Ocuda CT-100, Analog multimeter

[omarbeyaty]

Hello.

Can anyone please identify what kind of multimeters I have? I dug up internet for it and no trace. Mine is defective and needs to be fixed but I have not its drawing. So please anyone can provide me the circuit drawing? I would appreciate it and if anyone has the same multi-meter let me know to exchange thoughts how could we fix it.

Thank you.

[camtechman]

If you could provide some photographs of the unit, it may be helpful to identify it.

[omarbeyaty]

Thank you

[karesz*]

Hallo,
some http://www.ebay.de/itm/Kawasaki-Zund...AOSwA3dYiH3Has tester producer, preciser called is "Okudakoku Co. Ltd."...
Karl

[camtechman]

Omar,

Unfortunately, even with the information supplied by Karesz, there are no search results.

However, from the picture you supplied it does seem to be a meter with a good range of settings for testing DC & AC Volts, Ohms, 2 settings for measuring DC Amps and a battery compensation adjuster (black Knob).

For measuring DC Volts it has 5 settings: Up to 2.5,10,25,50, 500 Volts
For measuring AC Volts it has 4 settings: Up to 10,25,250,500 Volts
For measuring DC Current it has 2 settings: 250mA & 20Amps (via top left hand socket)
For measuring Ohms it has 4 settings: X1 (times 1), X10, X100, X1K (1000)

But I guess you already have an understanding of these.

How many, or what type of batteries does it take and is there any previous corrosion from battery damage.

Tony

[The Philpott]

I have a feeling this is the sort of thing that may have been marketed under more than one brand name/type number according to the territory it was created for. The problem is, finding any other names it may have been sold as..

The general style looks Japanese..

[Herald1360]

The limited number of current ranges and the automotive tie in of the other meter found rather suggest that this meter was sold into the DIY/Car maintenance market, rather than hobby electronics.

Is there any indication on the meter face or elsewhere of its sensitivity in ohms/volt which would tell us what the basic meter sensitivity is? For the likely end use it could be quite low- maybe only 1000 ohms/volt or thereabouts since this would make the meter movement more robust.

[omarbeyaty]

Originally Posted by karesz*

some http://www.ebay.de/itm/Kawasaki-Zund...AOSwA3dYiH3Has tester producer, preciser called is "Okudakoku Co. Ltd."...

Thank you, not the same meter, seems mine is rare version.

[omarbeyaty]

Originally Posted by camtechman

Unfortunately, even with the information supplied by Karesz, there are no search results.

However, from the picture you supplied it does seem to be a meter with a good range of settings for testing DC & AC Volts, Ohms, 2 settings for measuring DC Amps and a battery compensation adjuster (black Knob).

For measuring DC Volts it has 5 settings: Up to 2.5,10,25,50, 500 Volts
For measuring AC Volts it has 4 settings: Up to 10,25,250,500 Volts
For measuring DC Current it has 2 settings: 250mA & 20Amps (via top left hand socket)
For measuring Ohms it has 4 settings: X1 (times 1), X10, X100, X1K (1000)

But I guess you already have an understanding of these.
How many, or what type of batteries does it take and is there any previous corrosion from battery damage.

Thank you for your prompt reply. Yes it is decent meter with good specs, I remember I put it on DV current measurment for 5 minutes before it stopped working because that continuous 5A had baked some resistors as shown in below pic. since, I regret it. I shouldn't put it such long time measuring the current as it is home device and not industrial, this what put me in a challenges to repair it, the burned resistors don't show the written values because of deformation so I can't replace them until I find a drawing, I fixed the broken buses, tested the diodes and other components only the resistors in the ohm and DC current channels were defected. I searched a lot for this kind of meter but in vain, I tried here if someone have experienced the same problem to share with.

Yes I understand what you said I'm an electrical engineer.

It operates on one AA battery. 1.5 volt and no corrosion before.

[stuarth]

The circuit of these things is not usually complex.

We don't know what the symptoms of the "defect" are.

Try measuring a 9V battery on the 10 DC voltage ranges. If this reads correctly, the movement, the universal shunt, and at least parts of the range switch are OK, and we can move on to the defective ranges.

If there is no reading, then you can use the 9V battery and a resistor or two to check the movement.

The two connections to the movement should be easily identifiable with the back of the meter removed. Connect the battery in series with a 180k ohm resistor to the movement connections. This should give some deflection of the needle. If the deflection is backwards, reverse the battery connections. No deflection probably means the movement is defective.

The deflection will probably be either close to full scale, or very small - less than a tenth of full scale. This tells us whether the meter is high or low sensitivity.

Stuart

[omarbeyaty]

Originally Posted by The Philpott

I have a feeling this is the sort of thing that may have been marketed under more than one brand name/type number according to the territory it was created for. The problem is, finding any other names it may have been sold as..

The general style looks Japanese..

You are right, I hope to find another different name for the same device. but even this seems hard to get and yes it is Japanese made.

Originally Posted by camtechman

If you could provide some photographs of the unit, it may be helpful to identify it.

[omarbeyaty]

Originally Posted by Herald1360

Is there any indication on the meter face or elsewhere of its sensitivity in ohms/volt which would tell us what the basic meter sensitivity is? For the likely end use it could be quite low- maybe only 1000 ohms/volt or thereabouts since this would make the meter movement more robust.

I submitted some pics for the front panels it shows the sensitivity as 2kohm/V

Originally Posted by stuarth

If there is no reading, then you can use the 9V battery and a resistor or two to check the movement.

The two connections to the movement should be easily identifiable with the back of the meter removed. Connect the battery in series with a 180k ohm resistor to the movement connections. This should give some deflection of the needle. If the deflection is backwards, reverse the battery connections. No deflection probably means the movement is defective.

The deflection will probably be either close to full scale, or very small - less than a tenth of full scale. This tells us whether the meter is high or low sensitivity.

I tested the moving needle coil, it was operative. the ohm ranges are defected (just the 10k ohm is working) because of the burned resistors I have problems in reading the DC voltage, so I would move step by step starting in replacing the defective resistors after getting the right values.

I have a burned resistor in the series with the needle coil so, I jumped it and found a full deflection.

[Herald1360]

2kohm/V ties in with the robust rather than sensitive idea. It means the basic meter sensitivity is 0.5mA (or 500uA) for full scale.

TMK on the corner of the meter dial is possibly helpful- that's a quite well known make for hobby multimeters of the period which could help with your search.

It looks a bit like a variant of the TMK TP10

http://www.radiomuseum.org/r/tmk_mul...ter_tp_10.html

At any rate, the circuit for that could help to come up with realistic values for your burnt resistors given the known ranges of your meter and the likely basic configuration of the unit from the TP10 info.

[omarbeyaty]

Thank you so much Herald,

You really helped me in finding a solution and yes the both meters belong to same criteria and function and the internal components values should be identical per scale, I'll check it.

One more thing please, I opened the link you sent of Radiomuseum.org and I reviewed the drawing. I found a difficulty in registering on that site to download the drawing, so kindly if you are a member there could you please post the drawing here in order i can read the resistors values precisely.

Thank you again.

[Herald1360]

Ahhhh, Radiomuseum has very strict policy on their downloads for manuals etc. I believe as a non member you can download some information but I'm not sure how. If I were to post that info here for public access I'd fall foul of my membership conditions and the consequences of that can be unfortunate!

Sorry.....

I did find that the low res version of the circuit is just about readable if you right click on it and save it, then open in a graphics program- PAINT will do.

With the diagram it shouldn't be too difficult to reverse engineer your meter. In particular the TP10 uses a Universal Shunt arrangement and you need to work out whether yours does to0, or whether individual shunts are used- particularly for the high current range.

[omarbeyaty]

Thanks chris,

Didnt know about this strict matters and im sorry about that, anyway i will try read the values as it is kinda readable.

regards

[karesz*]

Hi Omar & Herald,
You can -newly- download docs from radiomuseum, you must click on and see for "to do"; you becomes pro action 1 site of documentation.I think its limited for 10 per month.

Well, I found a better way to get a Tmk500 manual:-

TMK 500 _Refer please to posts #4/11/22/27..

They are two really different populated values in reality.

Regards - Karl

[omarbeyaty]

thank you Karesz, well it is useful to navigate through the tmk 500 schematic to get the comp.values i will use the values of resistors as well to revive my meter. thanx for the advice about the downloading from radio museum

[karesz*]

Omar, your welcome,
here are (with schematics) possibly two more, same or minimum similar, versions;
Lafayette 99-51203 & Honor TE-100 VOM... http://www.antiqueradios.com/forums/...p?f=8&t=278698
Karl

[Herald1360]

Be wary about any resistor values from "Vetter" TMK meters. Everything will revealed proportionate to the movement sensitivity.

If you can draw out the circuit of your meter, together with any known resistor values, we can probably come up with suitable values for any unknown fried ones.