Problems with external pot on at1 vfd

Hope someone can help. Have a myford 7 with an at1 vfd and 3 phase motor. Speed/frequency set to 50htz and runs up to that using the pot on the at1. Have wired an 10khm ext pot and set it to run from that. Wired to com and the 5v terminal on at1 and the pot centre wiper to vl1.

External pot works fine but max frequency only 25htz. Any ideas?

When I bridge the pot to give full output to vl1 still 25htz....it's as though the at1 wants 10v from ext pot but I can't see anyway if increasing the 5v from the at1 board.

Help / advice please.

If anyone has an at1 it would be helpful if you could tell me you voltage between the voltage output and com on the right hand end of the gree terminal block (the connection used for an external pot)

Thanks..Alan

From memory there's a couple of parameters that control the range the pot spans. They aren't obvious from the descriptions.

Edited By Mark Davison 1 on 04/10/2023 20:53:07

Edited By Mark Davison 1 on 04/10/2023 20:54:23

Probably not the best time to reply, as the forum's going off-line tomorrow
I've just pulled a new AT1 off the shelf and wired it up to a motor on the bench.
The 5v terminal does give out 5v.
I then wired up a 5K pot and changed parameter 10 to 2, so enabling external speed control.
I get the full frequency range from 0-50Hz as expected.

The last time I heard of someone having this problem was when they mis-wired the pot, and had the wiper to the wrong terminal.
Most pots I've seen have the wiper as the centre terminal, but maybe not all.

Also, whilst the wiring schematic refers to 10v/5v my own actual AT1 has the wiring terminal labelled as 5v (only)
The basic schematic is used for more than one model, so it may be that the AT3 has a 10v terminal instead of a 5v one.
The manuals supplied are pretty basic, and show 15v & 24v as the other outputs, depending on whether they are AT1,2, or 3. My AT1 terminal block is labelled as 12v, so don't put too much store on the manual's labelling of voltage outputs.

Bill

Thanks for the input gents. It was par 73 that was wrong. Was 61440 not 31440. Changing this to the default 31440 cured the issue. Vfd was set like that when I bought it so maybe there's a batch out there set up wrong. Hopefully this post may help others in the future