Ding dong, the 950i electronics are dead

On several occasions over many months I looked to the wisdom of the world wide web in an attempt to diagnose and fix my Brother KH-950i electronic knitting machine. I consulted manuals, google, web forums and mailing lists, service engineers, sellers and anyone else I could think of.

Eventually I reached the conclusion that the electronics, at least the main PC board, are beyond repair. Here’s how.

The M key does absolutely nothing

950i keypad

The symptoms my machine exhibit are thus:

  1. It takes an interminably long time between turning on the power and numbers appearing on the display.
  2. The M key does absolutely nothing – no annoying beep, no progression to the next part of programming a pattern. Nada.

The M key is important – it follows almost every button press in programming a pattern to knit on the machine to confirm each command.

Conventional wisdom said that there was a memory error, perhaps the previous owner had tried to upload too many or too big a pattern and the memory had overflowed. This should be fixable with the 888 memory erase function.

Except, to begin the 888 function one needs the M button and the M button doesn’t work.

The lithium battery

One other possibility was a dodgy battery within the electronics. There is a 3V Lithium cell battery soldered to the main PC board which is responsible for the machine remembering user programmed patterns when the power is off.

If the battery on your machine is at 2.5V or less, it needs replacing [1]. Mine was still at a healthy 3V, so at least that was one cause eliminated.

Side note – the BR3032 battery

950i Knitting Machine 3032 Cell Battery
The BR3032 battery from my Brother KH-950i knitting machine.

The battery used in the 950i machine is a Panasonic BR3032 3V Lithium coin or button cell with tab mountings, as shown in the photo. I believe the exact part number is BR3032F2N, with the F2N representing the 2 pin, flat mount,  with insulation wrap.

I could only find this exact BR3032F2N battery available at DigiKey UK.

The CR3032 is a similar battery, the difference being its chemistry [2]. The CR3032F2N appears to be more easily available and might work as a replacement.

Alternative replacements would be a plain BR3032 or a different size BR series battery with a holder . Other 3V lithium batteries might work too.

Back to the matter

If the battery is responsible for remembering custom patterns, surely then removing the battery should cause the machine to forget any incorrectly loaded pattern causing the issue?

Apparently not.

What does the service manual say?

After seeing how useful the service manual was for fixing the Toyota knitting machine in my first adventures with knitting machines I’ve tried to get hold of copies for every model I own. Unfortunately it has proved impossible to get hold of one for the 950i. I even asked Brother for a copy but they refused as I am not a Brother engineer.

Luckily, the KH-910 service manual (at least the electronics section) is floating about the internet. This is apparently the model immediately preceding the 950i – should be close enough!

The KH 910 service manual is available online
The KH 910 service manual

Section IV item 3 has a routine for checking the correct functioning of the pattern case (including the M key). Running through the test sequence on my machine results in a resounding fail.

The service manual’s verdict – replace the whole pattern unit or main PC board.


11 thoughts on “Ding dong, the 950i electronics are dead”

  1. I feel your pain. I plugged in the wrong power cord on my 965i and did damage to the board. I have spent many hours online trying to find a schematic so my husband (electronic tech.) can try to fix it

    1. Oh no I’m so sorry to hear that! Schematics seem impossible to obtain, have you had any luck?

  2. Wonderful website. Plenty of helpful information here.
    I’m sending it to some buddies ans also sharing
    in delicious. And certainly, thank you for your effort!

  3. There might be a dry solder joint or break under the M key – not sure how easy it is to fix that though! As for the other problem, I don’t know, mine switches on and beeps straight away. I do wonder whether somehow it “checks” for the M key on “boot up” and if you could fix that, whether it would fix the rest. My pattern reader is kaput – it goes through the motions, but only knits two random columns, so I use the PPD to program it. Good luck getting yours going!

    1. Thank you for your suggestion! I did inspect the board for suspect solder joints and did as much continuity testing as I could but couldn’t find an obvious suspect. Life got in the way for a while but hopefully I will revisit it soon and find a solution!

  4. this machine looks great
    but it seems lo longer is on production
    could you please advice me about alternatives
    I want something reliable and computer interface
    is there something as good as this machine
    need to buy a brand new machine

    1. Hi Rob

      I’m by no means an expert, but hopefully this will help – if you want to buy a brand new machine I think the Silver Reed line of knitting machines is the only “domestic/hobby” brand currently manufactured. They have punchcard and electronic lines. http://www.silverviscount.co.uk are UK and EU distributors.

      There is also the Kniterate (http://www.kniterate.com/) which is a kickstarter project.

      Hope you find what you’re looking for!

  5. Hi I am currently working on replacement electronics for brother 9XX machines. This is being done for my wife, who has various 900s including a 950I. The machine I am currently working on is a KH900. As far as I can tell there is no reason that a 900 cannot do all the knitting functions that a 970 could manage, its electronics was the limiting factor.
    If you look at the “knitic” web site they re-brained a brother machine using an arduino uno/due (due later) in the project.
    All this is open-source hardware and software. I am doing similar but will take sometime over it. If your hubby is an electronics tech, he might be able to use the knitic info to re-brain your 950.
    It should be able to knit, but the card reader bit is not addressed.
    Hope this is of some help. P.S. I will also release under open-source, when and if I ever get that far.

    1. Thanks for your comment. No hubby but also thankfully no need, I am an arduino enthusiast myself.

      I’m familiar with the Knitic and AYAB projects and was working on doing the same thing for my 950i. I designed and had manufactured a PCB and was testing it on my machine but life and an issue with the solenoids halted progress.

      Did you ever achieve success with your wife’s machine(s)?

  6. I have a 950i knitting machine, bought about 1986/7 which has worked beautifully all these years. I am now 90 years still able to useI the machine which I enjoy. Ialso have a Garter Carriage which does a perfect cast on and knits pearl and plain no effort. My problem is – when or comes to patterning 2 x2 rib it has started to drop stitches and plays up. It has been suggested to me that the patterning by the electronics of the knitting machine could be the cause of this.i have tried everything. and it has not improved.i would be pleased if you could give me a clue as to the cause. I find your website of immense interest to me , but have no knowledge of electronics. Thank you

    1. Hi Phyllis, thanks for your comment! What good service your machine has given you, it’s lovely to know you’re still getting enjoyment from it.

      Sorry to hear you’re having problems though. Have you managed to find a solution? There are still a few knitting machine service engineers around

      Do you use the G carriage for your 2×2 rib or do you have a ribber? Unfortunately I don’t have a G carriage so might not be of much help.

Leave a Reply

Your email address will not be published. Required fields are marked *