Checking JJ100 bias with Weber Bias Rite

[octopus]

Can any Weber Bias Rite and/or JJ100 owners help me out?

Changing power tubes in my JJ100 for the first time today. Never used the Bias Rite, but it seems to be giving me some strange readings.

Dave has suggested setting bias for this amp to 29-32ma. Plate voltage is reading 430. Bias Rite is showing individual readings for the stock tubes as 12.8, 9.2, 14.0, and 15.2. Readings for the new tubes are 3.9, 3.5, 6.7, and 2.5.

Am I doing something wrong? I can’t seem to make these numbers on the stock tubes make sense against Dave’s recommendation of 29-32ma. (I assume that is what they are set to at the factory.)

Thanks in advance for any help.

 

[GOHOINC]

Is the switch on the bias rite set to ik? Did you take the amp out of standby? Not being a jerk, just thinking youre not seeing idle current numbers.

 

[octopus]

Yes, and yes. Tubes and bias rite probes seated firmly into sockets, tubes warmed up. Think its an issue with the BR?

 

[LP Freak]

Did you pull the chassis and try raising the bias?

 

[octopus]

Did you pull the chassis and try raising the bias?

Well, that is where I am stuck. I wasn't sure if I should trust the Bias Rite or not. My buddy seemed to think that the readings I was getting were so off the mark that the BR must be malfunctioning, in which case, I didn't want to attempt to bias the tubes any hotter for fear of damage

 

[MantraSky]

Weber Bias Rite Alert!!

BIAS RITES

There have been issues with our Bias Rite tools lately, and we are freezing them temporarily to address the issues. The components in the Bias Rite adapters are fragile, and can easily be damaged by voltage or current spikes. Please excuse this inconvenience.
thank you.

**I've read that "if you play guitar while the Bias Rite is connected", there is a voltage "Increase" to the device as stated above, (I'm using either Tektronix oscilloscope or Fluke 87 DMM).
originally from the Weber Site (https://taweber.powweb.com/biasrite/br_page.htm) The link doesn't seem to be working now, this was from the "Marshall Forum".

If you contact Dave he will give the best advice to Bias your amp.

 

[CrazyNutz]

Ethier the Bias Rite is defective, as the above post eludes to, or your amp has a problem.

The plate voltage of the JJ100 should be around 480vdc.

My bet is its the Bias Rite. Don't go tweaking anything until you get known good bias tester.

 

[zewango]

Weber Bias Rite Alert!!

BIAS RITES

There have been issues with our Bias Rite tools lately, and we are freezing them temporarily to address the issues. The components in the Bias Rite adapters are fragile, and can easily be damaged by voltage or current spikes. Please excuse this inconvenience.
thank you.

**I've read that "if you play guitar while the Bias Rite is connected", there is a voltage "Increase" to the device as stated above, (I'm using either Tektronix oscilloscope or Fluke 87 DMM).
originally from the Weber Site (https://taweber.powweb.com/biasrite/br_page.htm) The link doesn't seem to be working now, this was from the "Marshall Forum".

If you contact Dave he will give the best advice to Bias your amp.

This was back in 2010!

 

[zewango]

Did you try it on a different amp?

 

[MantraSky]

Weber Bias Rite Alert!!

BIAS RITES

There have been issues with our Bias Rite tools lately, and we are freezing them temporarily to address the issues. The components in the Bias Rite adapters are fragile, and can easily be damaged by voltage or current spikes. Please excuse this inconvenience.
thank you.

**I've read that "if you play guitar while the Bias Rite is connected", there is a voltage "Increase" to the device as stated above, (I'm using either Tektronix oscilloscope or Fluke 87 DMM).
originally from the Weber Site (https://taweber.powweb.com/biasrite/br_page.htm) The link doesn't seem to be working now, this was from the "Marshall Forum".

If you contact Dave he will give the best advice to Bias your amp.

This was back in 2010!

Then apparently this applies "Today" as then! I own a Bias Rite that I bought New pretty recent and experiencing the same problem as the OP, it's information that I found on other forums and I also tried the device on other amplifiers with the same results.