malc-c

Rob, a bit more digging and came up with this Tangent Instruments, 1691 Spinnaker Drive, Suite 202, Ventura, CA 93001 Phone: +1 805-642-3136 Links to a website seem to fail.... but that may just be broken link

Must have been a different post as the chip was totally different. The microcontroller this board uses is the 16C57 in a Dual in line (DIL) package, which as you say looks to be socketed for replacement with a newer chip should the firmware be updated. I have two problems that prevents me flashing a new chip for you. The first is that I can't find the firmware used, which seeing the board uses a one time only is quite common as once the PIC has been programmed you can't program it again so there would be little point in making the firmware available. It's also quite possibly that Tangent Instruments own the IP of the code so won't publish it. The second issue is that even if the code were available my programmer (PicKIT 2) doesn't support this device (or even the flash variant which replaced it) due to the age of the chip (circa late 80's / late 90's), so I wouldn't be able to program a chip if I had one. Checking RS Components the 16C57 is in stock (single figures) at £8.30 inc VAT, but the flash version us back ordered to god knows when.... So basically, if you suspect the PIC is damaged or the code corrupted other than contacting Tangent Instruments (assuming they are still in business) to see if they can help I think you are going to be stuck. Chances are the code is protected so it would be impossible to read it back even if you could manage to get the PIC running.

Hi Rob, I read a recent post regarding the control board in a Celestron scope, but didn't comment for a couple of reasons. The first being I lack the tools to program a device in that package. I'm just a hobbyist when it comes to electronics and programming, and it was only recently I was able to get a ZIF socket for 28pin SOIC packages to make programming the 16F886's used in older Skywatcher boards easier. The second reason is that I have no experience in working with Celestron equipment, so don't know if the same workflow used with Skywatcher boards will / would work for the processors used in Celestron scopes.

The repair is an option, but if they are honouring the advertised price of £30 I would just buy a second board from them. Given the extortionate prices I had to pay for the PICs due to covid, and my preferred method of return postage it would be cheaper than a repair.

It's very rare to actually see anything physically blown on these boards when they fail. Result on getting a replacement for £30. I would use the new EQDIR cable just to be safe. You don't know if it was the original EQDIR that failed in some way and shorted the board ? I've dropped you a PM regarding the faulty board.

So what's the plan now..... If it were me I would telephone the company in Cambridge and ask if they have a replacement in stock, and if so place an order for one. If they state the price is more than advertised and is comparable with the other boards advertised, and won't accept the advertised price then the choice is to pay the normal RRP for it, or see if we can repair the one that's faulty.

There is not a lot to test on the small PCB that has all the sockets and power switch, other than for any obvious shorts and blown caps (if fitted). Let us know if the new cable did anything ?

The problem is that there are computer PSUs and then there are decent computer PSUs. If your old ATX case was originally supplied with some non branded plain metal box then I would not use it as a mean of supplying 12v to the equipment. Often these cheap units lack all the protection found on branded makes that often cost twice as much, and a branded supply could cost you more than a dedicated 13.8v regulated supply.

It is very odd indeed. Given your description of how the power is distributed, with everything coming form the one regulated supply one would suspect other items also showing signs of damage if the supply was at fault. As they are all effectively running at 12 / 13 volts even if the wrong plug was put into the mount it wouldn't cause damage unless the polarity was reversed. Having said that, these motor boards do seem to lack protection against spikes or reverse polarity. let us know if changing those two caps work.... If the board still fails to function and you get a replacement for £30 (I'm sure they have missed the 1 before the 30 as that would seem a more realistic price - but as they have it listed for £30 I wonder how they stand legally if it has been mispriced?) I would be more than willing to take the dead board off your hands to see if we can get to the bottom of this issue.

This is the baffling part. As I have mentioned, most boards have been damaged through human error and plugging in either the wrong cable or the wrong type of convertor. In this case that is less likely as the setup is semi-permanent and you seem to be someone who is not likely to make those mistakes, which as everything was working 12 hrs before backs that up. The only time I'm aware of someone who used the correct EQDIR cable blowing a board was when they inadvertently connected the wrong power lead and shoved 19v DC from a laptop supply into the mount, which it didn't like. Now not saying that's the case here, but an over voltage is one possibility. Maybe the PSU spiked or something happened to blow the board. One thing I would try before purchasing a replacement board (at £30 I would still get the one listed above) is to replace the two electrolytic capacitors circled below Ideally with ones of the same value but higher voltage rating. I've fixed my original HEQ5 board by swapping them out. This is a cheap fix, costing around 75p for the two and well worth trying. Just note the polarity

Adam, the OP has stated earlier that he no longer has a handset to try

It might be worth removing the module where all the connectors plug in, and check the board for any signs of damage, and look at the pins in the RJ socket to ensure they are OK

Replacing the board is straight forward enough. You do need to remove the Steppers to gain access to the two screws holding the board in place, but once the two screws are removed the board can be drawn forward and removed. Looking at the shops website I don't know if that is a mis-print as all the others are over the £100 mark - Even so I would purchase one whilst its still listed - I'm sure distant selling laws would still mean the price would be honoured if that was a mistake.

They appear to be open until 5pm today, so might be worth giving them a call. All the other boards are listed at the same prices RVO / FLO offer, so no idea why the HEQ5 is listed for £30... - Might be worth taking a punt anyway.. seems to have the 14 day return policy which should be long enough to confirm it's working 🙂

From what I've read it's no different other than the high pitched PWM sound you get when the motors are powered is different, and the board has a USB functionality which is not implemented, presumably as there is no option to fit a socket to the daughter board without redesigning that too. The processor is faster and serial communication uses 115200 baud, which really isn't any advantage as EQMOD and the handset send very little traffic between the mount and PC / handset. Other than a few components everything else is surface mount on one side so production costs would be lower as 95% of the board can be done by an automated pick and place machine and flow soldering station. That link I stumbled across may be worth a punt. As I mentioned, the cost of the two PICs and two lots of special delivery postal services wouldn't be far off the cost of the board. It may be worth making enquiries and see if it has any warranty.

See the images I posted earlier - page 1 of this thread

Mind you, by the time you factor in two lots of special delivery and the cost of parts an labour it my be cheaper to buy the one in the link I provided

Looks like an older board to me - it has through hole caps rather than surface mount and I see two crystals which is a distinct feature of older boards. - That means if it is the board that is fried it can be repaired.

Is that based on testing it as suggested or are you just making that presumption because it worked last time and looks the same? Not wanting to gripe, but it would be handy to have a little more detail on the results of various things I and other SGL members have suggested. Does the cable echo text back when the pins are shorted as suggested. Do you get any voltages on pins and if so what voltages are present. Have you inspected the main board and daughter boards for any signs of electrical damage. Have you removed the covers to confirm which revision of board you have.... A little more feedback wouldn't go amiss EDIT: - just seen your post which crossed with mine... Excellent, lets hope you can find a way to test

I stumbled across this whilst searching for a link to the new board https://www.campkinscameras.com/sky-watcher-motherboard-for-heq5-pro/ £30.00 - Not 100% sure, but from a reversed engineered schematic of the HEQ5 the LED is driven from a PIN on one of the PICs, rather then from the switch. I would need to strip my HEQ5 to confirm. On the RJ45 of the EQDIR cable you have, how many wires are terminated? - If you have access to a DVM, place the GND probe on pin 6 and check the other pins to see if there are any voltages present, if if so that they are 5v and not 12v. If the LED is faintly illuminated when just the EQDIR cable connected this would suggest that there is a path for voltage from the EQDIR cable to find its way to ground via the LED... How / Why ?? beyond my level of how these boards work / are wired.

I can't speak for commercial EQDIR cables, but for an HEQ5 all that is needed is TX, RX and GND. Using the standard colours used in FTDI cable this equates to Pin 4 of the RJ45 to the TTL232R Black wire (GND) Pin 5 of the RJ45 to the TTL232R Yellow wire (RXD) Pin 6 of the RJ45 to the TTL232R Orange wire (TXD) The fact the RJ45 is keyed means you can't rotate a cable and cause any damage. Most boards I've repaired have been Dobsonian where the interconnection cable and handset port allow them to be swapped, or an standard RS232 to USB adapter has been used rather than a TTL serial adapter, and 12v (or a differential of 24v) gets applied to the UART in the PICs and both get blown. The puzzling thing here is reading through the thread you have been using the same cable previously so its not as if the first time use and it's the wrong type of cable. I notice in your signature you state the mount is pier mounted. Do you store the mount outside, or is it stored inside and brought out as and when required? I know some keep the mount outside and protected by a plastic dustbin or similar. My thinking is that if kept outside this could be a dampness / condensation issue which has cause a short on the board. The way to test the EQDIR cable is to short pins 5 and 6 of the RJ45, and then use a serial terminal such as putty or even the one supplied with the Arduino IDE and with the correct port selected in the terminal software type in anything into the send box and hit return. It will then echo whatever has been sent back to the terminal. If this works remove the short between pins 5 and 6 and connect it to the mount. With the mount powered, type in :e1 (colon, lowercase e and one) and hit return. The mount should return a six digit number if the board is responding. If it report backs the six digit string of numbers then both the EQDIR cable and the mainboard is fine and the connection issue is software and not hardware related

It's dependant on the revision of board used. If its an older revision that uses two 16F886 PIC microcontrollers then its a case of converting the binary firmware from Skywatchers website into a HEX code format, reprogramming two new PICs with that converted file, and then removing (unsolder using a hot air gun, or cut the packages off with a dremel and cutting disk, and then unsolder the legs) the old ones and soldering the new programmed PICs in their place. It may also require two diodes to be replaced. However later revisions use an ARM based processor and as yet I don't think any of these have been repaired... mainly as the scope is probably still in warranty, but also as the equipment to program and reflow the chip is more complicated. This is the older revision board U2 and U3 are the 16F886 PICs This is a later revision board. More details of the procedure etc can be found in this thread

He's already mentioned he doesn't have the hand controller, so he cant use the PC-DIRECT mode and a USB A-B cable if the handset is late enough to have a USB port fitted

Same as yours only the LED on my HEQ5 hasn't worked for ages. The difference being I knew I had blown mine as I inadvertently plugged the wrong lead in to the RJ45 port when I was testing an MC004 repair. When the EQDIR cable was connected back to the mount there was no response

If it turns out the main board is the cause it can still be repaired. - I've done a few MC003 and MC004 boards where the PICs were blown, and even my own HEQ5 board when it died.