rOCKFORD P8002

[edfirebird68]

Hey guys I have a Rockford p8002 that had a few transistors burn in the power supply transistor Q9,Q7,Q10,Q12 AND C26 R35 R37 LOOK LIKE PN N351AB CAN SOMEONE SEND ME A SCHEMATIC OR ADVISE WHAT TO CHECK GOT A DVM SCOPE 12V PS...
jUST NO INFO
THANKS
eD

[Perry Babin]

I don't think rockford has released the schematic for that amplifier yet.


Check the other two gate resistors and Q3, Q4, Q5 and Q6. I think these are the drivers for the PS FETs. You can confirm if there is continuity between their emitter and the gate resistors for the FETs.

The capacitor appears to be for the snubber and isn't critical. It's likely a 0.01uf cap. Looking at other schematics, they used relatively low capacitance.


You should check the output transistors to make sure none are shorted.


You'll need a 'small' butane torch to change these power supply transistors.

[ppia600]

How do you use the torch? I used to have a tiny microtorch and I tried using it to melt off one of the transistors on a punch with the "soldered" on transistors. I just tried heating the metal tab hoping the heat would release it and the plastic body flamed. What kind of torch do you use?

[Perry Babin]

You clean all of the old heatsink compound from the insulator (very important -- ask anyone who has had the hot compound fall onto their hand) and heat the insulator from behind. The transistor will release after ~20 seconds of heating (for the first transistor - the others will release more quickly because the insulator is already hot).

Wear safety glasses. Keep the torch angled away from the board (important on the older amps where the insulator is parallel to the board).

I use the torch radio shack sells.

[ppia600]

Oh, I gotcha. DUH... can't believe I didn't try that

[edfirebird68]

Thanks Perry!
I was hoping you'd reply!
All the searching I did before posting I saw your intricate knowledge of amplifers!
Can you provide any simular schematic which is simular to this power supply.. or any voltages / schematics.
Thanks Ed
I have the right tools just no experience.

[Perry Babin]

Email me directly and I'll send you one of their schematics.

babin_perry@yahoo.com

The power supplies have been generally the same for many years. The newer amps added a second comparator so the control/protection circuit is a bit different but that shouldn't be a problem for the amp you're working on.

You can power up the amp with no B+ power (only remote and ground) and the power supply IC (TL594) should power up and oscillate. You can check the output on pins 9 and 10. If there is no output, post a list of the voltages on all of the pins of the IC. Depending on the condition of the driver transistors, the output could be pulled down. To remove them from the circuit (but leave them on the board), heat the two bottom legs of the driver transistors and lift those legs off of the board.

[Rigosuave]

Recently my P8002 had 1 channel bad and I found 2 MOSFET'S bad, 1 channel N and 1 channel P from the same channel, I replaced the bad ones and the sound gets amplified only from the N Side, the Side P is not working, POWER MOSFETS are OK, Gate Resistors are OK, looks like I have some transistor or resistor blown from the Pre-driver or buffer stage but I'm having hard time to figure it or find out, without the schematic is so difficult.
any ideas?

[Perry Babin]

Email Rockford tomorrow to get the schematic. If you still need help, email me a copy.

babin_perry@yahoo.com

[Solosound]

may someone help me?

In the same amplifier P8002 I need the values for the next resistors:

R2041, R2051, R2045, R2078 and R2088

Please I´ll wait your help.