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5F6A pics & build tales

6/19/2005 7:15 PM
joe6v6	5F6A pics & build tales Another one in the can! This time a scratch built 5F6A Bassman. For the most part I followed the original Schematic & Layout but I also referenced Dougs layout & weber. Two problems occured at start up, the first was an extremly idiotic mistake on my part. I initaly checked voltages with no tubes then with pre-amp & rectifier tube installed. I pulled them all out and looked things over one last time and decided it was ok to put all the tubes in and fire it up, in my haste I put a power tube in the rectifier sockett. there were a few tubes laying there & I didnt pay attention. When I threw the switch the fuse blew. I imideatly realized what I had done but what I didnt know was if I had destroyed any components ie; transformers,capacitors,diodes you know the usual stuff. Turns out everything was OK. After I put the GZ34 in and started it up there was a high pitched squeall that changed in pitch with the presence controll. Thanks to me paying attention to all the knowledgeable people on this forum & others I imideatly knew what to do to correct it. I couldnt find the post but I remembered reading about the same exact problem and I cured it by reversing the brown & blue output transformer wires to the power tubes. I dont know how it fixed it but I know it did! Other than that this amp is dead quiet even at full voulme. Its nice to know Im learning from past experiences with lead dress, sheilded wire and the importance of a proper ground scheme. There are a few pictures here http://photobucket.com/albums/v234/joe6v6/Bassman/ The Bias is fixed per the original schematic but if it would benifit me to put an adjustment in there I will do it, Im not sure what value pot to use or even where to put it so if someone will let me know the advantages of haveing one and how to install it I will consider it. The silver thing between the power trans & the boared is a home made cap can & it houses the 4 - 20UF capacitors for the power supply filtering. I think these were originaly outside the chassis. I built the cabinett with an angled front, stained it dark & cleared it with Urethane. I dont know if you can see in these pics but I made the feet for it out of 3/4" aluminum bar that I turned on a lathe. Im really happy with this amp , Thanks for all the help along the way . . . JOE

6/19/2005 7:15 PM

joe6v6

5F6A pics & build tales

Another one in the can! This time a scratch built 5F6A Bassman. For the most part I followed the original Schematic & Layout but I also referenced Dougs layout & weber.
Two problems occured at start up, the first was an extremly idiotic mistake on my part. I initaly checked voltages with no tubes then with pre-amp & rectifier tube installed. I pulled them all out and looked things over one last time and decided it was ok to put all the tubes in and fire it up, in my haste I put a power tube in the rectifier sockett. there were a few tubes laying there & I didnt pay attention. When I threw the switch the fuse blew. I imideatly realized what I had done but what I didnt know was if I had destroyed any components ie; transformers,capacitors,diodes you know the usual stuff. Turns out everything was OK.
After I put the GZ34 in and started it up there was a high pitched squeall that changed in pitch with the presence controll. Thanks to me paying attention to all the knowledgeable people on this forum & others I imideatly knew what to do to correct it. I couldnt find the post but I remembered reading about the same exact problem and I cured it by reversing the brown & blue output transformer wires to the power tubes. I dont know how it fixed it but I know it did!
Other than that this amp is dead quiet even at full voulme. Its nice to know Im learning from past experiences with lead dress, sheilded wire and the importance of a proper ground scheme.
There are a few pictures here http://photobucket.com/albums/v234/joe6v6/Bassman/
The Bias is fixed per the original schematic but if it would benifit me to put an adjustment in there I will do it, Im not sure what value pot to use or even where to put it so if someone will let me know the advantages of haveing one and how to install it I will consider it.
The silver thing between the power trans & the boared is a home made cap can & it houses the 4 - 20UF capacitors for the power supply filtering. I think these were originaly outside the chassis. I built the cabinett with an angled front, stained it dark & cleared it with Urethane. I dont know if you can see in these pics but I made the feet for it out of 3/4" aluminum bar that I turned on a lathe. Im really happy with this amp , Thanks for all the help along the way . . . JOE

Replies:

Casey Sackett joe6v6,Nice build!!... -- 6/19/2005 11:50 PM
David Is that a steel hammond chassis? If... -- 6/20/2005 7:14 AM
joe6v6 David - Yes its a steel hammond bla... -- 6/20/2005 8:28 AM
Simon Please can you answer a couple of q... -- 6/29/2005 2:10 AM