Please help me recognize clamp-meter's cap ratings for replacement

[BGAmodz]

ac and dc , and this meter also has OHM and diode test modes , if its for protection then it should be a varistor , i wonder why there would be a capacitor between positive input and the motherboard .

Am really confused about this thing .

 

[KeepItSimpleStupid]

Microwave serving is probably not at a level you should attempt, but here https://www.google.com/url?sa=t&rct...ogvJnMtdgm-N2wg&bvm=bv.52288139,d.dmg&cad=rja is a service manual for a microwave.

The real point to remember is that the magnatron is an electron tube with a 3000 VDC supply and a filament supply.
Most high voltage tests can usually be performed with the oven off and the capacitor discharged. Discharing the capacitor can be a feat in itself, but most have a discharge resistor across the terminals. But what if the resistor is bad? High voltage capacitors have this odd property: When discharged, they don't stay discharged. Some HV caps have to be stored with a keeper ( or short) across their terminals. So, it may take multiple attempts to discharge the cap.

 

[BGAmodz]

Thanks for the advices , actually the microwave is working fine now , but my meter is hanging , i don't know if that's a varistor or a capacitor , anyways here is some new pictures of it

 

[KeepItSimpleStupid]

It would be wise to perform the water test for microwave. I think its outlined in the manual I posted.

Intermittent operation and poor heating is usually seen prior to magnetron failure. Typically, the magnetron thermal is first affected.

 

[BGAmodz]

It would be wise to perform the water test for microwave. I think its outlined in the manual I posted.

Intermittent operation and poor heating is usually seen prior to magnetron failure. Typically, the magnetron thermal is first affected.

Thanks for the infos about the microwave but no offence lets just skip this and focus on the Clamp meter , i removed the component from the motherboard and i see PTC on the mobo and XP and last 2 numbers 02 on the black component .

 

[KeepItSimpleStupid]

No biggie the microwave.

PTC usullay means Positive Temperature Coefficient and usually refers to a thermister. This means a thermister whose resistance increases with temperature.

You still haven't answered
1. Is the unknown part in series or parallel with the binding jacks?
1a. Any other easily identifyable components when you trace the input out.

2. What is the function of the jacks. AC only, AMP, all other functions of the meter besides the clamp on ammeter?

Here is the manual I found for the CM-600 https://www.google.com/url?sa=t&rct...nSIx0N7-vOR0dTw&bvm=bv.52434380,d.dmg&cad=rja
H
If it's a ZNR, then it usually will be in parallel and the meter will work without it.

If it's a capacitor, then possibly series, but only if being used for an AC function.

If a PTC, then probably in series and a resistor would work temporarily, but it might not work for ohms.

 

[rumpfy]

Can I weigh in and say that the clamp meter is of a type generally used in power systems work. The google reference suggests the meter is protected to 660 VAC by means of a 'component' connected in parallel with the input terminals.
My guess is that the 'component' is a Voltage Dependent Resistor and these are commonly used nowadays in all kinds of mains connected equipment.
The meter is autoranging, so how the protective component is isolated from the measuring leads for ohms values above say 200,000 ohms is not clear.
However, if the component is a protective device, then the meter should operate with it disconnected.
Microwave ovens give pulsed power and it is not surprising that an oven would have a supply voltage seriously greater than 600 Volt AND a huge supply current which would destroy the protective component in no time.
I would check the meter for operation as is,on ohms and volts and take it from there.

 

[Nigel Goodwin]

Microwave ovens give pulsed power and it is not surprising that an oven would have a supply voltage seriously greater than 600 Volt AND a huge supply current which would destroy the protective component in no time.

No, they don't give pulsed power (other than on lower power settings - where they cycle ON and OFF on a ten second cycle), and as I've mentioned previously the supply is 3000V (and even higher until the mag fires up) at high current.

 

[BGAmodz]

Hi guys , i sent the unit for waranty exchange , after more researsh i found out that the writing on the broken component is SYP 12102 "PTC" , any ideas on this ??

 

[BGAmodz]

And another problem with this kind of tools is that the main processor is covered with a black material , is there a possibility to retrieve any information from that too ??

 

[Nigel Goodwin]

And another problem with this kind of tools is that the main processor is covered with a black material , is there a possibility to retrieve any information from that too ??

No, it's called 'COB' (Chip On Board).

However, blowing your meter up by doing something utterly stupid rather invalidates the warranty (as does disassembling it), so it'll be interesting to see if they exchange it OK.

 

[fezder]

Luckily it was the meter that got shocked, not you!. not that shocks would be nice anywhere....but they are nice at correct places. But as i said, good thing it didn't bite you.
Hopefully you'll get some sort of compensation of broken meter, but as nigel said, well, we'll see .

 

[BGAmodz]

I got a new one actually , if you dont believe it ill post pictures

 

[BGAmodz]

No, it's called 'COB' (Chip On Board).

However, blowing your meter up by doing something utterly stupid rather invalidates the warranty (as does disassembling it), so it'll be interesting to see if they exchange it OK.

So these chips on board are made on demande for a specific unit , don't they use commercial ones ???

 

[fezder]

I got a new one actually , if you dont believe it ill post pictures

wow, you got new, for free? cool, thumps up for ya

as for those COBs (chip-on-board) if i'm not terribly wrong, they use those to ensure that no-one tries to service them, keep their own ''secrects''. There are some stories, which are true, like an example usb-hubs. There is COB, so there's gotta be something inside that black resin? wrong, turns out, some companies just like to put that black resin, just for cheating upon customers.....and please correct me if i'm wrong .
And COB's save space too at pcb. Google chip-on-board to see how much is pressed in tiny square :S...

 

[BGAmodz]

i agree its usually for keeping the companies secrets .

 

[Nigel Goodwin]

I got a new one actually , if you dont believe it ill post pictures

No I believe you, you were lucky they didn't check for customer damage to the original one

 

[Nigel Goodwin]

So these chips on board are made on demande for a specific unit , don't they use commercial ones ???

They might be commercial, they might be custom chips, they may even be programmable ones - but it's done for cost and size reasons (it's cheaper and smaller), not the suggested 'secretive' reasons. Often a circuit diagram is even included in the instruction manual.

 

[BGAmodz]

And its damn hard to get service ' not user 'manuals for them

 

[Nigel Goodwin]

And its damn hard to get service ' not user 'manuals for them

Why would you expect a service manual to be available? - people seem to want cheap products and then want expensive service provided for free on them.

There's also the added 'problem' that as you aren't an authorised service centre they probably wouldn't supply you a manual (or parts) even if they were available.