Servicing amps

[thinman]

Having spent the last few weeks looking at amp adverts a fair number use the phrase "just serviced".

What does that mean really? I have a bit of electronics knowledge and I've always thought that in general there's not a lot to be done apart from hoover if the thing's working. OK, some have the odd internal adjustment that may need altering due to age and there may be signs of things getting too hot but there's no moving parts, no antifreeze and no oil to change.

If I put a solid state amp in for a "service" what would I expect for my money - a shot of contact cleaner in the pots and a wipe with a dish cloth?

[thinman]

[quote name='finnbass' post='151331' date='Mar 4 2008, 08:53 PM']If you were lucky.... [/quote]
And what would they do to the amp?

[johnnylager]

They'll PAT test it, put a nice sticker on it and enable you to say "just serviced" in the eBay ad, thereby filling the buyer with confidence that he's not buying anything like that backbreaking, stupid-handled, flappy speakered Peavey combo (£50 - buyer collects, no postage, no returns) I had "just serviced" by a twat in Brighton, that now needs a hefty kick when turned on to get it working. Never let me down once it starts working though, I should thank him for that. I might put a free ticket to the next gig through his door. With a brick wrapped round it.

[thinman]

[quote name='johnnylager' post='151361' date='Mar 4 2008, 09:41 PM']They'll PAT test it, put a nice sticker on it and enable you to say "just serviced" in the eBay ad, thereby filling the buyer with confidence that he's not buying anything like that backbreaking, stupid-handled, flappy speakered Peavey combo (£50 - buyer collects, no postage, no returns) I had "just serviced" by a twat in Brighton, that now needs a hefty kick when turned on to get it working. Never let me down once it starts working though, I should thank him for that. I might put a free ticket to the next gig through his door. With a brick wrapped round it.[/quote]

Isn't PAT testing where you nick a kettle lead from work with a sticker on it?

[johnnylager]

[quote name='thinman' post='151365' date='Mar 4 2008, 09:48 PM']Isn't PAT testing where you nick a kettle lead from work with a sticker on it?[/quote]
Or get some bisciuts for the lads in electronics and swap for a strip of labels

[Lfalex v1.1]

In fairness, I've had two SS amps serviced;

[b]A Trace 1110 (Mk7?) 4x10 Combo[/b]. Serviced by Trace at the now defunct Maldon plant.
They hoovered it out, put new cabinet damping in. Replaced all the old corroded connectors and jack sockets with new ones. Took all the (yellow) EQ slider knobs off and put new white ones on, cleaned all the pots, switches & sliders, changed all the fuses, just about everything they could feasably do.
They turned it around in 3 days and were really helpful. £60 (10 years ago!) I traded it in for £90 MORE than I paid for it against a....

[b]Trace H122SMX 2x10 combo [/b](pre Gibson for the Anoraks!) This developed an intermittent fault and would cut out sonically, but not electrically.
I had it serviced by Gavin at GM Audio (also Maldon), who's an Ex-Trace service engineer.
He knew immediately what was wrong; To save money, the inter-circuit board connections WERE wired with push-fit spade connectors. I use the past tense as he soldered all the connections up instead, put a new (better) AX7 in the pre-amp (and gave me the old one as a spare), cleaned it all out and tested it thoroughly on his bench (not just a PAT test) before giving it back. Better than new. £100. 7 day turn around.

It's worth taking your amp to someone who knows what they're doing with your particular amp. I'm not sure I'd trust some shops and their attendant "solder monkeys"... Head (if possible) for the manufacturers or reputable amp techs. For example, Chris @ the Bass Centre (RIP) used to be good...

[mike257]

Having said that, back when I wasn't brave enough to dabble with my own gear, my Trace stopped making noise one day and earned a trip to our local 'reputable' amp service establishment.

It came back with a 45p parts charge, and £50 labour! He'd changed a fuse, and allegedly 'thoroughly tested, given a full service and internal parts cleaned'.

When it stopped working again within half an hour of switching it on, I opened it up myself, and there was more dust in there than in a used hoover bag, and not a damn thing but the fuse had been touched. You can never be quite sure what you're getting from these places, but they've had no more of my business since then.

[CPBass]

[quote name='mike257' post='152147' date='Mar 6 2008, 02:29 AM']Having said that, back when I wasn't brave enough to dabble with my own gear, my Trace stopped making noise one day and earned a trip to our local 'reputable' amp service establishment.

It came back with a 45p parts charge, and £50 labour! He'd changed a fuse, and allegedly 'thoroughly tested, given a full service and internal parts cleaned'.

When it stopped working again within half an hour of switching it on, I opened it up myself, and there was more dust in there than in a used hoover bag, and not a damn thing but the fuse had been touched. You can never be quite sure what you're getting from these places, but they've had no more of my business since then.[/quote]


I would definately had gone back and stuck the fuse in one of his recepticles.

Refund NOW.....please!!

[thinman]

Having been tinkering around with an old amp I did a bit of reading round and have to concede that there are number of things that can reasonably done as part of a service. Whether these are actually done I do wonder. These ar enot my opinions or recommendations - just a summary of what I've read on various web sites.

However, if anyone has a service done I wonder if these are covered:

1. A good hoover out or blow out with compressed air. Apparently a lot of the dust that accumulates gets there because it's attracted by charged components. That dust can conduct a bit and cause crackles, other noise and even burn outs. The amp I'm looking at used to have a rat-fur covered case and the circuit board looked like someone had emptied their shaver onto it. Oddly, the hairs had tended to align themselves to various components making me wonder if they're not totally electrically inert.

2. Pots - clean with a suitable cleaner and lubricant. Replace if necessary.

3. Jacks - clean and replace if required.

4. Valve amps. Opinions seem to vary but some say valves in the power stage need to be changed every 1-2 years depending upon use. They have to be biased when changed. Pre-amp valves would then typically be changed at half that frequency but some say if they work then leave them alone.

Corrosion of the sockets is apparently a common problem so a service should include cleaning/replacement.

5. This one surprised me but apparently aluminium electrolytic capacitors are usually best replaced after 10 years regardless of use. These types are most commonly used for smoothing/filtering of the power supply (these look like small drinks cans and most have 2 or 4) although they're use all over the place. Over time their performance degrades. Supposedly the most subtle manifestation can be less filtering leading to more 50Hz (or harmonics of) overtones being introduced into the sound thus clouding notes. At worst they can go bang.

So, some would recommend that if you have an old amp it's best to have the electrolytic caps changed. They're not that expensive - a big one for a power supply is around £3.

6. General safety/integrity of wiring - especially any mains or high voltage stuff.

So if I'd spent £50 I'd expect that to go a bit further than unscrewing the case.

[ahpook]

[quote name='thinman' post='180186' date='Apr 18 2008, 10:14 PM']Having been tinkering around with an old amp I did a bit of reading round and have to concede that there are number of things that can reasonably done as part of a service. Whether these are actually done I do wonder. These ar enot my opinions or recommendations - just a summary of what I've read on various web sites.

However, if anyone has a service done I wonder if these are covered:

1. A good hoover out or blow out with compressed air. Apparently a lot of the dust that accumulates gets there because it's attracted by charged components. That dust can conduct a bit and cause crackles, other noise and even burn outs. The amp I'm looking at used to have a rat-fur covered case and the circuit board looked like someone had emptied their shaver onto it. Oddly, the hairs had tended to align themselves to various components making me wonder if they're not totally electrically inert.

2. Pots - clean with a suitable cleaner and lubricant. Replace if necessary.

3. Jacks - clean and replace if required.

4. Valve amps. Opinions seem to vary but some say valves in the power stage need to be changed every 1-2 years depending upon use. They have to be biased when changed. Pre-amp valves would then typically be changed at half that frequency but some say if they work then leave them alone.

Corrosion of the sockets is apparently a common problem so a service should include cleaning/replacement.

5. This one surprised me but apparently aluminium electrolytic capacitors are usually best replaced after 10 years regardless of use. These types are most commonly used for smoothing/filtering of the power supply (these look like small drinks cans and most have 2 or 4) although they're use all over the place. Over time their performance degrades. Supposedly the most subtle manifestation can be less filtering leading to more 50Hz (or harmonics of) overtones being introduced into the sound thus clouding notes. At worst they can go bang.

So, some would recommend that if you have an old amp it's best to have the electrolytic caps changed. They're not that expensive - a big one for a power supply is around £3.

6. General safety/integrity of wiring - especially any mains or high voltage stuff.

So if I'd spent £50 I'd expect that to go a bit further than unscrewing the case.[/quote]

bloody hell...i could do that !!

[Count Bassy]

You're right about electrolytic capacitors. IIRC they actually degrade more quickly if not used for a long time than when they are being used. They can be 'regenerated', but at the cost of a new one it's not worth the bother.

To anyone considering replacing electrolytic capacitors, remember that they are polarised. If you connect them the wrong way round they will fail very quickly, and posibly with a bang.