Bernina 770 QE Service and Maintenance – What Our Engineers Check

The Bernina 770 QE sewing machine is currently in our workshop for a full service. Bambers are authorised Bernina agents and have been since 1958. As a Bernina service centre we regularly carry out Bernina 770 QE service and repair work for customers across the UK. In this technical post we explain some of the checks we carry out on Bernina sewing and quilting machines.
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The Bernina 770 QE in our workshop is sat on a blue anti static mat. Our mechanics will attach the bracelet to their wrists in order to reduce static discharge when handling sensitive Bernina circuit boards. The modern Bernina has several ‘Prints’ (printed circuit boards) that control the stitches and functions. A small static spark can sometimes damage these delicate prints, hence our anti static mat.
Just another part of our care for your Bernina sewing machine.

I’ll list just some of the checks on our service list when your machine comes into our workshop for service or repair work.

• • Remove all Covers

All the exterior covers are carefully removed. Care must be taken here because some of the cover fittings have internal moulded clips. The inexperienced hand might snap one of these fastenings. Once the covers are removed, the whole interior mechanism is revealed and can be cleaned.

• • Bernina Motor

We then inspect the Bernina motor. This involves checking carbon brushes and the commutator for wear and damage. On older Berninas, the carbon brushes are often worn down to the springs and the commutators covered in too much carbon deposit. We quite often replace carbon brushes and always clean and inspect the commutators.

• • Bernina Foot Control

After checking the motor, we check the foot control. We test the circuit board rheostat and carbon peg contacts. On older Berninas, the rheostat is the old fashioned carbon pile variety. The small discs have often worn out, or the two contacts can be bent or damaged.

• • Bernina Drive Belts

The modern drive belts, such as the type used on the Bernina 770 QE, rarely wear out. They are very durable. However, they do sometimes work loose, especially if the user is a busy quilter…

• • Stitch Length & Reverse

Although one of our more basic checks, the balance between stitch length and reverse is critical. And although the Bernina 770 QE no longer relies on simple linkages to make the adjustments, the test remains the same.

• • Foot Lift Height

Another critical test. The Bernina 770 QE, like all Berninas, has a lift mechanism built into the presser bar. It’s chiefly designed for use with the freehand embroidery foot, but also works in tandem with every Bernina presser foot. If it isn’t set correctly your fabric won’t feed properly.

• • Feed Dog Height

Another small but critical check. We always use the official Bernina gauges when testing and resetting the feed dog height. Steve and I have been on many of the Bernina training courses over the last forty odd years, bother at Bernina UK and Bernina headquarters in Switzerland.

• • Shuttle timing

Timing issues occur on all sewing machines and Berninas are no different. Although it must be said that Berninas are so robust and well-engineered, it takes some doing to knock one out of time. Again, the shuttle timing reset is critical. Especially as so many people buy a Bernina quilting machine. Quilters can regularly sew for four or five hours a day, or more. So the timing has to be perfect for quilters and dressmakers alike.

• • Shuttle Driver Spring

The shuttle driver spring must remain perfectly formed. Use and hard sewing can bend it out of shape and, in many circumstances I’ve seen, it can snap in two. A critical part, the Bernina shuttle spring acts as a shock absorber as the shuttle is oscillating at 100 mph.

• • Shafts play

• A big one. Every now and then a Bernina sewing machine is brought in by a customer who has accidentally dropped their beloved machine. In some of these cases, the impact can cause the top shaft to slip from it position within the chassis. This can lead to all kinds of trouble and in many cases it will jam the machine solid. So, we always test the fixings along the top shaft.

• • Zig Zag timing

This is not a general shuttle timing test. This tests the movement of the zig zag. The needle should form the shape of a perfect arc, or parabola, as it rises on the left side, travels up and across and then lowers on the right. If this movement isn’t smooth and even, the stitches will be poor and distorted.

• • Tensions balanced

We take great care in cleaning, resetting and balancing the top and bottom tensions. A good tension produces a good stitch.

• • Bench cleared – nothing left out

An old favourite that insisted on being added to the list. So, I’ve given you a small snapshot of what we check when a Bernina comes in for maintenance. There are actually 46 check points on our service/repair sheet. The last of all our checks is to ensure the bench is cleared and no parts are left behind.