Tech: Seeburg 100JL Amp HFMA1-L6 Resistor Wiring

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NCC-1701
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Joined: Thu Apr 28, 2011 2:34 am

Tech: Seeburg 100JL Amp HFMA1-L6 Resistor Wiring

by NCC-1701 » Thu Apr 28, 2011 2:44 am

New guy on the block here, need some help with R48, combo value pale blue ceramic resistor, mounted on the tube side of the amp between 5U4 and 6L6.

I have a reading on the 2500 but dead on 25K, obtained a 27K replacement but not sure how to rewire onto the old 3 leg resistor. I marked my old disconnected wires as follows:

A=1 Ivory color cloth wire, 1Gray wire

B= 2 Red wires

C= 1 Brown wire, 1 bare, both going to ground

appreciate any help, thanks guys


Ron Rich
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Re: Tech: Seeburg 100JL Amp HFMA1-L6 Resistor Wiring

by Ron Rich » Thu Apr 28, 2011 5:14 pm

Hi New guy,
Welcome !
Looks to me as though Seeburg had some confusion in drawing that Schemo--I have two different versions----
I do recall having problems ID'ing exactly how to replace one of those, in the past--
Looking at the schemo--the lower resistor is the 25k the upper is the 2500. -- a note added to what appears to be the later schemo, points out the bottom of the 25k as being "grounded to lug near J2"--and also shows the classic three line ground sign, while the older (?) schemo shows it as a "chassis ground" ("v" with a line across the top).
Wire colors are very confusing--and I have no one but myself to blame here, as I wrote them in-- I show "red" and "gray" on the upper (B+) line, Red only at the center line(junction of the two resistors), and brown going to ground, on the other side of the 2500.
In other words--add your new resistor "across" C6 D.
Hope that helps ! Ron Rich


Topic author
NCC-1701
Junior Member
Posts: 12
Joined: Thu Apr 28, 2011 2:34 am

Re: Tech: Seeburg 100JL Amp HFMA1-L6 Resistor Wiring

by NCC-1701 » Sat Apr 30, 2011 10:57 am

Ron, You Rock Man, Thank you. It works, placed the new 25K resistor on the chassis snug between the existing resistor and 5U4, reconnected original wires back onto my old resistor reviving the 2500K, disconnected ground off the old resistor. I ran a new short 2" ground wire from one end of the new resistor to the center leg of the Hum Balance control which leads to ground on J2. connected the other end of the new 25K directly to the old resistor center leg which connects to positive side of C6 D. I am a bit curious as to what kind of problems arise from that original 25K ohm resistor not working.


Ron Rich
Forum Moderator
Posts: 8195
Joined: Sun May 06, 2007 11:31 pm
Location: Millbrae (San Francisco area)CA, USA

Re: Tech: Seeburg 100JL Amp HFMA1-L6 Resistor Wiring

by Ron Rich » Sat Apr 30, 2011 5:58 pm

Glad you "got-it"--I dono, all of them that I have seen with that resistor out, have just been brought to me for repair--never saw one fail "in service"-- Ron Rich

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