Heq5 pro motherboard

[Robd]

Good morning all, first post since I don’t remember when.

 I took my Heq5 out last weekend to take to our star party. Had all sorts of problems, error messages on hand set etc. finally  realised that it was not tracking so gave up in disgust.

Error messages include ‘Dec/Alt no response’ then nothing works. Power light is on a steady, no flickering.

Stripped it down over the weekend and removed the motherboard. By my reckoning the large capacitor at the bottom of the image is blown. The only remaining lettering on it is E203. Item is marked as L42, which now makes me think that it is not a capacitor , seem to recall a thread elsewhere on here saying that the ‘L’ items are not capacitors.

Second image close up of L42

Is it blown?

Any ideas on what it is for replacement?

If not blown any other ideas. As far as I can see none of the capacitors are blown.

Thanks 

rob

 

 

[Mandy D]

7 hours ago, Robd said:

Good morning all, first post since I don’t remember when.

 I took my Heq5 out last weekend to take to our star party. Had all sorts of problems, error messages on hand set etc. finally  realised that it was not tracking so gave up in disgust.

Error messages include ‘Dec/Alt no response’ then nothing works. Power light is on a steady, no flickering.

Stripped it down over the weekend and removed the motherboard. By my reckoning the large capacitor at the bottom of the image is blown. The only remaining lettering on it is E203. Item is marked as L42, which now makes me think that it is not a capacitor , seem to recall a thread elsewhere on here saying that the ‘L’ items are not capacitors.

Second image close up of L42

Is it blown?

Any ideas on what it is for replacement?

If not blown any other ideas. As far as I can see none of the capacitors are blown.

Thanks 

rob

 

 

That item is almost certainly an inductor. It's designation of L42 further confirms this. What makes you suggest it is "blown"? I would suggest that an inductor of that size is part of the power supply, but you indicate that the power lamp is showing steady, so looks unlikely that this is faulty.

[Robd]

Thanks Mandy.

My first thought was that it was a capacitor that had blown especially given that there is no indication as to what rating it is etc, just the E203 and a fair splattering of white  dots made me suspicious.

 I think that I will try connecting without the hand set from laptop snd see if it works, in which case hand set to blame.

 

[malc-c]

Two things that result in the "no response ..... XX/YY axis" message.   The board has lost power and thus nothing is getting to the microcontrollers, or the serial ports on the microcontrollers have been blown by too high a voltage.  The latter is more common on older dobsonian scopes where two identical boards are linked and the cables are inserted into the wrong port on the board.

As Mandy has pointed out the part is an inductor, and generally doesn't fail.  I've fixed my own HEQ5 board by replacing the two electrolytic capacitors C3 and C41 next to the connector J1.  I've used the same values but with a higher voltage rating.  If this doesn't resolve the issue, and you get a similar "comms failure" when using EQMOD or similar then this would suggest that the fault lies in the serial communication circuits.  This can be down to a blown signal diode(s) (mainly fitted to MC003 / 004 boards found on Dobs) or damaged PIC microcontrollers.  I've managed to program 16F886's for a variety of boards which has been documented in this thread including my own HEQ5.

If you find that you get similar issues with an EQDIR cable as you do with the handset and you are in the UK, then drop me a PM and we'll see about repairing the board.  

[Robd]

Thanks Malcom.

Good news is that the mount now seems to be working. The bad news is that I have no idea why.

To expand a bit on the saga.

This mount has not been used since I upgraded to an EQ6. Until then it had been permanently mounted in the observatory and only driven from pc with Eqmod.

This was the first time that I had used it in the field connected to pains adaptor  with 12v 2a supply.

Initially I thought that all was OK using the handset - set date/time /location  and polar aligned. Slewed to Jupiter and took a couple of images. It was then that I realised that it was not tracking so went through all of the synscan setting but found nothing that would get it tracking.

Tried connecting to the laptop but failed. Checked Com ports still no connection.

Turned off, closed all windows, gave it a good hard stare  still no tracking. Then started to get the no response messages, one axis then both so gave up.

Took motherboard out as above.

Today I have put it all back together  and  started again. Still the same result with the handset connected so removed it and connected to laptop, still no joy so raided the observatory for cables, usb to serial etc.  Still no joy. Finally stripped anther cable from the observatory - the serial that connects to the mount. Connected to laptop and  ....... strewth it works, there's that nice little whine from the motor, it slews, it tracks.

I then realised that I had been connecting to the guide port not the handset port with an st4 cable.

Disconnected and plugged in the handset and it works. Turned off and on and it still works. Currently checking the tracking rate.

This leaves me with a number of questions.

Why have I got an eqdir plug etc with st4 connectors that don't seem to do anything when connected?

Why did the handset initially half work and then give up?

Did connecting the laptop to the guide port screw something up?

Why did I start this game in the first place?

 

Since all seems OK now I guess I'll never know.

 

 

 

[malc-c]

Can't really comment , however, most synscan mounts are shipped with a long serial serial cable that has an RJ 11 at one end and a 9 pin D type plug on the other.  This is designed to upload firmware to the handset, and if the handset is placed into PC-DIRECT mode, as a pass through to update the mounts firmware.  Thing is these days most computers no longer have a true serial port so a USB to true RS232 convertor is needed.  This was originally the way to  control the scope in the early days of EQMOD.  The problem comes when you then use the same lead in the handset port, which then shoves +/- 12 (ie 24 volt potential) into the PIC's serial UART which they can't handle and blow.  An EQDIR cable uses a USB to 5v TTL Serial chipset with the other end of the cable terminated with an RJ45.

12v 2amp may be close to the limits.  It only leaves around 200mA with both axis slewing.  Plus if its out in a cold damp environment it could cause the voltage to drop.  These boards whilst rated at 12v  really like one or two more volts and get upset if the voltage drops below 12v.  It could have been the case that caused it to fail half way through.  Bearing in mind that the handset is powered through the supply to the main board, and will use up at least 50mA just to illuminate the display, reducing that 200ma headroom even more.

Anyway, glad you have the thing working