Transformer Failed? Thinking about a TAD Replacement?

Sporky

Hope you get things sorted.

This moment must be ripe with "do I put a poo in the box as well or not?" type feelings.

martinw

Sporky said:

Hope you get things sorted.

This moment must be ripe with "do I put a poo in the box as well or not?" type feelings.

I wouldn't do that.  :-S

Or would I.......?

Modulus_Amps

In my 8 years of doing parts selling I have fallen out with 1 guy badly, maybe he caught me on a bad day, but the way a complaint is made can make a big difference to how it gets resolved.

@RiftAmps I have it on good authority that TAD do not only use Heyboer for transformer production, probably worth asking them when ordering.

ICBM said:

Was it definitely shoddy to begin with, or the result of overheating when it failed? It can end up looking a bit similar - if you've ever seen the joints on a typical overheated Zener diode in a solid-state amp you'll know!

now I wish I could find the picture/story again

RiftAmps

@modulus_amps Correct. I was talking about that specific C30 replacement although it may have changed since I last ordered one, apologies for not being clearer.

Modulus_Amps

ok just wasn't sure. cheers

martinw

Modulus_Amps said:

In my 8 years of doing parts selling I have fallen out with 1 guy badly, maybe he caught me on a bad day, but the way a complaint is made can make a big difference to how it gets resolved.

Not sure if you're implying that I complained in the wrong way?

RiftAmps said:

@modulus_amps Correct. I was talking about that specific C30 replacement although it may have changed since I last ordered one, apologies for not being clearer.

It doesn't look like a Heyboer to me.

martinw

In the second pic you can see the melted insulation or bobbin former that has emerged from the PT. The secondaries are shorted together, but each secondary is not shorted. The primary is ok, and there are no shorts to ground.

The transformer went off to Germany today (at a cost of £20) (sans poo, I've been a bit bunged up and the cat had already been) so we'll see what they say.

Modulus_Amps

martinw said:

Not sure if you're implying that I complained in the wrong way?

No, I have no idea how you complained, but it may have been a bad day there or something was lost in translation along the way.
Not really defending them, most times companies will sort out issues without making a big fuss about it, maybe they are upset about Brexit or something 

jpfamps

Looks Chinese in origin from the construction details.

Not of course that makes it a bad product.

Definitely not Heyboer.

RiftAmps

Yup those definitely aren't the same as they used to be. Reminds me of some of the Dagnall branded stuff in some modern Marshalls.

EDIT: Actually maybe not, not sure. Maybe all of his sun has got to my head

martinw

Update:

The PT has arrived back in Germany, and I have had notification that they will examine it and get back to me. Fingers crossed.

In related news, I have just taken in yet another Peavey Classic 30 with a failed mains transformer (a friend of @Rowby1 ). The primary winding on this one is o/c, possibly a thermal fuse as @jpfamps said. I'm tempted to dismantle the old one to check.

I'll also be doing the @ICBM mod (as it's now called!) and change R67 to 1k. It seems like it might be a good idea to add 1k screen grid resistors too.

DJH83004

I have to say as a newcomer to the site, the thing that impresses me the most it that it is a great knowledge sharing base, which you just don't get working away in isolation, and of course everyone ultimately benefits, through getting a more thorough professional job done. 

JookyChap

As an aside, I was just thinking of buying a P30, but I don't think I'll bother now

martinw

Well sure enough its the thermal fuse that's the fault. The PT is otherwise in good condition, and given that this particular amp is about 20 years old, it's not done too badly. They do run very hot, and with repeated heating and cooling cycles and vibration, it's entirely possible that this fuse has failed due to age, with no underlying cause.

Markings on the fuse show it's rated at 141 deg C, so I'll get some more with a similar rating and run the amp to see how hot things get. If it's ok, maybe the customer doesn't need a new PT.

jpfamps

RiftAmps said:

Yup those definitely aren't the same as they used to be. Reminds me of some of the Dagnall branded stuff in some modern Marshalls.

Because they use the same Chinese made bobbins.

jpfamps

martinw said:

Update:

The PT has arrived back in Germany, and I have had notification that they will examine it and get back to me. Fingers crossed.

In related news, I have just taken in yet another Peavey Classic 30 with a failed mains transformer (a friend of @Rowby1 ). The primary winding on this one is o/c, possibly a thermal fuse as @jpfamps said. I'm tempted to dismantle the old one to check.

I'll also be doing the @ICBM mod (as it's now called!) and change R67 to 1k. It seems like it might be a good idea to add 1k screen grid resistors too.

If I'm taking the amp apart to get to the PCB I will change the screen grid resistors as a matter of course, but I won't do this unless the PCB is coming out anyway as I always concerned about breaking the jumper wires between the 3 PCB assemblies (correctly in my view from experience of working on these amps).

Do you have a Megger to test transformers?

martinw

jpfamps said:

martinw said:

Update:

The PT has arrived back in Germany, and I have had notification that they will examine it and get back to me. Fingers crossed.

In related news, I have just taken in yet another Peavey Classic 30 with a failed mains transformer (a friend of @Rowby1 ). The primary winding on this one is o/c, possibly a thermal fuse as @jpfamps said. I'm tempted to dismantle the old one to check.

I'll also be doing the @ICBM mod (as it's now called!) and change R67 to 1k. It seems like it might be a good idea to add 1k screen grid resistors too.

If I'm taking the amp apart to get to the PCB I will change the screen grid resistors as a matter of course, but I won't do this unless the PCB is coming out anyway as I always concerned about breaking the jumper wires between the 3 PCB assemblies (correctly in my view from experience of working on these amps).

Do you have a Megger to test transformers?

Yes.

ICBM

Can you fit a self-resetting thermal fuse?

I'd go for a lower temperature than 141 degrees though! That's pretty much a last-ditch backup and might be above the melt temperature of some of the plastics.

jpfamps

ICBM said:

Can you fit a self-resetting thermal fuse?

I'd go for a lower temperature than 141 degrees though! That's pretty much a last-ditch backup and might be above the melt temperature of some of the plastics.

The main issue would be the core temperature of the transformer. As the fuse is on the outside its getting ALOT hotter in the core.

Maximum permisible core temperature will depend on the insulation rating of the transformer wire.

Given the prevalence of the fuse failing in usage using a lower temp rated rated fuse is likely to blow in "normal" useage.

ICBM

It does worry me that a fuse with as high a temperature as 141 blew when it was on the outside, yes! No surprise the wiring insulation sometimes goes first.

It really is a very marginally-spec'ed amp. Not impressive, for Peavey.