technologically challenged carpenter requires help

[Boogies master]

Hello people, I should start by explaining I'm a carpenter and as a result my limit of anything technical requires measuring one piece of timber, cutting it and nailing it to another. Please do bear with me...

I was lucky enough to inherit some rather lovely yamaha seperates which, whilst clearly quite old, are beautiful to look at and, I would like to hope, of a decent quality. First problem is that whilst the amp turns on and lights up, it won't produce any sound from any of the seperates. The general consensus is that repair is uneconomical but I'm very much of the school of thought that things should be fixed rather than replaced, I could of course be wrong in this instance. Is there a common problem with Yamaha a500s that people know of?

Secondly, in what was in hindsight a rash decision, I invested in two pairs of Bosch ceiling speakers (1 pair in the kitchen and 1 pair in the dining room) the problem it turns out is that the speakers are 100v speakers and therefore not suitable for home audio as they'll end up blowing the amplifier, is this true? I read somewhere once that bypassing the transformer on the speaker should resolve this problem, is this also true?

To my mind at least, it would appear i have ended up with a pretty worthless pile of lovely looking stuff, I do hope this isn't the case and would greatly appreciate any advice as to whether any of this stuff might be salvageable.

In return, I am happy to offer any carpentry/diy advice that may be required!!!!

Many thanks

Justin

 

[Benedict_Arnold]

Generally speaking these days if a modest amp like yours won't work, and assuming you've wired it up correctly, it's not economically viable to repair it unless you know some bloke with a shed and a soldering iron.
As for the speakers please post the make and model.

 

[iQ Speakers]

100v speaker, systems are for PA and background music systems in order to link many over long distances without loss, Even if you could work out how to use them the speakers are not designed to be the last word in musicality. My first job some 35 years ago was building 100V music systems foe pubs etc!

 

[andyjm]

100v line speakers work in the same way as power distribution, where the voltage is stepped up using transformers at the power station to travel long distances and minimise losses, then stepped down again close to your house to mains voltage.

In the case of 100v line speakers, a transformer on the amp output boosts the voltage to a nominal 100V (hence the name) and each speaker has a step down transformer to drop the level back down to a level suitable to drive the speaker. As mentioned above, commonly used in PA systems where long cable runs and multiple speakers are used.

Using 100v line speakers on a normal amp won't blow the amp, but the volume will be so low that it may be inaudible. Removing the transformer connections and driving the speaker directly from the amp should work OK. 100v line speakers aren't the peak of audio performance, but much of the problem is usually the transformer - good transformers cost money, so this is the area that costs are saved. Driving the speakers directly will improve the sound quality.

Tough to comment on the amp problems - though if you were trying the amp with the 100v speakers with the transformer in place, the volume may have been too low to hear.

 

[thewinelake.]

Have you opened up the amp and looked inside? It might be that there are fuses in the output stage that have blown. I had exactly this with an old amp recently. As the fuses had clear cases, it was obvious that they had blown. Replacing them fixed the problem.

 

[Boogies master]

Thanks thewinelake, I did take the cover off and took one look at the circuit boards, transistors, resistors and fuses and promptly put the cover back on. I would hope it's something as simple as a fuse and it's booked in for a general once over with a local whizz so hopeful for a reasonably quick, inexpensive repair.