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ESR Meter Repair

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Gregory

Member
I have a esr meter that I have been using ,the meter has stoped working.
I am not very good a fault finding proceadure .I know how to test most components.Except IC
If i post a circuit digram of the meter can you indicate by a arrow and writing alongside of the arrow on different sections on the circuit what I should expect with my meter.
and the step by step method.
I am using a veriable power supply to powr the Meter
I would apperiate your help
I need guidence in this area to get my meter working.
Greg
 

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mneary

New Member
You could begin by telling us what it does and/or does not do :D compared to what it is supposed to / not supposed to do :confused:.
 

Gregory

Member
When I apply power and push the switch there is no Display but the 7L805 gets hot and there is 8.5 Volts DC on the input to IC 1 (78L05) but there is no volts out on the 5V rail
 

Gregory

Member
I have found the short and fixed that problem It was solder which was touching the 5V track.
I have 5V on the 5volt rail to the IC's when i push the switch and the led's comes up EA and the display goes out and only leaves the center of the led on, which is on the LH Led
When I connect the test probes together the display is 0 on the left led and number's 2 to 9 on the other display.I then remove the test probe's the display goes back to the above display on the LH led.
When I push the switch to turn the Meter of the display is a ? mark on each led then turns off when release the switch.
 

Gregory

Member
Can you advise me as to where to test as the above symptoms are what is happening even when I test a cap.
The meter is not operating as it did when I was using the device previous to all this trouble.
 

mneary

New Member
How did it operating when you were using the device previous to all this trouble?

What is the operating procedure? What did it do previously? What does it do now instead?

You have told us nothing, nada, nil, about what this meter is supposed to be doing. From the schematic we are pretty certain that it doesn't dance and spit pennies, but that's about it. If you want us to bother with any more replies, please humor us. Please tell us something about the meter. If it's a common model that we can find on the net, a manufacturer and model number might be enough. If it's a kit or magazine project, we'll need to know where you got the plans and we might ask for a copy of the operating instructions. We cannot read your mind.

Of course you can continue begging for help without telling us anything about the meter model. Yes, you certainly could.
 
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mvs sarma

Well-Known Member
Can you see the relevant parts of the link below

ESR meter fault-finding....

it relates to problems while making of ESR kit once sold by Dicksmith of Australia
i think it has something related to Mk2 version published by Silicon Chip and perhaps by UKs EPE mag even Hardware being same, see whether the attached Dicsmith's manual helps

BTW, you may be having the entire article that describes the working of the meter and post assembly test process etc
 

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Gregory

Member
It is a Dick smith ESR Meter.
When you first turn on the Meter the displays should display 0.0 but this dose not happen as explained above.
Then when I connect the 2 test probes together to zero then the display comes up as 0.0 I then connect a known cap to the meter then jumps all over the place not giving a constant reading.The cap is a new 100uf 25V electro.
I have replaced the IC 3 - 4094,Crystal XTAL1, two 27pf capstested all diods and transistors.
If I can give any help to resolving this problem please ask.
Photo's etc.
I have checked all the solder joints and track's but I still may have overlooked something in my testing.
Greg.
Sorry about not giving a enough Information.
I am very thankful that there is help on this forum
 

Nigel Goodwin

Super Moderator
Most Helpful Member
It's a processor controlled ESR meter, and from what I've read about it in the past, you can destroy the processor if you connect it to a charged up capacitor. The original author did make the processor available as a spare part.
 

mvs sarma

Well-Known Member
It's a processor controlled ESR meter, and from what I've read about it in the past, you can destroy the processor if you connect it to a charged up capacitor. The original author did make the processor available as a spare part.
Then, probably every now and then we need to change the processor.
 

mneary

New Member
The microprocessor is good. We're making progress now.

Your "FA" code indicated that Q6 was not switching on. Check the soldering around R24 and Q6, and make sure the microprocessor pin 1 is straight in the socket and not curled under.

If all is OK, then run the test on page 11 again.
 

Gregory

Member
I am still testing thank you for your enquiry .
I replaced Q6 but the component tested ok. Tested R24 ok checked IC3 ok checked solder jonts that I thaught wer suspect and resoldered.
Powered up meter and both displays light up with 10
Connect test leads and I can 0 both displays to 00 with the LH decimal powed up.remove test leads and meter reverts back to the above.then can turn off.
How do I remove the 10 display and obtain 00 display.
Greg
 
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Gregory

Member
I have checked the trackes and all of the transistors and replaced 27pf caps and now I have the problem where the meter right hand display and decimal led lights up when I push the switch but will not stay on.
Can you advise me what to try next.
 

mvs sarma

Well-Known Member
I have checked the trackes and all of the transistors and replaced 27pf caps and now I have the problem where the meter right hand display and decimal led lights up when I push the switch but will not stay on.
Can you advise me what to try next.
Did you try to follow the test sequences described in the article attached by me
or the one original you have, as one i loaded is MK2.
you should follow the article , and stage by stage, see what should come and what is coming.Only that can help. PLEASE SEE INITIAL CHECKS ON PAGE 7 OF MY PDF. There after slowly follow the pdf. write down on a word file as a table , what to and what IS happening.

mean time we have to see whether Mneary logs in for further comments
 
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