So I just repaired this JL 600/1v3, PS blew, took out FET, gates, and half the OP.
I replaced PS FETs with 3205@10Ω gates, and replaced the OP FETs with IRF540. PS gate wave seems to build slow, but could be a feature of JL boot process, but I’m getting crazy feedback on startup and shutdown, DC offset on each process gets into the single digit volts, I’ve tried cleaning the Pots/switches as well. There is 2 Pots near OutPut area, but I don’t know what they are for and I’ve never had to mess with them before, I’ve never had a problem with DC offset on JL amps before. Is that what this is or something deeper?
Video link below.
I replaced PS FETs with 3205@10Ω gates, and replaced the OP FETs with IRF540. PS gate wave seems to build slow, but could be a feature of JL boot process, but I’m getting crazy feedback on startup and shutdown, DC offset on each process gets into the single digit volts, I’ve tried cleaning the Pots/switches as well. There is 2 Pots near OutPut area, but I don’t know what they are for and I’ve never had to mess with them before, I’ve never had a problem with DC offset on JL amps before. Is that what this is or something deeper?
Video link below.
Someone else may find the video useful but so may have been a waste of time over the years, I will not watch them.
Post a photo of the main board.
Do the pots have circuit board designations.
Post a photo of the main board.
Do the pots have circuit board designations.
The video just shows the weird feedback during boot up and shutdown, like it’s excessive DC offset, probing with multimeter while no RCA or Speaker leads connected shows it’ll jump +1-2 Volts during boot up, one of the inductor “squeaks” for a quick second as well sometimes (I am now just seeing one of the OP inductors is cracked 🤦🏼), most of the time the current jumps up to 8-10a during boot up as well, which is when the feedback hits. PS is cycling at 37k and OP is cycling at 73.5khz and
Attachments
Do you have excessive noise on one of the speaker terminals where the other is clean?
Don't turn the pots. What are their circuit board designations?
Do you see the noise at startup on the muting transistor (marked 6P near the 10 ohm 10w resistor)?
Don't turn the pots. What are their circuit board designations?
Do you see the noise at startup on the muting transistor (marked 6P near the 10 ohm 10w resistor)?