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Showing posts from September, 2016

6J1 Preamplifier

6J1 Preamplifier I purchased this 6J1 amplifier from eBay. The seller was located in China. Below is a my experinces building the preamp. I have not had a chance to give it a full test. I will update this post once I have had that chance. 
It took a little over an hour and a half to finish building the kit. The board seemed a little tight for installing everything. The board itself runs on 12AC and from what I can gather it takes the 12AC and runs it through a voltage doubler which then gives the "B+" voltage.The tubes are 6J1's and obviously have 6volt filaments that run in series. I can not find a lot of info on the 6J1. Link to Data Sheet .
There is not a lot of instructions. Most everything is in chines and so I cannot read it. I was able to follow down the parts list and figure out what everything was and where everything went. I used a multimeter to check the resistors before installing them because the colors were not easy to interrupt. Overall this is a neat lit…

Seeburg MRA1-L6

Seeburg MRA1-L6
A friend of mine sent this Seeburg MRA1-L6 to me to be gone through. At first glance I thought it should be a typical recap job, but it was quickly discovered this things has some big issues . I will discuss those a later. 
This amplifier came out of a Seeburg M100A.  This jukebox plays 100 sections. There is a total of 50 discs and this player will play either side. My friend is currently working on mechanics of jukebox while I am working on the amplifier.The photos below show the amplifier as I received it.

The issues with this amplifier besides the old capacitors from about 1948 is the output transformer and possibly the power transformer. The output transformer is near the center of the first photo at the top. I believe it has been chewed on by possibly mice. The inner wrapping is showing and the wires are loose. The power transformer checks out fine with an ohm meter, but the wires to the primary and the center tap of the high voltage has been cut. This made me wonde…