MCE Problem with Quad Pulser : LUSENET : Elevator Problem Discussion : One Thread

MCE VVMC 1000 Controller, 1995/96 vintage - "Quad Pulser Relation" Errors (QPR's) LS-Quad Distance Feedback tape reader. Replaced GIO, DDP, SB1 sensor, LS-quad board, painted tape black, replaced twisted pair traveler, confirmed shielding and grounding,...scope shows good signal, quadrature good (there is a 15 volt, 12-15 hz sawtooth waveform riding on top of the 60 vdc square wave "on" signal, cannot confirm if it is acceptable or not) Intermittent problem - can be good for days or occur multiple times in a short period. Any ideas ???

-- WL (, November 30, 2002




I'm reaching here, have you taken a voltage reading of the dual sensors for the quadrature signal? If you have a voltage out side of MCE's spec's would it cause the QPR error?

Also I read that triacs on the LS-qute had failed prematurely due to induced voltage from other wires in the proximity. Does the LS-quad use similar triacs? If so look under the cover of MCE's LS-quad for triacs numbered lower than 3355. These triacs will likely need to be replaced. Please keep us posted of your progress.

Best wishes,


-- Jon (, December 02, 2002.

MCE, correction to my posting.


The triac part numbers should be;

MAC228A10 or MAc228A8FP

If they are not you will likely need to replace them.


-- Jon (, December 02, 2002.

Just went thru the exact same thing. #1 the triacs on the quad board don't have much to do with DP1 and DP2. They (DP1&2) are located on the SB board. Three things. Check the tape guides! Clean the dust from the tape and clean the milar mirror on the top aluminum plate. With .050 clearance the tape can hit the sensors. Check the clearance...make sure they aren't getting hit. My problem turned out to be a faulty RB board...problem gone. Good Luck!

-- Donald Davis (, March 11, 2003.

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