Old Bando Transformer question

Thread Starter

tristanmac72

Joined Jul 26, 2019
41
Hi All,

Im an AV/Studio Tech and just come across an old classic piece of vintage kit.

However I was told it was plugged in to a 240v uk, even though it was originally a Japanese 110v spec.

Attached is a photo now, someone seems to have swapped from 110v to 240v, but possibly after the error.

It doesn't show any power on testing, so need to replace,

any ideas what updated version of this would work/where to buy?
 

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Thread Starter

tristanmac72

Joined Jul 26, 2019
41
sorry I'm not an expert, I just plug dit in and no power to device, so assumed not working as it was blown up with 240 v input. shock resistance be somewhere on transformer?
 

Thread Starter

tristanmac72

Joined Jul 26, 2019
41
would the plugin gin to 240v when set to 110v totally blow this attached transformer?
I could try and solder wires to different outputs but not sure what to do? It set sits on 240v now
 
Your, the TS/OP, posts are hard to follow.

If line is 240 and set to 240, OK
If line is 120 and set to 240, damage not likely

If line is 240 and set to 120, damage likely.
If line is 120 and set to 120,then OK

the transformer is 7 VAC out 23.5 VA with a tapped input.

So, you move the wire from 240 to 120 if that's what you want.

Go/No go can be tested with an ohmmeter.

==

If you apply 120 to the 240 tap, the output of 7 VAC would be 3.5 VAC aproximate.

7 VAC is good for a 5V supply; guessing...the system might operate off of 5V/

EDIT: Which it does.
There is a fuse F2, which should be changed to different values based on the operated voltage.

You at least need a multimeter.

At the very least:
Check the line tap. Change if necessary.
Check the fuse. EDIT: Replace with the correct size.

Anything else requires a multimeter.
 
Last edited:

AlbertHall

Joined Jun 4, 2014
8,498
would the plugin gin to 240v when set to 110v totally blow this attached transformer?
I could try and solder wires to different outputs but not sure what to do? It set sits on 240v now
It would probably blow a fuse and might damage the rest of the circuitry but the transformer might well survive.
 

BobTPH

Joined Jun 5, 2013
2,047
Agree with @AlbertHall, probably xfmr is OK and there is a blown fuse.

You should be able to test it easy enough. If you have no better instruments, touch the secondary wires together briefly and look for a spark.

Bob
 

Thread Starter

tristanmac72

Joined Jul 26, 2019
41
looking at the attached, what wires should I solder to what ?

I took three photos of the whole circuit board, so open to any advice!

BTW fuses seem not to have blown and I was told the transformer did smell after being pluggedd in to 240
 

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Thread Starter

tristanmac72

Joined Jul 26, 2019
41
I will get one tomorrow, could you kindly take me through the steps in testing the various stages out. Using the meter.

However of course at the moment tit seems the transformer is soldered to 240v?

Thx!
 

AlbertHall

Joined Jun 4, 2014
8,498
Check the resistances across the transformer windings. They should read very low - say less than 100Ω.
If they are both OK then check resistances from the mains input terminals to the transformer primary.
 

Lo_volt

Joined Apr 3, 2014
81
Check the resistances across the transformer windings. They should read very low - say less than 100Ω.
If they are both OK then check resistances from the mains input terminals to the transformer primary.
Just make sure it's not plugged into the outlet when you make these measurements!

To most of us that's obvious and I don't want to sound condescending, but it needs to be said.
 

Thread Starter

tristanmac72

Joined Jul 26, 2019
41
no please be basic! I'm a musician/studio tech not an electrical engineer!
appreciate all help!

masy I ask looking at my photos, what would be the steps and setting on meter, and what connected to what?
 
The SM suggests 0.8 A for 120 V and 0.8A for 240.

They should be 3AG size. The coil suggests a time-delay or slow-blow fuse.
The BLACK is suggestive of being blown.

A multimeter in the US can be had for about $5.00 USD. (Harbor Freight)
 
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