Amplifiers that are a total pain in the arse to repair and reason(s) why ?

ICBM

ThorpyFX said:

How are mesas to work on? I've heard they won't release schematics and looking in my mark V it seems massively cramped indeed. 

Not too bad unless you need to replace something which can't be done from the top of the board, eg a relay. They are complicated, and cramped, but usually reliable so it's not often an issue.

Voxman said:

Not being a techy I have no clue from an amp tech perspective of which amps are good and bad to work on - but reading these posts I was curious as to what amps you guys think are well built, well designed and easy to work on?

Generally if they're well-designed and built, they don't need working on . Most of the high-end mass-produced amps are pretty good, really - whether PCB or hard wired. High component quality and solid construction that's designed for hand assembly usually makes them fairly easy to re-assemble, if that makes sense.

Voxman said:

Also, I was just curious. If a customer brings in an amp that you know is going to be awkward to work on (Laney perhaps!) and take three times the time, do you quote three times the cost, or charge just a bit more, or just accept that some amps take longer than others and base charges on a set scale linked to what the fault is on a 'swings/roundabouts' basis?

Same as jpfamps - if it's a small job on a cheap amp I'll accept the extra hassle (though not always without grumbling ) and charge the same. If it's a bigger job on a more expensive amp I'll tend to charge accordingly.

Misty

jpfamps said:

Misty said:

How are the latest Fenders for quality and ease of repair, specifically the '68 Princeton, and Vibrolux? (Not the Custom Vibrolux Reverb, the newer one). 

Fine.

Removing the PCB is straight forward.

Thanks. I can't help thinking of these as lesser products with all the pots PCB mounted and so on, but maybe I'm wrong. I just prefer hand wired amps, but these days perhaps there's no reason to.

ecc83

I do not have the vast experience of guitar amps outlined here but I did spend most of my working life repairing "domestic" electronics and some of that was a right PITA  to fix! Continental audio gear that was fiendishly difficult to get into and virtually impossible to work on "live" (ya hear me B&O?)

Tellies were generally easy enough to access but many PCBs were of the "one use only" type, i.e. they lifted off at the least provocation. GEC print was double sided and especially feeble.

I am of course biased but pleased to see Blackstar have not been included in the "bad guys"? I sympathize with heavy chassis and snaggy Tolex tho! (there is a bit of a trick to removing the S1 45 chassis) B's print is pretty good IMHO. Not as rugged as the FR4 stuff I found in the network industry but not at all bad.

SM build is I think no serviceman's friend but if "they" want the bells and whistles at affordable prices there is really no alternative. I strongly believe that PCBs should be made available to bona fide techs and thus a customer can be given a pretty firm quote for a repair.

I have said this before but I have my own ideas as to charges. First up a non-returnable deposit. £20 is nothing these days and barely covers a tech's time booking in and dealing with the client, phone, rates and other overheads per repair item. There can be few devices so cheap that you would expect to pay LESS than a score to get them fixed? Deposits also deter time wasters and the cluttering up of the premises.

Then, I don't really see why THE SAME GUY should charge LESS per hr to fix a beat up budget amp than a £2000 bass rig? I am a big fan of a fixed service charge per item (techs usually have a good idea of the problem and how long it will take to fix it) Odd ball gear with which you have no experience can be the fixed charge plus "time&materials".

The TV etc repair trade has gone, stuff is SO cheap now (bought a stonking 24" FSTV from a charity shop for £20 last year for grandson's Xbox) but we really cannot go on having things break/wear out and being landfilled. Repairing stuff MUST be the norm and techs need to be able to make a decent living out of it and designers NOT send them mad!

There orta be a LAW(s) or at the very least a trade association along the lines of the old Radio Trades Retail Association.

Dave.

Danny1969

The biggest points of value do tend to be related to putting everything on the PCB. The cheapest amps tend to have as much as possible on the PCB because that's the cheapest was in terms of labour and parts. If designers gave more fault to what the product is they might able to make it more reliable. 

For example I had a Carlsbro bass head amp in. Very simple circuit and not a lot to go wrong except the bridge rect was on the PCB and then bolted to the chassis for cooling. Now as it's a bass head it spends it's life sat on top of a vibrating speaker, the PCB flexs because it not on enough standoffs but the bridge rect can't move because it's bolted to the chassis. So after enough gigs the bridge rectifier legs will break due to metal fatigue. You often see the same thing on numerous amps that use an I.C output stage on a PCB but the IC is bolted to a heatsink that's bolted to the chassis. If one thing can move and the other can't then it will eventually fail .... you don't need to work for NASA to realize you need to either let everything move together or stop everything moving completely. 

DJH83004

Just to reiterate ICBMs point about Mesas - because they tend to opt for relays on the channel switching, it is a real pain to replace them, which I have had to do on a number over the years. It is a messy job to get to the underside of the pcb and this where charging becomes very difficult, as diagnosing the problem and getting access to swap out a relay, could be a days job, (including a thorough test afterwards). If there are any solicitors out there, you could always work it out on your hourly rate    

ICBM

ecc83 said:

I am of course biased but pleased to see Blackstar have not been included in the "bad guys"?

It's not all good. I know they did fix the problem quite quickly, but I've just sent another customer away to contact Blackstar about a HT-5R with a fried phase inverter - burned out resistor and PCB damage. The early Series Ones had flimsy PCB-mounted pots with no proper chassis support too. They're not too hard to work on, but these are clearly design flaws which should have been obvious - especially the pots.

ecc83 said:

Then, I don't really see why THE SAME GUY should charge LESS per hr to fix a beat up budget amp than a £2000 bass rig? I am a big fan of a fixed service charge per item (techs usually have a good idea of the problem and how long it will take to fix it) Odd ball gear with which you have no experience can be the fixed charge plus "time&materials".

It comes down to whether you want to help the customer or not, and whether some money is better than no money. I'd rather charge £20 to fix a little solid-state combo that should have been a pain-in-the-bum £40 job really, than scrap the amp and not get anything because the customer can buy a brand new one for £49 and thinks £40 is too much.

On the other hand I'd be happy to charge £40 to fix even a trivial fault on an SVT, since by owning it at all, the owner has already committed to spending about that much every time it needs one new power valve...

With the oddball gear the first one is usually a 'self training exercise' too - although it's not a certainty, it's remarkable how often you then see the same gear again at some point, and then the job takes half the time, or less... but you charge the same.

Telejester

When I see pcb's with valve bases mounted on them I know it's an amp to avoid.

Danny1969

pre amp valves on a pcb is fine, power valves and transformers not so much

ecc83

Hi IC. Yes, totally agree about the early HT 5& the S Ones. As a politician who's name escapes me said "Mistakes have been made"!

Power valves on PCBs? Depends on the PCB! Time will of course tell but I never had a problem with this and if the boards prove to cook up over the years I truly hope Bs will make replacements readily available. I agree that transformers should not be on PCBs. They were in the aforementioned tellies and caused no end of grief. Line and field OP valves were also print mounted however and they got bloody hot! Cannot remember an issue.

MUCH of course depends on original design criteria (and "we" learn from mistakes ^! ) If the circuitry around the valve is protected from "collateral damage" print damage should not occur.

Tend to agree about charges for the lone tech IC. Sometimes a couple of beers and a curry will do! I based my ideas on a mate who took on almost anything electronic (I did his "better" audio kit) and if he did NOT have a deposit system he would never have done any work and his house would be slammed with junk!

Another mate, now sadly gone, opened a shop, mainly computer repairs/builds but took on other stuff to start with. Well, he hardly GOT started because, despite my protestations he would not take money upfront and had sunk within the year.

Dave.

ICBM

Telejester said:

When I see pcb's with valve bases mounted on them I know it's an amp to avoid.

As already said it depends greatly on the type of valve, the quality of the PCB and the cooling available.

Preamp valves are almost always fine - they don't get hot enough to damage any decent-quality PCB.

Power valves mounted above a decent board, biased sensibly and with good cooling provision are also fine.

EL84s mounted underneath a cheap board in a enclosed chassis and run at 18W are *not* fine...

jpfamps

Pre-amp valves on the PCB are fine in my view, as the worse think that can happen is you need to replace a socket, which is rare.

Power valves on the PCB can be very bad if a valve arcs over, but can be OK, although I would always prefer power valves to be off the PCB.

Gassage

Aren't the old 30th Anniv horrendous to work on?

jpfamps

ecc83 said:

Hi IC. Yes, totally agree about the early HT 5& the S Ones. As a politician who's name escapes me said "Mistakes have been made"!

Power valves on PCBs? Depends on the PCB! Time will of course tell but I never had a problem with this and if the boards prove to cook up over the years I truly hope Bs will make replacements readily available. I agree that transformers should not be on PCBs. They were in the aforementioned tellies and caused no end of grief. Line and field OP valves were also print mounted however and they got bloody hot! Cannot remember an issue.

MUCH of course depends on original design criteria (and "we" learn from mistakes ^! ) If the circuitry around the valve is protected from "collateral damage" print damage should not occur.

Tend to agree about charges for the lone tech IC. Sometimes a couple of beers and a curry will do! I based my ideas on a mate who took on almost anything electronic (I did his "better" audio kit) and if he did NOT have a deposit system he would never have done any work and his house would be slammed with junk!

Another mate, now sadly gone, opened a shop, mainly computer repairs/builds but took on other stuff to start with. Well, he hardly GOT started because, despite my protestations he would not take money upfront and had sunk within the year.

Dave.

I'm not sure taking a deposit would be expedient in this business. I think you would lose a lot of work.

Also having a fixed charge for amp repairs would, in my opinion, be unfair.

What I do do with lower value items is that I will do the repair for less money but I will not prioritise them.

Having said that I do have a fixed charged for (most) pedal repairs as these are a lower value item, and if I charged an hourly rate this would would become uneconomic for some repairs.

ICBM

Gassage said:

Aren't the old 30th Anniv horrendous to work on?

Yes, especially the combo. The head isn't so bad, because the same boards are spaced out instead of being one above the other - unless the fault is something to do with the switching control board, and then they can be a pig. I wouldn't recommend owning either though...

impmann

ICBM said:

Gassage said:

Aren't the old 30th Anniv horrendous to work on?

Yes, especially the combo. The head isn't so bad, because the same boards are spaced out instead of being one above the other - unless the fault is something to do with the switching control board, and then they can be a pig. I wouldn't recommend owning either though...

Yes... I have first hand on one of these.

The guys at Marshall made a complete arse of repairing it - it worked fine outside the case, then would go bang not long after coming home... y'see there is a sheet of ally foil on the inside top of the combo cabinet and the glue fails with heat (*slow hand clap*) and droops into the chassis. As soon as you withdraw the chassis, the action of pulling it out flattens the foil back down so the issue is invisible again.

It went back four times with much head scratching in Bletchley and eventually they gave up.

It took five minutes with a Line6 engineer to spot the fault and about the same to fix it permanently.

It was then offloaded on eBay with great speed!!!!

Gassage

It's a shame as the 6101 is tonally one of Marshall's finest, IMO.

Danny1969

I think on the whole everything about the repair business is getting harder. It's not just the surface mount approach but the complete lack of documentation and the fact product lines change so quickly. I work on a no fix no fee system with the exceptions of board repairs on things like laptops, iPads etc. If a customer wants me to have a go then it's generally  £50 labour fixed or £20 for trying.  Parts for I.T products are rarely an issue cost wise, but tracking down a shorted 2 pence SM cap can take hours, In general with my failing eyesight I'm quite pleased when I get something biggish ...... got a 100V line amp on the bench at the moment and some crazy Meridian all in one vocal \ keys \ bass \ guitar combo amp and I can actually work on these with the naked eye

I'm quite envious of guys who fix amps only. You actually get to know a product over the years without it being completely redesigned  every 18 months. For the most part there is documentation and you generally deal with customers who want it fixed because they have affection for the product  Plus you got this huge resource of experienced guys on places like this that are so familiar with amps then can often tell you exactly what's failed before you even look at it. 

ICBM

Danny1969 said:

some crazy Meridian all in one vocal \ keys \ bass \ guitar combo amp

Those are great! I've got the earlier LEEM-badged version in the traditional guitar-combo box rather than the carpet-covered monitor . I did have to fix mine recently but it was just one of the jumper connectors to the front PCBs not making a good contact.

Danny1969 said:

I'm quite envious of guys who fix amps only. You actually get to know a product over the years without it being completely redesigned  every 18 months.

… although Marshall have had a good go at upsetting this, sometimes. Largely because they seem to design amps with obvious faults built-in. They've had quite a few examples of real design stupidity which must have cost them a fortune in warranty work. I can only assume that they don't have anyone with real repair experience working in their R&D department.

Danny1969

ICBM said:

Danny1969 said:

some crazy Meridian all in one vocal \ keys \ bass \ guitar combo amp

Those are great! I've got the earlier LEEM-badged version in the traditional guitar-combo box rather than the carpet-covered monitor . I did have to fix mine recently but it was just one of the jumper connectors to the front PCBs not making a good contact.

Yeah this is the combo that looks like a guitar amp



This one just got some bad pots which I replaced and a couple of iffy joints, all seems fine now. 

Danny1969 said:
I'm quite envious of guys who fix amps only. You actually get to know a product over the years without it being completely redesigned  every 18 months.… although Marshall have had a good go at upsetting this, sometimes. Largely because they seem to design amps with obvious faults built-in. They've had quite a few examples of real design stupidity which must have cost them a fortune in warranty work. I can only assume that they don't have anyone with real repair experience working in their R&D department.

Well I think there is or will be a shortage of people with good design principles related to good valve design practices ..... it's such a small field now. With the extinction of CRT tellys and FL backlights on laptops and such the only place you tend to encounter or design for high voltages is in solidstate is in the SMPSU. I work on so few valve products I probably couldn't design much of a good amp around valves

Having said that I don't know if the Marshall designers don't know putting HT voltages on close PCB tracks and similar stuff is a bad idea or whever they do know but ultimately doing it that way and swallowing the warranty returns is still cheaper than the labour of putting more stuff wired off board. 

When I was selling laptop parts on a large scale people used to ask me why I used Royal mail standard post to ship thousands of parts a month rather than DHL or a similar more reliable trackable courier and the answer was at the end of the year even when you swallowed cost of the RM parcels that went missing or got damaged ... it still worked out cheaper overall to use RM than anyone else 

ICBM

Danny1969 said:

Yeah this is the combo that looks like a guitar amp 

This one just got some bad pots which I replaced and a couple of iffy joints, all seems fine now.

That's what I meant by the 'carpet monitor' one - the LEEM is more like a Marshall/Park MG, with a vertical front and vinyl covering.

Mine is one of the most useful bits of kit I own, and it cost me £40… the only changes I've made are to fit a switch for the tweeter so it can be an electric guitar amp if I need it, and to convert the headphone jack to a far more useful power amp input, which can be done by swapping a couple of connections (it breaks the signal path before the power amp, normally). The only downside is that the very cheap vinyl chews up extremely easily, and I'm forever sticking bits back down - the carpet covering is far better. I might re-box mine in a hardwood cabinet or something one day .