I have purchased a very old and rusty Gibson BR-9 guitar amp as a restoration project
Found one secondary of the interstage transformer was shot. I tried taking the transformer apart and finding if the fault was near the end of the winding but no luck.
The amp needs a new interstage transformer but I am not sure of what to replace it with. The original in my amp was an Halldorson, probably custom part number
Mercury Magnetics GA-PI which is a replica of the TF-1001-D Gibson used in other amps, like in some version of the GA-5, which has a similar pi and output stage as the BR-9 but uses EL84s instead of 6V6s
The Mercury recreation is 2.4 : 1 ratio and fits the GA-5 amp that's all i know. Some people on forums reported using it successfully for BR-9 as well but the thing is, after overseas shipping and taxes this little transformer is gonna be very expensive at about $120
Hammond 124 series offers a few cheaper options but they all have different ratios than the Mercury GA-PI. I am thinking the 3 :1 versions could work as well but I am not sure. Can someone please explain me what should i be looking for ?
http://www.hammondmfg.com/124.htm
One more problem, the speaker was also torn apart and because it is a field coil type i decided to just replace it with a pm and put a choke in the power supply
Do you think I could use an Hammond 155J choke ? It's 15H / 30mA / 1.026KOhm / 400V max
I have attached schematic for this amp
Found one secondary of the interstage transformer was shot. I tried taking the transformer apart and finding if the fault was near the end of the winding but no luck.
The amp needs a new interstage transformer but I am not sure of what to replace it with. The original in my amp was an Halldorson, probably custom part number
Mercury Magnetics GA-PI which is a replica of the TF-1001-D Gibson used in other amps, like in some version of the GA-5, which has a similar pi and output stage as the BR-9 but uses EL84s instead of 6V6s
The Mercury recreation is 2.4 : 1 ratio and fits the GA-5 amp that's all i know. Some people on forums reported using it successfully for BR-9 as well but the thing is, after overseas shipping and taxes this little transformer is gonna be very expensive at about $120
Hammond 124 series offers a few cheaper options but they all have different ratios than the Mercury GA-PI. I am thinking the 3 :1 versions could work as well but I am not sure. Can someone please explain me what should i be looking for ?
http://www.hammondmfg.com/124.htm
One more problem, the speaker was also torn apart and because it is a field coil type i decided to just replace it with a pm and put a choke in the power supply
Do you think I could use an Hammond 155J choke ? It's 15H / 30mA / 1.026KOhm / 400V max
I have attached schematic for this amp