Why does my amplifier keep cutting out?

[swee'pea99]

It's old - getting on 20 years - but it's good: a Harman Kardon Festival 500:

I've had it for about five years, and it's always been great. But this summer it started cutting out, just for a second or three, then the sound would come back again. I thought it was probably overheating, and that the problem would go away with the cooler weather, but it hasn't. I decided it might have dust, so I took the casings off and blasted it (though there was little or no visible dust) with an air-blaster aerosol. No difference.

Is it time to lay it to rest (which I'm loath to do) or does this sound like something relatively easy to fix?

Any help/advice much appreciated.

 

[slowmotion]

Does the sound distort just before and after it cuts out, or does it do so cleanly? If it distorts, it could be that the output stage transistors are on the blink.

 

[derrick]

Time to get a proper amp


worth getting it checked out i would have thought.

 

[swee'pea99]

No, there's no distortion at all. Or volume slide or anything. It's playing, then the sound stops, then it comes on again.

 

[G2EWS]

With electronics as it is, I would not bother as it is so old and resign it to the scrap heap.

Oh, I am an electronics engineer by the way! To me with this type of product there comes a time when cost of repair outweighs value of product.

The only thing you could do is search on the interweb to see if anyone has a similar problem and solution?

Regards

Chris

 

[david1701]

can you hook it up to another source just to check? maybe try spare cables too just in case......?

 

[swee'pea99]

can you hook it up to another source just to check? maybe try spare cables too just in case......?

Hmmm...that's an interesting idea. Obvious, perhaps, but I hadn't thought of it! Thanks. I will.

 

[MontyVeda]

yes. double and triple check the source and replace all phono cables.

My trusty 30yr old JVC was cutting out and after much (but not enough) testing, i decided it was time to buy a new one. So £170 later on a new amp, I realised that my trusty 30 yr old JVC amp is still in perfect working order as it did turn out to be a cable problem between amp and source. The new amp does have a remote though, which is nice.

 

[green1]

With electronics as it is, I would not bother as it is so old and resign it to the scrap heap.

Depends what it is, I'd rather have a 30 year old bass guitar amp than a new one. Modern ones just sound crap.

 

[ColinJ]

yes. double and triple check the source and replace all phono cables.

The thing is - how would a dodgy phono lead cut both channels at once?

==========================================

Not an answer to this problem, but on the subject of fixing hifi amps ...

Once, when I was still in my 20s, I was having a drink with my mates when a stranger walked up to me in the pub and asked if I was named Colin. I said yes. He turned out to be a friend of a friend and his amp was playing up. Could I take a look at it? Damn - who told this guy that I was interested in electronics!

I tried fobbing him off, but he said that he only lived round the corner and he would make it worth my while. So, we walked round to his place and he showed me his hifi amp. I asked what the problem was and he said that he would demonstrate it.

The music was blasting away until he walked across the floor and it suddenly stopped! He walked back and I heard a distinct 'click' as the music came back on. He did that a few times with much the same results. Interesting ...!

I thought for a few seconds and looked around the room. Aha! I saw that the speaker wires came down from the back of the amp and under the big rug in the middle of the floor, and then emerged to connect to the speakers.

I asked the guy if he had moved his speakers recently. He said that he had. They used to be on the same side of the room as the amp, but he wanted them on the opposite wall. Yes, he had extended the speaker cables ...

I lifted the rug and there was the problem - he had used some cheap and nasty bell wire to extend the speaker cables. Where he'd made the joins, he had just twisted the cables together and had not insulated them! The bare cables were right next to each other, just chucked down on the floor and the rug dumped on top of them. Every time he walked across the floor, the cables shorted out and the amp's protection circuits kicked in and tripped a relay!

I told him what the problem was and he looked blank and said "Oh, I didn't know about insulation!"

I did a temporary fix with Sellotape (he didn't have insulating tape) and told him that he should buy a couple of pieces of decent quality speaker cable long enough to reach from the amp to the speakers.

He was really grateful, and true to his word, he made it 'worth my while' - he bought me one pint back at the pub!

 

[swee'pea99]

I played CD's for a couple of hours tonight. Not a single dropout. Hmmmm....(the dropouts have all been happening while I've been playing MP3s from a player. I've tried more than one player - same thing. What I never thought of was the cable. I shall have to try a different one and see if it makes any difference.)

Thanks all.

 

[david1701]

I played CD's for a couple of hours tonight. Not a single dropout. Hmmmm....(the dropouts have all been happening while I've been playing MP3s from a player. I've tried more than one player - same thing. What I never thought of was the cable. I shall have to try a different one and see if it makes any difference.)

Thanks all.

definitely a poss with mp3 cables as they tend to be left and right channels close together so more likely to break both and the jack at the end can fail too