Hi everyone, my first venture really in audio electronics repair and customisation so please forgive any n00bness 🙂
As the title says I'm fixing up a Auna Concept 620 subwoofer (this is it). The original main fault with the subwoofer is that a buzz noise started happening when powered on - a sure sign of faulty capacitors.
The Story
As a IT engineer my electronics knowledge is average at best but I know enough to identify and repair most electronics issues. In this case I first opted to take my sub to a electronics repair shop figuring they would have better equipment than I do to fix the problem so would be far less time consuming to take it somewhere with better equipment to carry out the repair rather than do it myself.
After the guy telling me the sub was only fit for the trash while trying to flog me something he had I promptly told him where he could get stuffed and duly informed him I already knew the problem with the sub and how to repair it.
Currently...
So that brings us to now, my repairs on the subwoofer so far;
Completely recapped both PCBs
Fixed a rather loud "boom" the sub used to make whenever switching it on
Replaced thermal interface material
Other minor fixes like broken solder joints (I'm assuming this happened when I took the sub to the repair shop I never noticed them before)
I have replaced (what is unknown to me so I assume they are crap) mlcon, H (just "H", no other brand name..), and LSHC capacitors with Rubycon and Nippon Chemi-Con capacitors rated for 10,000hrs and 7000hrs for the Nippons and 5000hrs for the Rubycons, all specced for 105c+.
The replacement capacitors also vary from being able to handle 56% to 100% extra voltage compared to the old capacitors but keeping the capacitance of the capacitors the same where I really wanted to meat up endurance and lifespan primarily where I hadn't owned this subwoofer set that long before the sub decided to start giving up on life (about 2 years).
The Problem
The sub is now mostly fully repaired and the heatsink the main PCB is attached to now barely even gets warm thanks to the much better capacitors but I do still have one issue that is bothering me; the transformer in the unit to my mind seems to be getting rather hot. With a DT8380 I measured the temperature at 60-67c on its outer metal casing. This is with cutting to size and using graphite pads rated for 10w/mk thermal efficiency and placing them between the transformers inner heatsink and metal outer shell.
I'm assuming the graphite pads (which I also chose to use to double as some EMI shielding as well) are just transferring a lot of internal heat from the heatsink to the outer metal casing thus keeping the transformer inner core cooler and thus extending its life but I'm not sure.
The Question
My question is, is 60-67c on the outer transformer shell seem like the transformer is running too hot? These temps were taken after the subwoofer was left plugged in for about 15 hours. If these temps are too hot some recommendations for cooling it down would be appreciated I have some ideas, but if others think what I do I'll know I'm thinking along the right lines. If you think I should replace the transformer, a link to somewhere I can get a compatible replacement would be great as my attempts at finding a compatible replacement to add to my spare parts has not bore any fruit.
These are the specs of the transformer; Input: 230V~50Hz, Output: 12Vx2~3.2A, 10V~0.5A. Other Transformer info: Shenzhen Enkor Electronics, JJC6645230-L01 (H15-66230-L01), Number: 2012JJC06.
Thanks for your time reading that wall of text 😀
As the title says I'm fixing up a Auna Concept 620 subwoofer (this is it). The original main fault with the subwoofer is that a buzz noise started happening when powered on - a sure sign of faulty capacitors.
The Story
As a IT engineer my electronics knowledge is average at best but I know enough to identify and repair most electronics issues. In this case I first opted to take my sub to a electronics repair shop figuring they would have better equipment than I do to fix the problem so would be far less time consuming to take it somewhere with better equipment to carry out the repair rather than do it myself.
After the guy telling me the sub was only fit for the trash while trying to flog me something he had I promptly told him where he could get stuffed and duly informed him I already knew the problem with the sub and how to repair it.
Currently...
So that brings us to now, my repairs on the subwoofer so far;
Completely recapped both PCBs
Fixed a rather loud "boom" the sub used to make whenever switching it on
Replaced thermal interface material
Other minor fixes like broken solder joints (I'm assuming this happened when I took the sub to the repair shop I never noticed them before)
I have replaced (what is unknown to me so I assume they are crap) mlcon, H (just "H", no other brand name..), and LSHC capacitors with Rubycon and Nippon Chemi-Con capacitors rated for 10,000hrs and 7000hrs for the Nippons and 5000hrs for the Rubycons, all specced for 105c+.
The replacement capacitors also vary from being able to handle 56% to 100% extra voltage compared to the old capacitors but keeping the capacitance of the capacitors the same where I really wanted to meat up endurance and lifespan primarily where I hadn't owned this subwoofer set that long before the sub decided to start giving up on life (about 2 years).
The Problem
The sub is now mostly fully repaired and the heatsink the main PCB is attached to now barely even gets warm thanks to the much better capacitors but I do still have one issue that is bothering me; the transformer in the unit to my mind seems to be getting rather hot. With a DT8380 I measured the temperature at 60-67c on its outer metal casing. This is with cutting to size and using graphite pads rated for 10w/mk thermal efficiency and placing them between the transformers inner heatsink and metal outer shell.
I'm assuming the graphite pads (which I also chose to use to double as some EMI shielding as well) are just transferring a lot of internal heat from the heatsink to the outer metal casing thus keeping the transformer inner core cooler and thus extending its life but I'm not sure.
The Question
My question is, is 60-67c on the outer transformer shell seem like the transformer is running too hot? These temps were taken after the subwoofer was left plugged in for about 15 hours. If these temps are too hot some recommendations for cooling it down would be appreciated I have some ideas, but if others think what I do I'll know I'm thinking along the right lines. If you think I should replace the transformer, a link to somewhere I can get a compatible replacement would be great as my attempts at finding a compatible replacement to add to my spare parts has not bore any fruit.
These are the specs of the transformer; Input: 230V~50Hz, Output: 12Vx2~3.2A, 10V~0.5A. Other Transformer info: Shenzhen Enkor Electronics, JJC6645230-L01 (H15-66230-L01), Number: 2012JJC06.
Thanks for your time reading that wall of text 😀
That temperature is nothing to worry about. It's probably undersized, so it is working harder than a properly sized transformer would be, but 60-65 is not out of spec. Wouldn't get too worried until you get to 80.
If the sub is ported, it will get some air movement as it plays.
If the sub is ported, it will get some air movement as it plays.
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