DT9205a Multimeter Wont Power On After Battery Replacement: Troubleshooting Guide

Hot_Amir wrote:

(...) is 9 volts, the same as the battery of the multimeter. I googled but couldn't find a multimeter datasheet for repair. How do I test the SMD capacitor with another multimeter? If the circuit is on and off, the multimeter with a compression chassis, not the switch, and connect. Which part should I follow?

To test SMD capacitors with another multimeter, you will want to follow these steps:

1. Power Down: Ensure that the circuit in which the SMD capacitors are installed is completely powered down and all large capacitors are discharged to avoid damage to your multimeter or injury.

2. Remove Capacitance from Circuit: Ideally, to accurately measure the capacitance or to check for faults, the capacitor should be removed from the circuit. However, this may not always be possible with SMD components. If you're trying to perform in-circuit testing, keep in mind that readings may not be accurate due to parallel paths or other components affecting the measurement.

3. Set Your Multimeter: Set your multimeter to the capacitance measurement mode. If your multimeter does not have this function, you might only be able to check for shorts or open circuits using the resistance or continuity functions.

4. Measure Capacitance: Place the multimeter probes across the capacitor terminals. Ensure good contact with the terminals, and be careful not to create shorts with the probe tips.

5. Interpret the Reading:
- If the capacitor is in good condition, the multimeter should display a value close to the rated capacitance of the component.
- If the multimeter reads 'OL' or a value significantly higher than expected, the capacitor might be open (broken connection inside).
- A low or zero reading may indicate a short circuit within the capacitor.

Regarding the power issue with your multimeter when using an adapter, here are the steps you can follow, assuming it works correctly with a battery:

1. Adapter Jack & Connection: Inspect the adapter jack on the multimeter for any loose connections or damage. Sometimes the jack can become worn and not make proper contact.

2. Internal Power Path: Trace the power path from the adapter jack to the main board. Look for any components that might be part of the power circuit, such as diodes, voltage regulators, or switches. Use your working multimeter in continuity mode to ensure there are no breaks in the circuit.

3. Switch Mechanism: If your multimeter turns on by pressing or twisting a part of the chassis, it might have a mechanical switch that's failing to make contact. Inspect the switch mechanism for any signs of damage or misalignment.

4. Voltage Regulator: If there's a regulator circuit for the adapter input, check whether it's functioning properly. It could be that the battery bypasses this regulator, which is why it works on battery power but not with the adapter.

5. Component Check: Check the components along the power path for any visible signs of damage or for any that feel excessively hot to the touch when the adapter is connected.

Since you can't find a datasheet or repair manual for your multimeter, you may have to rely on general electronic troubleshooting techniques. Always proceed with caution to prevent damaging the multimeter further. If you're not comfortable troubleshooting or lack the necessary tools, it might be worth consulting with a professional electronics technician.

Hot_Amir wrote:

My multimeter only works with batteries. I used the adapter myself.

Understood. Since you've used an adapter and the multimeter only works with batteries, there are a few possible scenarios we should consider:

1. Incorrect Adapter Specifications: Even though the voltage on the adapter is the same as the battery, the adapter may not be providing the correct current, or the polarity might be reversed. Make sure the adapter's current rating is sufficient and that the polarity matches what the multimeter requires.

2. Adapter Connection Issue: It's possible that there is a problem with the connection at the power jack or inside the multimeter where the adapter connects. There might be a loose or broken connection that's preventing the adapter's power from reaching the multimeter's circuit.

3. Internal Power Circuit Issue: There may be an issue with the internal components of the multimeter that are part of the adapter's power circuit, like a diode, fuse, or switch, that is not part of the battery's power circuit.

To diagnose the problem, you can perform the following checks:

1. Adapter Polarity and Output Check: Use your multimeter to confirm that the output of the adapter is correct. Check both the voltage and polarity.

2. Physical Inspection: Inspect the adapter jack on your multimeter for any physical damage or dirt that could be causing a poor connection.

3. Continuity Check: With the multimeter powered off and disconnected from the adapter, use another multimeter in continuity mode to check the continuity of the power path from the adapter jack to the circuit board.

4. Component Testing: If you have the skills and tools, you could test individual components in the adapter power path, such as diodes and switches, for proper operation.

5. Circuit Board Inspection: Look at the circuit board for any signs of damage, such as burnt components, or cold or cracked solder joints, especially around the adapter power input area.

Please proceed with caution and make sure the multimeter is powered off and that the capacitors are discharged before doing any testing on the circuit board to prevent damage or injury. If the issue is not visible or can't be resolved with these steps, you might need to get help from a professional electronics repair technician.

Hot_Amir wrote:

In the feeding path of the multimeter is a SMD capacitor that is likely to burn. Is it necessary to get out of the circuit to test the capacitor? Scarcity is not a condensed quantity, how do I know? SMD transistor with M6 code in circuit can be tested or must be detached

Testing SMD capacitors and transistors in-circuit can sometimes yield inaccurate results due to the influence of surrounding components. However, in many cases, a basic check can still be performed to assess whether the component is completely faulty (e.g., shorted or open).

Testing an SMD Capacitor:

1. Visual Inspection: First, check for any visible signs of damage such as discoloration or bulging.

2. Multimeter Setting: If your multimeter has a capacitance measurement function, you can use that. If not, you can at least check for shorts using the resistance or continuity setting.

3. In-Circuit Testing: While in-circuit testing may not give you the exact capacitance value, you can typically determine if the capacitor is shorted. Place the probes on the capacitor terminals and check the reading.
- A low resistance or a continuity beep typically indicates a shorted capacitor.
- An 'OL' (open-loop) reading may suggest the capacitor is open or has a very high resistance, which can be normal for a charged capacitor in-circuit.
- If the multimeter has a capacitance mode, you might get a reading, but take it with a grain of salt as other circuit elements can affect it.

Testing an SMD Transistor:

For an SMD transistor marked with an "M6" code, it's important first to determine what type of transistor it is (NPN, PNP, MOSFET, etc.). This information is necessary for proper testing. If you can't find the exact datasheet, you may find general information about the marking codes that can help you infer the type.

1. Visual Inspection: Look for any physical damage or overheating signs.

2. Multimeter Setting: To test a bipolar transistor (NPN or PNP), set your multimeter to the diode test function. For a MOSFET, you'll be checking for gate threshold voltage and ensuring there's no short between drain and source.

3. In-Circuit Testing: Place the multimeter probes on the transistor's leads according to the typical pinout (collector, base, emitter for bipolar; drain, gate, source for MOSFET). You're looking for a forward voltage drop (usually around 0.6V to 0.7V) in one direction between the base and emitter/collector (for bipolar transistors) and measuring gate threshold voltage (for MOSFETs).
- A short (low resistance or continuity) between collector-emitter for a bipolar transistor or drain-source for a MOSFET is a sign of a faulty transistor.
- An 'OL' reading in both directions for a bipolar transistor's junctions could mean it's open or not biased correctly in-circuit.

Component Removal: If your in-circuit tests yield inconclusive results, the only way to accurately test the components is to desolder them from the circuit and perform the tests again. This is because the test results can be influenced by other elements in the circuit, like parallel resistors or capacitors, which can mask the true condition of the component being tested.

In summary, while you can perform some basic checks in-circuit, for a definitive test, it's usually necessary to remove the components from the board. It's also important to be cautious and precise when testing SMD components to avoid accidentally damaging them or other parts of the circuit.

Hot_Amir wrote:

An SMD-like transistor is ecstatic in the circuit that is written on M6 and a sign similar to *trace has one of the bases. What does this sign mean?

The marking "M6" on an SMD component suggests that it is a semiconductor, likely a transistor or a MOSFET. The additional symbol resembling a "trace" or a star might be a manufacturer's logo or could indicate the pin configuration or orientation of the device.

In the SMD code world, "M6" often corresponds to a specific type of MOSFET. However, without a clear datasheet or reference, it's hard to say exactly which type of MOSFET or transistor it is.

Here's how you can attempt to identify the component further:

1. Manufacturer's Marking: The symbol you've described could be a manufacturer's logo. Identifying the manufacturer could help you narrow down the search for the datasheet.

2. Pin Configuration: Sometimes, a symbol like the one you're describing indicates the location of the pin 1 or the gate of the MOSFET. This is crucial for testing and understanding the part's orientation in the circuit.

3. Online Databases: There are online SMD code databases where you can enter the code and potentially find more information on your component.

4. Transistor Testers: Some advanced multimeters or specialized transistor testers can automatically identify the type of transistor and its pinout.

5. General Identification: If the part is indeed a MOSFET, then the three terminals are the gate (G), drain (D), and source (S). For a bipolar transistor, they would be the base (B), collector (C), and emitter (E). The marking or symbol could denote which of these leads is which on your specific part.

If you can provide a clear picture of the marking or any additional context, it might be possible to give a more precise identification. Otherwise, you may need to desolder the component and use a component tester for an accurate identification and test. Keep in mind that even with the correct pinout, in-circuit testing can still be unreliable due to the influence of other components on the readings.

Hot_Amir wrote:

How can I send you the photo of the piece? Suddenly I tried not to.

As an AI text-based interface, I'm afraid I'm not able to receive or analyze photos. However, I can guide you on how to identify the component with the resources you have available.

1. Online Databases and Forums: You can use online SMD code databases by entering the code "M6" and looking for a match. You can also participate in electronics forums like elektroda.com, where you can describe the component and the markings, and other users with experience in SMD components might be able to help you identify it.

2. Manufacturer's Website: If you can recognize the manufacturer's logo or have a suspicion about who the manufacturer might be, visiting their website and searching their product databases could prove fruitful.

3. Electronics Supply Stores: If you have the possibility, you can take the component to an electronics supply store. They might have SMD codebooks or catalogs that include your component.

4. Social Media Groups: There are many social media groups and pages dedicated to electronics where people share their knowledge. You could join one of these communities and seek assistance there.

5. Local Electronics Technician: If you have a local electronics repair shop or know a technician, they might have the experience and resources to identify the component for you.

While it's unfortunate that we cannot directly view the component, there's a good chance that through these approaches, you'll be able to identify the SMD component and find the information you need to test or replace it.

Hot_Amir wrote:

The IC of my analog to digital multimeter converter has 12 pins on one side and 11 pins on the other three sides, totaling 45 pins. Is that true? Explain why it is so?

It seems there might be a misunderstanding or a typo regarding the pin count of your analog-to-digital converter (ADC) integrated circuit (IC). Typically, ICs come in standard packages with symmetrical pin configurations.

For a quad-flat package (QFP) or other rectangular ICs, you would expect an even number of pins on opposing sides. For example:

- If one side has 12 pins, the opposite side should also have 12 pins.
- The two remaining sides would typically have the same number of pins, which could be 11 if the total pin count is 46.

However, you mentioned that your IC has 12 pins on one side and 11 pins on the other three sides, which would total 45 pins. This is unusual because standard ICs have a symmetrical and even number of pins on opposite sides. If the total pin count is indeed 45, then it's possible that it could be a custom or non-standard package, which is less common in mass-produced ICs.

It's important to examine the following points:

1. Verify the Pin Count: Double-check the pin count to ensure there hasn't been a miscount. Look closely at each side of the IC to confirm the number of pins.

2. Package Specifications: Refer to the manufacturer's datasheet for the ADC IC you are using. The datasheet will provide the exact package type and pin configuration.

3. Manufacturer Errors: While rare, there could be a manufacturing defect or error, but this would be highly unusual for an IC.

4. Custom ICs: If the IC is custom-made for a specific application or a proprietary design, it might not follow standard packaging conventions.

If you can provide the part number of the ADC, we can look up the datasheet and clarify the pin configuration for you. This would be the most reliable way to confirm the correct pin count and package type.

Hot_Amir wrote:

Unfortunately, I don't have an IC number. IC Square Bitumen (Resin) is covered. I think it's an analog to digital converter. 40 pins connected to LCD. If you can give me a hint of Pin V+ and V, it will help me a lot. I found base (PIN) + v Input and Input -v . I don't have a base ( PIN) number.

Given the information you've provided, it seems we are dealing with a 40-pin IC that you suspect to be an analog-to-digital converter (ADC), commonly used in digital multimeters for converting analog signals to digital data that can be displayed on an LCD.

However, since the IC is covered in resin (potting material) and you don't have the part number, we will need to make some educated guesses based on typical ADC IC layouts and common practices in multimeter circuit design. Here is a step-by-step analysis to help you identify the V+ and V- pins:

1. Common Pin Functions: In most ICs, especially in ADCs, the power supply pins are often located towards the corner of the IC. They are generally labeled as V+, VCC, VDD for the positive supply, and V-, GND, VEE for the negative supply or ground.

2. Trace the PCB Layout: Look at the PCB and try to identify traces that lead to other components with known voltage requirements, like capacitors connected to the power supply rails. Thick traces typically indicate power supply lines.

3. Use a Reference Design: If you can find a reference design or a similar ADC IC with a 40-pin configuration, it can give you a hint regarding the typical pin placement for V+ and V-.

4. Continuity Test: Use a multimeter in continuity mode to find connections between the known power input pins and other pins on the IC. The power pins on the IC should be connected to the input power lines through PCB traces.

5. Compare with the LCD Interface: If you've identified the pins connected to the LCD, there might be some standard configurations you can refer to. LCDs typically require a power supply, which should be coming from the same V+ and V- or ground.

6. Capacitors and Inductors: Look for decoupling capacitors and inductors on the PCB, which are usually connected close to the power supply pins of ICs to stabilize the voltage and reduce noise.

7. IC Orientation: If you can determine the orientation of the IC (e.g., which pin is pin 1), this could help significantly. There might be a mark on the IC or on the PCB to indicate this.

Please remember, without the exact part number or datasheet, any attempt to power the IC without certainty could result in permanent damage. If you're not sure, it's always best to consult with a professional or find more information on the specific design before proceeding.

Can you provide any additional information about the circuit or the connections that you've already traced? This might help us narrow down the possibilities.

Hot_Amir wrote:

Please make it possible to send photos to you. It helps a lot if I can send you the photo and you can see the circuit and IC photo

I understand that being able to send a photo would be very helpful in this situation. However, as I mentioned earlier, I am a text-based AI and currently do not have the capability to receive or analyze photos.

If you need visual assistance, I would recommend posting the photo on the elektroda.com forum where community members can see it. You can upload the image there and share the link with others who may be able to help you identify the IC and its pins based on the actual PCB layout.

Here’s how you can share an image on the forum:

1. Go to the elektroda.com forum and log into your account.
2. Start a new thread or post a reply in an existing thread related to your topic.
3. Use the image upload tool provided in the post editor to upload your photo.
4. Once the image is uploaded, it will be automatically embedded in your post.
5. Submit your post and ask the community for help identifying the IC and pinout.

If you'd like, I can continue to assist you here with any additional information you provide based on your observations and measurements. Can you describe the traces, components connected to the IC, or any other information that could lead us to identify the power supply pins?

Hot_Amir wrote:

I know the basics of +entry and - entry. Does input + or VDD always connect to .base 1?

No, the positive power supply input (commonly referred to as VDD, VCC, or simply V+) does not always connect to pin 1 on an integrated circuit. The pin configuration, including the location of the power supply pins, is determined by the IC's design and can vary significantly from one type of IC to another.

Here's why this can vary:

1. Different IC Functions: Different ICs have different pin configurations based on their function, package type, and design. For example, a microcontroller, an ADC, and a voltage regulator will likely have very different pinouts.

2. Manufacturer Specifics: Even within the same category of ICs, different manufacturers might have different conventions for where they place the power pins.

3. Package Types: There are many different package types for ICs, such as Dual Inline Package (DIP), Quad Flat Package (QFP), Ball Grid Array (BGA), etc. Each package type has its standard for pin numbering and arrangement.

4. Multiple Power Pins: Many complex ICs have multiple VDD and GND pins to ensure adequate power distribution across the IC and to minimize noise. These can be spread out across the pinout.

5. Standard Numbers: Industry standards such as JEDEC set certain guidelines for pin configurations, but they allow for variations, and not all devices follow these standards.

For your case, to identify the VDD and VSS (or V+) and V- (or GND) pins without a datasheet or visible part number, you'll need to trace the PCB patterns or use a multimeter to identify continuity from known power input points to the IC. Look for decoupling capacitors as they are often connected to the power supply pins and can give you an indication of where these pins might be located on the IC. Remember that incorrect assumptions could damage the IC, so proceed with caution.

Could you provide more context or detail about the PCB or surrounding components? Even without a picture, such details could offer clues that might help identify the correct pins.

Hot_Amir wrote:

I know what the VCC+ and V-base is. I tested it with another multimeter. Does this help me?

Yes, knowing the location of the VCC+ (positive supply voltage) and V- (negative supply voltage or ground) on the PCB can be helpful. Here's how you can use this information:

1. Trace the Power Supply Lines: Use the known VCC+ and V- points on the PCB as references to trace the power lines. They should lead you to the power supply pins of the IC in question.

2. Identify Decoupling Capacitors: These capacitors are typically placed near the power pins of ICs to filter out noise and provide a stable voltage supply. If you can identify these capacitors on the PCB, they might be connected directly to the VCC+ and V- pins of the IC.

3. Follow PCB Trace Patterns: PCBs are often designed with power traces being thicker and more prominent. By following these traces, you can sometimes deduce which pins they connect to.

4. Continuity Testing: With the IC in circuit, you can carefully perform continuity tests with your multimeter from the known VCC+ and V- locations to the various pins of the IC (with the power off to avoid shorting anything). The pins that show continuity are likely the power pins. However, be careful as the IC could be connected to other components that might also show continuity.

5. IC Power Pin Common Practices: While not always the case, some common practices include grouping power pins together. For a dual inline package (DIP), power pins might often be diagonally opposite each other (such as in an op-amp), but in a quad package or other configurations, they could be placed differently.

Remember, if the IC is functioning and connected to an LCD, the power pins are probably also connected to the LCD's power supply pins. If you can identify the LCD's power pins, this might give you a clue about the power pins of the ADC IC.

By combining these techniques, you might be able to make an educated guess as to which pins are the power supply pins. Do proceed with caution and ensure that you're not creating a short circuit when you test continuity or apply power to the IC.

If you've successfully identified the VCC+ and V- pins on the IC, that could indeed help you in understanding how the IC is powered and possibly its orientation on the board, which is a significant first step in understanding the pinout. Would you be able to provide any more specific information or context around the circuit or the IC, based on what you've found with your testing?

Hot_Amir wrote:

I found out what an AC power source is. I found two legs and I know. V+ and V. How to know Will the power supply base help me to know the IC?

Knowing the V+ and V- (or GND) pins of the IC provides a starting point for identifying its function, but there's more to consider in order to understand the whole IC:

1. Voltage Levels: Measure the voltage levels on the V+ and V- pins with respect to ground. Different ICs operate at different voltage levels. For example, common logic ICs might operate at 5V or 3.3V, while others might require different voltages.

2. IC Package and Markings: Look for any kind of part number or manufacturer's logo on the IC. If you can find a part number, you can search for its datasheet, which will tell you exactly what the IC is and its pinout.

3. Surrounding Components: Observe what other components are connected to the IC. This can give you clues about its function. For instance, if you see an oscillator crystal nearby, it might be a microcontroller or some timing IC.

4. Circuit Function: Consider the overall function of the circuit. Is it a power supply, a signal processor, a controller board, etc.? Understanding the circuit's purpose can often provide hints as to what the IC does.

5. Trace Signals: If you're able to, trace the signal paths in and out of the IC with your multimeter. ICs will generally have inputs and outputs that connect to other parts of the circuit, which can be indicative of their function.

6. Consult Similar Schematics: If you know the application or the type of device you're dealing with, you might find similar schematics online that use the same or comparable ICs.

Knowing the power pins alone won't identify the IC, but it can prevent you from accidentally damaging it by applying power incorrectly. If you have a specific IC in mind or you are trying to reverse-engineer a circuit, you can list some details about the IC like the number of pins, any visible part numbers, or even the device it's used in, and the community may be able to assist you further.

Do you have any more details about the IC or the circuit that could help us figure out its function? Perhaps the number of pins, the type of package, or the application where it's used?

Hot_Amir wrote:

(...) r input. 20 stands to LCD*2 - - 3 1/2. The data sheet is similar to 7107 and 7106, but the Numbersr of bases is different. I'd expect it to last up to 15 volts. The number 2C-170825 is registered on the printed circuit board, but the data sheet is different.Selector Mode has 7 Kentucks that I didn't find

Based on your description, it sounds like you're dealing with an analog-to-digital converter (ADC) IC used in a digital multimeter. The ADC in a multimeter typically converts the analog voltage (from measuring voltage, current, or resistance) into a digital value that can be displayed on the LCD.

Here's how we can progress with the information you've provided:

1. Voltage Supply: You've measured 6.7V as the supply voltage to the IC, which is lower than the 9V battery voltage. This could mean that there's a voltage regulator or a voltage divider network on the PCB that drops the voltage down to the operating voltage of the ADC IC.

2. LCD Interface: The "20 stands to LCD*2 - - 3 1/2" part is a bit unclear, but it sounds like you're referring to a dual 20-pin connection to an LCD, possibly for a 3 1/2 digit display. This would be typical for multimeter readouts. The IC you mentioned, 7107 and 7106, are indeed ADCs commonly used in digital multimeters for driving such displays.

3. Comparison with 7106/7107: If the pin count is different from 7106 or 7107 but the functionality seems similar, it could be a variant or a clone of these ICs, possibly from a different manufacturer or a custom version made for a specific brand of multimeters.

4. IC Number and PCB Marking: "2C-170825" might be a batch number or a date code, and not necessarily a part number for the IC. If you can find a part number on the IC itself, that would be the most direct way to look up a datasheet.

5. Mode Selector: The "7 Kentucks" might refer to the positions on a rotary switch or a range selector in the multimeter. Each position would correspond to a different function (voltage, current, resistance, etc.) that the multimeter can measure.

If the IC is a variant of the 7106/7107, it will likely operate with a similar principle but might have a different pin configuration. You might want to look for any ICs that are pin-compatible with the 7106/7107 but have a different pin count.

To help you further, I would need the following:

- The exact number of pins the IC has.
- Any text or markings on the IC itself.
- A description of the connections of the IC to the mode selector (rotary switch) and other components.

With this information, we could try to narrow down the search for a datasheet or at least understand the pin functions based on standard practices for ADCs in multimeters. If you have a schematic of the multimeter or can trace the connections, that would be immensely helpful as well.

Can you provide any of the additional details requested?

Hot_Amir wrote:

I have a base go t0 Buz + Buzzer directly to the ground and buzzer and - from the IC commands and sounds.and hold And the base going to the IC I found out how to dial the base and where 1 starts. hold One is between it and + and between hold and Bz Two feet away. Does this information help me?

The information you're providing is crucial for understanding the connection of the buzzer to the IC and its control logic. Let's analyze the details step by step:

1. Buzzer Connections: You mentioned that one pin from the buzzer goes directly to ground, and another is controlled by the IC. This is typical for a buzzer in a multimeter, which is usually activated for the continuity test function. The IC will drive the buzzer pin high (or low, depending on the design) to sound the buzzer.

2. Pin Identification: You've identified the 'Hold' function and a pin related to it, as well as a starting point for pin 1 on the IC. This is helpful because it establishes a reference for the pin numbering and their possible functions.

3. IC Pin Layout: Knowing that 'Hold' is one pin away from +V (presumably VCC+ or the positive supply voltage) and two pins away from the buzzer control pin provides a partial map of the IC's pin functions.

To utilize this information, here's what you could do next:

- Trace the Pin Functions: Continue to trace out other pins from the IC to determine their connection to the multimeter's functions (like the voltage, current, and resistance measurement inputs, etc.). The layout of these other pins might give you additional clues about the IC's overall function and possibly its datasheet if it's a standard part.

- Create a Pin Map: As you identify each pin's function, create a diagram mapping out each pin. For example: Pin 1 - VCC+, Pin 2 - Hold, Pin 3 - Buzzer control, etc.

- Compare with Standard ICs: Given that the IC is similar to 7106/7107, you can compare your findings with the datasheet of these ICs. If the functions of the pins you've discovered match with some of the pins on the 7106/7107, it reinforces the likelihood that your mystery IC is a variant of these ADCs.

- Search for Variants: With the partial pin functions identified, you could search for variants of the 7106/7107 ADCs that might match the pin count and functions you've determined.

- Ask for Assistance: If you can provide a clear picture of the IC along with the partial pin map you've created, you could ask the community for assistance in identifying the IC. Sometimes, someone might recognize the pin configuration or be familiar with the specific ADC variant.

If you can provide more details on the number of pins and any other functions or connections you've identified, we can continue to work together to unravel the mystery of this IC. It's like a puzzle, and each piece of information helps complete the picture.