What’s wrong with my transformer?

[Drea]

I want some info how a transformer works.

I have a transformer Haufe bv-08 that in the beginning works without problems. But after 20 minutes the amplified volume cut down to a 5the of the amplified volume. When I switch the pattern from cardiod to omni and back the transformer works normal for 20 minutes. How is this possible and what can I do.

 

[JohnRoberts]

perhaps a bad solder connection?

JR

 

[Drea]

i have solder it rehearsal 3 times but the fault still remains. I have solder it now inverse red on black and black on red … but of course it doesn't make any difference.

 

[rock soderstrom]

i have solder it rehearsal 3 times but the fault still remains. I have solder it now inverse red on black and black on red … but of course it doesn't make any difference.

Are you sure the transformer is the problem? Do you have a second one to test? Have you replaced the tube already?

PS: Repair concerns fit better into the Lab(or the Microphone/Transformer section). Many members do not frequent the Brewery.

 

[pucho812]

If the circuit works and then after 20 minutes drops in volume, a transformer would the last place I would look for a fault. This is because it’s either going to work correctly or not. If it was at fault the issue would be all the time.
Perhaps you need to check elsewhere for a fault. Start with the power supply. Perhaps you have a faulty capacitor.

P.s. this should be in the lab

 

[Drea]

Problem solved for now , the wire (2 green) where not soldered only together bounded.

 

[JohnRoberts]

Problem solved for now , the wire (2 green) where not soldered only together bounded.

That symptom is typical of dry connection where a thin oxide layer builds up that is an insulator. Signal voltage can punch through the thin oxide layer and work until the oxide layer builds up again.

This symptom is commonly seen in switching jacks, dry solder joints, etc.

JR

 

[Drea]

Thanks for looking with me…

 

[Newmarket]

That symptom is typical of dry connection where a thin oxide layer builds up that is an insulator. Signal voltage can punch through the thin oxide layer and work until the oxide layer builds up again.

This symptom is commonly seen in switching jacks, dry solder joints, etc.

JR

So true

 

[Drea]

 

[Drea]

Factory sealed. But not soldered. I scratch my chin!

 

[Bobby bot]

View attachment 96789

Just a quick note that top left white wire looks a bit crispy on the insulation. Be a good idea to either replace or if core is still good heat shrink to give it a bit of extra insulation.

 

[Drea]

Good idea … thumb.