Can anyone help me biasing a Jadis Defy 7?

Sounds like an extremely promising discovery, Matt! The "5w" undoubtedly refers to the wattage that the resistor is rated to handle, which is consistent with the shape you are describing (a power resistor).

If Brooks can't readily supply them, any major electronics distributor should have suitable equivalents. Digikey.com is one such place.

Good luck!
-- Al

OMG! Somehow I don't think that amp will appear on my short list when it comes time to upgrade.

Can't offer any suggestions on the question being asked, but if you want to purchase insulated alignment tools as the article quoted by Schipo suggests, they can be found here (search under "Tools"):

http://www.radiodaze.com/

Regards,
-- Al

Thanks Wendell. Yes I'm sure it is a magnificent sounding amp, and I mis-phrased my comment, which was not intended to be pejorative in any way.

Regards,
-- Al

A word about safety, beyond what was said in the article Schipo quoted. And this is particularly applicable if you are using an uninsulated metallic screwdriver to adjust the bias pots.

There is an old adage that when working under the chassis of powered up tube equipment you should have one hand tied behind your back. Obviously you don't literally have to do that, but the point is that if the hand you are doing the work with, or a conductive object that it is holding, were to inadvertently come in contact with high voltage you MUST not simultaneously have your other hand, or any other part of your body, in contact with the chassis, or with any other circuit point or conductive surface.

The reason, of course, being that if one hand is in contact with high voltage, and the other hand is in contact with ground or some significantly different voltage, there would be a large flow of current directly through your body.

Best regards,
-- Al

Matt -- Not sure I follow that. Per your previous post, shouldn't you be looking for 33mv across the resistor, and shouldn't the voltage at the fuses be irrelevant?

Best regards,
-- Al

Matt,

Not sure what all that adds up to, but the following questions seem to suggest themselves:

1)Can you discern what the two ends of the resistor are connected to (i.e., which pin(s) of the 6550, and/or chassis ground, or some other circuit point)? And are the resistors marked as 1.5 ohms, or if not do they have color-coded bands encircling them, and if so what are the colors (from which we could determine the resistor value).

2)What range of voltages CAN you get across the resistors?

3)Have you checked the fuses with an ohmmeter or multimeter?

4)I would strongly suggest that you ignore the instruction that it is ok to have the speakers not connected. As you probably know it is certainly not ok to have no speaker load present while a music signal is being processed through a tube amp (other than an otl, possibly). However, even with no music or other signal present, if you were to turn the amp off with no speaker load present, it seems to me that an internally generated turn-off transient could lead to an inductive kickback effect that would damage the output transformers, just as might happen if a music signal were being processed with no load.

Regards,
-- Al

All voltages are much higher than 33mv.

Do the voltages vary as you turn the bias pots? And how much higher than 33mv are the readings? I would imagine that if they were WAY higher than 33mv, and the circuit is presently wired such that the voltage across them represents bias current, and if you are measuring correctly, then the plates of the tubes would be glowing red or orange (they aren't, are they?).

Also, just to make sure nothing simple is being overlooked, are you using the dc (not ac) voltage function on the meter, and are you connecting the meter leads to the two ends of the resistor, and not for instance between one end of the resistor and chassis?

Beyond those things, I'm not sure what to suggest.

Best regards,
-- Al