Rockford MEHSA needed

Jat40 · 27th January 2011, 11:31 PM

Been working to repair this T4000.1, see thread below, for a while now. The amp runs but has an output whine that I just can't locate the cause. The only difference in this amp and others that I have repaired, is it is missing the MEHSA boards in the power supply. I got the amp and these were missing. As a temp fix, I am using insulators.

So, my next option is to see if anyone has a compliment of MEHSA boards for a T4000.1 power supply that they would be willing to part with?

Rockford Fosgate T4000 - Output Whine

Jat40 · 29th January 2011, 12:12 PM

As reference, these are the MEHSA boards

Dr Zeus · 25th February 2011, 12:27 AM

I also need a MEHSA board just like the one you have pictured for 4 output transistors in a Punch 500. Were you able to source any or have any to spare?

Perry Babin · 25th February 2011, 02:49 AM

Dr Zeus, did you see the MEHSA conversion page on the DVD?

Dr Zeus · 12:58 PM

I did, and I realize what I can do to convert this MEHSA for my 4 output transistors... However, this MEHSA board has a single surface mount transistor right on it and would need to be retro-replaced as well.

Can I convert it to say a TO-92 style transistor? What transistor could be a suitable replacement?

Perry Babin · 25th February 2011, 06:01 PM

You can use a TO-92 transistor. What is the exact model number of the amp.

Dr Zeus · 06:13 PM

Rockford Punch 5002. The one under the \puncht5002\ folder on the DVD is the one.

Is the surface mount transistor a 6B? BAT54A? Barrier Diode? Also it looks like from the picture theres a single surface resistor or diode as well.

Perry Babin · 25th February 2011, 06:29 PM

It's a transistor. An MPSA06 should be OK as a sub but you'll have to do some testing after setting the bias to confirm that the bias is not drifting.

You'd have to find the terminals of the 3-legged jumper that correspond to the base, collector and emitter of the SMD transistor so you'll know how to install the TO-92 transistor.

For this amp, I'd suggest using the Kapton MT film or Mica as insulators. Kapton tape may not work well enough.

Dr Zeus · 25th February 2011, 06:42 PM

Sounds good; thank you. If you think MPSA06 may not work, I should have more/other driver and pre-driver transistors in my toolbox.

Thanks!

27th January 2011, 11:31 PM	#1
Jat40 diyAudio Member Join Date: May 2010 Location: Birmingham, AL	Rockford MEHSA needed Been working to repair this T4000.1, see thread below, for a while now. The amp runs but has an output whine that I just can't locate the cause. The only difference in this amp and others that I have repaired, is it is missing the MEHSA boards in the power supply. I got the amp and these were missing. As a temp fix, I am using insulators. So, my next option is to see if anyone has a compliment of MEHSA boards for a T4000.1 power supply that they would be willing to part with? Rockford Fosgate T4000 - Output Whine __________________ JT

25th February 2011, 02:49 AM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Dr Zeus, did you see the MEHSA conversion page on the DVD? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th February 2011, 12:50 PM	#5
Dr Zeus diyAudio Member Join Date: Oct 2010	I did, and I realize what I can do to convert this MEHSA for my 4 output transistors... However, this MEHSA board has a single surface mount transistor right on it and would need to be retro-replaced as well. Can I convert it to say a TO-92 style transistor? What transistor could be a suitable replacement? Last edited by Dr Zeus; 25th February 2011 at 12:58 PM.

25th February 2011, 06:01 PM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	You can use a TO-92 transistor. What is the exact model number of the amp. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th February 2011, 06:08 PM	#7
Dr Zeus diyAudio Member Join Date: Oct 2010	Rockford Punch 5002. The one under the \puncht5002\ folder on the DVD is the one. Is the surface mount transistor a 6B? BAT54A? Barrier Diode? Also it looks like from the picture theres a single surface resistor or diode as well. Last edited by Dr Zeus; 25th February 2011 at 06:13 PM.


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25th February 2011, 12:27 AM	#3
Dr Zeus diyAudio Member Join Date: Oct 2010	I also need a MEHSA board just like the one you have pictured for 4 output transistors in a Punch 500. Were you able to source any or have any to spare?

25th February 2011, 06:29 PM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	It's a transistor. An MPSA06 should be OK as a sub but you'll have to do some testing after setting the bias to confirm that the bias is not drifting. You'd have to find the terminals of the 3-legged jumper that correspond to the base, collector and emitter of the SMD transistor so you'll know how to install the TO-92 transistor. For this amp, I'd suggest using the Kapton MT film or Mica as insulators. Kapton tape may not work well enough. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th February 2011, 06:42 PM	#9
Dr Zeus diyAudio Member Join Date: Oct 2010	Sounds good; thank you. If you think MPSA06 may not work, I should have more/other driver and pre-driver transistors in my toolbox. Thanks!

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