both LED'S were high.

I have unit down with similar problem.:
Original condition: Power supply(P-16835)both led's ON; could not reset. SRB 'RST" ON, Could not reset. NO out put 's on.
Replaced Power supply board. Both RST led's (on pwr.sup. & SRB) flash on regular clock ; No output boards on. Voltage checks all appear correct.
My 'miprom' info is for '80's miproms. this system installed 1999. upper card rack is pwr, & inputs. Lower rack is outputs. Suspect a card rack but have no info on how to isolate failure to one.
Any Help ?

Recheck voltage's, it is not unheard of to get a bad Board out of the box. if voltage's are OK, pull the SRB Board and see if the reset lights still blink. The SRB takes the place of the older CPU and program Boards. It is very possible you have a bad Card Rack. We never tested Card Racks, if we suspected them we just replaced them. Also if you have one or two bad input or output boards it can cause the Miprom to go off in the Weeds and blink everything because the computer doesn't know what to do.

Thanks.
I have worked on miproms off and on for quite a number of years. Normally work .. rarely need to trouble shoot.
This one reported started last Sat...... would ans. hall call.. accept car call start door close ....drop all lamps and door operation. Restart (self re-start) and accept call and run to destination. Also not always stopping at floor level.. sliding through floor and re-leveling (sometimes).
I will update when I have a solution.

Some times plugging and unplugging the boards clears up problems also. Just another thought.

This happen to me,try to change power supply board,the problem is a small IC.

Replaced: power supply board : better but not fixed. Replaced both CPU card rack & I/O card rack (I/O first) still no outputs & power & SRB "RST" flashing steady.; Replaced SRB. All good.
SRB is a high dollar board from KONE spares.

Did you get your Miprom up again?
Just had similar problem. SRB (SC/MP) board fail. From what I read you do not have the SC/MP board ... takes place of Prom & CPU.
With Job # (CP#####) KONE Spares may be able to supply (SRB = $1995.00, may not include program) A lot of dollars but less than MOD.

Did you try swapping the interface board?
The board beside the timer board. I had a similar problem on a miprom a few months ago. Actually it was due to water damage that had not been corrected several months prior. The repair team had overlooked that board.