These new digital amps and serviceability ?

TimmyO

I recall there was some hoo-hah re things like the Blues Cube and Nextone and the deliberated unavailability of spares and lack of general serviceability - and wondered if the same was true of Fender Tone Master range - is it intrinsic tomthese style of amps or was that likely a decision Roland made that Fender haven't? 

Also - am I misremembering the hoo-hah or are folk storing up problems for later and don't realise they have 'throwaway' amps? 

Danny1969

From what I have seen the Tonemasters are using of the shelf Icepower class D power amps with integral switch mode power supply. Basically one small board is the whole power amp and available to buy for £90. 
Terribly complex to fix at component level ( I spend hours on one ) but at least for now available as a complete unit. 

No idea about the pre amp and processing but these parts are unlikely to go wrong as the voltages and (more importantly) currents are tiny in comparison to the huge surge currents in the class D power amp. 

I think serviceability means different things to different techs. Repairing electronics by changing QFN chips and sm resistors / caps / diodes is commonplace now if I can do it then anybody can learn the skills. Equipment wiser I use a Weller hot air gun and a weller long conical iron and plenty of magnification. I had to learn in order to fix Macbook boards, as unlike PC laptop boards they were too expensive to replace. These skills carry over nicely to todays modern digital amps. However there's a lot of shared knowledge in the fix Macbook Pro boards world, not so much shared knowledge in fixing modern amps. This will change though over time.

The big problem is specific IC's and their coding. replacing a generic general purpose SMC,  DSP chip is pointless unless it has the right code in it. This is a problem with Macbook boards, there are around 3 or 4 chips that have to be salvaged from scrap boards to complete repairs as new IC's are either not available to the public or won't have the correct code in them. 

TimmyO

Danny1969 said:

From what I have seen the Tonemasters are using of the shelf Icepower class D power amps with integral switch mode power supply. Basically one small board is the whole power amp and available to buy for £90. 
Terribly complex to fix at component level ( I spend hours on one ) but at least for now available as a complete unit. 

No idea about the pre amp and processing but these parts are unlikely to go wrong as the voltages and (more importantly) currents are tiny in comparison to the huge surge currents in the class D power amp. 

I think serviceability means different things to different techs. Repairing electronics by changing QFN chips and sm resistors / caps / diodes is commonplace now if I can do it then anybody can learn the skills. Equipment wiser I use a Weller hot air gun and a weller long conical iron and plenty of magnification. I had to learn in order to fix Macbook boards, as unlike PC laptop boards they were too expensive to replace. These skills carry over nicely to todays modern digital amps. However there's a lot of shared knowledge in the fix Macbook Pro boards world, not so much shared knowledge in fixing modern amps. This will change though over time.

The big problem is specific IC's and their coding. replacing a generic general purpose SMC,  DSP chip is pointless unless it has the right code in it. This is a problem with Macbook boards, there are around 3 or 4 chips that have to be salvaged from scrap boards to complete repairs as new IC's are either not available to the public or won't have the correct code in them. 

Interesting - ta. 

Yes I was thinking more about the power sections - I'm happy (rightly or wrongly) to assume that low voltage stuff is likely to be reliable (subject to not being cooked by the hot parts or bumped and broken) 

Danny1969

TimmyO said:

Danny1969 said:

snip

Interesting - ta. 

Yes I was thinking more about the power sections - I'm happy (rightly or wrongly) to assume that low voltage stuff is likely to be reliable (subject to not being cooked by the hot parts or bumped and broken) 

Yes, exactly. The only problem will be whether they have designed the boards to cope properly with vibration. Todays chips are BGA soldered with lead free solder and these joints are prone to failing with heat and vibration. On a device like a phone which gets a lot of vibration the chips are under-filled to stop the chip moving. The cables are also clamped to stop them coming loose. This needs to be done on any PCB put into a combo guitar amp IMHO

One of the reasons valve amps are so reliable (actual valves aside) is the power is voltage based rather than current based right up until the secondary side of the output  transformer. So high voltage, small currents in the actual amp  means generally very reliable unless they do something stupid like solder output valve bases to the PCB or under-spec the caps and diodes. 

The trouble with class D is we actually don't have any capacitors capable of surviving the conditions in a high current switch mode power supply for 10 years or more of hard use. Even the best stuff I've seen like HK Actor DX amp modules fail after around 10 years of 50 gigs a year in my experience. Thankfully guitar amps don't need to produce low frequencies at high power like bass amps or PA amps so they will last a bit longer.