bernina 801 why is my foot pedal only operating on warp speed?

Hi I have a Bernina 830 with bernina 237 electronic foot control it was not working when I bought the machine but I have removed the the PCB and resolderd the component connections and checked values they appear to be ok the .01 cap shows the corect value, It now runs ok but the start speed seems high and ramps up to full speed but will not creep start like the other Bernina 830 I have, the trim pot seem to have little or no effect has anyone had this problem or is this the characteristic of this control

Teddy
May 2020

Hi there,
Not sure if this is still alive.
I did the repair as instructed by Jo, now the machine starts humming when i press the foot pedal and it starts moving real slow. before repair it was full speed only when foot pedal was pressed al the way down.
Any hints? many thanks in advance

Hamid
March 2017

Have not been back to this site for some time. Glad everyone is having success at fixing their foot controllers. As I mentioned, the electronic parts in this controller are not critical. Just be sure you replace the 0.01uF mains capacitor with a similar X2 600v type. The transistors can be any small signal silicon types. Just get the npn and pnp transistors in the correct positions and the pin outs correct. Data sheets are available from www.alldatasheet.com
Any 5 amp 600v or better TO-220 style triac will be OK.
Good luck
Jo.

Jo
November 2016

I used the following parts from Digikey:
399-9641 R46KF210050N0K .01uF X2 film capacitor
497-6663-5 BTA08-600BRG standard TO-220 Triac
BC547CTACT BC547CTA NPN transistor (for ZTX107)
BC557BTACT BC557BTA PNP transistor (for ZTX212)

went from humming to working great once all these parts replaced.
I spent a good 30 minutes making sure I had EBC in the right order though - bottom view in old datasheets to top view in new ones along with curves in opposite directions makes life confusing! Basically printed sides go in same direction, so nothing is "backwards".

Bigup to Jo for figuring this out. My wife and kids are very happy!

drmike
April 2016

I have two type 289 foot controllers, neither of which worked correctly. I followed Jo's instructions and both are now functioning.

A point of interest: one of the controllers had the transistors listed by Jo and one did not. Instead of the BC237 there was a ZTX107 and for the BC307 was a ZTX212. It did not look like these had been replaced perviousy. I used BC547 and BC557 and everything seems fine.

Nik
October 2015

I eventually found the correct X2 capacitors on eBay. They are rated at 630 volts(DC), or 400 VAC. The AC rating number will always be lower. I found the recommended transistors at Amazon. I had to buy large quantities, but the total cost was low. My 830 electronic controller is now working. The transistor pinout is the same with the replacements. The board is not marked, but the PNP one is closest to the end of the board.

There are two different Bernina 830 Record machines. The later one is marked "Electronic" and designed for the electronic controller. The older machine will run with the electronic controller, but will run slow. The electronic machine will work with the older controller.

Jim
December 2014

I repaired a Bernina 830 controller by replacing the 0.01 capacitor. I just wantet a quick test to see if that would fix it, so I used a 400 volt Radio Shack cap.

I'm looking for a 600 volt X2 cap, but don't see them.

What I see are 275 VAC and 300 VAC. Looking at industrial suppliers, I see that they rate the DC voltage at four times the AC voltage. So that would make a 275 VAC cap an 1100 volt DC cap. Am I wrong about this?

Reasoning backwards, if the original cap was 630 volts DC, it would be 158 VAC, which should be okay for U.S. households. So a 275 should be better.

Jim
August 2014

My foot control runs full speed only after being fully depressed (not just touching it). I replaced the .01 Uf capacitor, the two transistors, and the triac, to no avail. Now I'm wondering what else could be causing this. the carbon track is conductive, but the slider has to travel to the bottom before the machine runs full speed. Anyone have any other ideas?

Thanks

Bonwit
June 2014

Sorry Seegy.
Have not been back to this site for a while so missed your question regarding the diac, but see that you worked it out for yourself.
The diac can be anyway around as it 'breaks over' at the same voltage in either direction and is used to turn on the gate of the thyristor.
Fine on the transistors. Any small signal general purpose silicon transistors would do, the circuit looks non-critical. Just be sure the PNP and NPN types go in the right places and the pinouts are correct.
You are right about the X2 capacitor. It has to withstand the full mains voltage and any spikes that come along.
It is always a good idea to un-plug the machine from the mains when not in use to remove the stress from this part.
Congratulations on the successful repair.

Jo
November 2013

>Next to the triac it appears there is a diode on the same side >of the carbon tracks as the triac - no markings. I have >continuity both directions through this part.
>
>Is it a diode? It looks like a glass diode...

The part is called a diac ( bi-directional diode, commonly used in triac circuits).

Got my pedal working.

It turns out the issues with mine were the X2 type capacitor (important from a safety perspective to replace with an X2 type capacitor), the potentiometer (the one with an adjustment accessible through the bottom) and the carbon tracks - the rivets were a little loose - not visibly loose, but an ohm meter showed some oddities.

Also replaced the transistors and triac, but probably did not need to. I replaced with NTE equivalents. Note: pinout for NTE parts is reversed from original parts, so they need to be installed 180 degrees from original

Works great now.

seegy
November 2013

This message is for Joe...fixing the bernina pedal...Thanks for the good info on the parts replacement/repair....got the parts, installed and now working as it should. Again, thanks for the part numbers and tips

Paul Schankin
November 2013

I am working on a 290 foot pedal (the 120V version).

I see the two transistors, the two diodes next to the transistors and the triac.

Next to the triac it appears there is a diode on the same side of the carbon tracks as the triac - no markings. I have continuity both directions through this part.

Is it a diode? It looks like a glass diode...

Do you have any idea what the part number is for an acceptable replacement? If it is a diode, what is the orientation of the diode in the circuit (remember...no markings)? Cathode end toward the triac? Or the other way around?

Thanks,

Seegy
November 2013

OK, here is how to fix the Bernina foot controller for the 801 series machine. My foot controller is a type 209 for 230 volt supplies. there is a similar controler for 110v.

If you do not understand the electronics here,you maybe should not be opening things up.

Unplug the controller from mains cord and open it up by removing the 4 screws that hold the saddles at the pivots. Look inside and gently detach the black hook on the speed control by tilting one half of the controller body. Save all the 4 screws and 2 springs in a safe place.
Once apart you can now remove the 3 screws holding the black cover on the top of the circuit board.Take off the cover and then detatch the wing shaped clip holding the circuit board in place. Slide out the circuit board gently, leaving in place the speed control slider.

Now carefully check the circuit board components for any discoloration or burning. Replace parts as needed. Using an ohmmeter, check the resistance of all the resistors against their color code. Replace anything suspect.
Look at the resistance tracks of the speed control. If there are worn spots, this can be fixed by filing a small amount off the end of the circuit board where there are some block capacitors and the two transistors. This allows the board to be moved sideways a little so the speed control slider runs on a new part of the resistance tracks.
The low voltage supply for the timing circuit for the triac comes via a 0.01uF 600v mains type capacitor. This has usually failed or is leaky. Replace this capacitor regardless with a similar mains rated X2 type capacitor of the same value -even if it looks and tests good.
If the capacitor has failed it will have taken out the two transistors on the board. They are a BC307 pnp and a BC237 npn. Replace with modern types. Type BC557 for the BC307 and type BC547 for the BC237.
They are pin for pin replacements, but make sure the right type goes in the right position on the board.

The only other device prone to failure is the triac.
The original device is a very rugged TAC 225-600 which is still available. If it has failed then it can be replaced with any TO-220 style 600 volt 5 amp or better triac. There is a good article on testing triacs here: http://www.ab.com/support/abdrives/documentation/fb/1012.pdf

In my case the triac was good, just the mains voltage capacitor mentioned earlier had failed and taken out the two transistors. Replacement of the transistors and capacitor had the sewing machine running normally again.

Finaly re-assemble everything, making sure the circuit board is properly clipped in place and the speed control slider is running on its tracks properly. Plug the controller back into the mains cord and check for proper operation.
Good luck.
Jo.

Jo
May 2013

The Triac in the foot controller has to deal with 230 volts at 1.1 amps for the European model and 110 volts 2.2 amps for the US model. Any triac rated at 600 volts at 7 amps or more would be suitable for both models.

Jo
May 2013

Regarding the AlsaceTech post from January 2008 explaining that the capacitor C1 or the Triac on the 232/290 foot control PCB are likely failure points, can anyone provide the specifications for these components or their currently available equivalents? For example, the manufacturer of the Triac in my 290 is no longer extant and no one has been able to cross-reference to a current equivalent from the markings on that part. Any guidance would be greatly appreciated.

George
November 2012

Just to mention when I said interference with tvs, I meant old tvs and not modern ones.

Pipdabassman
May 2011

My wife has a Bernina 807 minimatic, over 40 years old. One day it ran at maximum speed by itself. I took the foot pedal apart and the capacitor was burned out, it smelled like burned sugar LOL. This capacitor is only there to stop interference with other components like tvs etc. Make sure pedal is not plugged in and just cut the wires holding the capacitor at both ends (Wires usually black in color). Get some heatshrink over ends of cut wire and carefully heat with lighter, this will insulate ends to stop shorts. Put cover back on and off you go, just as good as new.

Pipdabassman
May 2011

i have got a minerva 122 sewing machine but my foot pedal runs on its on when plug in .will it be exspensive to mend .as i cannot find anything on the internet about the machine

SANDRA
February 2011

There is a capacitor in the foot pedal this would of burnt out and close circuited causing it to short out across the 2 wires and make your machine run at fast speed it is a quick fix and only involves replacing the capacitor.

Alan Wakeling
November 2008

Hi Amanda:

The 801 Bernina used a type 232 foot control and later models used the 290 foot control with a phase controlled PCBs. The foot control runs only at full speed or higher speeds is becasue of two reasons:
1. The capacitor C1 on what is called a voltage divider had failed and someone has tried to compensate speed with the plus/minus trimming pot on the bottom of the control.
2. The Triac for the motor control on the PCB has shorted to a closed circuit.
The control can be repaired by contacting a Bernina dealer here in the USA for about $45 to $60. For further advice, you may contact the email address listed.

The advice provided by Blain is generally correct. For exact specifications however, the oil specified by Bernina for this machine is DTE Heavy Medium oil (Mobil) or a #68 R&O oil. These oils are excellent for lubrication as they have an oxidation inhibitor, corrosion ihnibitor, and other additives that work so well with Bernina bearings and steels.
Regarding the gear however, the material is Delrin and is impervious to greases and oils. The reason for using this material is that not only is it strong but has its own lubricating qualities. This is the reason for using the combination of a steel and Delrin gear engagement. They require no oil. It has been found that too much oil is more harmful than not enough oil in Bernina machines due to machine's precision and the natural degrading of oils themselves. Normally, one would lubricate the machine at wear surfaces with 1/2 drop once a year to every two years. The hook race should use the same amount per garment after cleaning.

AlsaceTech eng@legacyquilt.com
January 2008

Amanda, I've just had the same problem with my Singer Scarlet .. there is a part in the foot pedal that's hooped (broken). We are working ours, trying to repair, but a sewing machine store offered to sell me one for £80!! OW!
We are hoping for a cheaper option. Claudia

Claudia
December 2007

If the machine tries to run at slower speeds, ( you hear motor hum, but no go) then it could be very much in need of a clean and lube.

Open the bobbin access door, and on the upper left inside that door, there is a latch to push. that will pop the lower cover off. ( Needle out, foot off, or at least up on both.) Then clean out all the lint (if any) and add one drop of very high quality sewing machine oil to every joint (hinge) where metal slides, rotates, or otherwise changes direction.

inside the top front door where the light is, there is a round "button" near the top, push it in, that will pop the top off. Lift it off, and add one or two drops of sewing machine oil to every joint, hinge, bearing, etc. DO NOT ADD OIL TO THE NYLON GEARS. They need a special "grease". petroleum based products will cause the nylon gears to crack over time. (very expensive to replace). There is a "cam" near the hand crank that can use a small dab of lithium based white grease.

There are online manuals here and there. Google for them.
The 830 series manual is close enough, since they are very similar.

The general rule is, one or two drops of a fine oil, (tri flow is great, as is Break Free CLP, but don't "spray" everything in sight. Spray some into a small glass container, and then suck it up with a syringe and apply with that. Or use the tri-flow with the small extension tube.

DON'T USE.... WD-40, silicone, cheap "walmart" sewing machine oil, Motor oil, etc. This is an expensive machine, even if you got it for a great price it is worth far more than you proboably paid for it! ( You could never duplicate the swiss quality of that little jewel of a machine today for less than $1000 or so. These things are an absolute bargain and sew WAY better than the $600 whiz fancy computer machines that are made of plastic and will be in the landfill in a few years.)

Otherwise, check ebay for a foot control This machine is a true jewel.
If it still does not work well, get it to a good, OLDER sewing machine repairman who knows how to properly take care of these things. It should last you almost forever.

best wishes.
Blaine

blaine
October 2007

Hello Amanda,
Does the machine continually run without pressing it or does it run very fast the minute you touch it?
If the machine runs on it's own just undo the foot control and you will a suppressor , it looks like a big fuse, take it out and throw it away, if the machine is just very fast when you touch the control you may be wise to get a foot control only, does not have to be the same make, there are only two wires on the control very easy to fit and the foot controls are not very expensive, if you are in the UK let me know if you need a foot control and I will give you some sites to purchase one, if you are in the US same applies, the Bernina foot controls will cost you a fortune, the machine is good though. contact me on drivewithken@blueyonder.co.uk
Ken

drivewithken@blueyonder.co.uk
October 2007