YAHA HELP - Page 5 - 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 31st July 2013, 05:09 PM   #41
dfy is offline dfy
diyAudio Member
 
Join Date: Jun 2013
Another important point: The pad with the screw-hole of the LM317 is connected to Vout. Either use an insulating washer and an insulating pad for mounting the LM317 to the heatsink, or take great care in ensuring that the heatsink does not touch other parts of the circuit or enclosure.
  Reply With Quote
Old 1st August 2013, 03:52 AM   #42
prezden is offline prezden  Canada
diyAudio Member
 
Join Date: Nov 2008
Hi guys- Well I have had some success. One channel is working the other is dead.
The measurements on the regulator are are a bit low at 4.47v. Between pins 4 and 5 it reads a bit high at 7.68.
I put on a much larger heatsink with an insulating pad and washer. It still gets fairly warm but not so hot that I can't touch it.

Thanks again for all your help
  Reply With Quote
Old 1st August 2013, 11:06 AM   #43
dfy is offline dfy
diyAudio Member
 
Join Date: Jun 2013
Quote:
Originally Posted by prezden View Post
Hi guys- Well I have had some success. One channel is working the other is dead.
The measurements on the regulator are are a bit low at 4.47v. Between pins 4 and 5 it reads a bit high at 7.68.
I put on a much larger heatsink with an insulating pad and washer. It still gets fairly warm but not so hot that I can't touch it.

Thanks again for all your help
You are measuring Vin vs Vout on the regulator, I guess? You're supposed to measure Vout vs GND, which should give you the same 7.68V as you have on the heater pins. These do seem a bit high. You can get this nearer to the 6.3V in the data sheet by either

(a) replacing the 5K resistor with a 4K one,

or if you don't have a 4K part,

(b) putting a 22K resistor in parallel to the 5K one, giving a total resistance of approximately 4K. Important: If you do this, really make
sure you have correctly paralleled the two. If you disconnect the 5K resistor accidentally, leaving only the 22K, you WILL kill your filament. If you make modifications to the regulator circuit, consider desoldering the wire from regulator to heater, making the modification, measuring the voltage again and then reconnecting the heater if the voltage is okay.

Also note that the author of your PDF may well have had a reason to make the heater voltage that high, although I can't think of any.

When you say one channel is dead, are you still talking about the headphones or the actual amp? If it's the amp, I would try replacing the opamp chip, because that one may have taken some damage through that solder blob connection.

Last edited by dfy; 1st August 2013 at 11:21 AM.
  Reply With Quote
Old 1st August 2013, 12:58 PM   #44
diyAudio Member
 
Avro Arrow's Avatar
 
Join Date: Sep 2010
Location: Toronto, eh
It's good to hear you are making progress.

If you are going to get new resistors for the regulator...

Replace the 1k resistor with 243 ohms and the 5K with the 1K.
That will give you 6.4 volts. The resistors don't need to be as large
as the 5k you have. Both can be the same size as the 1K you have now.

Follow the advice as above. Test the heater voltage with the tube removed.
  Reply With Quote
Old 3rd August 2013, 05:42 PM   #45
prezden is offline prezden  Canada
diyAudio Member
 
Join Date: Nov 2008
I am going to order a new op amp and regulator for this amp. Also I thought to order new resistors for the regulator. What do you think would be the best ones given that I am getting new ones.

Thanks!
  Reply With Quote
Old 4th August 2013, 12:18 AM   #46
diyAudio Member
 
Avro Arrow's Avatar
 
Join Date: Sep 2010
Location: Toronto, eh
From Digi-Key:

243 ohms

1000 ohms
  Reply With Quote
Old 14th August 2013, 07:16 PM   #47
prezden is offline prezden  Canada
diyAudio Member
 
Join Date: Nov 2008
Well I think this guy is doomed
I replaced the reg and the resistors on it as well as the op. Unfortunately I managed to lift the pad on one of the outputs I've tried wiring the output onto the pin of R4 but the dc offset of that channel is completely out of whack. I noticed a few pads on this board lifting a bit. Maybe just a poorly made board as well as my less than perfect technique
I might try to build it point to point. Can you use a piece of pvc instead of perfboard as I happen to have a piece the right size at hand and have to drill holes for the tube anyway.

Once again - thanks for all your help. You guys are great
  Reply With Quote
Old 14th August 2013, 07:52 PM   #48
dfy is offline dfy
diyAudio Member
 
Join Date: Jun 2013
Piece of PVC? No. PVC doesn't like heat at all, it will decompose and melt at soldering temperatures.
  Reply With Quote
Old 14th August 2013, 08:13 PM   #49
prezden is offline prezden  Canada
diyAudio Member
 
Join Date: Nov 2008
ok I will have to order a piece of perfboard.
  Reply With Quote
Old 31st August 2013, 11:46 PM   #50
prezden is offline prezden  Canada
diyAudio Member
 
Join Date: Nov 2008
Hy guys- Looks like I will need your help again
After a lot of screwing around I have managed to rebuild the amp on perfboard. The power seems ok- aprrox. 12.5 input, 6.5 out at the reg. and 6.5 on the tube. The tube glows and there are no problems indicated with the dim bulb tester. That's the good part
Unfortunately there is no sound- absolutely nothing Somewhere in the input or output I've got something wrong but I can't figure out what.
Any advice would be most welcome
Attached Images
File Type: jpg yaha top.jpg (800.6 KB, 33 views)
File Type: jpg yaha bottom.jpg (824.8 KB, 31 views)
  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 06:06 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