Bando transformers

johnemonahan

SIDEVALVE
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Can anybody me about them? Good, bad? I have one in my Toshiba amp [sc-665 ] it's round and encased. I think the year is 1978 to 198? thanks for any help anybody can give me.
 
Sound's like a standard toroidal transformer with a cover on it. These are basically dounut looking ferrite ring's wound with magnet wire. Don't think there's anything really special about them, but this design tend's to emit less hum inducing magnetic field. Pull the cover of most car stereo amp's, and you'll see one of these in the DC to DC voltage up converter circuit. Some computer and video cable's use small ferrite ring's and terminal end's to help block interferance.
 
I need to find a replacement transformer for my amp - its just a small one but it was made by Bando and I wondered if there is anyway of working out what voltage etc I require.
 
I need to find a replacement transformer for my amp - its just a small one but it was made by Bando and I wondered if there is anyway of working out what voltage etc I require.

I'm fairly good. But I can't "read minds". Would be real helpful If I knew what the make and model number is of your amplifier. It would at least provide a starting point.:thmbsp:
Second question-Are you sure your transformer is bad? How did you verify this? Inquiring minds would like to know.
 
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Hi and sorry yes - forgot to mention all that!

It's a Pioneer SA-420. Picked it up off someone who couldn't get it working. I've got power going in up to the transformer then nothing afterwards. The outputs on the transformer move from 0VAC to 0.01VAC when I apply power so I think its the transformer. Nothing looks blown in there either - maybe a few baked resistors but thats all.

If it helps the main electrolytics are rated 4700uF @ 35V
 
Hi and sorry yes - forgot to mention all that!

It's a Pioneer SA-420. Picked it up off someone who couldn't get it working. I've got power going in up to the transformer then nothing afterwards. The outputs on the transformer move from 0VAC to 0.01VAC when I apply power so I think its the transformer. Nothing looks blown in there either - maybe a few baked resistors but thats all.

If it helps the main electrolytics are rated 4700uF @ 35V

Do you have a schematic or service manual?
 
Have you disconnected the secondary wires and tried to measure the secondary AC voltage(s) off the transformer?
 
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I've got a schematic

When I measured the voltage on the transformer previously it was with the secondaries disconnected from the amp and reading from them in AC.
 

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Looks like you have a blown thermal fuse within the transformer. Sometimes these are accessable for replacement. What resistance do you measure between the transformers two primary wires?
 
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:yes: Here's three
 

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Stand -by. OK.. Its not going to look pretty..But you need to slice the wrap across the transformer indicated by the white line. Peel back the wrapper To gain access to the plastic terminal binding posts.The fuseable device should be in the area indicated by the green line.
 

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Ok, bear with me while I take it out and try this. Is there a quick way of taking the copper band off or do I need to cut that too?
 
Before cutting the copper band.See it you can cut away the paper by the primary side solder posts enough to locate the fuse. Or provide a close up photo of that side of the transformer.
 
I couldn't spot anything so I've cut it away but I'm still no closer. Here's a picture.
 

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