Wiring the transformer to the Tubelab SE - Page 2 - 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 5th March 2010, 01:51 AM   #11
diyAudio Member
 
Join Date: Jul 2009
I checked, it's 2.2ohms even after it cooked itself. With both 5842s in, neither tube lights up and R3 starts to smoke after less than a minute. With just one in, the tube lights up and R3 starts to stink like it's burning, but it doesn't seem to want to smoke itself.

The 5842s I bought are Russian, I wonder if they aren't really 5842's. They say CC45P E 0280
  Reply With Quote
Old 5th March 2010, 01:57 AM   #12
rknize is offline rknize  United States
diyAudio Member
 
rknize's Avatar
 
Join Date: Feb 2009
Location: Chicagoland
Send a message via AIM to rknize Send a message via Yahoo to rknize
3W is the spec'ed part.
  Reply With Quote
Old 5th March 2010, 02:04 AM   #13
diyAudio Member
 
Join Date: Jul 2009
Yup, it's a 3 watt resistor
  Reply With Quote
Old 5th March 2010, 02:06 AM   #14
rknize is offline rknize  United States
diyAudio Member
 
rknize's Avatar
 
Join Date: Feb 2009
Location: Chicagoland
Send a message via AIM to rknize Send a message via Yahoo to rknize
Sure that's not 6C45P? If so, the heater current requirements are higher. 440mA each, IIRC. Some eBay vendors peddle these as 5842/417A, but they are not quite the same. You would need 1.5 ohm, 3W or 5W here to get the same drop. If you bought spares when you got the parts, put two of the 2.2 ohm resistors in parallel to get nearly the same effect.
  Reply With Quote
Old 5th March 2010, 02:11 AM   #15
diyAudio Member
 
Join Date: Jul 2009
On closer inspection, you're exactly right. It says 6c45P. I'll check my spare parts bag to see if I got an extra one.

Edit: Closest I have is a giant sandbox 1 ohm 10 watt resistor.

Last edited by blue lander; 5th March 2010 at 02:17 AM.
  Reply With Quote
Old 5th March 2010, 04:29 AM   #16
rknize is offline rknize  United States
diyAudio Member
 
rknize's Avatar
 
Join Date: Feb 2009
Location: Chicagoland
Send a message via AIM to rknize Send a message via Yahoo to rknize
That 2.2 is probably on its last legs and is still under-rated even if you put a couple of 10 ohms in parallel with it. Maybe go see what Rat-Shack has, but they stock fewer parts every day.
  Reply With Quote
Old 5th March 2010, 01:48 PM   #17
diyAudio Member
 
Join Date: Jul 2009
According to their web site, radio shack does carry a 1 ohm 10w wire wound resistor (I already have one) and a .47ohm 5w wire wound resistor. If I put them in serial, would that work as a temporary work around? Is inductance going to be an issue?

Or would it be better to buy six 1/2 watt resistors of the appropriate values to add up to 1.5 ohms and wire them up in parallel or serial?
  Reply With Quote
Old 5th March 2010, 02:06 PM   #18
rknize is offline rknize  United States
diyAudio Member
 
rknize's Avatar
 
Join Date: Feb 2009
Location: Chicagoland
Send a message via AIM to rknize Send a message via Yahoo to rknize
Either way will work just fine!
  Reply With Quote
Old 5th March 2010, 11:40 PM   #19
diyAudio Member
 
Join Date: Jul 2009
I popped in the .47 ohm + 1 ohm sandbox resistors, and now it does power up and the 6c45p tubes do glow very dimly. The resistor does smell a little, but there's no visible burning anymore. Hopefully that did it...
  Reply With Quote
Old 6th March 2010, 12:50 AM   #20
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
Quote:
On closer inspection, you're exactly right. It says 6c45P. I'll check my spare parts bag to see if I got an extra one.
I saw this post at work today, but couldn't look this stuff from work (big brother is watching comuter use). The 6C45P has a completly different pinout than the 5842, and will not work in the Tubelab SE board. The 5842 has the filament on pins 3 and 9. Pins 3 and 9 are both connected to the cathode in the 6C45P, so they are shorted together. This will make R3 very unhappy as you found out, and may damage other parts too, since none of the pins match a 5842.

I'm guessing that you got these "5842 equivalents" from the same Ebay seller that sells some "6AQ5 equivalents" that have 9 pins on them. A 6AQ5 only has 7 pins. Maybe the word "equivalent" lost something in translation.

The purpose of R3 was questioned in a previous post. In my board with the typical Hammond 7 volt filament windings I was getting over 7 volts on the 5842 heater. 2.2 ohms gets me to 6.3 volts even with silicon diodes. That value seems to work in most boards except maybe a 2A3 board. Most experts will agree that tube life is compromized by high filament voltage, and slightly low voltage is preferred over too much voltage. If your 5842 is running below 6 volts a lower resistor value may be worth trying.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  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
Tubelab SE - alternate power transformer Evenharmonics Tubelab 22 14th June 2010 12:17 AM
Power Transformer for Tubelab SE Nikon1975 Tubelab 11 12th February 2010 02:17 PM
Tubelab Simple SE - Transformer Assistance ChrisR1983 Tubes / Valves 17 7th August 2009 07:08 PM
Edcor Universal Power Transformer for Tubelab SE rknize Tubelab 43 19th June 2009 09:11 PM
tubelab SE 300b power transformer Dhoff Tubes / Valves 27 14th March 2008 04:56 PM


New To Site? Need Help?

All times are GMT. The time now is 11:49 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