NEQ6 controller board went to heaven

[Shimonu]

I was about to do some testing tonight and started everything up like normal when suddenly things wouldn't connect. What I saw was my Pegasus Pocket PowerBox wouldn't connect but as I later noticed it wasn't even getting power because the power cable stopped delivering which I now believe is due to the mount shorting and burning the cable. I can't see anything wrong with the cable but I've confirmed with a multimeter and trying another cable. Apart from my mount no longer turning on I also noticed that when I tried turning it on while having everything else on the serial communication with my Pocket PowerBox would fail. Of course the mount is also powered through that unit.

I'm hoping this is just a coincidence as I've just bought a new dedicated astro camera.

This is one of the older models with the RS232-port. Are there any typical components that might fail or things that are worth investigating? I don't see anything that looks damaged but one of the bigger capacitors looks a bit suspicious. Any other options for getting this back in working order?

 

[Dr_Ju_ju]

I don't have one, but what I suspect you think is a capacitor is actually an inductor, which might well have blown out if there was sufficient current trying to pass through it....

[gajjer]

I managed to blow mine up a couple of months ago. I was using an old power pack with banana plugs and doing it in the dark I managed to reverse power it. I was gutted but took it apart and noticed that a big capacitor was blown. ( It may have been two capacitors, I can't remember. ) The ends of the cap were blown out, so it was pretty obvious. 

Well, I swapped the capacitors for something similar ( bigger volts and bigger value ) and to my surprise it worked perfectly. One word of caution. It was quite difficult removing the capacitors. Be careful you don't damage the through plated holes of the PCB. I managed to cut the body from the leads making it easier to remove just the leads.

Hope you get it going again.

cheers

gaj

[Pixies]

Judging by the 'L' on the circuit board, that's an inductor. Inductance is measured in units of Henry [L]. What text is on the body of the component?

If you are going to remove it, as @gajjersays, cut the wires near the component body, so you are only trying to remove the wires when you desolder it. 

If you've never desoldered anything before, check YouTube for tips, using desoldering wick,

 

[Shimonu]

1 hour ago, Dr_Ju_ju said:

I don't have one, but what I suspect you think is a capacitor is actually an inductor, which might well have blown out if there was sufficient current trying to pass through it....

You're right, of course. After seeing the L I realized it wasn't a capacitor.

1 hour ago, gajjer said:

I managed to blow mine up a couple of months ago. I was using an old power pack with banana plugs and doing it in the dark I managed to reverse power it. I was gutted but took it apart and noticed that a big capacitor was blown. ( It may have been two capacitors, I can't remember. ) The ends of the cap were blown out, so it was pretty obvious. 

Well, I swapped the capacitors for something similar ( bigger volts and bigger value ) and to my surprise it worked perfectly. One word of caution. It was quite difficult removing the capacitors. Be careful you don't damage the through plated holes of the PCB. I managed to cut the body from the leads making it easier to remove just the leads.

Hope you get it going again.

cheers

gaj

I'm not sure what could have happened to mine. I wasn't doing anything out of the ordinary and normal just plug the cigarette plug into the battery. But this time things just wouldn't quite start. I tried replugging my pegasus powerbox and that's when some sparks started flying but my guess is something was already broken by that time and caused the sparks rather than the other way around.

Thanks a lot for the soldering tip.

43 minutes ago, Pixies said:

Judging by the 'L' on the circuit board, that's an inductor. Inductance is measured in units of Henry [L]. What text is on the body of the component?

If you are going to remove it, as @gajjersays, cut the wires near the component body, so you are only trying to remove the wires when you desolder it. 

If you've never desoldered anything before, check YouTube for tips, using desoldering wick,

 

Yeah, I saw the L after I wanted to see if I could measure anything with a multimeter. I've got experience with soldering just not usually with these kinds of boards but I'm not too worried for the coil, it's quite big and easy to access.

 

Do you have any ideas for any troubleshooting I can do before I start desoldering. I was wondering if it was worth getting a small variable power supply and set it to some low voltage and see if I can measure the supply and perhaps find some indication of a culprit that way.

[Dr_Ju_ju]

Start by tracing the circuit with a resistance/continuity tester & ensure that there are no obvious short circuits on the input and that the incoming 12v reaches the stepper driver chips and  what I expect will be a regulator providing approx. 5v to the control components.

If all appears to be ok, go ahead & apply volts to the board & re-check the incoming and regulated voltages.  

[malc-c]

Julian is correct, the component is an inductor not a capacitor.

Two things can happen with these boards.  The first is that the power regulation fails, so the PIC microcontrollers stop running as they are no longer receiving 5v, which will give the "no response both axis " message in the handset, or a "time out" in EQMOD.  The second is that if the wrong cable gets connected to where the handset connects it can sometimes damage the serial port built into the PICs which gives the same response.

Power supply issues are harder to resolve, but there have been accounts (including my own HEQ5 board) where replacing the electrolytic capacitors with ones of identical value but higher voltage rating resolves the issue.  These boards run the steppers at 33v, which is IMO too close to the 35v rating of the capacitors used.

If you are interested in possible caused and fixes have a read of this thread

There has been a lot of work on reverse engineering the SW boards.... It's in french, but this is the schematic for the EQ6 power regulation that someone reverse engineered - I can't vouch for its correctness, but it should help you trace out the components, and even gives manufactures part numbers for the inductors etc.

Edited July 10, 2021 by malc-c

[malc-c]

If you get stuck, and after replacing capacitors it still won't come to life and if your board used the 16F886's then drop me a PM and I might be able to take a look and see if I can fix the board in the same way as I've fixed the MC003 and MC004 boards for other SGL members.  The alternative will be a new replacement board at around £130 - £160  from FLO.   

[Shimonu]

1 hour ago, Dr_Ju_ju said:

Start by tracing the circuit with a resistance/continuity tester & ensure that there are no obvious short circuits on the input and that the incoming 12v reaches the stepper driver chips and  what I expect will be a regulator providing approx. 5v to the control components.

If all appears to be ok, go ahead & apply volts to the board & re-check the incoming and regulated voltages.  

Great advice and with the schematic below it helps so much! When applying voltage later, what sort of supply would be appropriate. I feel that I don't want to use the battery pack I normally use as it's able to supply quite a lot of current. So perhaps a mains supply with more limited current capacity is better?

55 minutes ago, malc-c said:

Julian is correct, the component is an inductor not a capacitor.

Two things can happen with these boards.  The first is that the power regulation fails, so the PIC microcontrollers stop running as they are no longer receiving 5v, which will give the "no response both axis " message in the handset, or a "time out" in EQMOD.  The second is that if the wrong cable gets connected to where the handset connects it can sometimes damage the serial port built into the PICs which gives the same response.

Power supply issues are harder to resolve, but there have been accounts (including my own HEQ5 board) where replacing the electrolytic capacitors with ones of identical value but higher voltage rating resolves the issue.  These boards run the steppers at 33v, which is IMO too close to the 35v rating of the capacitors used.

If you are interested in possible caused and fixes have a read of this thread

There has been a lot of work on reverse engineering the SW boards.... It's in french, but this is the schematic for the EQ6 power regulation that someone reverse engineered - I can't vouch for its correctness, but it should help you trace out the components, and even gives manufactures part numbers for the inductors etc.

That is so helpful, I haven't gotten all the way through but so far it seems accurate! Thank you! I've had a good look at the electrolytic capacitors and they don't show any sign of damage. Doesn't mean they're fine but none of them went pop. From the schematic I can't see the power LED, it should be D3. It would be nice to know where that comes in as it didn't light up, so it's a clue of a power supply issue but I'd like to know how much it limits the search.

EDIT:  Managed to follow the trace and saw now that it's driven off one of the PICs

28 minutes ago, malc-c said:

If you get stuck, and after replacing capacitors it still won't come to life and if your board used the 16F886's then drop me a PM and I might be able to take a look and see if I can fix the board in the same way as I've fixed the MC003 and MC004 boards for other SGL members.  The alternative will be a new replacement board at around £130 - £160  from FLO.   

I had no idea there were replacement boards. Would it really work for an older mount like mine? I've got the 16F73 I'm afraid. I really appreciate the suggestion!

Edited July 10, 2021 by Shimonu

[malc-c]

That's really an old board if it has 16F73's... The firmware available form SW is for the 16F886's so it wouldn't be possible to program replacement 73's without the old code.

The full schematic for the 16F886 based boards is attached, and it follows that a lot of the layout would be common to other boards that use the same stepper motors etc.

Schéma électrique eq6 v1.pdf

The caps can look perfectly normal but still be duff.  It can take a hell of an inrush current to pop them....  C3, C48 C41 and C14 would be my first choice for replacements, with 50v or 100v rated caps.

[malc-c]

It may be possible to replace the complete board with one based on the 16F886's  https://www.teleskop-express.de/shop/product_info.php/info/p3446_Skywatcher-Hauptplatine-fuer-Montierung-EQ6-SkyScan-Pro.html

As far as I know the EQ6 was only available in one version and thus the gear ratios and steps per worm revolutions will be the same.  So it should be possible to drop in a new board for around 170 euro.  - I would certainly drop Teleskop express a mail to enquire if that is the case, and then if  attempts to fix the board by replacing the caps fails you have a fall back plan

[Shimonu]

Well I'm a little embarrassed/confused. I was about to start measuring voltage after I went buying a PCB holder and other stuff for soldering. I plugged in the cable and noticed the LED came on. Connected the controller board and plugged in the handset which seems to work just fine, slewing no problem. But I don't get why powering on the mount yesterday caused the serial communication with the PPB to fail, even though nothing but the power cable was connected to the mount. I haven't tried running the whole rig, so maybe it'll show the issue again. Perhaps the second cable I used wasn't good enough, I just opened it too and there's no fuse in it. But that's the cable I got with the mount. I feel like if it can handle the mounts requirements it should be able to just power on stuff.

I dismantled the first cable I used yesterday which stopped working and sure enough the fuse is blown. That's an 8A fuse.

I'll hold off on doing any more testing until I get some more input.

I don't feel like an 8A fuse just blows for no reason. I'm powering from a 12 V battery which at the moment shows 12.6 V and that isn't going to suddenly unload high current unless there's a short. But where would that happen? The cables are all factory made and are not just going to switch polarity and everything is center positive.