GFA 5503 Bias adjustment - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 26th March 2014, 04:35 AM   #1
diyAudio Member
 
Join Date: Mar 2014
Smile GFA 5503 Bias adjustment

Hey guys and gals, I have a new to me Adcom GFA 5503 that runs quite a bit hotter than my GFA 5500. After an hour or so it heats up to 125-130 degrees F at the cooling fins. Almost as hot as my pure class A Plinius. Anyway I was wondering if a bias adjustment may be necessary or if this is normal operating temperature?

Im a rookie to the diy audio world. My limited experience includes assembling 3 bottlehead kits (Foreplay, Paramount monos and a Crack) and a Welborne Labs Ultrapath pre amp a few years back. I have the basic tools and I'd like to check the bias on this amp myself. I'm not one to ship an amp off to have someone else look at it.

Having said that, Im not exactly sure what emitter resistors legs to measure or exactly where to find the correct pots. Manual says bias pot P2, emitter resistor R52 left and center, R51 right. (Whatever that means) Target is 50mV +/-5mV

I want to learn, Anyone want to walk a rookie through a bias adjustment?

I'm sure it has to be similar to this... http://www.youtube.com/watch?v=HR2DsmnAG1k

Thanks in advance

Last edited by Race Director; 26th March 2014 at 05:17 AM.
  Reply With Quote
Old 26th March 2014, 12:58 PM   #2
diyAudio Member
 
Join Date: Apr 2010
Location: Coffs Harbour
If the guy in that video, following Parasound's instructions for their model was more careful with distinguishing volts from millivolts, it might be useful for others like him, who own that model amp.

Adcoms vary in their bias sensitivities and setting methods. The service manual, such as it is, describes the procedure.
You can quickly search the model for a free (with registration) download here: Free Manuals User / Service / Schematics for Download | HiFi Engine
__________________
Ian
  Reply With Quote
Old 26th March 2014, 08:14 PM   #3
Mihkus is offline Mihkus  Estonia
diyAudio Member
 
Mihkus's Avatar
 
Join Date: Jul 2012
For me that video was full of dump, all you need is the amps circuit.
You need to find bias pot or fixed resistor... Whats the point of setting your bias to higher point? On most amps its optimised .
  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
Help with bias adjustment. victo Solid State 2 2nd September 2014 10:54 AM
Looking for some help with Adcom gfa-5503 Royxc800 Solid State 4 6th June 2013 07:50 PM
bias pot and adjustment for gfa-5400 bikerblue711 Solid State 0 24th February 2013 06:57 PM
Adcom GFA-2535 Bias Adjustment dblack4 Solid State 0 28th October 2012 07:06 PM
Adcom GFA-565 Bias Adjustment Instructions? MDchanic Solid State 7 3rd August 2011 03:09 AM


New To Site? Need Help?

All times are GMT. The time now is 09:50 PM.


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