Kendrick DigiFire 10 Controller

Lester · #1 28-03-2010, 05:38 PM

Hi all, I have had this unit for about 6 months now, and seems to be working. However whenever humidity rises above 80% the corrector on the LX200 14" will dew up. So I have used a hair dryer to help the Kendrick keep the corrector dry.

I had the Kendrick set at 50% duty cycle and 5 degrees above ambient.

I just tried to reprogram the controller to 100% duty cycle and 5 degrees above ambient, and the output socket got very hot= too hot to keep hold of. Some sticky stuff oozed out of the connector.

Has anyone else had similar?

Comments welcome.

gb_astro · #2 28-03-2010, 06:59 PM

Hi Lester.

If the control box is heating up then there is something wrong with the circuitry and it should be returned for service.
Sounds like something is shorting out inside.
The control box contains the ambient temperature sensor so I would assume it is not meant to get warm at all.

Perhaps this problem has been happening for awhile and your heater strap has not been getting enough juice?

The LX200 14" is a big scope and I guess it would need plenty of heating at 80% humidity.
Are you using the higher wattage Premium heater strap?

Setting 100% duty cycle and even maximum degrees above ambient (is it +10 deg. ?)
will not damage the unit unless it already has a latent problem just waiting to be made worse.

BTW when using the external temperature sensor the duty cycle setting is just a fall back setting in case the temp sensor fails.
As I understand it when using the temp sensor the unit will use it's own variable duty cycle
to maintain the required temp difference no matter what you have manually set the duty cycle to.
If you have set the duty cycle to say 50% and the temp. sensor fails the output will operate at 50% duty cycle.

gb.

Lester · #3 28-03-2010, 07:30 PM

Hi gb, thanks for your reply. I have sent a email to the supplier. The controller box isn't getting hot, only the socket; but it isn't good and needs some attention beyond my capabilities.

gb_astro · #4 28-03-2010, 08:03 PM

Ok Lester, let us know what happens.

gb.

DavidTrap (David) · #5 28-03-2010, 09:11 PM

What happens if you plug into another socket? Aren't they individually controllable?
DT

Lester · #6 28-03-2010, 09:31 PM

Good point David, will have a go at that.

Lester · #7 28-03-2010, 10:06 PM

Someone on another forum mentioned was the socket inserted fully. It wasn't, as when it was hot I pushed it in a bit more. I don't know if this would cause any over heating.

Just tried it again and there was not any over heating, so perhaps the socket not pushed in can cause it to get hot.

Can anyone with more knowledge on this give their advice, thanks.

gb_astro · #8 29-03-2010, 12:43 PM

Hi Lester.

Can we clarify just what is over heating?

The DigiFire 10 has four RCA sockets along one side.
Into these you insert the RCA plug of each heater lead.
So are you saying the heater lead RCA plug is heating up?

If so it is likely there is an intermittent short happening with the plug wiring.
It may come and go depending on how you handle the lead.
The black stuff oozing out could be the black plastic sheathing on the lead melting.

The silver cover of the heater plug can be unscrewed.
Unscrew it and see if there is any evidence of melting inside.

gb.

Lester · #9 30-03-2010, 08:07 PM

Hi gb, yes the socket itself was heating up.

I have recieved 2 emails from the Aus. supplier, the first saying that the unit should not be run at 100%, and also to say that when the humidity reaches 80% and above, I should call it quits and go inside. I was not impressed with these comments, and told them so.

The second email was to say send it back to them and they will post it to Kendrick to be checked under warrenty.

I informed them that I will check it again, just to make sure the loose socket was the only problem.

gb_astro · #10 30-03-2010, 08:40 PM

Hi Lester.

I agree, that is a ludicrous response form the supplier.
Kendrick has a pretty good reputation, I am sure they will sort it out.

gb.

Lester · #11 30-03-2010, 09:18 PM

Hi gb, just tried the Kendrick again this evening and all seems to be working, the strap is heating up and the socket is not even getting warm.

So perhaps others may learn from this; don't allow the socket that connects the heat straps to the Kendrick unit to get slightly un-plugged. This can easily happen when slewing around the sky, and cords can get tight.

All the best.

citivolus (Ric) · #12 30-03-2010, 09:47 PM

I'd still get it checked. You don't want a fire to happen on your scope.