Home Forums General Discussion Technical Questions Dover solid state

I've got a dover solid state 3 stop installed in 1982. It runs up on auto and up and down on inspection. When it runs down on auto from 3rd floor it goes into high speed but when it comes off top slowdown it stops and immediately goes back up to 3rd floor. When it leaves the 2nd floor it comes off the up slowdown for the 2nd floor stops and goes back up. When the car goes back up to the floor it started at it re tries the run and it keeps doing the same thing. I've replaced all cards, Checked slowdown circuits, leveling circuits, and everything else all the way back to the pins on the back of the card slots. Voltages all check out and slots the cards slide into look good as well. Has anyone had a issue with these units that could give me direction to go in

I would start at the down valve coils "Is S or D dropping out" and work back from there. Look in your PM...

did u check your slowdown limit?

S doesn't drop out but d does and the up relays pick the instant d drops. It's like something in the logic of the boards doesn't like what it sees (inputs or inhibiters for the gates) when the unit is in between floors and not on any slowdowns in the down direction . I've got a block diagram for the card's test points but it's kinda hard to follow because there are places in the circuits that don't have test points. It also doesn't have an option card so that should make it a little more simple.

How bout 1a and ta relays

1a and ta seem fine especially their nc contacts. Another thing, if I jump out the slowdown it stop after coming off of, it will continue to run until it hut the next slowdown. Like I'm tricking it for a moment and it think it's not between floors until it sees two slowdown at the same time other than 2su and 2sd.

I've got to figure out what it's seeing or not seeing when it's "between landings"? And it's more than likely something I wouldn't expect.

Have you replaced any boards yet?

it could be one of the slow down switch's at the bottom floor

I've swapped all boards with ones from another controller that was working fine. I've also checked & cleaned contacts, Checked every inch of wiring from switches back to pins on the back of board slots for slowdowns and leveling sensors, I've checked input voltages for slowdowns and sensors at pins on board slots, and I've used crocus cloth to cleaned the slots to board connection points. Interlock, gate , dcl, safety edge, safety circuit all check out fine too. The only thing I haven't done is set the building on fire...yet!

I have only had board, valve and door issues.

I've always heard to make sure that the main filter cap is good and you don't have any ripple on the DC.

Heres a shot...
Bad leveling inductor?

Did you try disconnecting the fast speed coil and call it to run down?

Jkh, no I haven't but I'll see what happens when I do Monday morning. Elmcannic, I've checked leveling inductors all the way back to card slots but I will try swapping them around to see if problem changes. Eman, I'll also check for ac ripple, I think all I've done so far is just check the dc voltage for the 24 and 5. Thanks for the tips.

Someone above said to check ripple on DC. Very good suggestion. Does the call you registered to run the car cancel when the car levels back to the floor? If it does your power is probably bad somewhere. Does it do the same both directions or only down? Make sure the 24V and 5V do not drop when car starts, This would be an indication of a bad filter and ripple. Do not let the 5v drop below 4.8. If you have to adjust 5v to 5.2v. If the call does go out when it levels back you probably rebooted power supply for some reason. I believe there are some relays and it is possible for an armature rivets loose and contacts not making. Examine all the relays carefully. Good Luck.

Call doesn't cancel. When it relevels back into floor the doors open, close, and then it tries to run down again without having to register another call. It only does this in the down direction. I've checked all relays but I will double check and also double check the bases.

I have scanned books for these controllers but the .pdf files are huge. If you have a drop box I can send them to it. Way to big to email. PM me info for send instructions if you need the books.

THANKS Rolly, but I have a lot on these including the troubleshooting manual, block diagrams, prints, Backplate charts and diagrams, etc. I really appreciate everyone's tips and willingness to provide stuff like this. I just know it's going to turn out to be something fairly simple that I overlooked.

Hey guys I have a unit doing this exact thing, what was the issue in the end?

Hello
The unit we are working on was installed in 1972 and had the exact issue of running correctly on inspection and in the up direction on auto.
However, on auto in the down direction as soon as it came off of the position switch it would stop and run back up to the floor.

The fix was adding a 250 Mfd cap between 24D and PC. This is mentioned in one of the manuals, Never needed it the first 54 years but does today.