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View Full Version : Newbie in need of HELP! With 4333a repair



alke1234
07-08-2010, 09:37 AM
I've been searching for the resistors for the xovers and have had little to no luck finding them. If anyone could help me, or do the dirty work for me I'd appreciate it immensely.
Also would like to know if there is upgrades as far as the resistors go? If so what? I'm not really a tech so if you could put in terms a green guy can understand that would be appreciated.

Thank You:bouncy::confused:

Robh3606
07-08-2010, 10:29 AM
Which resistors are you trying to replace?? If they are the 20 watt values they will be hard to find. All you need to do is parallel up a pair of 10 watt resistors to replace them. So as an example if you needed a 10 ohm 20 watt resistor you could use 2 20 ohm 10 watt resistors. Parts Express should have any value you would need.

Rob:)

alke1234
07-08-2010, 07:48 PM
Thanks,

Got it figured out and appreciate the help. Parts express had all I need to get em' going. There are 2 more I can't find they say omite on them and the values and numbers are, or numbers and values-

F407
75 OHM Dimension is 2''x1''
40 watt

and

F204
10 OHM 20 watt 7814 Dimension is 2''x 1/2''

these are flat and brown in color. I can get pics and try post if that would help. If I can figure that out.
I'm ultimately trying to restore these and am doing the veneer now, and I thank you for your help.
I also called Mouser and they did not recognize these.

Robh3606
07-08-2010, 08:23 PM
You sure that's 75 ohms?? From what I see on the schematic it look like it's 7.5 If it's 7.5 its 4 10 watt 30 ohms in parallel

http://www.jblproservice.com/pdf/Network%20Schematics/3133A%20Network.pdf

Rob:)

alke1234
07-09-2010, 08:55 AM
Yes it's 7.5, and do you think I have a chance of finding ones like the original? Does it make a difference in performance when you couple resistors? I am also putting 2235h woofers in, instead of the 2231a does that make a difference, or is the cab enclosure to small? I thought I read that it did not and that the 2235h would be an upgrade. I started this project some time ago and need to refresh my memory.

Thank again in advance.

Robh3606
07-09-2010, 10:43 AM
Maybe you could find the originals?? Using multiple resistors to get the required power rating and value will work just fine. 2235 should work just fine.

Rob:)

4343
07-09-2010, 11:00 PM
Maybe you could find the originals?? Using multiple resistors to get the required power rating and value will work just fine. 2235 should work just fine.

Rob:)

Also, using two resistors in parallel also lowers the inductance to half that of the individual resistors... (You'd be surprised what the so called "Non_Inductive" resistors actually measure, let alone the standard types!)

alke1234
07-20-2010, 09:17 AM
Got them up and running and thy sound great, just wanted to say Thank You.

Robh3606
07-20-2010, 10:14 AM
You are welcome. Thank you for letting us know it worked out for you

Rob:)

4313B
07-20-2010, 10:26 AM
Just in case anyone else references this thread in the future I want to make sure that everyone is aware that the 7.5 ohm 40W resistor shunted across the 1.55 mH tapped autotransformer generates ALOT of heat. It's used to counter the inductive reactance of the tapped autotransfomer so the preceeding 16.5 uF capacitor functions correctly. It really is a good idea to use the four ten watt (or 12W if Mills) resistors as replacement should that original Omite burn up. They do burn up.