Burnt AC/DC Power Chip (TNY26x) on Control Board – Need Pinout/Replacement Help
Hello everyone,
I am trying to repair a small control board from a consumer electronic device - Sonic Relief Ultrasound where the main power supply chip has visibly failed and is burnt. I need help confirming the part number and finding a reliable replacement, as the original markings are damaged.
1. Board Context and Chip Location
- The device is powered by an external AC/DC adapter with an output of 15V/2A.
- The burnt chip is marked U5 on the PCB.
- It is located in the power input section, directly next to the large electrolytic capacitors (C7 and others), indicating its role as a power supply controller.
- Based on its function, I suspect it is an AC-DC CONVERSION IC.
2. Visible Markings and Suspected Part
The chip is severely burnt, but I can make out the following partial lines:
- Line 1 (Top): TC...26
- Line 2 (Middle): ...KT
- Line 3 (Bottom): ...49
Educated Guess: Based on the "26" suffix and its function as an SMPS controller, I strongly suspect this is a TinySwitch-II IC from Power Integrations, likely a TNY266PN or TNY268PN.
3. Request for Assistance
- Confirmation: Can anyone familiar with this product line or these markings confirm if the chip is definitively a TNY266 or TNY268 (or suggest an alternative part that matches the "TC...26" clue)?
- Replacement: If confirmed, which one would be safer to use (TNY266 or TNY268), or does the board design imply a specific current requirement?
- Potential Secondary Damage: Given the visual burn, is it highly likely that the surrounding components (resistor R5, capacitors, or the transformer/coil on the far right) need to be checked as well?
Thank you in advance for any expertise or guidance you can provide!
(Note: I have attached close-up photos of the burnt chip (U5) and a wider shot of the board for context.)
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Hello everyone,
Thank you for your initial guidance. I have some updates based on the manufacturer's feedback and close inspection:
1. New Findings and Confirmed Details
- Manufacturer Confirmation: Power Integrations confirmed the chip does not belong to the TinySwitch family, but is likely an older generation TOPSwitch series IC.
- Package Confirmed: The chip (U5) is an 8-pin (4 on each side) through-hole DIP (Dual Inline Package).
- Original Markings: TC...26 / ...KT / 49.
- Power Requirements: The external adapter is $\mathbf{15\text{V} / 2\text{A}}$, meaning the chip must handle at least $\mathbf{30\text{W}}$ of power.
2. Targeted Request for Help
Given the TOPSwitch confirmation, I am now focusing on identifying a specific 8-pin DIP TOPSwitch that matches the "26" suffix and the power requirement.
The most likely candidates appear to be the TOP226PN or TOP246PN (or a similar variant in the 8-pin package).
My specific request now is for help in comparing the internal pin functions of these candidates with the board's layout:
- Pinout Match: Could someone familiar with the TOP22x/TOP24x series in an 8-pin DIP package (like the PN package) please advise which pins typically connect to the following external components:
- The large primary capacitor (High-voltage DC input)
- The external transformer/inductor (Switching node)
- The feedback circuit (Optocoupler/VREF on the secondary side)
- Datasheet Comparison: If you have access to archived Power Integrations datasheets for this era, could you look for a part where the marking "TC...26" is a known shorthand for a specific TOPSwitch IC?
By comparing the known pin functions (D, S, C, F) to the copper traces around the burnt U5, we can definitively confirm the part number.
Thank you again for helping me narrow this down!
Hi SJ,
We’re still unable to confirm whether the burnt device belongs to the TOPSwitch family, as we couldn’t find a matching part number. We just mentioned that it appears to be the closest device.
While TOP226 is part of the TOPSwitch-II series, the datasheet specifies that it is only available in a TO-220 (Y) package. There is no known variant with a part number ending in “6” that comes in a DIP package.
As for the TOPSwitch-GX series, we’ve reviewed the markings and can clearly see that the digit preceding “6” is not a “4,” which rules out the possibility of it being a TOP246P.
You may check the datasheet via the link below.
Hi SJ,
Good day. Thank you for using Power Integrations Solutions.
We’ve reviewed the photos you provided, but unfortunately, we’re unable to conclusively identify the device. However, we can confirm that it does not belong to the TinySwitch family.
The markings appear most similar to those found on our TOPSwitch series, though we suspect this may be one of Power Integrations’ older-generation products or possibly a special-case device. At this time, we’re unable to locate a part with matching markings and package type in our current or archived datasheets.
Thank you for your understanding.