Harman Kardon FA-3000X questions

[gadget73]

Thats just what I usually use. Its not carrying any kind of current, so the value isn't too critical. With 100 ohm resistors, each one dissipates .1 watts, which is very comfortable with a 1/2 watt part. Its also only a 3 ma load on the heater string.

With a 33 ohm, each one dissipates 0.3 watts and loads the heater string with 9.5 ma. Still nothing significant but when you have a bag of 100 ohm parts it makes the choice easy.

 

[buickguy62]

Hey Gadget, do you know why on the HK A300 and also on the HK A500 they use two different resistor values on the heater string to ground? One side is 33 ohm, the other 15 ohm, seems to be consistent on the A300's and A500's I've seen.
Thanks,
Tom

 

[gadget73]

guessing the wiring system has some imbalance, or it just happens to work out quieter that way. Dunno, I usually figure stuff like that was done for a reason.

 

[jtperrine]

Started my refurb on this unit last night. I DBT'ed it, filled the empty tube sockets & fired it up. As received, it does play but has bad hum and the tuner is definitely wonky - stereo light comes on only when stations are mistuned to give loud noise. I did a basic chassis & faceplate cleaning, cleaned the posts, switches, and tube sockets, and started on the power supply caps. That's where it got interesting.

On the schematic I have (attached), R110 is 3900 ohms. On the actual unit, the original looking resistor is marked and measures 39K ohms. 3900 is more in line with what the other sections of this can cap use (they have 4700 ohm resistors, which match the schematic. Any thoughts on which is right? Anyone else have on of these they could look at?

I also found that R107 (1500 ohm resistor) was burned completely up, so I will probably replace with a higher wattage rating - 1 or 2 watts instead of 1/2 watt. Any risk there?

Thanks!

Started my refurb on this unit last night. I DBT'ed it, filled the empty tube sockets & fired it up. As received, it does play but has bad hum and the tuner is definitely wonky - stereo light comes on only when stations are mistuned to give loud noise. I did a basic chassis & faceplate cleaning, cleaned the posts, switches, and tube sockets, and started on the power supply caps. That's where it got interesting.

On the schematic I have (attached), R110 is 3900 ohms. On the actual unit, the original looking resistor is marked and measures 39K ohms. 3900 is more in line with what the other sections of this can cap use (they have 4700 ohm resistors, which match the schematic. Any thoughts on which is right? Anyone else have on of these they could look at?

I also found that R107 (1500 ohm resistor) was burned completely up, so I will probably replace with a higher wattage rating - 1 or 2 watts instead of 1/2 watt. Any risk there?

Thanks!

The link to the schematic does not work. Could you upload it again or send it to me at: jtperrine@hotmail.com Thanks!