800B Power Transformer too hot?????

[sloane freeman]

Got the unit working after replacing all electros in both units.  Checked the remaining caps for value and leakage and they SEEM OK.   However the transformer gets HOT!  After about two hours it radiates heat.  Is this normal or am I missing something.

I measured the plate current at 80 mils but did not check the screens.   With the B+ disconnected, the transformer stays cool.

[sloane freeman]

Changed the 6L6's which helped a bit.  Replaced the .05mf bathtub cap on one of the 6L6's control  grid and the cathode voltage dropped several volts and putting the 9K resistor back in the field circuit brought the K voltage down to appx. 22 volts and the plate and screen voltage are within 2 volts of spec.

I will change the rest of those bath tubs!!  Then I will take a toothbrush and Deoxit to those switch contacts.

Thanks for the help!

sloane

sloane

[sloane freeman]

replaced the .05 mf   caps on the 6L6's    Voltages near spec now....    K voltage 22.8, Plate and Screen within 2 volts of chart....power transformer still gets dang hot!  It has been a long time since I have fooled with a tube receiver/amp and have lost the feel for how much heat is too much from the power transformer.  The 5Y3's and 6L6's do not appear to be overloaded.

Has anyone taken the temperature of the power transformer in a properly operating setup?

[Angelo]

Make sure you have the right 6L6G  in .The transformer will run hot after a few hours of playing.You could use a variac to drop input voltage to the set.Check your mains to see what it reads.

[sloane freeman]

Mains read 119.0-120.2 taken several times over an hour.  What do you mean right 6L6G?   I could use a quick course the differences, if any, between the standard brand tubes and the foreign made equivalents sold today.  I see where a lot of soviet made tubes are being touted as "replacements" for certain popular audio tubes on Ebay with "near beer" specifications.

Put in two brand new 6E5's and was amazed at the brightness.  I get over deflection on the AM and barely any deflection on the FM.

[Angelo]

OK  on the mains that's good readings.6L6G  G== glass  .You can google to see diffrences between all the 6l6s out there metal ,6l6ga, 6l6gb,6l6bc...

[sloane freeman]

ok....thanks!   I have seen photographs with metal 6L6 being used...I guess this would be the lowest current design? I have noticed that one of the 6AG5's gets much hotter than the other one.  In trying to find the current drain I have pulled all tubes and pilot lights and disconnected the magnetic phono preamp.  The transformer, to me, still feels warmer than it should be with no load.  Is there anyone who has charted the temp of a properly operating 800B?