Coreblade problem

Hi

I have a problem with the Coreblade. The effects (reverb & modulation) no longer work. I can switch channels and the clean/crunch/ultra 1/ultra 2 all work (distortion works) but the other effects don't.

My tech (a very good one) opened the amp up and does not want to touch anything unless he has a service manual. We emailed H&K and their response was to send us the user manual which does not help him.

He has not seen an amp like this before and there are so many connections and he does not want to touch it without seeing schematics/service manual.

Has anyone else had this problem? Does anyone have schematics or a service manual? I tried Googling this issue but could not find any further information.

Even though the amp works and I could technically use pedals to get effects, it defeats the purpose of this head. I got this head for the purpose of no tap dancing, super easy to use, and great sounding effects. Would hate to give up on it.

Thanks

In case anyone is wondering what happened:

1. H&K will not send customers schematics or service manuals (fair).
2. Yorkville is the official H&K servicer in North America. They are also related to Long & McQuade.
3. I emailed the H&K service team in Germany who put me in touch with the guys at Yorkville.
4. The guys at Yorkville indicated that I practically need the entire preamp circuit to be replaced. This costs $975 + labor + shipping.
5. There is no guarantee that Long & McQuade can do this repair. If they can't they will ship the amp to Yorkville in Ontario.

All things considered, the total cost may be similar to what it would cost me to get a Grandmeister 40 Deluxe.

My only concern is if the Coreblade has higher quality sounds than the Grandmeister since the Coreblade was over $3k new when I bought it vs the $1.5k Grandmeister 40 Deluxe. From what I am reading, the GMD 40 is based on the Triamp MK III so I think I am ok.

What would you guys do in my shoes?

1. Go for the GMD40 (I will buy new so warranty, newer technology, etc...) or
2. Repair the Coreblade (I love this amp and sold 4 amps as this is the end-all amp for me).

The 4 Channels of the Coreblade work it is just delay/reverb/modulation that do not work. I could technically put a multifx unit (I have a 80s Rocktron mfx rack unit that is amazing) however I would then have to program another midi pedal to get the channels on the Coreblade to sync with the FX unit. Also, it would be another thing to carry around for jamming/gigging.

Thanks for reading. Hopefully will get some advice!

Just found your post CrazieDiamond.  Sorry for missing it for so long, it isn't a place I usually go as I have no knowledge of the Coreblade at all.  That said, it is a tale of woe and I'm surprised it is as complicated or as expensive to get your amp fixed.

I understand your techs position.  The H&K amps are complex, way way more complex than the average Marshall/Fender/Peavey types.  I would definitely agree it would be almost impossible for him to work on some areas without those schematics but straight replacement boards shouldn't be a problem if he can get his hands on them.  Everything I had seen inside H&K gear shows they do things properly with easily managed interboard connectors rather than a rat's nest of soldered flying wires as some are.  I have to say I am surprised that it would take a whole preamp replacement rather than just the effects module(s) but they are the guys who know the amp innards, I'm not.  Maybe the effects are built onto the preamp board.  This is one situation which shows where that could turn out to be a bad idea.

On the score of the quality of effects my own view is the same as most other things of this nature.  Can you really hear any difference in use?  It's one thing to sit there in a quiet environment and listen carefully side by side to two units while tweaking levels to try and spot some subtle little variation in the sound, it's another to take it out into the real world and play it at volume with the rest of a band around you.  I have never found much difference in even cheap and expensive units under real conditions.  That is, unless you are heavily into high quality recording and work in a pristine studio environment a lot.  And as someone once pointed out and I keep repeating as it is a good observation, no one walked out on Hendrix at Woodstock when he played through his cheap old gear before the idea of the mythical "tonesuck" had been analysed and completely done away with.  Is there really any difference in practical terms?

I've dug around my own sources but can't come up with a schematic to help, the only info or pictures out there seem to be GM36.  I didn't think I would be able to, H&K are very close with their circuit data as you are aware.  It's their bread and butter so they should be of course.

Just one thing.  I have done a little digging looking for info and found this in the Coreblade marketing copy from Full Compass:  "Effects: 3 independant Digital-FX processors: Reverb, Delay,Modulation (Chorus, Flanger, Phaser, Tremolo)".  I would find it hard to believe that 3 independent processors would go up the spout together.  I wonder if this is a simpler issue than your tech may be imagining.  The GM36 has effects which are simply bled from the signal path and blended back into the raw signal after processing.  If the Coreblade is similar that would account for the fact that your amp is still working in every area except the effects.  The Modulation effects and Reverb are handled separately at different points in the signal path.  If that sort of setup is the case with the Coreblade then is it not possible that the problem is simply in the control/switching and not in the effects themselves, or even in the power supply to the effects board(s) if they are dedicated and separate from the main preamp board?  A little poking around could possibly show that the boards are not needed.  It's a remote chance but it is a real one.

I understand and share your reluctance to give up your own perfect amp having found it, for a new one which is always a gamble.  If it were me I would get in touch with H&K on their Facebook site rather than email, they respond much quicker via Facebook, and ask them if they would be prepared to supply the preamp/effects board direct to you or your tech.  I would do this by Private Message rather than on the open forum.  If it is public they would be more likely to say no to prevent a rush of people trying to buy H&K parts based on your precedent.  I am assuming this isn't involving a warranty claim so I don't see why they shouldn't.  If it is a straight replacement of a plain board or two in a unit without any real diagnostic or repair work to do at the component level, your tech should be able to handle that.  If not, I am sure there would be others who would be prepared to do it for you.

I've looked all over the net, and haven't had any luck finding a service manual for my Coreblade. I contacted Hughes, and Kettner once asking for a service manual for my Switchblade, and they sent me it via email. Have you sent a query through Facebook. Maybe you should consider having your tech send the email. Maybe if you have the a actually tube amp repair shop request it maybe they would give out the service manual.

I have a old Alesis Matica 500 amp, that I've taken to a couple of places, and they claimed there was nothing wrong with it, but when I got it back home it would keep going into a protection mode (shutting off sound, and fan would kick on), till it cooled down. I practically gave up on it for some 8 years, but recently I accidentally didn't plug my speaker cable into a new Boss Katana all the way in, and blew some Pico fuses, and something else. I gave Marshall Music in Lansing, Mi try, because they were listed as a warranty repair shop for my Katana  amp, and they fixed it. So with that win, I decided to take in in my old Matica amp in to see if they could figure it out, and they did. He said he had to pull the board out, and found a 5 watt resistor that needed resolder, or replaced, don't recall which. I got the amp home, and it lasted about 30 minutes before the clip light went out, and the sound barely heard. I took it back to the guy, and he cleaned out the jacks with contacted cleaner, and it so far so good. This was mostly my fault because I forgot to mention that the amp's jacks were in about a inch of water when my basement flooded. I didn't think to mention this, which cause some oxidation.

I think the trick is to find a electronics technician/ amp repair guy. I think there are a lot of amp techs, that can't test, or maybe don't want to because it would take some time to hunt down the problem, by checking all the caps, resistors, etc. You might be able to get a Multi meter, and ESR (for caps), and at least test to see if it has any bad capacitors. Capacitors have a tendency of not lasting long, because the electrolytic component inside will dry out eventually.

I know with my Switchblade amp, the effects module is separate. I haven't had a chance to look into the Coreblade, but there probably is a good chance it is not separate. I read recently in a forum that someone said the Coreblade had a extra gain stage, but I wonder how much different these amps are really. Maybe if you get the Switchblade amp schematic you could use it to guestimate what is the effects section is at.

DiB wrote:I think there are a lot of amp techs, that can't test, or maybe don't want to because it would take some time to hunt down the problem, by checking all the caps, resistors, etc.

The real truth is that nowadays most people don't want to put their brains into gear and actually think their way through the symptoms towards the solution.  While many good technicians have a real wide experience of the problems which occur in general and specifically in some amp models and they know exactly where to go when a problem crops up, too many people just follow the basic "common knowledge" approach and just swap out anything that they have heard may be a problem, like capacitors...

DiB wrote:Capacitors have a tendency of not lasting long, because the electrolytic component inside will dry out eventually

...and this is where that music industry hype leads.  This is absolutely not true in any way DiB!  Capacitors do not dry out in use.  The drying out process only applies to electrolytic types when they are physically or electrically abused and they burst and leak electrolyte or use it up in an exhorbitant way due to severe and continuous abuse.  In normal use they will always last for decades!

One reason for the electrolyte inside is for them to self heal when they develop molecular micro-punctures to the insulating layer between their two plates.  This is the normal designed behaviour as that puncturing is a fact of their life.  Over voltage causes it, as does too high ripple currents or even simply sitting without a polarising voltage on them such as when they are switched off.  When they are on with a sensible voltage within their design limits they will go on for decades without complaint.  A few molecules of the electrolyte is used in repairing those micro-punctures so you hardly notice the effect.  Every time you turn on your amp the electrolytics do this self-repairing process in the first few minutes and every time you turn it off the insulating layer begins to develop tiny punctures but not in any big way.

I have posted before on how to work out the lifespan of an electrolytic and taking worst case figures your amp could be in use continuously 24hrs per day for years before you should expect a capacitor to go down.  Statistically there will always be some outliers which give up early, VERY occasionally very early.  And it is reports of these statistically predicted few which make people believe that caps are a weak link in the chain.  They aren't.  No, really, they just plain aren't!  The idea of swapping out all of your electrolytics because they are ageing after 18months is viewed as a joke amongst engineers who actually know the components.  It's also viewed as a holiday bonus come early for some technicians!  You fix them when they go as it should be easy if you are any good with circuitry, not when you the internet tells you they must be going.  Do you swap out your car's fuel injectors every couple of years because a vanishingly small few fail in the first 18months?

As I said before:  

Bordonbert wrote:The components used inside in all of the circuitry, including the solid state stuff, are the same as have been used in valve amps for many years.  They have ratings of thousands of hours life working at temperatures way above any found around them in the amp.  Choosing the probable worst example, electrolytic capacitors today's "bad boy" components, (the ones people feel the need to block replace every few years    ), have a design temperature at which their expected lifetimes are quoted.  The cheapest category is designed for constant working at 85degC with higher spec devices at 105degC.  Arrhenius' Law of Chemical Activity says that the working lifetime of a capacitor doubles for every 10 degree Celsius decrease in temperature you drop below that.  65degC will feel very very hot to your hand but means 4 times the quoted lifetime, (as it's 2 x 10degC it means 2 x 2 x the quoted lifetime).  And remember this is thousands of hours IN USE!  I've posted figures for this before to show how unlikely it is to be a problem.

An example from RS Components catalogue:  Nichicon UPS1E101MED 100uF 25V 105degC electrolytic, nothing special today and cheap to buy.  Quoted life expectancy at 105degC = 3000hours (pretty average).  If used at around 65degC, (too hot to hold so still ridiculously high in real terms), life expectancy increases by 16x (Arrhenius Law, 2x for each 10degC below quoted max) to 48,000hrs IN USE!  That's 5.5years of continuous use if not abused, and playing through it loud or overdriven doesn't abuse it in any way.  Even a cheaper 85degC device would still have 4x the lifetime, 12,000hours or 15months continuous use.

Well! I'm sorry but like you I can't come up with a schematic or Service Manual for the Coreblade. H&K are very precious about their schematics as you would expect they would be, their business is built on them after all. They just aren't available out there in internet land as widely as other more common makes are.

If they won't supply one for your own personal tech how are you placed to use a H&K recommended repair centre for the area you are in? They do have a network of their own recommended repairers which they sanction but I know that sometimes means shipping the amp as the centre is too far away to visit. We certainly don't have the circuit diagrams here, not being affiliated to H&K in any way. We even have a policy of supporting H&K by not allowing the free spread of any of their schematic info in our own site. Some are out there of course, the TM18 and GM36 Service Manuals are well known for example. Some have just never appeared and yours is unfortunately one of them.

Can anyone else help with this one?

I had the same issue called a few go to amp repair places and one claimed to not be doing any amp repairs anymore and they referred me to another place and they were too backed up. I got the impression. they heard the amp name and realized it be a bad idea.

It finally crapped out and wouldn't turn the tubes on because the TSC was not getting the proper information from the 10 amp fuse. I tried to figure out the issue myself but accidentally toasted some resisters in the process and the put up 80 dollars, and they fixed it for 280 dollars, which included new tubes.

Note Yorkville is the authorized repair facility for H@K.

Note 2: If you ever had issues with the transformers coming lose like I did in last and had decided to fix and tighten them down yourself make darn sure the transformer and the bell housing is tight against the metal amp housing, because mine was not and the amp case it was got dropped at some point on the way back which jarred the amp so much that the transformers were so lost that I could see 3/8 inch gap between the bell housing and the amp. The transformer bolts also pull up the metal about 16th of an inch. Since it was my fault because I didn't have the transformer and bell housing tight I gave it a second go at fixing that issue with a couple of big washers on each.

Great advice there DIB. It's sad that H&K won't address this problem of releasing the schematics. I agree with them that it is their intellectual property and that is what their business is founded on but I think there comes a time where you have to say they are harming their own reputation by impeding the repair process.

Yorkville is the known name for repair but I had assumed that was simply the centre of a network. It can't be good to not have a number of acknowledged centres across somewhere the size of the USA. In the UK alone we seem to have a shed load of places which take on repairs. Are you in a situation out there in the US where you can find a dealer but they all send their warranty repairs through to Yorkville?

Which is likely due to the fact that the amps don't seem to be super popular in the USA. I think they are having more of the Grandmeister's.