Yamaha M-70 / Light bulb tester - Question! - 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 6th September 2010, 03:34 AM   #1
diyAudio Member
 
Join Date: Sep 2010
Location: Way out West
Default Yamaha M-70 / Light bulb tester - Question!

Hello, I picked up an old Yamaha M-70 a while back and I JUST decided to clean it up and start replacing all the original electrolytics and old carbon resistors.

Before replacing ANYTHING, I plugged it in (using a mains light bulb tester). I used a 3 way bulb (25W; 60W; 100W).

When I powered it up, the lowest setting (25W) did not light whatsoever, The 60W was very dim and the 100W was a bit brighter! Then I turned the bulb (switch) in to the off position AND ran through the process again WITHOUT turning the amp off. This time, the first setting (25W) started off dim and progressively glowed brighter, the next setting (60W) was brighter yet and the final (100W) was Very bright.

I powered off the amp and repeated the process! The EXACT same thing happened.


Can someone PLEASE Explain what is happening?
why do the bulbs only glow slightly the first time through the sequence of wattages (25,60,100) and then actually light (and grow brighter) if I go through the process again WITHOUT POWERING OFF THE AMP?
Then, when I DO power off the amp, The bulbs lowest setting (25W) shows nothing???

I know that using a Light bulb tester is essential for plugging in any old electronics to check for possible problems BUT I would like to know what is actually happening in the process!

Thank you


Brock
  Reply With Quote
Old 6th September 2010, 08:39 AM   #2
Bone is offline Bone  United Kingdom
diyAudio Member
 
Join Date: Jun 2004
Location: Dorset, UK
How is the light bulb tester wired?
The light bulb must be in series with the amplifier. Your description indicates otherwise.
  Reply With Quote
Old 6th September 2010, 11:59 AM   #3
diyAudio Member
 
Join Date: Sep 2010
Location: Way out West
Quote:
Originally Posted by Bone View Post
How is the light bulb tester wired?
The light bulb must be in series with the amplifier. Your description indicates otherwise.

How so?




YES the bulb is wired in-series! It's an old extension cord. Clipped the (+) wire, placed the bulb socket between the "clipped" wire. The other wire (-) side is uninterrupted! Plug the ext cord in to the mains socket, plug amp in to ext plug!

I've used it before... For instance, on my small integrated amp, the bulb Lights Bright for a SPLIT second, then dims completely and then reaches a steady glow after about 15 seconds. But my integrated is up to spec (been re-capped) and only draws 1/5 of what the M-70 draws. The M-70 is old and likely needs complete re-capping.

Something different is happening with the Yamaha M-70!

I want to know how to interpret the ways in way the bulb lights (OR doesn't light) with respect to the amp powering up!





Brock
  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
Light Bulb Tester Speedskater Power Supplies 42 22nd July 2014 02:58 PM
mains light bulb tester. bryantramos79 Power Supplies 16 17th April 2010 05:16 PM
Yamaha MX-70 bekim Solid State 5 23rd April 2007 06:38 AM
Looking for schematics... Yamaha M-70 akguzzi Solid State 0 2nd August 2005 06:29 PM


New To Site? Need Help?

All times are GMT. The time now is 11:50 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