• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Music angel el34b problem

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hi guys,

I've got one of these chinese thingys:

http://hi-end.on9mart.com/products/amplifiers/integ_amp/AI-MA-MENG-EL34-6bkbk/TIA13-photo_04.JPG

Bought off a well known auction site...

It was working brilliantly... until i decided to fit magic eye vu meters to the sucker. I proceeded to burn out 2x resistors on the tube socket side of the board. Does anyone here have a picture of that side? I can find plenty of the underside of the board, just not the top.

How it blew: I hooked up the magic eye board as it should be (or how i thought it should be) and turned it on. no input connected & volume at minimum. after about... 6 seconds one resistor caught fire (yes. fire.) and the second followed shortly after. as a result i am unable to identify the values to replace them.
It turns out the magic eye tube socket was on the wrong side of the board - me= stupid for doing that. and a short circuit resulted. I have since removed the magic eye stuff so i can focus on getting the amp back to normal.

(i suppose this is what i get for assembling a kit without instructions) It would have been nice if the guy i got the kits off supplied me with them, but the damage is done. Now it's fixing time!

I'll see if i can rustle up a pic of the board soon
Thanks in advance... :)
 
Here's the board...
Not in it's original case. I butchered a bamboo cutting board & glued some hardwood to it.

The pics might not be too clear, but l/h channel went from pin 4 of the two el34s to a 220UF cap (big sucker)
the r/h did similar, but the cap is a 180.

Without the resistors it sounds like a boss DS1 distortion pedal maxed out. and really quiet. not exactly the sound i was after...

When i guestimated the values (1k for L/H & 4.7k for r/h - from what colours i could make out), it made an almighty squeal/bassy rumble that terrified the neighbours dogs :D

The other possibility is when i blew the resistors i may have damaged the tubes, but i'll start with replacing these 20c parts first.
 

Attachments

  • amp1.JPG
    amp1.JPG
    222 KB · Views: 136
  • amp2.JPG
    amp2.JPG
    170.8 KB · Views: 131
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.