rockford fosgate BD1500 stopped working

[Perry Babin]

I'm not sure if this is normal. I've never had an amp with this exact configuration of missing parts. If the voltage on the output of U5 doesn't change, it's probably normal but inconclusive.

When you order parts, order an HCPL2211 in case it's defective.

 

[NauTech]

well when we tested the amp yesterday i had a nice -9.6V/9.6V everywhere so i guess there is something related to the missing U6 maybe...
is there a way to further check the optocouplers ?

when i directly check at the right FET's pin 1 and 3 as we did earlier i get +7.6V instead of 5.x something at U10 ... could it be cause the battery is getting lower in voltage ? i am now at 11.19V
and since there is no "load" from the left side FETs the voltage is higher than on the right side FET's wich as all of the 8 FET's applying load on U10 and U9 lowering the voltage a bit ??
just a theory

 

[Perry Babin]

Things are different now.

I think we should wait until you get the replacement parts. There are other tests but they're much more involved.

 

[NauTech]

allright
what about the small voltages on the speaker terminals ? something normal ?

 

[Perry Babin]

I don't think it's anything to be concerned about.

 

[NauTech]

good news
i will install those parts and before powering up and remove the resistor between gate and source i will confirm that U6 sends a good signal and measure all of the FETs again to be shure there is none leaking and then i will remove the resistor and see what do i have between gate and source on the left and right bank of FETs and if i have any voltage on the speaker terminals and let you know the results to see what will be next... does it sound good to you?

 

[Perry Babin]

I think you should remove the resistor, replace the FETs and driver and power it up. If you'd like, you can confirm that the gates read open before installing the driver.

 

[NauTech]

allright i will remove the resistor when replacing the FETs
would you suggest only replacing the 2 FETs that failed for testing purposes and when everything looks in working order i could replace all of the other FET on the left bank ?? this way if something happens i wont waste all of the new FETs again!!

 

[Perry Babin]

I would try it without adding any new FETs but there's always the chance that the FETs are damaged in a way that doesn't show on the meter. If they fail when you power it up, you won't really know why they failed. If they survive, you'll know that everything else is probably OK. Double-check the gate resistors before you apply power.

 

[NauTech]

when you say try it without adding any new FETs do you mean without any new FETs except replace the 2 that failed... or without adding any new FETs at all and only replace the driver
i didnt exactly get what you meant

 

[Perry Babin]

If you have at least one 6215 and one 3415 on the side that failed and they read in the mega-ohm range (gate to the other legs with no driver), install the driver to see if the amp will power up and produce low level audio, with no significant turn-on/off pop.

 

[NauTech]

I have 3 of each working, 3215's and 6415's, on the failed side, this should be enough to power some low level audio for testing...
I will start with this and let you know what happens.
how about the punctuation

 

[Perry Babin]

Punctuation and paragraphs make it easier to answer questions. It's not a big deal when there's only a couple of posts a day but when 4 or 5 people are constantly asking questions, it makes it much tougher to get to everyone if I have to try to determine what the posters are asking.

 

[NauTech]

of course! i understand... specially with me and Sean being abusive on you all night long
you should have told me earlier...
I dont want you to get tired of me cause its hard to read my posts.
I dont really notice those things when typing, but you make me remember that i often read post of people not using puncuation at all and i have to read 2-3 times to understand what they are saying exactly. I will be more carefull on this.

 

[NauTech]

first of all thanks Sean Kane for sending me the parts they are all looking good

I just installed them and checked them for continuity before and after install and its good to go
double checked the gate resistors and its all good to
about to power it up to see if all the gates have -9V/+9V and if the speaker terminal has DC on them
will let you know the results

 

[seankane]

You are welcome, glad I could be of help.

 

[NauTech]

what the hell
now the protect LED stays on...

 

[seankane]

What are the dc voltages on all the pins of U21?

pin 1:
pin 2:
pin 3:
pin 4:
pin 5:
pin 6:
pin 7:
pin 8:

Just click quote and use my numbers and fill in the blanks.

 

[seankane]

Do you still have DC on the speaker terminal?

 

[NauTech]

0.5v on speaker terminal