Pioneer A400 renovation- where to start?

[Dougal1331]

Hi folks,

I can see from other threads that we have some A400 experts in the house.

I have one of said beasts, but it is on its last legs and needs some help.

When powered up, there is an odd, squelchy, radio interference-like sound coming through the speakers. This gets progressively more squelchy, and louder as the amp warms up. It is loud enough to impinge on the music.

Obviously, the amp is not used, as I believe it is only a matter of time before it pops and kills itself (and my speakers too).

Has anyone experienced similar? Would this be knackered caps or something more serious? I don't think it is RF interference- tried it through my Tacima and no better- and it certainly seems that the amp is generating this noise itself...

I'd love to get her up and running again- she blew my old Roksan Kandy mk3 clean away!

 

[Anonymous]

Hi Dougal, sorry to hear you are having problems with your A400. Did you have a look inside to make sure all the caps are ok? Just a quick visual inspection for any bulging of the top of the cap or any leaking is what you are looking for. Let me know how you get on as there are other things you can look for if its not the caps...

 

[Dougal1331]

The only caps I can see- the two big 'uns and all the ones on the board- all look fine, no bulging or splurge... The amp is in good nick overall, doesn't look abused (bought off ebay for £50 in an auction that finished at 4am...), and worked fine for a fortnight. Then all went a bit weird...

 

[Anonymous]

It sounds as though there is a major component failure somewhere unfortunately. Before you take the amp to a specialist who can run some diagnostics there are a few simple troubleshooting things you can do yourself to save you any potential embarrassment:

Have you isolated the amplifier as the cause of the problem - ie checked all the other components (cdp, cables, speakers) to make sure they are not the problem.

Have you checked to see if the problem is affecting all the inputs on the amp?

Do you have access to a multimeter?

Let me know how you get on...

Chris

 

[Dougal1331]

The amp is definitely the problem- my other components are all fine with a different amp.

The noise is present on all inputs. Sadly, I do fear that this could be fairly major, and perhaps terminal.

Should be able to get hold of a meter easily enough... I'll make some enquiries and let you know if I find one!

Many thanks for the help so far!

 

[Anonymous]

Hi Do you know anyone in South East London who can repair my A400 amp? Left channel has gone