Type 4 Class D Automotive Amplifier Burnt Board Repair with Full Output Repair

[@roberthemphill6242]

Great work as always todd. More on the way to support this excellent content. This is where those new via are good to have. Excellent work. So sending another package tomorrow. Great information.

[@ellensburgamplifier]

Thank you Rob! These and Hifonics are my absolute favorite boards to repair.

[@Mymatevince]

Great video Todd, fantastic fault finding as always 👍

[@ellensburgamplifier]

Thank you Vince!

[@strictlyamps820]

Great video Todd, I like your list. I am building a BOM database for amps as I am watching your video. Just something that I wanted to do for my own records. I will be putting amplifier model number and parts and locations together for future repairs or help. Original part number along with subs if necessary. May be for nothing but who knows, may come in handy down the line.

[@ellensburgamplifier]

Most excellent! I have the same thing but it's getting to be such a large collection of folders that the organization is lacking. Having a list of substitute parts is a huge help for the older amplifiers.

[@joelburton4023]

Great video. I am really enjoying your repair videos. Also just wanted to say thank you for the detailed narrations that you give as you troubleshoot the circuits. It has really helped me immensely as I am new to amplifier repair.

[@ellensburgamplifier]

Thank you Joel. I cover quite a few types of class D amplifiers. I am trying to get more videos up about class AB. thank you for watching!

[@Tekjive]

This board is what I am working on right now (Rockville RXDm4) basically same setup except it’s all through hole from what I remember, this is going to help tons in tracking down my problems ...cuz I still haven’t grasped the whole binary thing yet 😅 just knowing the signal path from card to gate helps tons! Watch it be some of those through hole color coded resistors ...I’m colorblind 🥴 lol, ty Todd!

[@ellensburgamplifier]

I am always happy to help! Being color blind makes things much more difficult when it comes to resistors and inductors.

[@FrankStPeter]

Thank you for the tidbit of information,,, so to dumb it down a little bit,,, the burned board between the traces will actually Arc causing the mosfet to fail

[@ellensburgamplifier]

Yes, when PCB boards "burn" it turns to carbon which is conductive. You will see on a scope that your signal will not be "clean" due to the conductivity of the PCB. You have to dig it all out until you see the clean signal on the scope.

[@shanebanks5216]

I have 3 of them Amps same exact board I'm trying so hard to learn how to repair them I also have another similar amp that's A little different from them do you do repairs for people

[@ellensburgamplifier]

I will admit class D might be a tough design to start with. Once you understand how the modulated signal works with the output filtering then it will get easier. I am more than willing to help if you have any questions. I do own a repair business and if you need any parts just head over to www.ellensburgamplifier.com as I have parts listed and also parts that are not listed.

[@peterb7399]

Good night , Nice video . Would you mind if I ask what is the name of the epoxy?

[@ellensburgamplifier]

I use the JB Weld 2 part epoxy and also the Gorilla Glue 2 part epoxy.

[@peterb7399]

@@ellensburgamplifier Thank you for finding the time to respond

[@ellensburgamplifier]

@@peterb7399 Any day Peter!

[@celvindietloff2321]

Good day i am having the same board but having a problem positive Railvoltage on the positive speaker terminal and its present without the driverboard installed, when the driverboard and output fets are out of the board then that Rail voltage is not present on the positive speaker terminal.When the output fets are out and the driver board are in place there is also then no Railvoltage there on the positive output speaker terminal,as soon as the output fets goes in then that Rail voltage is present on the positive output terminal again.What could possibly causing this.Thank you in advance.

[@ellensburgamplifier]

Hi Celvin. In that instance, something is turning a gate "on" or pulling it high. You will need to check the SMD transistors located next to the optocouplers. These transistors pass the gate signals. The best thing to do is put the card in, no outputs installed, and check your gate drives at the gate pads.

[@celvindietloff2321]

@@ellensburgamplifierThanks Mr Todd for your reply ive managed to find a 074C OP AMP that was bad it was giving me a square wave into pin one of the driver card, i replaced it and the positive rail voltage on speaker terminal is totally gone, without and with output fets in place and driver card in, im just not having a sine wave on my positive speaker terminal still needs to check that, and i dont have any square wave on low side drain of output fets.

[@ellensburgamplifier]

@@celvindietloff2321 Do you have the square wave on pins 6,7 and 10,11 at the header of the drive card?

[@celvindietloff2321]

@@ellensburgamplifier Good day Mr Todd i will be busy with amp later and make some notes of what i am having and what is missing, can you mayb give me a value of D1 and D3 please

[@ellensburgamplifier]

@@celvindietloff2321 Those are standard LL4148 signal diodes.

[@tanjuertuning8836]

hello, I have a few of these amps, the main problem is in all of them, there is no problem when driving irfz640n to one side, but when double-sided, it burns them all, all amps have this problem, I tried transformer signal cards, the result is always the same short-circuited + pole 640n works alone - pole 640n drives all It's on again. I'm in trouble because of this problem. Can you help me?

[@ellensburgamplifier]

Hi Tanju, I can do my best to help you. From what you are saying it sounds like the low side drive is the problem. Do you have an oscilloscope? With all the 640's out of the circuit I will need to see what the low side drive looks like and the rail to rail drive. You can email me directly which will work better for troubleshooting.

[@tanjuertuning8836]

@@ellensburgamplifier So the general problem is why the irf640n lights up when it is active on both sides, what is the cause of this problem, it has happened to you before, although there is no short circuit, all the irf640ns are on when it is driven on both channels.

[@ellensburgamplifier]

@@tanjuertuning8836 It sounds like they are being driven on at the same time which will cause a rail short. I will need to see the low side drive signal to help understand what is going on. Have you checked the 2T and 2X transistors?

[@tanjuertuning8836]

@@ellensburgamplifier When I check, 2t and 2x short circuit does not appear, short circuit does not appear on the circuit, can you give your e-mail address, can I call you on whatsapp?

[@ellensburgamplifier]

@@tanjuertuning8836 Please feel free to email me. [e-mail] They may not show a direct short but may still be leaking to a point where they may not be turning off fully. This goes back to seeing the drive on a scope.

[@commonsenseisdeadin2024]

Amp actually does 1900 watts rms up to clipping at 13.8v

[@ellensburgamplifier]

It does! Now that is impressive. I just opened up a AP3000.1D that just came in so stay tuned!

[@commonsenseisdeadin2024]

@@ellensburgamplifier How long it does it...well that is a entirely different question lol. I have 8 of these boards, some old sinks I could make something work and push them to see hahaha. Oh I am not envious of you. Audiopipe said; "FULL BRIDGE!!!!...meh close enough" lol