Acoustic 320 Inductors

[plexi50]

I was thinking of learning how to make inductors to repair an old Acoustic 320 amp i have. I have one 3.00 hy inductor that is dead. All other inductors are good as of today. And of course they are absolutley obsolete parts. Mesa has some inductors but nothing in the value that i need. Have any of you tried to build your own inductors? I have actually really enjoyed working on this SS amp. Very straight forward and the best part is all the boards are dedicated to seperate functions of the amp from preamp to power board. It sounds great and is dead quiet. Just one EQ slider not working

Lawrence has a 300hy inductor for $24.95. I may spring for one but would like to find an original part if possable

[PRR]

Try a little 10K transistor-radio driver transformer.

Try a small to medium 120V PT winding.

In theory it is not very hard. In practice, hand-winding inductors can be frustrating. $25 may seem cheap in the end.

[plexi50]

Try a little 10K transistor-radio driver transformer.

Try a small to medium 120V PT winding.

In theory it is not very hard. In practice, hand-winding inductors can be frustrating. $25 may seem cheap in the end.

I think i have some old transistor radio parts some where. Oh dam! I just remembered something. I threw out a ton of stuff 2 months ago that i though i would never use. I now recall an old piece that had those brown inductors in it. Holy crap. This is the perfect example of why i am a pac rat in the first place. I dont belive i did that/

Went out to look to see what i had left and found this old Realistic EQ. Look whats inside? I need a 3.00hy inductor. Im not sure what i am look at as far as these values go. Have to Google

[sluckey]

I have one 3.00 hy inductor that is dead.

How did you determine it is dead?

[plexi50]

Well i have 3 of these amps and i was taking ohms readings on all 3 amps and comparing the inductor ohm readings. The ones that had no ohm readings were the ones that i deemed bad. The 3.00hy inductors read 300 ohms. Dont know if thats how its done but i have 2 amps working out of the 3. I could use some inductor testing info

Also my solder gun went wild on all the JRC 4558D chips that were in that old Realistic EQ 

[plexi50]

I took apart one of the 3.00 hy inductors to see how it was made. A small plastic wire wound bobbin inside a round ferrite enclosure

I can see the two leads of wire in the bobbin that were suppose to be going to each leg of the soldered leads

I am going to measure if i can any ohmage again connecting to these two wires on the bobbin and see if is internally open or was it shrinkage of the inductor shell or material that may have pulled a lead away and off it's soldered lead

Just interesting to me. I dont have an LCR meter so i cant make mhy or hy readngs for any kind of accuracy. It looks easy enough to duplicate. I found the bobbins at Newark. Id like to try and duplicate these inductors. The wire gauge and bobbin diameter along with the number of turns of wire should give me a new 3.00 hy inductor. Finding a bobbin and ferrite that are a mate may be harder though than i think. Maybe not

Does it matter if the inductor coil is wound in a CW or CCW direction? I quess that wouldnt matter because you could just flip the coil around. Im just thinking out loud

I have the number of turns of the coil winding.  Im going to use a small variable speed motor attached to an old belt driven tape recorder counter geared for a 1.1 turn ratio to rewind the bobbins. Getting primative but i think it will work

[6G6]

If you have sucess replicating these, you should put an add in the for sale section of the unofficial Accoustic forum.
I bet you can sell all you can make.

[plexi50]

I have not had the time to get setup to try making one. I had knee surgery last month and getting back into the swing has been a B. I still intend to give this a shot