Jubilee 2555 Bias Reads 0.00

[Mxzx]

Bias tested my new to me 1987 2555 and it reads 0.00 with Eurotubes tester and Snap On meter. I have done the test many times and know how to do it.

Swapped meters, power tubes, checked connections, continuity on tester, everything I can think of. When the bias pot is turned, still reads 0.00.

Amp plays and sounds good, maybe just a little quiter than normal for a given volume setting.

This is the same amp that has the backward channel switching issue.

Any ideas?

Thanks

 

[mickeydg5]

Something is not right. Give pictures of all while testing showing the 0.00 readings and all connections.

 

[Mxzx]

Here is a Youtube vid of the test.

 

[charveldan]

I would suspect faulty meter and/or probes.

Your meter probes look suspect.

Might replace the battery in the meter too.

 

[Gunner64]

Somethings amiss with the tester I think. No ground or something If you had no bias at all you would know it before you put the probes to it.

 

[Mxzx]

I'll go test it on another amp.

 

[Mxzx]

Well I guess the 3rd meter is a charm!

Just an FYI the Eurotube tester probes don't work on Snap On or Fluke meters, but do on a Greenlee.

 

[charveldan]

http://www.compu-bias.com/order.shtml

Buy yourself one of these and thank me later.

100 watt quads should really be biased in pairs anyway.

 

[Gunner64]

The internal fuse in the meter could be toast too..if so it can give you some wonky readings.

 

[mickeydg5]

Yes, the bias monitor(s) and meter need to be checked.
Is there 1 ohm resistance across the bias monitor leads?
Are the battery, DCA and fuse of the meter working properly?