USB connectors

If you're having problems with the hardware of a DM41X or DM42, post about them here.
x55
Posts: 19
Joined: Sun Jul 26, 2020 7:32 am

Re: USB connectors

Post by x55 »

cdmackay wrote:
Tue Jan 08, 2019 9:05 pm
I had read that the power pins of the USB connection may be slightly longer, so that power is up before the data pins are connected. Whether that's true or not, I don't know, and I think it referred to the USB-A (i.e. PC/host) end.
Yes, it refers to USB v1 Type A 'plugs'. On inserting the plug the grounded metal shield makes contact first, then the longer 'pins' establish a steady power supply (in a USB connection the 'host' always supplies the power), then the data lines are connected. In MiniUSB and MicroUSB connections there are no 'longer' pins but a fifth ('ID') 'pin' that, in conjuction with some simple electronics, is used to determine which is the host and prevent conflicts that way. MiniUSB and MicroUSB 'receptacles' can also come in an 'AB' format that accepts either type of plug and utilizes the ID 'pin' to sort out which is which in "On the Go' connections. In charge-only cables the data lines should be shorted out at the device.

In USB connector are there no 'pins', but flat strips positioned against a solid substrate to form an arrangement that makes the connections much more robust and durable (no actual pins to get easily bent or broken). Also, where possible stress points are moved into the cable, which makes for easier and cheaper replacement if wear does cause a problem. In terms of durability, v1.0 connectors are the least rated, then Mini connectors then Micro connectors, with C connectors providing the highest specification. Each one of that sequence is about an order of magnitude more durable than its predecessor.

E&OE.
--
HP: 55/67/41C/HP-IL/ProtoCODER*/41CL/MLDL**/41CX/16C/71B/42S/33s***/35s ...
DM: 42 ...
Etc: If a calculator has equals, why buy one unless it's the cheapest?
* ProtoTECH, USA / ** Eramco, Netherlands / *** Carly Failurina model
cdmackay
Posts: 162
Joined: Fri Oct 05, 2018 8:33 pm
Location: Cambridge, UK
Contact:

Re: USB connectors

Post by cdmackay »

thanks!
Cambridge, UK
41CL/DM41X 12/15C/16C DM15/16 71B 17B/BII/bII+ 28S 42S/DM42 32SII 48GX 50g 35s 30b/WP34S Prime G2
& Casios, Rockwell 18R :)
Alessandro
Posts: 1
Joined: Sat Oct 03, 2020 10:04 am

Re: USB connectors

Post by Alessandro »

Hi all,
I received my new DM41X (s/n 501) and it gives a very good keyboard feedback.

I am experiencing USB connection issue, even after cutting the plastic shell of it as mentioned in this post.
My Win10 reports a "device descriptor request failed" inside the USB controller (control panel) and I do not have any chance to see the drive.
Do you have some suggestions?

Thank you,
Alessandro
ljf2
Posts: 1
Joined: Wed Apr 29, 2020 11:37 am

Re: USB connectors

Post by ljf2 »

I had the same problem with my new DM42: it dit not mount, be it on MacOS or on Linux file system). I solved the problem by removing even more plastic from the USB connector (approx. 2 mm in all). 100 % successful connections ever since.

It seems to be an issue that cannot be solved with the current design of the board.
cdmackay
Posts: 162
Joined: Fri Oct 05, 2018 8:33 pm
Location: Cambridge, UK
Contact:

Re: USB connectors

Post by cdmackay »

It's been pointed out in other threads, but note that not all micro-B cables have the same length connector.

I just compared lots of mine, and selected one that was the longest. Worked perfectly with my DM41X. I've had problems with randomly selected cables before, including trashed FAT disks.

You can test it in the calculator; before enabling the USB disk, make sure that the connector protrudes slightly from the calculator case. If you think that the case is touching the plastic of the connector, and stopping it travel far enough into the calculator, find another cable, or trim some of the black plastic.

I wouldn't rely on the power symbol on the calculator, since the power pins may contact first, but it's the data pins that are important here. I think that may be only for USB-A, perhaps, but I prefer to verify it visually and by feel.
Cambridge, UK
41CL/DM41X 12/15C/16C DM15/16 71B 17B/BII/bII+ 28S 42S/DM42 32SII 48GX 50g 35s 30b/WP34S Prime G2
& Casios, Rockwell 18R :)
nephilim
Posts: 22
Joined: Sat Sep 12, 2020 10:09 pm

Re: USB connectors

Post by nephilim »

I can confirm that the USB connector of the following cable can be fully inserted w/o touching the DM42's case. https://www.amazon.de/gp/product/B07JB6V66H. I had to wait a few weeks but the wait was worth it.

Borrowed from amazon...Image
User avatar
salvomic
Posts: 184
Joined: Sat Dec 30, 2017 10:09 am
Location: Ragusa, Sicily
Contact:

Re: USB connectors

Post by salvomic »

today I had a problem with the DM42 and the USB disk in macos Big Sur: the disk of the DM42 was mounted at first, then I tried to delete two files in the States folder and the disk disappeared from the Desktop, I had to press "Exit ", fearing that it would be damaged. After I unplugged the cable, hung up and it didn't appear, again I had to press "exit" ...
I was able to mount the disk by changing the USB port, the disk looks ok, I hope it really is.

I used the Prime USB cable with a USB 3 / C adapter, as I did before the new operating system.

Some advice?

Salvo

EDIT: now I'm trying a direct cable: USB-C/micro USB (Ugreen type) and it seems to be better...
∫aL√0mic (IT9CLU) :: DM42 (SN: 00881), DM41X (SN 00523), DM16, HP Prime, 50g, 41CX, 42s, 71b, 15C, 12C, 35s, WP34s -- Free42
User avatar
salvomic
Posts: 184
Joined: Sat Dec 30, 2017 10:09 am
Location: Ragusa, Sicily
Contact:

Re: USB connectors

Post by salvomic »

today same problem with the DM41, as with DM42: the cable USB-c/micro is ok, but the disk stuck accessing the folder /State (with a spinning wheel), I had to force expulsion, then the calc also was stuck and I performed a pin reset, losing all. I've loaded an old backup, putting the cable in another port of the Mac as in the previous the disk icon didn't appear...

Maybe there are some problems with macOS Big Sur?

Salvo
Last edited by salvomic on Sat Feb 20, 2021 8:53 pm, edited 1 time in total.
∫aL√0mic (IT9CLU) :: DM42 (SN: 00881), DM41X (SN 00523), DM16, HP Prime, 50g, 41CX, 42s, 71b, 15C, 12C, 35s, WP34s -- Free42
itscosmo
Posts: 3
Joined: Thu Nov 12, 2020 5:29 pm

Re: USB connectors

Post by itscosmo »

I bought this https://www.amazon.com/gp/product/B013C ... UTF8&psc=1

It has an extra long tip.
User avatar
salvomic
Posts: 184
Joined: Sat Dec 30, 2017 10:09 am
Location: Ragusa, Sicily
Contact:

Re: USB connectors

Post by salvomic »

mine now is this one, and it seems to be good enough, however I had the problem also with this: FAT disk stuck, spinning wheel and so on, so I would like to understand if there are some software problems here in macOS Big Sur or other issues.

Salvo
∫aL√0mic (IT9CLU) :: DM42 (SN: 00881), DM41X (SN 00523), DM16, HP Prime, 50g, 41CX, 42s, 71b, 15C, 12C, 35s, WP34s -- Free42
Post Reply