lukepower

Hi Waldemar, my personal guess is two-fold: First, we had a very stron thunderstorm last summer, when a lighting struck a construction crane at our neighbour (about 20 meters from the observatory). We only had a few power units of some security cameras that got burnt (mostly capacitors), but others had broken TVs and so on. Might well be a cause of the defect Second, the mount was off since may 2013 till beginning of december, when we got the new OTA. During the first test, there was something smelly around the mount, but it kept on working and it disappeared, so I didn't care. SO, my guess would be that the lightning ruined the capacitor and/or the voltage regulator. All other problems might well be the result of that event...

Alright, enjoy: Especially on the top and bottom there are quite some smoked components...

Roger, I will take a picture and put it here so you can look at it. To me, it seems that part of the PCB got burnt like under short-circuit or similar. Maybe with time, the current spikes kept on damaging it more and more, till th epoint that it wasn't running anymore. I have confidence that the guys at ASA will be able to fix it and that they have enough understanding of electronics (which I don't) to make it work reliabily.

Addendum: I just came back from unmounting the OTA and mount. Once the OTA was away, the DEC axis had a very strong smell like burnt plastic. I removed the cover of the DEC axis (with those 4 small screws) and found a circuit under there with part of it completely burnt. Looks to me like a voltage regulator, but I might be wrong. Will post a picture afterwards. So, at least I know it is a defective electronics which probabily is cause of the problem.

Hi Nigel, agreed. USB is easy and all, but the troubles you can have with those stupid drivers and cables... RS232 or similar serial connections should be fast enough and stable. I personaly would also consider an Ethernet connection. My guess is anyway that the issues arise, at least in my case, between the mount electronics and the Serial-to-USB converter sitting in the mount, as only the connection is lost but the motors are still tracking...

Oh well, when it works... We will probabily feel the effect of "Grenzgrößenwasser" once we start with it, but who cares, the system is automatic and we can look at the pictures the day after

Hehe, well, we do have enough bottles in the cellar to survive quite a bit of harsh times, so... Let's see. Once it works I am quite sure to have a party over here

Hi Waldemar, heh, your post got me smiling I literally smelled it since a while, that I would have to return it. These moments I wish I had a crane or lifting system in the observatory to get the OTA down from the mount. But heck, at least I have an excuse to convince my +1 to go to the Steak house once again I actually hope that the guys at ASA will give it a nice Upgrade (*cough* maybe they are reading this? *cough*) with stuff like 50A-motors and ethernet connection I might add a few bottles of beer or wine to help out a bit So for now, I'll just keep this beast of an OTA asleep, hopefully they find the flaw and can fix it

Hi George, yes, I did. No change at all :/ By the way, I had a remote support session with ASA today, and they decided I should return the mount for a closer inspection. It looks like the electronics have something wrong with them...

Let's see what the remote support tomorrow yields. I changed USB cables (several times), added an industrial grade USB hub (with filters), and countless trials of changing location of the cables running from the mount to the power supply and to the computer. Cross fingers and let's see...

Hi Roger, I do have a remote support session planned for tomorrow, and I will ask their (ASA) engineer what are his toughts on this. Too bad that there is no way of easily exposing the electronics of the mount (without disassembling everything). I could try with something like a 40A PSU: http://www.tpautomation.de/shop/Stromversorgungen/SITOP-Stromversorgungen/SITOP-modular/6EP1337-3BA00-SITOP-modular-Stromversorgung-1-2-ph-DC24V-40A::3557.html The thing that disturbs me is that in fact we talk about loosing the communication channel to the mount, the mount itself kept working. Once I had it tracking for over half an hour before I saw that Autoslew lost the connection. A voltage drop might well be the reason why the electronics loose USB connectivity for a fraction of a second...

Hmmm, the PSU should also have apeak of higher than 24V... Well, have to investigate this, too...

Well, I use a Siemens PSU with 24V and 20A output, short leads (it's sitting at the base of the mount). FUnny enough, the motors keep often running even without connection to the PC

Hi Roger, well, when the connection is lost the camera and all other stuff on the USB hub of the mount still work. I anyway have to power cycle the mount (or its electronics, whatever) to get it recognized again from Windows... That's the main problem. Unplugging and replugging the USB cable doesn't help.

Hi Roger, well, it actually sounds like the problem I am having. Please correct me if I'm wrong, but if I understand this correctly then this could be addressed by changing the circuit/PCB design? My hope was more like "add a condensator somewhere and you're done"

Hi Roger, hmm, but wouldn't a brownout mean that the connection is lost without being able to return it to life (without modifying/changing the electronics)?

Hi Bernard, I have ordered a similar system for my scope, your solution looks good! Will definitively be an improvement

Hi Evgeny, hm, that's a good question. Maybe ASA is planning to make a new mount version (read: new electronics) with a RJ45/ethernet socket. Would definitively be cool

Evgeny, I wonder if Dr. Keller's solution would still require WIndows/ASCOM at all. If you could control Autoslew via SOAP requests, and Autoslew itself would run on a linux box (take a Raspberry Pi, for example), then we would have a self-contained control box for the mount, controllable from ethernet. Shouldn't be difficult to be able to control it using INDI, or am I wrong here?

ALright, small update: I inspected the light path from the front of the scope to the camera, and saw three stainless steel screws (with a respectable head), which keep the last bit of the main mirror baffle in place. They definitively reach into the light path, as I am seeing them in the defocused star images. They are made of shiny steel, so reflections should be there. I removed one (as I have no exchange part for them) to see if it makes any difference from yesterdays image. Let's hope for clear weather and I'll try. Damnit, yesterday we had 21.5 SQM over here, would have been a great night

Hi Nigel, well, the OTA is about 84kg (that is, just the tube with the mirrors). Add to this: 4" focuser (about 2,5kg) ASA OK3Z focuser (about 2kg) ASA 4" Cassegrain corrector (heavy, would guess 3-4kg) some spacers (maybe 2kg) FLI CFW 5-7 + FLI Proline 16803 (nearly 5kg) one 2kg weight to handle the OK3z imbalance so, all in all we are approaching 100kg. I am sure my balance is not perfect, I am still waiting to get some custom-made weights designed to exactly counteract the radial imbalance of the OK3Z, that should help alot. This Cassegrain-Newton tube is cool but difficult tobalance properly.

Hi Waldemar, failing electronics would be bad news, to return the mount I would have to take some muscle strengthener to get the OTA off of it (100kg) I guess that it's a combination of long OTA and heavy weight, these mounts are great but sensible to balancing issues. I am now going to remove an additional mounting plate I have on one side of the OTA, let's see if that helps. Thanks

Hi Bernard, drop of dew... Hmm, actually in the morning there was heavy dew on both the main mirror and the carbon structure. Could be a possible cause... I will try to rotate the individual components first, as the tube is heavy and very (!) prone to fine balancing. If I remove the corrector I can forget to use the mount as it would go crazy Nigel: The OTA is custom-made by a renowned german telescope builder, with a 20" mirror from Zen (Italy) and correctors from ASA. As I was so concentrated on getting decent collimation and the mount to work, I dedicated no time to this problem, at first I even considered it small I thought covering the open truss with a black cloth would be enough, but nada

Here again... IMHO it's the imaging train, either the corrector or the camera, as the position stays always the same. I still have to try to rotate the camera and corrector to see if the rings follow them...

This has always been so Well, the scope is new, so "always" means since it is running, a few days ago...