Bottlehead Crack 1.1 OTL Fuse blowing [resolved]

[nigebarrett]

All the earlier voltage and resistance tests were passed during the build but now its completed it instantly blows the fuse. I have checked all the connections for a possible stray earth, checked the all the capacitors and rectifiers installed direction and removed the valves and the fuse still blows. So I tried to isolate the problem by disconnecting terminals 11 and 12 from the transformer (mines wired for 240v) thinking that effectively cuts out just about everything except the transformer and I still have a fault. I can no longer check the transformer voltages as the fuse would blow the moment I switch it on. Are there any further resistance checks I can do without needing mains power?

Regards

Nigel

 

[Jameson]

Can you post some photos of your build please?

 

[nigebarrett]

Thanks for getting in touch… please don’t be too critical of my soldering.. I’m nearly 70 years old and haven’t picked up a soldering iron for the last 40 of them! My son bought it for himself for Christmas and thought it would a good idea for me to build it … I will never hear the end of it if I’ve messed it up.

 

[Paul Birkeland]

The wire going to B4 does not take our recommended routing and is very likely to cause problems down the road.

You have completely different wiring on the primary of the power transformer between the second and third images you've posted.

The flux I see on your build is very lightly colored, can you post a picture of the solder you're using to build the kit?

 

[hmbscott]

You say that your transformer primary is wired for 240VAC. However, you appear to have a red wire connecting terminals 14 and 17, which is incorrect for 240V. Remove that wire.

 

[nigebarrett]

You say that your transformer primary is wired for 240VAC. However, you appear to have a red wire connecting terminals 14 and 17, which is incorrect for 240V. Remove that wire.

Good morning........Many many thanks for spotting my error. I disconnected the wire between 14 and 17... resoldered all the connections which I had removed during previous fault finding attempts and installed the valves. All voltages are now correct, no blown fuses and the valve leds' illuminate. I haven't got any headphones to try so will have to wait for the final test but I will spend the time until then tidying up the earlier appalling soldering with my newly acquired skill (practice makes perfect!) Cant thank you enough...have a great Christmas.

 

[nigebarrett]

The wire going to B4 does not take our recommended routing and is very likely to cause problems down the road.

You have completely different wiring on the primary of the power transformer between the second and third images you've posted.

The flux I see on your build is very lightly colored, can you post a picture of the solder you're using to build the kit?

Hi Paul....It seems I had the transformer incorrectly connected, so the problem appears to be resolved subject to the final test. For the record I have no idea what type of solder (which I've run out of) or flux I used as it came with the soldering iron bought decades ago. The new solder purchased from amazon specifically for electrical work is so much better and I will spend some time now tidying up and making the build look a bit more presentable. Thanks for taking the time to get back to me.