Ebay AL-811H, What Have I done?

[BJ radionut]

Do NOT turn that ON with cover OFF...Has safety switch it will blow the fuses...
Check to make sure it has correct fuses...Remove the back plate make sure the jumpers are set-up for 120 volts
All the Best
Gary

Very Clean inside though!

 

[543_Dallas]

Do NOT turn that ON with cover OFF...Has safety switch it will blow the fuses...
Check to make sure it has correct fuses...Remove the back plate make sure the jumpers are set-up for 120 volts
All the Best
Gary

Very Clean inside though!

The safety interlock breaks the connection to the mains. Is doesn't short the HV circuit to ground but a lot of people believe it does.

From the manual:

"The interlock switch stays closed to allow AC line voltage to reach the power transformer as long as the AL-811H's top cover is in place. When the top cover is removed, the interlock opens and disconnects the input line voltage. This does not discharge the bank of power supply filter capacitors. Be sure to allow the filter capacitors to discharge before you touch anything inside the amplifier. "

 

[338_MtRushmore]

I can't believe I didn't question that. Before Gary had even posted that I checked the wiring. I verified the switch worked and it was on the hot leg with a dmm (the wires were not B, W&G) Nowhere in the circuit did the switch ground out, or I would have tested the ground. Fortunately, I have zero desire to have that top off when it's powered up.

 

[BJ radionut]

Mt R: You being a Tradesman know this, however most people don't.
That any removable or replacement cord cap(plug) does have a specific way to be wired.
3 wire cord and plug
Gold Screw is ALWAYS Hot...Black or Red(rarely though)
Silver Screw is Always Neutral….White
Green ALWAYS...Ground/Green
2 Wire cap Should be marked the same, however if it is not....The Neutral is the LARGER/Wider Bar on those caps.
Now some cords have EURO/ASIA Colors: Brown/Blue/Green with Yellow Stripe.
BROWN-HOT
BLUE-Neutral
Grn/Yel - Ground

This applies to 120 Volt Circuits in USA.

Plus Mt. R. I mentioned the plate on the back because I have found those Jumpers misplaced.
I have seen people wire those Buck/Boost windings on the Transformers wired for 110 or 100 Volts, and not the 120 volt locations.
This is a futile attempt to get more High voltage and increase output power. Yes it will raise the HV.
However it ALSO raises the FILAMENT Voltage, which will shorten the life of the tubes.
SEE Page 4 of manual for Correct locations of these jumpers.
So just FYI check everything for correct wiring and that amp will give you many years of good service.
Have Fun and Enjoy
All the Best
Gary

PS: I only mention this due to any cord that can be wired for 240/120 needs to be correctly landed if someone has used it on the Higher/Lower voltage configuration and is user changeable. One never knows what someone else has done before!
Check everything/Assume nothing

 

[Road Squawker]

...edit.... I verified the switch worked and it was on the hot leg with a dmm (the wires were not B, W&G) ... Fortunately, I have zero desire to have that top off when it's powered up.

Just because it is unplugged, doesn't mean it is safe.

Don't rely on the bleed resistors to discharge the caps, use a "chicken stick".

BTW, does it have 110 or a 220 plug?

 

[338_MtRushmore]

Just because it is unplugged, doesn't mean it is safe.

Don't rely on the bleed resistors to discharge the caps, use a "chicken stick".

BTW, does it have 110 or a 220 plug?

The amp was in the mail for several days, and I still checked for voltage on each cap, then I shorted each one to be sure. I am pretty chicken when it comes to getting fried.

It is wired for 110, and I think I'm going to leave it since it will be on a strong circuit.

 

[338_MtRushmore]

Will this work for a gas tube? Is there anything else I should replace to be safe?
https://www.mouser.com/ProductDetai...=sGAEpiMZZMsdWQmBKEIh8j28ZBWPkYlxcGLaIk2idh0=

 

[nomadradio]

A gas tube?

For what?

Those are meant to limit surges on a power line.

73

 

[338_MtRushmore]

A gas tube?

For what?

Those are meant to limit surges on a power line.

73

It seems to be the consensus to ground the grids on these, then add the GDT like the new models are made now. MFJ lists the GDT for sale, but don't list any specs except for 150v. MFJ wants $13 shipping, and I'd rather get it somewhere else.

 

[nomadradio]

Whups!

Looks like I'm a little out of date. Haven't see one of these new enough to have those changes in them.

I always assumed that the grid resistors served to limit grid current. If the factory builds it this way, you would assume that they thought it through.

Gotta track down a little more info on this setup.

73

 

[338_MtRushmore]

https://www.w8ji.com/al811_important_modifications_changes.htm

 

[Shadetree Mechanic]

https://www.w8ji.com/al811_important_modifications_changes.htm

Lots of good info here.

 

[kopcicle]

 

[338_MtRushmore]

What does this mean?

 

[kopcicle]

https://www.w8ji.com/al811_important_modifications_changes.htm

It means there is lots of good info there