WANTED - a REAL electronics expert

[Terry]

This is a REAL challenge

First of all I am a MECHANICAL Engineer - VOLTS & Stuff leave me cold..............

I am the proud owner of an AUDIOLAB 8000A Integrated Amplifier which is now some 25 years old and is the mainstay of my audio system at the Lodge.

It is a collectors piece amongst Hi-Fi buffs and I can remember paying a small fortune for it back in my 'first life' in the UK.

Frankly I would be lost without it and I know that getting a replacement is almost impossible and likely to be prohibitively expensive.

When it works - it's great - with a sound quality that (to my ears at least) is second to none. If you wind up the volume at party time - you can hear it in Chumpon............

The old fella has developed a niggling problem and even the tried & trusted local guy in Cha Am is too scared to try and fix it - so I need some help.

Problem

When you switch it on, there is normally a 5-10 second delay before hearing a discernable 'click'. This I have deduced is the main relay cutting in and livening the whole thing up. When it works - all is good.
However
Over the last year or so the 'click' has taken longer and longer to occur and sometimes not at all - leaving me 'soundless'

Fault Diagnosis

According to an ELECTRONICS ENGINEER colleague the fault lies with a small resistor which has apparantly snuffed it - or is about to anyway. My colleague has managed to download the circuit diagram from the net and identify the culprit.

Surgery Required

I need to locate somebody who can
1) - Read the circuit diagram and Concurr with the diagnosis
2) - Obtain a replacement resistor
3) - Perform the surgical removal of the duff resistor and solder in a new one
4) - Mop my brow afterwards

Is there anyone out there who knows of such a genious? - is such a genious?

Recompense for such outstanding achievement to all mankind is guaranteed.

Interested candidates - or likely leads to solve my dilema, please PM me or email me on terry@huahinfishing.com

[lazerlab]

You will not fint any workshop competent to fix problems with high end audio equipment in Hua Hin. Try BKK.

[Terry]

Hi lazerlab

Regrettably you may ultimately be proved correct - and if I HAVE to - then I will take it to BKK

However - having lived in BKK for 8 yrs (and yes I'm well aware that I could probably get it done there - in Amarin Plaza) and now in HH for over 10yrs - I simply cannot believe that there is NOBODY who can do this kind of work in HH.

I get a little tired of the 'you must take to Bangkok' syndrome for anything that requires a little more than using a screw driver.

It has to be a question of just FINDING the local artisan.

Hence the question

[poosmate]

Terry. I have had several tvs and computers repaired by a guy near to you in Nong Korn. His shop is just before Le Valley ( coming from Hua Hin ). The shop has a large handmade sign advertising network and internet wiring and CCTV.The guy seems fairly competent and intelligent. He has just managed to repair ( not replace ) some air con PCB's that had been fried by overcurrent.

[Randy Cornhole]

Locating the resistor in question is quite easy as they are all colour coded. The code is as follows -

BBROYGBVGW - Bad Boys Rape Our Young Girls But Violet Gives Willingly.
Black, Brown, Red, Orange, Yellow, Grey, Blue, Violet, Green, White.

You also need a solder sucker soldering iron and the hands of a surgeon.

Having said that it can be tricky if you haven't done it before.

[Nereus]

Sorry, cannot help you with a local repair shop,Terry. But I would just like to say that a couple of other things come into it.
The main one is the quality, or tolerance, of any replacement component(s). You have a high spec piece of gear that will have good quality components fitted, and it is essential that the correct replacements are used. You may well find a local tech, but obtaining good replacement components is something else.

I would also be a bit sceptical about any diagnosis given just by reading a schematic, without seeing the equipment, even with the best of intentions. It is rare, but not unknown, for resistors to fail, but not usually over a period of time like you have indicated. It is more likely to be a failed capacitor, or a component in what is called the oscillator circuit, or a component associated with the power supply. With equipment like that a good oscilloscope for testing is essential, or you run the risk of ruining the whole thing. I think that your tech in Cha Am has indirectly told you that.

[Norseman]

I agree with Nereus that it most probably is a capacitor failure because of the slowly increase in time before you heard the "click" and that's a typical capacitor mass reduction failure.
The breakdown of a resistor is not a usual component-failure in a costly amplifier like yours.
If one of it's circuit resistors are broken you shouldn't be able to load or unload the capacitor and it would most certainly bring your amplifier to a sudden "death".
I therefore don't believe it's a resistor failure alone as pointed out.
In conjunction with the capacitor you'll find a rectifier and most probably three resistors.
If it's not the breakdown of the capacitor I would think the rectifier is the culprit.
You'll need instruments and the correct wiring diagram to find the broken part though.

[STEVE G]

If you get an audible click on power-up, it could be a muting relay that's used to stop a big "thump" from damaging your speakers when the power comes on line.
If that's the case, it could be the capacitor or resistor used for the delay.
I'm only guessing really, but I'll ask a couple of the big hi-fi buffs at work as they're always messing around with amps.

[Terry]

Thanks for the comments chaps - really appreciated
Randy - It's been a long time since I cam across BBROYGBVGW - thanks

However - it shows what a d**k I am - it IS a capacitor - not a resistor that my electronics colleague here in Delhi has highlighted

According to him, the offending blighter is also part of the power supply circuit.

As said before, I have the cicuit diagrams for
1) Power Amplifier Circuit &
2) Protection & Relay Drive Circuit.

Offending capacitor has thus far been identified in the latter

I did say that this was a real challenge and I am not about to let my prize posession to be 'operated upon' until I am sure that a successful conclusion will be obtained. But as you can appreciate - it's worth the effort to save a superb piece of hardware because as of now, it is an unreliable and possibly dead piece of junk!

I appreciate the feedback - no pun intended

Keep it coming

[Terry]

AN UPDATE

Well - I got the Amplifier fixed.

However - much to my chagrin - NOT in Hua Hin of course.........but in Bangkok, as usual.

Oh well

Anyway - for those who have ailing Hi Fi and come up against the usual 'NOT IN HUA HIN' syndrome, I can thoroughly recommend MR. BALANCE

Located on the 5th floor of Panthip Plaza (Car park end), this guy owns a proverbial Aladdins Cave of top end old Hi Fi bits. He buys and sells and of course carries out repairs on the old beauties.

In my case he (or his techie) carried out a complete check, and found the power relay and associated CAPACITOR to be at fault. These have been duly replaced and all is working well, with the neighbors in Chumpon complaing again

Cost THB 3,000 - a bit steep, but in the circumstances well worth it.

Mr. Balance - 5th Floor Panthip Plaza
081 644 0543 begin_of_the_skype_highlighting              081 644 0543      end_of_the_skype_highlighting begin_of_the_skype_highlighting              081 644 0543      end_of_the_skype_highlighting or 081 341 2000
http://www.misterbalance.com .....this site is a listing of stock
Open 12.00 to 18.00 hrs Mon to Sat

Apparantly been there for 15 years and speaks good English.

[chelsea]

Terry just for future reference, just found this guy listed on the Audio Lab UK website as the Thai distributor.
http://www.audiolab.co.uk/Support.aspx?State=25
Might help if you need some further info.

[Terry]

Thanks chelsea - useful and appreciated

Hopefully won't need it

cheers

[chelsea]

Terry when I looked on the internet, there was also some upgrade kits that other people had listed to update to more modern specifications.

[Terry]

Chelsea, I've seen some of these, but I'm a great believer in leaving things alone when they are working well.

My trusted Audiolab is a bit like me, old, cranky but still capable of delivering the goods when called upon...........

The very trouble with modern designs is that they are simply 'unfixable'

For example - many years ago - I kept my old Triumph Spitfire MkIII sports car, running with not much more than a set of bicycle spanners for 9 years - except for the occassional bit of major surgery.
I look under the bonnet of a modern car and I would not know where to start.