Repairing a PURE SSW-1817 power supply

My thanks to H. Hans-Jürgen Weber who contacted me for help repairing a PURE Avanti Flow problem recently. He asked:

"The power supply of my Avanti is broken. The transistor Q1 is broken and the labeling is illegible (TIP ?? c, 144). Can you help me there? Do you have a circuit schematic? Thank You and best regards from Germany, Hans-Jürgen."

Unfortunately I don't have a circuit diagram and PURE was always very awkward about releasing circuit details, like most makers they guard their IP closely. If it's the PURE  SSW-1817 power supply, problems seem to be common on the Pure Avanti judging by online forums.

Photo of damaged transistor:

[click to see full size]

Although I don’t have a schematic, I used some Photoshop filters on the burnt-out transistor and reckoned it was a very common TIP32C:

 [click to see full size]

I also suggested it’s worth swapping the old electrolytic capacitors at the same time, which Hans-Jürgen proceeded to do. He replied:

“The radio is fixed and it works again. I exchanged the transistor TIP32C (picture 1) and a capacitor 1200 µf / 35V and as a precaution a capacitor 680 µF / 10V. Here are a few photos of it. The housing can be opened using 8 screws on the back. The back can then be pulled out (Fig. 6). After unplugging three plugs, the power supply unit can be removed by loosening four screws (Fig. 5). The power supply unit (Fig. 4) can also be opened by loosening four screws.

Photo 1 [click to see full size]Photo 2 [click to see full size]Photo 3 [click to see full size]"After loosening the screws for the circuit board, the defective transistor and the two capacitors were replaced (Fig. 2 and 3). Now just reassemble everything and the radio will work again (Fig. 7). The repair cost less than €2.5 euros. But prevents a lot of electronic waste!

Photo 4 [click to see full size]Photo 5 [click to see full size]

Photo 6 [click to see full size]

Photo 7 [click to see full size]Photo 8 [click to see full size]"Thank you for your help. In 2019 I was able to repair my PURE Evoke Flow (see my entry on your homepage from May 27, 2019 at 18:56 | Unregistered CommenterHJW). You are welcome to use the pictures and the text for a publication. Best regards,    Hans-Jürgen”

Update on Saturday, May 7, 2022 at 10:41PM by Alan W

Thanks as ever go to David Pye who wrote:

I was going to suggest - if replacing the TIP32 and the electrolytic adjacent to it doesn't get the PSU running, there's a schottky SMD diode on the rear of the PSU labelled D3. It's an SS24A and on two blown PSUs I've repaired, this diode was blown as well as the TIP32 and cap. I've replaced it with an SS26A which might be more robust (hopefully).

Here's a photo from David:

Avanti PSU Schottky diode worth replacing

Comments

[Piotr P]

Hello

I have a problem with this power supply. Spalił się rezystor R5 i nie mogę odczytać jego wartości. [R5 is burnt out and I can't read its value.] Can you send a picture of the markings of this resistor or its value?

Thank you in advance.

[LATER]
The colors of this R5 resistor are yellow, unknown, black and gold, so it is either 43Ohm or 47Ohm. The power supply works steadily on both, giving 18.90V and 6.20V. You can add this comment on the site.

[Mike Ferris]

Good afternoon,
I have a problem with this PSU. Could you tell me what voltages I would expect on each of the output pins, please? Thanks in advance.
Regards, Mike.