[RobxMcCarthy]

Hi, I have to replace a transformer in a class A single ended amplifier.

The transformer currently in there has a labdle that says

115v 0v 115v 0v

50VA "Chinese symbols"

0v 280v 0v 6 3v 0v 6 3v

Now I live in the united states, so I don't require a 280v transformer section.

However I can't figure out the 50va rating. Presuming that this is a 50 watt transformer I've found several that offer "similar" ratings, however I can't find any at exactly 50va.

http://www.partsexpress.com/pe/showd...number=120-205 IE this one's 60va but how can I find one that will work?

Thanks,
Rob

 

[ATAT]

First, only use transformers above 50VA. this is a must.. this is the amount of current the trafo will give / voltage before dying (or at least thats what I learned that was.)

Not sure how its wired, but doesnt it look like a dual secondary 6VAC transformer?

Someone check please =p I could be completely off (trafos I dont like dealing with..)

 

[dsavitsk]

You should probably not be repairing this, and should instead give it to someone qualified. One slight wrong move, like leaning on the chassis wrong while you are trying to repair it can kill you in an instant. If you do not know what every part of the circuit does, don't go near it. Part of the bargain of buying cheap underspec'd tube equipment is that sometimes it dies and needs to be fixed. There is a reason that tube amps tend to cost a lot.

Anyhow, that said, it sounds like you need a transformer with a 280V center tapped secondary and 2 6.3V taps. The one you linked to will not work.

 

[ATAT]

dsvitsk is absolutely right here.. HV equipment (like tubes) can kill you..

but if you want to disregard that advice and go ahead and attempt to fix this, make sure you have absolutely no connections to ground (ie insulating shoes) and always keep one hand behind your back... why? it prevents you from grabbing two things and completing a circuit =).

Anyway, good luck..

 

[cetoole]

Quote:

Originally Posted by ATAT dsvitsk is absolutely right here.. HV equipment (like tubes) can kill you..

I agree with ATAT and dsvitsk here, dont try repairing that amp yourself. Those voltages you will be messing with are deadly, as has been said before, and you seem to lack experience with this type of work. This amplifier has parts running well over 2x your mains voltages.

Quote:

but if you want to disregard that advice and go ahead and attempt to fix this, make sure you have absolutely no connections to ground (ie insulating shoes) and always keep one hand behind your back... why? it prevents you from grabbing two things and completing a circuit =). Anyway, good luck..

Keeping one hand behind your back does not prevent you from completing a circuit, it keeps you from completing a circuit that passes through your heart.

Quote:

Originally Posted by RobxMcCarthy Hi, I have to replace a transformer in a class A single ended amplifier. The transformer currently in there has a labdle that says 115v 0v 115v 0v

These are the primaries, the input voltage to the transformer. These numbers mean that, depending how the primaries are wired, either in series or parallel, this amp is able to work off US or EU voltages.

Quote:

50VA "Chinese symbols"

VA=Volts*Amps, basically the same thing as watts.

Quote:

0v 280v 0v 6 3v 0v 6 3v Now I live in the united states, so I don't require a 280v transformer section.

These are the secondary voltages, the output of the transformer, and what powers your amplifier. The location where you live does nothing to change what voltage the amp needs, that 280v secondary is critical no matter where you are.

 

[RobxMcCarthy]

Ah, ok, now I understand.

I've done a bit of electronics work, however I've never dealt with a transformer like this or tube equipment in general.

I'll probably send it to the "us repair station", However, incase I don't, where can I get this kind of transformer? I haven't been able to find one on the web. (perhaps a higher wattage would be appropriate, seeing as this one choked).


So basically I need a > 50VA transformer with a 115 input voltage and a 280 center tap with a 6.3v secondary output. Is this correct?

However, without a proper schematic of the current transformer in use, as well as a schematic of the original amplifier it might be difficult to repair.

 

[Giant2eviL]

Quote:

Originally Posted by RobxMcCarthy Ah, ok, now I understand. I've done a bit of electronics work, however I've never dealt with a transformer like this or tube equipment in general. I'll probably send it to the "us repair station", However, incase I don't, where can I get this kind of transformer? I haven't been able to find one on the web. (perhaps a higher wattage would be appropriate, seeing as this one choked). So basically I need a > 50VA transformer with a 115 input voltage and a 280 center tap with a 6.3v secondary output. Is this correct? However, without a proper schematic of the current transformer in use, as well as a schematic of the original amplifier it might be difficult to repair.

Which "us repair station" u are sending too? what is the cost of repairing?