Dx Blame MKIII-Hx - Builder's thread - Page 24 - 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 12th October 2011, 02:21 PM   #231
diyAudio Member
 
vargasmongo3435's Avatar
 
Join Date: May 2011
Location: Quebradillas, Puerto Rico
Send a message via Yahoo to vargasmongo3435
Quote:
Originally Posted by ByronInLawrence View Post
I already asked this question, but I'll try one more time.

I like the profile for the heatsinks for the MJE15030 and MJE15033 transistors Alex drew in the silkscreen, but can't find them. Does anyone know of such heatsink? If not, what is everyone using?

-Byron
I'm not sure but I think this are the ones,
TO-220 Heatsink Voltage Regulator Isolation Kit 4 pcs | eBay

regards
vargasmongo
  Reply With Quote
Old 16th October 2011, 12:20 AM   #232
diyAudio Member
 
ByronInPortland's Avatar
 
Join Date: Nov 2010
Location: Portland, Oregon
Unhappy My board is not working

I suspect I damaged something on the board, but don't know where to start looking. Here is the whole story:
  1. I thought I had my power supply working (which I later learned was not the case). I fired up the board for the first time without a bulb tester, which I hadn't built yet.
  2. I heard a brief crackling. I didn't see or smell smoke. I carefully checked for hot components and didn't find any, so I continued.
  3. I was trying to adjust the bias, but the board was not behaving as I expected. I don't remember what tipped me off, but I re-checked my power supply.
  4. I had two diodes on my rectifier flipped! I was sending AC through my filter caps and then, presumably, to the board. My multimeter measured this as about the correct DC voltage from rails to ground.
  5. I'm pretty confident I fixed my power supply, which measures ~59VDC positive-ground and ground-negative, and ~118VDC positive-negative. No AC voltage.
  6. I built a bulb tester and resumed setting the trimmer resistor. I found I could not get the voltage drop across the 100ohm test-resistor up to 4.4VDC.
  7. I thought that maybe I'm not supposed to have a jumper from signal ground to main ground, so I tried cutting it. I also thought maybe I needed an 8R resistor from speaker-out to ground. The included chart shows all the permutations, and the voltages I got for them.
  8. Typical test was: 1) put the light bulb in line and hook up the test leads. 2) Turn on. The bulb would glow brightly, then gradually dim. With the 8ohm resistor between speaker out-and ground it never dimmed completely. 3) Measured voltage would jump around at first, then slowly move to some final value, which is the value I recorded. 4) Bypass the lightbulb. Measured voltage would jump a bit, then settle on its new value.
  9. I removed and tested the trimmer resistor, and it works fine from 0 to 1020R.
At no point in the building or testing did I ever see or smell any smoke. I would frequently search for hot components, and never found any except those center transistors, which are now heatsinked.

I would appreciate any suggestions about where to start troubleshooting. I've not started on the second board yet, but have at least 2 of everything.
Attached Images
File Type: jpg not working far.JPG (105.6 KB, 520 views)
File Type: jpg not working closeup.JPG (114.7 KB, 520 views)
File Type: jpg testing voltages.JPG (63.9 KB, 499 views)
  Reply With Quote
Old 16th October 2011, 09:00 AM   #233
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Discard the 50W dummy load. It is drawing current to Audio Ground due to the output offset. No useful information in there as far as I can tell.

The open output and shorted input shows output offset. Can this be adjusted towards zerovolts?
Thankfully the offset is not near rail voltage. I think that is telling us that the outputs are not blown. Can you check current is flowing through every emitter resistor of the output stage. List all the Vdrops.
__________________
regards Andrew T.
  Reply With Quote
Old 16th October 2011, 12:34 PM   #234
Junie is offline Junie  Philippines
diyAudio Member
 
Junie's Avatar
 
Join Date: Sep 2010
Location: Dubai, UAE
I'm suspecting a wrong value resistors mate.
  Reply With Quote
Old 16th October 2011, 06:20 PM   #235
diyAudio Member
 
destroyer X's Avatar
 
Join Date: Feb 2004
Location: Recife - Brasil Northeast
Default My Blame amplifier is not working uncle charlie!

Yep... sometimes this happens;

My Blame amplifier is not working uncle charlie! - YouTube

regards,

Carlos
__________________
DxS, the best from the best...the cream from the cream, the best wide world ever made audio amplifier.
  Reply With Quote
Old 17th October 2011, 03:51 AM   #236
diyAudio Member
 
ByronInPortland's Avatar
 
Join Date: Nov 2010
Location: Portland, Oregon
Thumbs up I found a problem

I don't know if it's the problem, but it's something. Two of the supplemental power supply filter caps - the big ones on either side of the board - are inconsistent. Sometimes they measure spot-on, and sometimes they give crazy values which are all over the place. They did this on the board, and after I took them off. Monday, I'll put back all the other components I removed to check and try again. And I'll try Andrew's suggestion.

I do have a question: There is a resistor right next to the trimmer pot. On my schematic I named it R21. Alex put the value 680R on the board, but Carlos' schematic shows 1200R. I used 1200R. I verified the value of it and all the resistors anywhere near that trimmer pot with my multimeter. Should I have used a lower value there, especially considering my <64V rail voltage? Presumably, that value of 1200R was chosen for 64V rails. If getting rid of these filter caps doesn't solve the problem, that will be plan B.

Thank you, everyone, for your suggestions.

-Byron
  Reply With Quote
Old 17th October 2011, 02:34 PM   #237
diyAudio Member
 
vargasmongo3435's Avatar
 
Join Date: May 2011
Location: Quebradillas, Puerto Rico
Send a message via Yahoo to vargasmongo3435
Hi mister Junie I read on the forums and the 1.2k resistor is not showing on mister Alex MM board it has 680 ohms will that make a difference?



regards
vargasmongo
Attached Images
File Type: png 1.2kR 680R.PNG (112.3 KB, 410 views)
  Reply With Quote
Old 17th October 2011, 04:07 PM   #238
diyAudio Member
 
Join Date: May 2011
Location: Quebec
This resistor value is determined by the bias transistor chosen. See the attached pictures. I don't remember on what forum / page I picked these pics, but they come from DX-man himself about the Hx amp.

Martin.
Attached Images
File Type: jpg Bias transistor____BD139 in place.jpg (131.3 KB, 379 views)
File Type: jpg MJE15030.jpg (46.5 KB, 158 views)
  Reply With Quote
Old 17th October 2011, 04:38 PM   #239
diyAudio Member
 
vargasmongo3435's Avatar
 
Join Date: May 2011
Location: Quebradillas, Puerto Rico
Send a message via Yahoo to vargasmongo3435
Quote:
Originally Posted by canonnica View Post
This resistor value is determined by the bias transistor chosen. See the attached pictures. I don't remember on what forum / page I picked these pics, but they come from DX-man himself about the Hx amp.

Martin.
Thanks! I already have the NPN transistor MJE15030 so it should be 1.2KR instead of 680R. oh boy!

regards
vargasmongo
  Reply With Quote
Old 17th October 2011, 05:00 PM   #240
diyAudio Member
 
vargasmongo3435's Avatar
 
Join Date: May 2011
Location: Quebradillas, Puerto Rico
Send a message via Yahoo to vargasmongo3435
Thumbs up 680 or 1.2K

Yes! it is 1.2K I just want it to make sure thanks!
Attached Images
File Type: png 1.2k.PNG (73.2 KB, 215 views)
File Type: png 680.PNG (78.3 KB, 201 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
Dx Blame ST - Builder's thread - post pictures, reviews and comments here please. destroyer X Solid State 1730 15th September 2014 10:01 PM
Dx Blame MKIII Supercharged will soon be released destroyer X Solid State 346 22nd April 2014 03:01 PM
group buy for DX Blame MKIII Hx PCBs ByronInPortland Group Buys 247 5th December 2012 12:05 AM
Group By: DX Blame MKIII Hx boards ByronInPortland Group Buys 9 19th July 2011 07:21 AM
Dx Blame MKII, an obvious evolution from the Dx Blame ES/ST destroyer X Solid State 4 25th September 2010 06:41 PM


New To Site? Need Help?

All times are GMT. The time now is 05:45 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