Hello STW Fountain of Knowledge 🙂

I have a problem with my 80’s Hi-Fi setup. Any input sounds very quiet and muffled. You have to turn the amp onto full volume to hear anything. I normally have it plugged into a laptop, if you plug this into the Phono input rather than the Tape/Radio, you get a louder output but it is very distorted. I believe one of my housemates may have left it at full volume for ages, after selecting the wrong input and wondering why it didn’t work, grrrr 🙁

The amp is a Boothroyd Stuart Meridian 101 preamp with 105 poweramps. I can’t see anything obviously wrong inside the preamp, I haven’t had a look at the poweramps yet as I figured for both channels to be broken it must be the preamp.

Does anybody have any genius ideas how one might go about fixing this or who might be a good person to send it to repair? It used to sound lovely, so I’m reluctant to replace it with some modern budget replacement.

Cheers 🙂

Too busy drooling at those pictures…

Hi If your near Leeds I can recommend Abacus Electronics he is a one man band working from home very reasonable and knowledgeable

That’s lovely, shame it’s broken 😥

I’d guess a transistor has gone in the output module, I’ve got similar vintage rotel pre/power amps which have done something similar.

Service manuals are available here and here so you should be able to get it fixed. I’d try a tv repair place or maybe if you know anyone doing electronics at college.

Good luck 🙂

I’d be getting some switch cleaner through the volume pot first. Power off, small squirt and rotate the pot fully both ways a few times. Tissue for any excess and leave a few minutes to dry before powering up again. Make sure you took the volume back to zero before starting up again…

The phone stage is amplified to boost the low-level output from turntables, which do not have pre-amps like CD/tape/radio players. That’s why it distorts any line-level signal you plug into it.

Nice kit, hope you get it fixed. Any reputable HiFi dealer ought to have someone who can fix audio equipment, old and new, might be worth having a shufti in the classified in something like one of the hifi mags in WHSmiths.
I would say those speakers aren’t really placed to their best possible advantage, they’re really a bit too close to the wall for their size, and too close together; you’re going to get boundary effects which will cause the bass to be over-emphasised, which is how small bookshelf speakers get their bass, through deliberate placement close to rear and side walls.
Anyways, that’s not helping the problem at hand, which might, and I say might, possibly be power transistors blown through being over-driven, or the bass drivers in the speakers blown for the same reason; if the signal distorts, that causes clipping, which can cause the voice-coils in the speakers to over-heat, then the coils collapse, stopping the cones from moving smoothly. You can test this easily by taking the grills off, then gently pushing the bass drivers in and out; if they move smoothly, and silently, they’re fine, but if they feel rough, and there’s a sort of grating noise through the cones, then they’re FUBAR’d.
Hope this helps a bit, that set-up’s worth keeping going.

This^^^ the fact it’s a pre-amp / power combo suggests it ain’t the power amps (as you’d loose a channel). The fact it’s quiet on all input selections suggests the volume pot!

I’d plug the laptop directly into your power amps and test them and your speakers first, make sure the volume is low but your laptop will act as a adequate preamp for the purposes of a test.
If the power amps and speakers are OK just call Meridian service and have them fix the preamp, it’s probably worth dropping a little cash having the whole lot serviced and recapped as that was a nice combo.

I’d plug the laptop directly into your power amps and test them and your speakers first, make sure the volume is low but your laptop will act as a adequate preamp for the purposes of a test.
If the power amps and speakers are OK just call Meridian service and have them fix the preamp, it’s probably worth dropping a little cash having the whole lot serviced and recapped as that was a nice combo.

Forget all that just seen it’s din connections, bugger.

Cheers for the help guys 🙂 Have ordered a can of switch cleaner. I use a 3.5mm to Din cable to input into the preamp, so tried plugging the laptop direct to a poweramp and didn’t get any sound at all. Will take it apart and see if anything looks damaged. Pretty sure the preamp was wired up correctly to provide power to the poweramp as the poweramps do not have their own power supply, fuses are fine but the power lights have never worked, so hard to tell if it was powered on.

Do you have a spare cable to try, or means to test your current cable?

I agree with joolsburger re. testing the power amps without the pre-amp. But yes, it’s nice vintage kit and well worth fixing.

Just tried the other poweramp and it does make some noise, kind of. It is extremely quiet and very distorted, so it looks like both the poweramps are unhappy.

I have the same b&o speakers except some idiot knocked the grills off slightly ripping the base driver – on both. Still sound good though.

If you have not bought DeOxit as your switch cleaner order some now. The stuff is magic – does the job and doesn’t leave any annoying residue.

Us hams swear by it for cleaning vintage radios – wouldn’t use anything else.

I have dismantled one of the poweramps to have a peek inside … it appears to have a baby Starship Enterprise inside!

There is one obviously damaged component, the brown thingie

Could this be the problem?

Cheers
Chris (Mr ZeroKnowledgeofElectronics)

Rich Penny to the forum.

My endeavours below.

http://singletrackworld.com/forum/topic/any-hi-fi-techie-types

Hmm, that’s a cracked resistor – i guess that’s your problem identified – it looks like a 4 band so (rummage’s in distant memory for resistor codes) without the benefit of a better pic to fully identify the colours and to see whether it’s a 4 band or 5 band i’d say it’s a 30? ±10%

orange – black – black – silver to my eyes.

take a side on pic so we can see the stripes as that is what signifies the ?

Used to be a place called The Hifi Emporium with a good reputation, worth doing a search for them. Theres a seller on Ebay could be same place