YAHA HELP - Page 4 - diyAudio
Go Back   Home > Forums > Amplifiers > Headphone Systems

Headphone Systems Everything to do with Headphones

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 30th July 2013, 09:19 PM   #31
prezden is offline prezden  Canada
diyAudio Member
 
Join Date: Nov 2008
Well I have made the changes suggested by dfy and almost got it working. When I turned it on the dim light bulb flared quite bright went off, The regulator got very hot instantly and the right channel on my headphone got toasted.
Fortunately they were cheap earbuds and not good phones
I'm sure I've done something stupid here so once again I will need some help please
Attached Images
File Type: jpg yaha again.jpg (641.7 KB, 26 views)
  Reply With Quote
Old 30th July 2013, 09:58 PM   #32
dfy is offline dfy
diyAudio Member
 
Join Date: Jun 2013
Okay, so a few safety rules first before you plug it in next time:

Power it on without phones or source plugged in of course! Then check DC offset at the output (measure voltage between GND and both channels at the output) before plugging anything in.

As to what went wrong... I re-checked all your pictures again, and it seems you have a large solder blob that connects two traces that shouldn't be and therefore put the right channel of your headphones at +12V DC. See attached picture.

The regulator may or may not be dead after this. There may be more wiring/soldering problems, really do some extensive testing with a multimeter (for connections that shouldn't be there before(!) you turn it on and for sensible voltages after you turn it on, but before you plug in phones or sources).
Attached Images
File Type: jpg yaha bottom (1).jpg (46.6 KB, 25 views)

Last edited by dfy; 30th July 2013 at 10:00 PM.
  Reply With Quote
Old 30th July 2013, 10:31 PM   #33
prezden is offline prezden  Canada
diyAudio Member
 
Join Date: Nov 2008
Hi- I cleaned up the solder on the board. The dc offset is 1.7mv on one channel and .7 on the other. This seems high to me
The LM317 gets very hot in a matter of seconds
  Reply With Quote
Old 30th July 2013, 10:45 PM   #34
dfy is offline dfy
diyAudio Member
 
Join Date: Jun 2013
Quote:
Originally Posted by prezden View Post
Hi- I cleaned up the solder on the board. The dc offset is 1.7mv on one channel and .7 on the other. This seems high to me
The LM317 gets very hot in a matter of seconds
No, those millivolts should be fine as a DC offset. I'm at a loss about the regulator getting super hot though. Either it's dead or there is a wiring mistake that I missed or don't understand correctly. Let's wait for someone else to weigh in on that.
  Reply With Quote
Old 31st July 2013, 03:33 PM   #35
diyAudio Member
 
Avro Arrow's Avatar
 
Join Date: Sep 2010
Location: Toronto, eh
Time for some basic troubleshooting.

What is the output voltage from the regulator?
With a 1k and 5k resistor, it should be 7.5 volts.
Even that seem pretty high. the tube should have
6 volts between pin 4 and 5 +- 15%. People usually
use 6.3 volts. If, as you said, the tube glowed very
bright and then went dark, the tube is trashed.

If the regulator is blown and putting out 12 volts, that
will be why the tube is blown.

You mentioned the offsets were 1.7mV and 700mV,
is that correct?

dfy has been giving correct advice. The picture in post 14
is how it should be wired.
  Reply With Quote
Old 31st July 2013, 03:39 PM   #36
diyAudio Member
 
Avro Arrow's Avatar
 
Join Date: Sep 2010
Location: Toronto, eh
I check my 6922 tube (an ecc88 family version) and have a resistance
of about 3 ohms between pin 4 and 5. Pin 9 is not connected to
the heater circuit.
  Reply With Quote
Old 31st July 2013, 03:40 PM   #37
dfy is offline dfy
diyAudio Member
 
Join Date: Jun 2013
Quote:
Originally Posted by Avro Arrow View Post
You mentioned the offsets were 1.7mV and 700mV,
is that correct?

Good thing you spotted that. I thought he meant 1.7mV and 0.7mV...
  Reply With Quote
Old 31st July 2013, 03:57 PM   #38
prezden is offline prezden  Canada
diyAudio Member
 
Join Date: Nov 2008
Hi Avro Arrow-
It's not the tube which flared and went out. It's the bulb on my dim bulb tester. Sorry if I said that incorrectly. The dc offsets were 1.7mv and 0.7mv. I will check the other measurements and let you know what I come up with. Last night I put on a larger heat sick and left it on for about 10min and it didn't heat up as much as before; still quite warm though. The tube was glowing steadily while it was on.

Thanks for all your help
  Reply With Quote
Old 31st July 2013, 04:16 PM   #39
diyAudio Member
 
Avro Arrow's Avatar
 
Join Date: Sep 2010
Location: Toronto, eh
Thats better news to here.
The offsets are fine.
If the tube heater is still glowing then the regulator
is probably fine too.
  Reply With Quote
Old 31st July 2013, 04:25 PM   #40
diyAudio Member
 
Avro Arrow's Avatar
 
Join Date: Sep 2010
Location: Toronto, eh
A basic rule of thumb for the heat sink is:
If it's uncomfortable to hold on to, you should
have a bigger heat sink.
  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
YAHA with output buffer: need help TB Headphone Systems 3 25th August 2010 04:17 PM
hummming YAHA frajavcar Tubes / Valves 0 1st July 2008 05:58 AM


New To Site? Need Help?

All times are GMT. The time now is 05:39 AM.


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