Rockford Power 650 Mosfet - diyAudio
Go Back   Home > Forums > General Interest > Car Audio

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 2nd September 2011, 01:37 PM   #1
diyAudio Member
 
seankane's Avatar
 
Join Date: May 2010
Location: Washington State
Default Rockford Power 650 Mosfet

Hello everyone.

I recieved a Power 650 in today for repair.

The amp is acting wierd. It powers up fine and produces sound.

It has a pop when turning the volume from zero to sound on and off.

Also The rear channels work fine, but to get the front channels to work right you have to partially unplug the rca's from the rear channels.

If you unplug the rear channel rca's totally or just enough to where the shield is not touching the front channels work great. If you plug the rca's for the rear channels in all the way the front channels get very quiet and you can hear a frequency noise through the speakers.

Also the amp while trying set bias climbs immediately upon moving the pot at all.

Also wondering what the 5th pot is to the left of the bias pots??

Any help would be great.
__________________
Pyramid 52 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch
  Reply With Quote
Old 2nd September 2011, 02:06 PM   #2
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
Measure the DC on the input signal lines where they come into the board. Is there any significant DC there?

Do you see a shift in DC as you go from 0 to 1?

The other pot is the threshold for the thermal control for the fan.

Do you mean if you move it from fully CCW or just at some point in the rotation?
  Reply With Quote
Old 3rd September 2011, 03:13 AM   #3
diyAudio Member
 
seankane's Avatar
 
Join Date: May 2010
Location: Washington State
Quote:
Originally Posted by Perry Babin View Post
Measure the DC on the input signal lines where they come into the board. Is there any significant DC there?

Do you see a shift in DC as you go from 0 to 1?

The other pot is the threshold for the thermal control for the fan.

Do you mean if you move it from fully CCW or just at some point in the rotation?
There is no significant DC on the input pads the highest reading was 0.050 vdc.

I see a tiny shift when going from 0-1 volume but only a couple of numbers.

The bias pots are fully counter clockwise and when you move any of them clockwise at all the amp immediately starts drawing current.

How do I set the threshold hold for the thermal fan?
__________________
Pyramid 52 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch
  Reply With Quote
Old 3rd September 2011, 03:48 AM   #4
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
Have the output transistors been replaced?

To set the fan, I connect the fan and turn it until the fan starts, then back it off just a bit.
  Reply With Quote
Old 3rd September 2011, 04:05 AM   #5
diyAudio Member
 
seankane's Avatar
 
Join Date: May 2010
Location: Washington State
I do not know the history of the amp, I suppose they could have been replaced. If so what resistor for the pot do I need to change and what value?

Any ideas in why the front channels only perform properly when the rear is unplugged or only partially plugged in to where the shield is not touching?
__________________
Pyramid 52 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch
  Reply With Quote
Old 3rd September 2011, 05:03 AM   #6
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
If there is no DC on the signal lines or on the shields, I don't know why it would pop. Are you using y-cables to feed all 4 channels at the same time?

I think you'd have to reduce the value of the 470 ohm resistor near the pot.
  Reply With Quote
Old 3rd September 2011, 07:54 AM   #7
diyAudio Member
 
seankane's Avatar
 
Join Date: May 2010
Location: Washington State
Not using Y cables just feeding it from a Rockford head unit using sub output to rear and front output to front.

WHat would be causing the front to be so quiet when the rears are plugged in? This is very strange to me. Maybe something is wrong with the rear section?
__________________
Pyramid 52 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch
  Reply With Quote
Old 3rd September 2011, 08:35 AM   #8
diyAudio Member
 
seankane's Avatar
 
Join Date: May 2010
Location: Washington State
What issues could a bad input selector switch cause?

With speakers hooked up but no signal touching the RCA sheilds with my fingers makes god awful loud humming and wierd noises through the speakers.

When adjusting the threshold for the fan the higher you turn the pot the faster the fan goes. Once the pot gets to half it just barely starts turning. How high do I go or know what rpm the fan should be at?
__________________
Pyramid 52 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch
  Reply With Quote
Old 3rd September 2011, 04:57 PM   #9
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
The fan setting is a personal preference. Some people may want to allow a higher operating temperature as a tradeoff for lower noise. I set them as I described. You'll have to decide what works best for you.

The TO-92 transistor that stands up against the heatsink must be tight against the heatsink with compound applied between the transistor and the sink. It's the temperature sensor for the fan. If you touch your soldering iron to it, you'll see the fan speed increase rapidly.

A bad selector would likely cause one or more channels to be dead or intermittent.

What resistance do you read between the RCA shield and the main amp ground?
  Reply With Quote
Old 3rd September 2011, 06:52 PM   #10
diyAudio Member
 
seankane's Avatar
 
Join Date: May 2010
Location: Washington State
Do you want me to measure with the black probe on amp main ground and red probe where the rca grounds solder to the board or at the end of the cable itself on the shield?
__________________
Pyramid 52 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Rockford power650 mosfet seankane Car Audio 6 2nd September 2011 09:02 AM
rockford fosgate power 650 mosfet mike49504 Car Audio 43 24th March 2011 11:21 PM
Help with Rockford Fosgate Power 650 shawnk Car Audio 31 14th July 2010 09:11 PM
rockford fosgate power 300 mosfet mike49504 Car Audio 26 23rd December 2009 05:06 AM
Rockford Fosgate/Mosfet steven123654 Car Audio 5 2nd September 2009 03:13 AM


New To Site? Need Help?

All times are GMT. The time now is 07:49 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2