Mettler K4T Balance

Cleanup and check of a Mettler Instruments K4T sin­gle pan top load­ing bal­ance.

Mettler K4 balance front left view
Mettler K4 bal­ance front left view

After own­ing and using this K4T bal­ance for over twelve years, I thought it was time for a full cleanup and accu­ra­cy check. When first pur­chased from Ebay it received a quick cleanup, func­tion, and accu­ra­cy check, before I quick­ly put it to use.

I already owned sev­er­al oth­er Mettler K5 and K7 bal­ances, and the K4T is basi­cal­ly an updat­ed ver­sion of the K5T. According to Mettler’s web­site the K4 has been dis­con­tin­ued since: Jan, 1965.
Now that I am retired I thought the old K4T deserved some atten­tion. I did a fair­ly exten­sive search of the inter­net, but did not find much infor­ma­tion or pho­tos of Mettler’s K4 bal­ance, which replaced the Gram-atic 4000 series of bal­ances.
So while clean­ing I took the time to pho­to­graph the inter­nals of the K4T.

Mettler K4 Back nameplate
Mettler K4 Back name­plate

The Mettler K4T bal­ance is a sin­gle-pan bal­ance, for rough weigh­ing.
The weight read­out is by gratic­ule pro­ject­ed on to a ground-glass screen. It has a capac­i­ty of 4,000 grams with a pre­ci­sion of +/- 0.2 grams. The beam uses mag­net­ic damp­en­ing with a sta­ble read­out in 2 to 5 sec­onds. The dis­play has an opti­cal range of 1,000 grams with 1 gram divi­sions. It has built-in sub­sti­tu­tion weights of 1 and 2 Kg, along with an adjustable spring type tare func­tion of 500 grams. This unit was built in the late 1950“s.

Click on gallery images for larg­er view.

  • Some help­ful notes for ship­ping Mettler K Series bal­ances:
    • First unplug the bal­ance from pow­er source.
    • Remove the pan and pan base from the top of bal­ance.
    • Carefully remove the met­al top cov­er sec­tion straight up, mak­ing sure not to put pres­sure on the front dis­play bezel.
    • Carefully remove the sub­sti­tu­tion weights from their hold­ers and place on a clean soft sur­face such as a tow­el.
    • Turn the “ARR.” knob on the low­er back of the bal­ance in the direc­tion of the arrow to arrest the beam.
    • Check that the knife edge piv­ots raise up, and the bal­ance beam is secured and not loose.
    • Using a flat blade screw­driv­er loosen the screw in the cen­ter of the weight range selec­tion knob two turns. Gently pull straight out clear­ing the side pin from the case.
    • Replace the met­al top cov­er on the bal­ance.
    • If the bal­ance has a tare knob on the left side, it is not remov­able and extra pre­cau­tions will need to be tak­en in pro­tect­ing it such as added padding on the left side around the knob. The knob will not sur­vive a direct impact dur­ing ship­ping!
    • The pan, pan base, sub­sti­tu­tion weights, and range selec­tion knob should all be wrapped and packed sep­a­rate­ly from the bal­ance. No loose items should be inside the bal­ance case.

6 Replies to “Mettler K4T Balance”

  1. Dear Sir,
    Do you have instruc­tions on how to cal­i­brate these? We have a K5 and would like to cal­i­brate it. I test a 500 g stan­dard, it shows just under 500 g.

    Thank you.

    1. Sorry no offi­cial instruc­tion man­u­al.

      Some things to check though:
      Balance must be sta­ble and lev­el, using the bub­ble lev­el on the side of the bal­ance.
      Adjust zero with an emp­ty pan.
      Check the stan­dard to ver­i­fy it is with­in spec­i­fi­ca­tions, and has a recent cal check.
      Check mag­net­ic damper blade to ver­i­fy it is not rub­bing. This is a com­mon prob­lem if not shipped or stored prop­er­ly.
      If all of the above are good, then check accu­ra­cy using 50g, 100g, 250g, then 500g stan­dards. If all read­ings are out of cal
      and get pro­gres­sive­ly worse with increas­ing weight, then it most like­ly could ben­e­fit from an adjust­ment.

      The fine adjust is a round weight on a small thread­ed rod. Recommend mark­ing the orig­i­nal posi­tion before adjust­ment.
      The course adjust is com­prised of two knurled weights that must be loos­ened and then adjust­ed using a thread­ed screw.

      Greg (Barbouri)

  2. Dear sir,
    I have a K5 . This week, the trans­former short-cir­cuit­ed -> bulb lamp does not func­tion any­more. Do you have the specs of the trans­former (220V12V) and the bulb (Watts or ampere)?

    1. Hi Ed,
      Here are the spec­i­fi­ca­tions for the bulb in the K4:
      Part# 1802‑L
      Voltage: 6.5V, Amperage: 1.4A, 9 Watts
      Maximum Overall Length: MOL 1.92″ / 49mm
      Maximum Overall Diameter: MOD 1″ / 25.4mm
      Base: BA15s, Single Contact Pin Bayonet
      Glass: S‑8, Painted, Black with Small Side Opening

      I am guess­ing that all the K series units use the same bulb.

      There seems to be sev­er­al dif­fer­ent types of trans­form­ers used in the Mettler K series.
      Most have been mul­ti-tap type, but there are some that are sin­gle-volt­age only.
      My K4T, K5T, and K7T units all have four input volt­age selec­tions.

      Greg (Barbouri)

  3. Thank you, Greg, most hel­ful.
    My K5 has a mul­ti-tap type 220V-trans­former (220V sup­ply). The bulb installed was a 21-Watt type; much too high I pre­sume. A replace­ment trans­former and bulb are hard to get, if not impos­si­ble.
    Do you know a sup­pli­er?

    1. Hi Ed,
      I would try Ebay.com for a donor unit that has a good trans­former and bulb, with pos­si­bly a spare bulb in the cov­er.

      Greg (Barbouri)

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