gemini gvx sub15p

[bobot62]

gud day to everyone,

i live in the philippines, and i have bought a used gemini gvx sub15p powered subwoofer, online and when it arrive here in my home town
open the box and set the voltage settings to 230 vac, and plug it in, i was surprise to know that it did not turn the power on, and open it,
sad to see that the power transformer was ripped off from the main board which causes the transformer to chipped some parts on the amplifier.
i tried my best to put it together turning it on it powers up seems to be ok, but when i connect the speaker it produces a humming sound and when i check it with a voltmeter the output has a 5.6 volts dc, i do need some help here on where might the trouble is?

[DrGonz78]

Can you return the item as it sounds like a shipping problem? To proceed can you post pictures of the damaged area on the amp? Make sure the pictures are close up and clear too. Hopefully it's not anything major to fix or possibly you can get it replaced.

[bobot62]

thank you DrGonz78 for your reply, i have already put it back together, my problem now is that dc voltage present on its output, and the shipping firm just ignore about the issue, i have put it back together and mounted the power transformer to its place and when i applied a signal trough it, the amp works but the humming is there.
i also got the schematics of the unit which help me to put it back together

[DrGonz78]

Well post the schematics up here on the site so we can help you along. Since you have 5.6vDC on the output do not connect speaker to the amp again until it has been repaired. You said the transformer had chipped some parts on the amplifier, so what exactly does that entail?

[bobot62]

it has chipped off resistor IR41, capacitor IC17, IC 16 and transistor IGB22, fortunately as i inspect it there is no crack on the mainboard, thank you for the help DrGonz78

[bobot62]

this is the picture of the gemini gvx sub15p the red markings are the parts that have been detached from the mainboard

[DrGonz78]

Do you have a multimeter to take some measurements? If so, test the voltages on the power amp and check if there are any imbalances of the power rails. Also, with the amp off do a quick test of all the transistors to check if any are shorted. Perhaps the amp being turned on the first time caused some damage to some components instantly. A schematic will help us see what we are trying to help you fix and is very beneficial going forward.

[bobot62]

gud day DrGonz78, thank you for your help, i have found it, it was a crack on the mainboard the bottom side and its like a hairline crack that is so difficult to see, just when i check it when there is no continuity on my multimeter , after that when i check the voltage in the output, its gone, thank you again