Hello guys, my second post, and the main reason for me joining the forum. I'm hoping someone could assist me with this issue.

I just got a Yamaha RX-V371 receiver from a friend, unit initially taken so I could strip it for spares. But, but....... it just looks so nice, and new! It was imported unit that he brought in from the States. He plugged it in not knowing that it was a 110v unit, and here in South Africa we use 220v.

And! Unit DEAD! Now I'm no electrical engineer, but neither a total idiot So today I checked the resistance on the standby transformer primary and i get no reading at all, secondary seems fine, and so does the main transformer, so at least that is okay, I hope. My question is, what else could have gone on the unit by plugging it into the supply? And is it possible to get a replacement standby transformer for it?

Thank you and have a great day.

Regard
Cedric

 

Is there a fuse anywhere in the primary circuit?

 

Hello guys, my second post, and the main reason for me joining the forum. I'm hoping someone could assist me with this issue.

I just got a Yamaha RX-V371 receiver from a friend, unit initially taken so I could strip it for spares. But, but....... it just looks so nice, and new! It was imported unit that he brought in from the States. He plugged it in not knowing that it was a 110v unit, and here in South Africa we use 220v.

And! Unit DEAD! Now I'm no electrical engineer, but neither a total idiot So today I checked the resistance on the standby transformer primary and i get no reading at all, secondary seems fine, and so does the main transformer, so at least that is okay, I hope. My question is, what else could have gone on the unit by plugging it into the supply? And is it possible to get a replacement standby transformer for it?

Thank you and have a great day.

Regard
Cedric

Lots of things might have happened.... from a blown fuse to a burnt primary. I suggest you post some pics

 

Is there a fuse anywhere in the primary circuit?

Forgot to mention, the fuse tested with a meter and it's fine. As for pics, should I upload some pics of the standby pcb?

 

Forgot to mention, the fuse tested with a meter and it's fine. As for pics, should I upload some pics of the standby pcb?

Load pics from the top and the underside of the PCB

 

coming!

 

get the back off and test the voltages to and from the transformer...

 

Pics as requested

 

get the back off and test the voltages to and from the transformer...

Gonna be a problem, the unit is 110v and here in SA we at 220v. Gonna see if I can get a step down convertor at work tomorrow and check it out.

This unit is literally brand new, so would really like to get it going. I also have a working RX-V361. Older unit but looks almost the same, quite tempted to yank the transformer pcb out there and sticking it in this newer unit.

 

Hello guys, my second post, and the main reason for me joining the forum. I'm hoping someone could assist me with this issue.

I just got a Yamaha RX-V371 receiver from a friend, unit initially taken so I could strip it for spares. But, but....... it just looks so nice, and new! It was imported unit that he brought in from the States. He plugged it in not knowing that it was a 110v unit, and here in South Africa we use 220v.

And! Unit DEAD! Now I'm no electrical engineer, but neither a total idiot So today I checked the resistance on the standby transformer primary and i get no reading at all, secondary seems fine, and so does the main transformer, so at least that is okay, I hope. My question is, what else could have gone on the unit by plugging it into the supply? And is it possible to get a replacement standby transformer for it?

Thank you and have a great day.

Regard
Cedric

A standby transformer will usually have a thermal fuse embedded in the primary winding. The fusible wire is very thin, so proably blew because of excessive current.

Sometimes you can expose the thermal fuse without digging into the winding - if you can get hold of an autotransformer with the correct output voltage, its worth temporarily linking the fuse so you can verify the correct secondary voltage to order.

For the main PSU, sometimes you can get lucky if its a SMPSU - the chopper transistor can blow before much damage happens downstream.

Linear supplies generally take longer for something to heat up and melt - by which time a pair of output transistors could punch through or multiple damage all the way through!

You could be lucky and the bridge rectifier died first and took out a fuse.

 

A standby transformer will usually have a thermal fuse embedded in the primary winding. The fusible wire is very thin, so proably blew because of excessive current.

Funny you should mention that, I watched a Youtube video regarding that. Will check it out now.

 

Okay, cut open the standby transformer on the primary side, and found the neutral wires was broken. Might be this, but will have to check tomorrow. That wire is very thin for 110v. Literally like a hair.

 

Okay, cut open the standby transformer on the primary side, and found the neutral wires was broken. Might be this, but will have to check tomorrow. That wire is very thin for 110v. Literally like a hair.

It would be nice if you could post a pic of that as well

 

Update, soldered the neutral wire back on, no resistance or continuity. So I guess it must be further down the winding :-(

Here is a pic of it cut open. More like butchered it open

 

It would be nice if you could post a pic of that as well

And once the secondary voltage can be ascertained - it should be binned - it would be a bad idea trying to get any further use out of it.

 

Update, soldered the neutral wire back on, no resistance or continuity. So I guess it must be further down the winding :-(

Here is a pic of it cut open. More like butchered it open

That looks more like a regular power transformer to me - sure you checked the primary where its leads solder to the board? - If you checked at the pins of the connector that eventually get there, you might have included a fuse and the relay contacts in the test.

Still, if the primary is the wrong voltage anyway, it has to be replaced.

You'll need to look at the design tables for capacitor input PSUs to guesstimate what secondary voltage to order, from the rectifier/reservoir ratings.

 

sure you checked the primary where its leads solder to the board?

Yes I am sure, straight into the board from the transformer, noting in between. Mains in to tha standby transformer and from that same point the live goes into the fuse and a few other components.

 

It's late, gonna take a look at this tomorrow again. Thank you to everybody for the replies and trying to assist.

It's much appreciated.

Regards
Cedric

 

Just a bit of an update, was in contact with the Yamaha agents of South Africa today, looks promising. They might be able to assist me with parts, especially the standby transformer. For now, just need to get it to switch on.

 

If it does not have a 220VAC setting, Switch it on with a 220V stby Tx and you will blow the main TX, If you are lucky the smoothing caps might survive.