BHC Assembly Question


 

I have all of the components needed to assemble the Basic Hand Controller (thanks George Cushing for selling the kit).  I can solder, use a multimeter, and know basic electrical principles, but I am not an expert on deciphering PCB layouts.

- Is there a proper orientation for the push buttons?
- Is there a proper orientation for the DPDT switches?
- What about the LED's polarity?  I see no markings on the PCB to indicate the LED's orientation
- Is the link below valid on how to wire the RJ12 jack from the OnStep controller (I am using an MKS v2.0, so I can see where the 6 different wires go on the board, I am just not sure about the RJ12 termination):  http://www.store.shoestringastronomy.com/guide_port_cables.pdf

In various posts there is reference to a schematic diagram on the wiki: https://onstep.groups.io/g/main/wiki/7150
@Khalid references a few times that the schematic is in the wiki, but I don't see it other than the EasyEDA PCB.  Is this in fact available somewhere on the forum?

Thank you!


Khalid Baheyeldin
 

On Sat, May 29, 2021 at 02:35 PM, Otto wrote:
In various posts there is reference to a schematic diagram on the wiki: https://onstep.groups.io/g/main/wiki/7150
@Khalid references a few times that the schematic is in the wiki, but I don't see it other than the EasyEDA PCB. 
The problem is this: as users post new images and attachments of their builds and such, Groups.io erases the images and attachments from old messages so that storage is not used indefinitely.


 

On Sat, May 29, 2021 at 01:41 PM, Khalid Baheyeldin wrote:

The problem is this: as users post new images and attachments of their builds and such, Groups.io erases the images and attachments from old messages so that storage is not used indefinitely.
Thanks Khalid.  If a schematic or diagram were available, could it be placed in a PDF in the Files section?


 

On Sat, May 29, 2021 at 01:35 PM, Otto wrote:

- What about the LED's polarity?  I see no markings on the PCB to indicate the LED's orientation

I uncovered the answer to the above question.  The right side of PCB marking is the LED's cathode.  I could not see it on the actual PCB, but can see it in the schematic on EasyEDA.


Khalid Baheyeldin
 

If a schematic turns up, I will put it in Files.

It is a shame that we are losing images, of older builds (like Rick Foust's monster 1960s mount), schematics ...etc.

One thing that can help is that users be sure that attachments and images be small (e.g. ~ 50k) instead of them being multi megabyte. However, it will be hard to get people to comply, unless there is a setting to enforce this.
I don't see one under Admin, but maybe there is such a setting that Howard can change.


George Cushing
 

The BHC is basically a copy of the Celestron Ultima PEC's (1990) hand control. The DPDT switches functioned to allow the user to reverse the effect of the buttons to be more intrusive and reflect the direction of the movement of an object in the type of telescope they had mounted. In 1992 when Losmandy had Tangent adopt the Ultima's drive system for the new G11's 492 Digital Drive System (so called as the final design was finished in April, 1992) they used the Ultima's hand control. Later the Celestron C5+, C8+, Celestar and Celestar Deluxe all used the Ultima hand control PCB, but the DPDT switches were omitted on these less expensive models.

When I started offering the BHC as a kit the only DPDT switches I could find that conformed to the PCB were from C&K that ran about $5 after delivery and taxes. That would double the price of the kit. So I decided to omit them.

I send this photo to buyers so they can set jumpers to get the button effect they prefer.



And here's a drawing of the PCB showing all the traces. The colors were from the cable I was using at the time.
.


 

Thanks George.  I believe I found the answer to my 1st and 2nd questions from the original post.  After looking online a bit, it looks like orientation is irrelevant for both the momentary push button switches and the DPDT switches.  I guess if one were really particular, you could orient the DPDT switches so that it matches the directional change you want based on the switch's movement, but I won't care.

I think the RJ12 connector pin-out is based on the PDF I linked above, but I'm not entirely sure.  If someone would confirm, that would solve/answer my last piece of the puzzle. 


 

Could someone confirm the pin arrangement for the RJ12 jack on the BHC?  I have the following reference, but it is from a paper called "Guide Port Cabling" which I found linked to one of the message threads.  I have not seen this official reference in any wiki.  I do have the matching pinout for my MKS v2.0 which is labeled on the Wiki.

Pin 1 - 5V
Pin 2 - Ground
Pin 3 - RA+
Pin 4 - Dec+
Pin 5 - Dec-
Pin 6 - RA-

Thank you!


 

On Sun, Jun 6, 2021 at 03:23 PM, Otto wrote:
Could someone confirm the pin arrangement for the RJ12 jack on the BHC?  I have the following reference, but it is from a paper called "Guide Port Cabling" which I found linked to one of the message threads.  I have not seen this official reference in any wiki.  I do have the matching pinout for my MKS v2.0 which is labeled on the Wiki.

Pin 1 - 5V
Pin 2 - Ground
Pin 3 - RA+
Pin 4 - Dec+
Pin 5 - Dec-
Pin 6 - RA-

Thank you!
I think the easier questions is...for the the PCB trace that George posted, which is 5V and Ground?  I assume the Red/Blue are RA +/- and Green/Yellow are DEC +/-


Drew 🔭📷🚴‍♂️
 

I found this in the old OnStep pictures


 

Thanks Drew.  Yours shows the reverse of mine.  After studying George's diagram a bit more (I am not an electrical or PCB layout expert), I think power comes on the beige conductor as that line goes through the resistor, into the LED, and then splits to the four momentary switches to close the circuit (depending on the button pushed).  Is that what you or others see? 


George Cushing
 

This is confusing as the PCB has the RJ-12 pin 6 labeled as 1.


Here's how the Losmandy 492 hand control is wired.


Drew 🔭📷🚴‍♂️
 

George, the pic I provided was yours. I am always confused by these connectors.  I end up redoing them several times, either because the reference is wrong or I am.


 

I did confirm with a twin AA battery holder that Pin 1 in George's diagram is 5V and Pin 2 is Ground. Everything else follows the order from the Ground pin to pin 6.

@George Cushing - Your ST-4 to BHC diagram, I believe, has the 5V and GND wires reversed.  You show the grey/white wire going to Pin 1, and Black to Pin 2.  All of the other diagrams on the RJ connectors show the opposite.

Thanks for everyone's help on deciphering this.