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josesony68 11th June 2012 11:22 PM

Rockford Fosgate T1500-1 BD
3 Attachment(s)
Hello, everyone,

I received this amp for repair, (as I await the arrival of parts for my other ampilicador ......)

Checked, all the transistors, both the output, such as the power source, and none is shorted, or give erroneous readings.

When connected, no sound from the speaker, only three seconds, there is a "clock" in the speaker, then go silent.

I noticed a little swollen capacitors of the power connection, I proceeded to take away, and I have noticed that on the board and under one (C1013) had a spark in the negative, which was also, in that capacitor (see photos)

I have measured their ability, and all I get 200uF less than its value, the latter including electrolytic capacitor, took longer to read me ...

I do not know if replacing the three capacitors, or only the latter, what do you think?

What may have been caused, that spark?

Perry Babin 12th June 2012 02:11 AM

The spark was caused by having a bad solder connection. It appears that the trace for that capacitor is on the top of the board. If there is no trace (not referring to the pad, but a trace that goes to the other capacitors) you will need to restore the connection between the bottom of the board (the solder pad) and the trace on top of the board.

How do you like that meter?

josesony68 12th June 2012 08:24 PM

Then I reset the connection, apparently, there was a short between the top and the bottom of the motherboard.

(that of the welds bad .... I think more than one ...)

I repositioned the electrolytic capacitors in place, (either tinned)

When connected, (no speaker) apparently seems a good start ... but after three seconds, you hear a "click" near the LEDs, and attempts to power the red LED, and then hear a small sound sparkling, for the same area ...

Consumption is low: 1.1 A
Speaker Terminals: 0.4 v

Speaker connected to three seconds, I heard a "pow" big, moves the speaker cone to its limits, and then disconnect the battery, for fear of burning something ....

I'm a little lost ... the truth ... I do not know which way to go ...
Any ideas of where to keep checking?

Perry Babin 12th June 2012 09:39 PM

If the speaker is driven to its limits, the amp has much more than 0.4v across the speaker terminals. Recheck the output transistors to see if they're shorted.

Also confirm that you have 15v on the power supply pins of the audio op-amps.

josesony68 12th June 2012 10:24 PM

Confirmed in more than 50v speaker terminals ....

I'll check the mosfet

Operational amplifiers, this amplifier are: U2000 and U2002?
(MSRA 5110 1M)

josesony68 12th June 2012 11:39 PM

How odd ....
I checked all the output MOSFET, and none has given me short, and not open ....

I have also checked U3 (TL072) (op amp, near the RCAS) is correct, + - 13v.

I think there are some more operational in the plates which are positioned vertically with respect to the motherboard, and are difficult to access ...

Maybe ask the scheme to Rockford ...
What do you think, Perry?

Perry Babin 13th June 2012 03:24 AM

Try to get the schematic diagram from Rockford. The last time that I tried, they had not released it but that was about a year ago.

josesony68 13th June 2012 10:39 PM

I changed a couple of emails with Rockford, unsuccessfully, it seems that you do not supply circuit diagrams ....

Well, I retired 4 MOSFET amplifier (Q2006, 2007,2008, and Q2009) I have checked, and seem to be good ....

I connected the amplifier, and interestingly, I still 14v. (decrease) in the speaker output (does not sound the previous sparkling sound)

I also checked some drivers (Q2005, 2002 and Q2004) that belong to the mosfet removed:
(tester negative probe to ground the amplifier)

B: 8.98
C: 0
E: 9.01

B: -4.20 V and decreasing
C: 4.70 V and decreasing
E: -3.40 V and decreasing

B: -3.90 V and decreasing
C: -3.90 V and decreasing
E: -3.10 V and decreasing

Are they correct these measurements?
this amp, is it also has a square waveform on the oscilloscope?
Perry, do you think I should make the circuit, the other four mosfet to make measurements more reliable?

Perry Babin 14th June 2012 02:26 AM

You cannot use voltage on the output transistors to troubleshoot with the output transistors out of the circuit.

josesony68 14th June 2012 06:54 AM

Okay, this evening I return to solder the mosfet, sorry for my ignorance and thanks for the help, Perry.

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