Welcome To the Hoffman Amplifiers Forum

September 06, 2025, 04:41:58 pm
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: Lexicon Signature 284 EL84 Stereo Amplifier  (Read 4851 times)

0 Members and 1 Guest are viewing this topic.

Offline plexi50

  • Level 4
  • *****
  • Posts: 4649
  • Tube Tone
Hoffman Amps Forum image
Lexicon Signature 284 EL84 Stereo Amplifier
« on: June 18, 2010, 11:34:34 am »
Hello all! It's a new day so here we go again:

This is a Stereo amplifier: Class A Configuration with 3 watts RMS per channel so the manual says:

I talked to the manufacturer and they told me 10 watt transformers. Single ended OT?

The customer said he put new EL84 tubes and afterwards the amp smoked and he shut it down

I have lifted the board and checked all PS caps and changed a few resistors that had stray values. Not bad but i changed them anyway

I removed the new EL84 tubes and checked the plate,screen and bias voltages / All is good with plates at 300VDC and grids at -10VDC

I put one of my EL84 tubes in one channel and all voltages are solid and steady / The amp sounds great!

I put in the second channels EL84 and tested all the voltages / The plate voltage drops from 300VDC to 83VDC and a PS resistor starts to smoke

Little sound and very distorted at best. I though it might be the new EL84 Yugoslavian tubes but thats not the case

At this time i have to believe it is the Output transformer for this channel / Any agreements?

http://www.triodeamplification.com/files/Lexicon_Signature_284_Schematic.pdf






« Last Edit: June 18, 2010, 09:03:15 pm by plexi50 »

 


Choose a link from the
Hoffman Amplifiers parts catalog
Mobile Device
Catalog Link
Yard Sale
Discontinued
Misc. Hardware
What's New Board Building
 Parts
Amp trim
Handles
Lamps
Diodes
Hoffman Turret
 Boards
Channel
Switching
Resistors Fender Eyelet
 Boards
Screws/Nuts
Washers
Jacks/Plugs
Connectors
Misc Eyelet
Boards
Tools
Capacitors Custom Boards
Tubes
Valves
Pots
Knobs
Fuses/Cords Chassis
Tube
Sockets
Switches Wire
Cable


Handy Links
Tube Amp Library
Tube Amp
Schematics library
Design a custom Eyelet or
Turret Board
DIY Layout Creator
File analyzer program
DIY Layout Creator
File library
Transformer Wiring
Diagrams
Hoffmanamps
Facebook page
Hoffman Amplifiers
Discount Program


password