R3 soldering pad ruined - Page 3 - diyAudio
Go Back   Home > Forums > Commercial Sector > Vendor Forums > Tubelab

Tubelab Discussion and support of Tubelab products, prototypes and experiments

Reply
 
Thread Tools Search this Thread
Old 3rd May 2011, 08:22 AM   #21
diyAudio Member
 
Join Date: Jun 2010
Location: SE Pennsylvania
Quote:
Originally Posted by rknize View Post
Are you using the AC volts setting on your meter? Also, pins 4 and 5 should be tied together, so you should read no voltage there. You should measure 6.3V between pin 4 or 5 and pin 9.
Yes, I used AC setting on the DMM. With 5AR4 and 12AT7 out but 6L6s still in.

Russ, I just tried what you said. I placed black lead on pin 9 and red lead on pin 4 and then on 5. The meter kept flashing between 3.0 to 3.5V at both pins 4 or 5 and 9.
  Reply With Quote
Old 3rd May 2011, 01:19 PM   #22
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
Quote:
The meter kept flashing between 3.0 to 3.5V at both pins 4 or 5 and 9.
It should read over 6 volts. Verify that the brown wires from the Edcor are connected to the T1-GRN terminals on the rear edge of the board and the brown / white wire is not connected to anything.

You can check the voltage at the 6L6 tubes by pulling them out and measuring the AC volts with one probe on pin 2 and the other probe on pin 7. Remove the 5AR4 so that the possibility of finding 500 volts on the 6L6 pins is reduced.

It is possible that the board is receiving 3.15 volts. The 6L6 types have a big enough heater to dimly glow on low voltage while the 12AT7 may not.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 3rd May 2011, 05:50 PM   #23
diyAudio Member
 
Join Date: Jun 2010
Location: SE Pennsylvania
Quote:
Originally Posted by tubelab.com View Post
It should read over 6 volts. Verify that the brown wires from the Edcor are connected to the T1-GRN terminals on the rear edge of the board and the brown / white wire is not connected to anything.
Brown wires are connected to T1-GRN and white/brown is sealed with ele. tape.

Quote:
Originally Posted by tubelab.com View Post
You can check the voltage at the 6L6 tubes by pulling them out and measuring the AC volts with one probe on pin 2 and the other probe on pin 7. Remove the 5AR4 so that the possibility of finding 500 volts on the 6L6 pins is reduced.
Octal sockets: 6.2V on both sockets between pins 2 and 7. All tubes taken out.

Noval socket: Reads 4.5V between pin 9 and 4 or 5 with all tubes out. Then I took another reading with 6L6s back in and it was 3.4V between pin 9 and 4 or 5.

Note: Readings taken with OPTs still connected. 5AR4 was out at all times.
  Reply With Quote
Old 3rd May 2011, 11:50 PM   #24
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
OK, the problem must be with the broken pad for R3. That pad not only connects up R3, but it connects the circuitry on the bottom of the board with the circuitry on the top of the board. You must have a good connection on BOTH sides of the board. The PC board has "plated through holes." There is copper plating INSIDE the component lead holes. This is used in some places to make the connection from the top of the board to the bottom of the board. R3 is one of those places. In fact it is the place where the power for the 12AT7 goes from the top side to the bottom side. Chances are the plating was still on the component lead when you removed it. The connection got broken in one or more places, so we need to figure out exactly where the connection is broken, and fix it.

To do this we are going to use the ohms function on the meter. The board must be powered off, and have been powered off for several minutes so that all the capacitors have discharged. Remove all tubes and disconnect the brown transformer wires. Flip the board over so that you can get to the back side. If you have to remove it from the chassis, this testing and repair can be done on a board that is not connected to anything. It might be helpful to mark pin 7 of V21 and pin 9 of V10 on the back side of the board with a sharpie, or at least be able to identify them, and the trace that connects them toigether as it travels from pin 7 of V21 to R3, therough the R3 hole to the back of the board, and to pin 9 of V10. We are looking for a break in this connection. Most likely it is right at the R3 hole on either side of R3.

Set your meter for the lowest OHMS scale. This is called "200" or "200 ohms" on most cheap meters. Verify that you get a low reading when you touch the two probes together (1 ohm or less). Some meters have a continuity function that beeps when you touch the leads together. If yours does, use it.

Step 1) Touch one probe to Pin 7 of V21 and the other to your R3 wire. Beep or low reading? Yes...good, move on to step 2. No? solder a short piece of wire (a resistor lead, wire wrap wire, or similar...insulation not needed) from V21 pin 7 to R3 on the back side of the board.

Step 2) Touch one probe to your R3 wire and the other probe to pin 9 of V10. Again you should get a low reading or a beep. If not a repair is needed. The simplest way is to solder a piece of wire from your R3 wire (or V21 pin 7) to pin 9 of V10. This wire is a few inches long and could come into contact with other circuitry, so it should be insulated. It should be heavy enough to carry heater current, but not heavy enough to cause damage to the board. Wire wrap wire, small gauge hook up wire, even a scrap of wire from trimming the transformer leads will work.

Verification) Flip the board over (top side up). Touch one probe to pin #9 on the 12AT7 socket and the other probe to pin 7 on the 6L6 socket. You should have a beep or low reading. Leave one probe where it is and touch the other to pin 7 on the other 6L6. Beep? Again move one probe to R3, Beep? And R4, Beep?

Now put one probe on pin 2 of a 6L6 and verify continuity to pin 4 and 5 of the 12AT7. Beep?

If beep happens, hook the board back up....it will work!
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 4th May 2011, 05:48 AM   #25
diyAudio Member
 
Join Date: Jun 2010
Location: SE Pennsylvania
It worked. Thank you George for your help and detailed instructions. I connected pin 7 with R3. Now the readings are 6.2V between pin 2 and 7 on octal sockets and 6.1V betweeen pins 4 or 5 and 9 on noval socket with all tubes out.

Since my roommates are asleep, I have not hooked up CD player to it tonight.

The XPWR035 transformer has lot of hum when powered on. Even on its own and without even connected to PCB, it's hum is so loud, I can hear it from 20 feet away right now at 1 am. The hum level of the transformer increases slightly while connected to the rest of the amplifier. I don't have it on chassis, the whole amp is on wooden table. I don't know if everyone's transformers have this sort of hum. I know some people report hum problems with their amp but I'm not talking about hum from the speakers (I have that too), I'm talking about hum from the transformer only...mine is kind of loud. The noise level is a bit higher than one of those AAA battery powered little pocket size fans. Is it possible I have a defective power transformer? See the last pic, The brown wires are located on primary side but on Edcor's webpage they are on secondary side.

Here is a picture of my amp. Notice the blue glow on 6L6s. There is a slight blue glow on one of the filaments of 12AT7 aswell. I checked and confirmed it's not the reflection of blue glow from 6L6s. I'm using 820 ohm resistors at R17/27 which is higher value than recommended for 6L6 tube yet still the blue glow. Perhaps defect in transformer?

http://img577.imageshack.us/img577/3205/img1566i.jpg
http://img219.imageshack.us/img219/76/img1561q.jpg
http://img836.imageshack.us/img836/1945/img1556g.jpg

Last edited by imnewbie; 4th May 2011 at 06:06 AM.
  Reply With Quote
Old 4th May 2011, 12:26 PM   #26
diyAudio Member
 
Join Date: Dec 2010
Location: Philadelphia, PA
I'm using the same transformer and mine is wired the same. It doesn't have a noticeable hum even from less than a foot away. Click the image to open in full size.
  Reply With Quote
Old 5th May 2011, 12:20 AM   #27
diyAudio Member
 
Join Date: Jun 2010
Location: SE Pennsylvania
I'm getting 943V across R4..yes..943V, please tell me this is not normal.

Thanks allentod for your reply, my XPWR035 hums like crazy. The 6L6s are running in triode mode with 8000 ohm load transformers(GXSE10-8-8k), and the speakers got louder than they can get with my 12Wpc EL84 amp.

Either I made a grand mistake somewhere or some Edcor employee needs to get re-trained.

Last edited by imnewbie; 5th May 2011 at 12:25 AM.
  Reply With Quote
Old 5th May 2011, 12:37 AM   #28
diyAudio Member
 
Ty_Bower's Avatar
 
Join Date: Mar 2007
Location: Newark, DE
Quote:
Originally Posted by imnewbie View Post
I'm getting 943V across R4..yes..943V, please tell me this is not normal.
Can't be. C1 and C2 would have long since exploded like grenades. Something is up with your meter, or the way you are taking measurements.
  Reply With Quote
Old 5th May 2011, 01:03 AM   #29
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
Quote:
Can't be. C1 and C2 would have long since exploded like grenades.
Maybe, but my bet is that the 5AR4 would have expired long before the caps built up steam if there really was 900 volts. Then a miswired HV secondary could cause a serious amount of high voltage. Check to see if C1 and C2 are getting real hot.

Blue glow inside a 6L6 type tube is somewhat normal, especially if its on the glass itself. The Russian versions seem to glow better than the Chinese tubes.

Some transformers hum more than others. Hammonds have a worse reputation than Edcors for hum. I have noticed that physical transformer hum is dependent on the quality (or lack of) of the electric power. All transformers will hum when fed a square wave. Make sure the screws that hold it together are tight. Buzz with nothing connected to any secondary is not normal.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 5th May 2011, 01:20 AM   #30
diyAudio Member
 
Join Date: Jun 2010
Location: SE Pennsylvania
I got 943V across R4 both times I turned on the amp. One alligator clip on each side of the R4 leads. My DMM is measuring 123V from power outlets so DMM is hopefully correct. I just turned on the amp again after Ty_bower's post but I got louder hum from speakers and it kept increasing, so I quickly turned off the amp. I turned it on again and the same thing happened. While this happened the voltmeter went upto 1000V and then went blank and upon turning power off the reading decayed slowly from 1000V to 0V. Upon inspecting the PCB, I see one of the 1500uF 50V electrolytic cap's top..sort of perforated, while the other looking normal.

Last edited by imnewbie; 5th May 2011 at 01:50 AM.
  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
LCDPS R1/R2 and R3/R4 question natzev_i Twisted Pear 5 16th February 2011 01:26 PM
tubelab se R3 Nikon1975 Tubelab 8 4th March 2010 12:47 PM
Soldering tips for soldering station BEST PRICE, FREE SHIPPING, 15% discount vtech9815 Vendor's Bazaar 0 27th January 2010 04:40 PM
R2 and R3 values on Linn Axis PSU martiny Analogue Source 3 4th March 2009 10:46 AM
Recommendation Audio Technology With Raven R3 JiriAU Multi-Way 2 29th October 2007 08:40 AM


New To Site? Need Help?

All times are GMT. The time now is 11:28 PM.


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