Yamaha Surgery

jackinnj · 15th February 2009, 10:07 PM

Well, this Yamaha baby cost just about nothing -- has a nice transformer and a heat sink radiator like those base-board heaters -- doesn't sound bad, but it is a mess cosmetically and soon to become "Franken-Receiver A-10".

THD% For 1W

THD% For 20W

Flatness -- you can't eliminate the tone controls:

Slew Rate:

jackinnj · 15th February 2009, 10:18 PM

Anyone think that an LM4702 could be fit in here:

I already cleaned up the output connectors -- who the heck needs an

A/B speaker switch anyway?

jackinnj · 4th March 2009, 01:15 AM

Changing the filter caps from 6,800 uF to 10,000 uF resulted in a 1.4V increase in the rail voltages. The old caps didn't even have to be desoldered -- just twisting a bit and they popped out. They were really dried out as well.

jackinnj · 4th March 2009, 07:27 PM

Well, this thing is going to run HOT!!! The rail voltage is now close to 44V each, but this receiver is only rated (I think) at 50 WPC -- here's a shot of the new driver board installed -- for the moment we are dispensing with the tone and loudness controls. The CD4066 analog switches are also going to have to stay for a while as I can't find an adequate replacement.

I've used this LM4702 driver in about 6 mods so far.

jackinnj · 7th March 2009, 09:37 PM

I am using Troy Huebner's method for determining the value of the gate resistors on the lateral MOSFETs. A pair of 1K trimpots set at center rotation. With a square wave, crank the amplifier up to where it sweats and adjust the trimpots until the rise and fall patterns are identical:

jackinnj · 15th July 2009, 05:12 PM

Oh well, forget the lateral MOSFETs -- the distances are too great so I am using bipolars.

Here's the new controller which will use Silonex LDR's -- the Yamaha has 4 inputs and a switchable loop -- so there are 2 loops in the code to read the button port -- I don't know if one resistor pack is going to work with the LED's.

15th February 2009, 10:07 PM	#1
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Yamaha Surgery Well, this Yamaha baby cost just about nothing -- has a nice transformer and a heat sink radiator like those base-board heaters -- doesn't sound bad, but it is a mess cosmetically and soon to become "Franken-Receiver A-10". THD% For 1W THD% For 20W Flatness -- you can't eliminate the tone controls: Slew Rate:

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Your surgery and operating table	jackinnj	Everything Else	14	6th June 2006 09:03 AM
Spider surgery - anyone?	Jorge	Multi-Way	6	11th November 2005 09:11 PM
Laser surgery on CDM-x	Thomas	Digital Source	19	10th May 2005 07:38 AM
Pioneer DV-414 smt surgery help -- please!!!	TrevorS	Digital Source	3	18th January 2004 05:50 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	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

15th February 2009, 10:18 PM	#2
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Anyone think that an LM4702 could be fit in here: I already cleaned up the output connectors -- who the heck needs an A/B speaker switch anyway?

4th March 2009, 01:15 AM	#3
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Changing the filter caps from 6,800 uF to 10,000 uF resulted in a 1.4V increase in the rail voltages. The old caps didn't even have to be desoldered -- just twisting a bit and they popped out. They were really dried out as well.

4th March 2009, 07:27 PM	#4
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Well, this thing is going to run HOT!!! The rail voltage is now close to 44V each, but this receiver is only rated (I think) at 50 WPC -- here's a shot of the new driver board installed -- for the moment we are dispensing with the tone and loudness controls. The CD4066 analog switches are also going to have to stay for a while as I can't find an adequate replacement. I've used this LM4702 driver in about 6 mods so far.

7th March 2009, 09:37 PM	#5
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	I am using Troy Huebner's method for determining the value of the gate resistors on the lateral MOSFETs. A pair of 1K trimpots set at center rotation. With a square wave, crank the amplifier up to where it sweats and adjust the trimpots until the rise and fall patterns are identical:

15th July 2009, 05:12 PM	#6
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Oh well, forget the lateral MOSFETs -- the distances are too great so I am using bipolars. Here's the new controller which will use Silonex LDR's -- the Yamaha has 4 inputs and a switchable loop -- so there are 2 loops in the code to read the button port -- I don't know if one resistor pack is going to work with the LED's.