HitecAstro 4 channel Dew Controller

[Peje]

NOTE:- The root cause of my problem was identified as using cabling that was not thick enough to handle the current required without excessive voltage drop across it's length. (The rest of the topic has been left for reference only)

 

Bought one of these last week from FLO and quickly noticed a problem. Upfront I'd like to say this is nothing to do with FLO, as always they are a joy to deal with.

https://www.firstlightoptics.com/hitecastro/hitecastro-four-channel-four-port-dew-controller.html

Firstly, I had the cigarette lighter input replaced with a DC socket (2.1mm) by one of the hardware engineers at work who is a soldering god When I took it home I plugged my 5A PSU into it and the connected it to the mount (granted I'm not using the actual outputs but this doesn't matter, as I'll explain later).

At first all powered up and everything connected without issue, everything seemed fine. I slewed to the moon and when I tried to adjust the position using the EQMOD screen on the PC the mount started moving and continued to move in that direction despite me only giving a couple of clicks, when I clicked stop the connection timed out. I had to go and manually switch the mount off to stop it from slewing. I repeated this a few times and decided to unplug the Hitec controller and see if the problem continued, which it didn't. I spent an hour last night debugging, trying different slews and in the end I ran a separate power feed to the Hitec controller and the problem is gone.

My theory for why this is happening is that the micro-controller inside the product which controls the PWM signals for the heaters is sending noise/signals out to the mount via the power line. The product description states 'Now includes two independent 2.1mm regulated power outputs to suit most Skywatcher and Celestron mounts.'. I opened the unit up again and had a look, the outputs are not regulated; they are simply wired directly to the input. See attached photos.

I have contacted FLO to get their opinion on this, perhaps I've got older stock which didn't include the power regulation. I did find some people online mentioning this problem on other forums, they had put the problem down to their PSU not having enough grunt, this is certainly not the case for me and the NEQ6 requires 2A peak and the ST80 heater only draws 0.7A peak.

Pete.

[FLO]

Whoa! Steady now. You've had it less than a week, dismantled and modified it and are claiming there is a major design flaw before having contacted us or the manufacturer.  

I will contact David at HitecAstro then will post an update. Needless to say if there is a problem we are here for you. 

Steve

[Peje]

4 minutes ago, FLO said:

Whoa! Steady now. You've had it less than a week, dismantled and modified it and are claiming there is a major design flaw before having contacted us or the manufacturer.  

I will contact David at HitecAstro then will post an update. Needless to say if there is a problem we are here for you. 

Steve

No problem Steve, though I technically did contact FLO first...by a whopping 5 mins! LOL

The power control side is extremely basic with no active components that could be providing the claimed 'regulation' so I stand by my statement.

[FLO]

I have just spoken with David at HitecAstro. 

The 'regulated' in our product description is my mistake, not HitecAstros. I am not an electronic whizz but was aware the PSUs sold at FLO are all regulated but the 4-port controller isn't a PSU, it's power comes from an external PSU. It is a typo. My apologies to you, Peter, and David. 

It won't surprise you to hear David is unhappy with the modification you made to the power input cable. HitecAstro fit a fused 10A cable whereas the cable/2.1mm plug you have fitted is unfused and unlikely to handle more than 5A at most, he says. 

The product does not introduce noise, interference or dropouts. 

HitecAstro has offered to email me a more detailed explanation of it's inner workings (hope I can understand it!) but it is already clear you are not happy with the product and HitecAstro are unhappy with your modification. Please stop using it and return it to us for a refund. 

Speaking from a retailers perspective, the HitecAstro 4-port controller is one of our most successful products. We have sold them for several years and have experienced very few returns. We don't believe it has a design flaw so will continue offering it, though from here onwards I will ask David to proof-read any edits I make to the product description...!  

HTH, 

Steve

[FLO]

Have just noticed our competitors have cut/pasted my typo into thier website's product description... 

[Peje]

3 minutes ago, FLO said:

I have just spoken with David at HitecAstro. 

The 'regulated' in our product description is my mistake, not HitecAstros. I am not an electronic whizz but was aware the PSUs sold at FLO are all regulated but the 4-port controller isn't a PSU, it's power comes from an external PSU. It is a typo. My apologies to you, Peter, and David. 

It won't surprise you to hear David is unhappy with the modification you made to the power input cable. HitecAstro fit a fused 10A cable whereas the cable/2.1mm plug you have fitted is unfused and unlikely to handle more than 5A at most, he says. 

The product does not introduce noise, interference or dropouts. 

HitecAstro has offered to email me a more detailed explanation of it's inner workings (hope I can understand it!) but it is already clear you are not happy with the product and HitecAstro are unhappy with your modification. Please stop using it and return it to us for a refund. 

Speaking from a retailers perspective, the HitecAstro 4-port controller is one of our most successful products. We have sold them for several years and have experienced very few returns. We don't believe it has a design flaw so will continue offering it, though from here onwards I will ask David to proof-read any edits I make to the product description...  

HTH, 

Steve

Thanks for the update Steve.. My unhappiness was with the 'regulated' description but you have clarified this was a simple error & I completely understand how it happened...no big deal. I have modified the product to suit my needs so I have no wish to return it, I'll run a second power line for the heater controller and all will be well As for HitecAstro being unhappy with my modification, I am well within my rights to modify the product once I own it.

I will bring the heater into work next week and get the engineers to hook it up to the oscilloscope to measure for noise and that will confirm once and for all if my theory is correct. Rest assured if I am wrong I will have no problem offering Dave (& HitecAstro) a sincere apology.

Again, thanks for your help.

Pete.

[Peje]

7 minutes ago, FLO said:

Have just noticed our competitors have cut/pasted my typo into thier website's product description... 

LOL At least you now know who is following your lead!!

[astronymonkey]

Hi Pete

this is an interesting thread but as the product has already been modified it would be unfair to hitec astro if the output from the modified version was found to have an issue, especially as the output from the unmodified version wasnt tested as a comparison .FLO have admitted that the statement about the supply being regulated was their mistake and are happy to refund the cost so this is always an option. Thanks for posting the pics of the internal workings though.... ive always wondered what was inside. Cheers

 

 

 

 

 

 

[Peje]

On 23/04/2016 at 23:15, astronymonkey said:

Hi Pete

this is an interesting thread but as the product has already been modified it would be unfair to hitec astro if the output from the modified version was found to have an issue, especially as the output from the unmodified version wasnt tested as a comparison .FLO have admitted that the statement about the supply being regulated was their mistake and are happy to refund the cost so this is always an option. Thanks for posting the pics of the internal workings though.... ive always wondered what was inside. Cheers

Hoping to get this on the scope tomorrow afternoon so will report back.

On Friday we tested the unit without a heater load and using a clean power supply and nothing untoward was found, tomorrow we will rerun the test with the heater attached & also repeat the test using my PSU to rule out noise coming from my PSU.

To rule out voltage drop as the problem I measured the voltage at my PSU's output and also at the end of the cable which plugs into my mount, 12.3v at both ends so no issue there. It's an interesting problem and I'm looking forward to finding the root cause.

The modification won't have caused this issue as the work was carried out in a lab by highly qualified engineers, I do concede that perhaps this was a faulty unit and there is not a design flaw. I would be happy to put another unit through the test cycle mentioned but not going to hand over £70 for one to do it LOL.

For those interested, PSU is a TTI CPX400DP & Oscilloscope is a Tektronic DPO 7254.

[FLO]

55 minutes ago, Peje said:

The modification won't have caused this issue as the work was carried out in a lab by highly qualified engineers, I do concede that perhaps this was a faulty unit and there is not a design flaw. 

I don't think you can dismiss your modification so casually. The dew-controller is sold with an integrally fitted fused cable rated to carry enough current for the dew controller and a mount. You have removed that and fitted a lower spec cable (looking at the thin white wires in your photo) that will not carry the type of current the unit is designed to provide. It is perfectly possible the issue you are experiencing is caused by your mount not being able to pull enough current through that thin cable. 

I noticed you have changed this thread title from "major design flaw" to "possible design flaw" but I still consider it unreasonable that you made this claim after having modified the product and without contacting ourselves or HitecAstro for advice. HitecAstro have sold literally thousands of these units and many owners are using the power passthrough feature to power their mounts and other equipment. I haven't seen or heard anything that suggests the product is flawed or faulty. 

Having said that, our offer to accept your modified unit back for a refund still stands. 

HTH, 

Steve

 

 

[Peje]

Steve,

As you quoted David stating "unlikely to handle more than 5A at most", I find it hard to believe this estimate would be off by a factor of two (NEQ6 manual states it needs a 2A & the heater draws 0.64a at peak load, the later I tested last week).

Anyway I shall gather the data, I will be looking into current limitations as part of my tests. It's a fairly simple test to run. I stand by the revised title, this is most possibly a design flaw given the data I have. If I had the schematics and/or gerbers for the product I could know more but I wouldn't ask (or expect) Hitec to provide them.

[Peje]

Well the results are in,

The first test was to test the voltage drop across the cable...which proved to be staggeringly bad. Down from 12.3v to 10.6v with only 1A draw. All other tests were abandoned at this point, a 13.8v regulated PSU is ordered and I'll replace all the cabling with something more substantial. So the thin cable is the cause of my problems and I was 100% wrong about the dew controller being at fault, adding a heater was simply the straw that broke the camels back. I would like to offer my apologies to Hitec Astro for stating their product might have had a design flaw & a big thanks to Steve for acting as the middle-man.

Steve, I'm happy to give this apology in person to Hitec so if you want to PM me a phone number I'll give David a ring. (I'll get the topic title edited and also put a big note on the first post.

[FLO]

22 minutes ago, Peje said:

So the thin cable is the cause of my problems and I was 100% wrong about the dew controller being at fault

Steve, I'm happy to give this apology in person to Hitec

No need. It's already water under the bridge  

[astronymonkey]

Hi Pete,

good to see you got to the bottom of this and the mystery is solved !