Blackheart Little Giant head blown.

[Duffy]

Possibly someone knows what happened or has had a similar instance of what follows.

I was playing my Little Giant at mid volume last night when it stopped producing sound and the red light went out.

An inspection this morning revealed that the fuse at the power cord input had blown, two amp fuse.

Opened the back and the EL84 has black flash residue on the inside of the tube glass at the site of the little rectangular openings in the tube plates. This appears to be burn marks from the tube blowing out catastrophically.

Remedy: a brand new Sovtek EL84 and fuse installation blew out immediately upon powering up the amp.

Condition: the amp is blowing the fuse immediately upon power up.



Plan of action: Tomorrow I am going to pull the amp chasis out of the head and closely inspect it for obvious hot spots, bare wire shorts, broken wire ground outs, burnt components, etc. I may possibly isolate an obvious short or other problem that will be easy to fix.

Help or ideas are definitely wanted. Anybody have this happen to their Little Giant?

What does this sound like; and does it sound like I will be able to isolate the problem and take corrective action?

I will take it apart tomorrow hopefully, and take some pictures of anything that looks suspecious.

I will not have this amp repaired by a pro tech because it cost only 139 US, and I'm not going to pay more than it cost to fix it.

Being a fairly simple amp design I'm hopeful that I will be able to identify an obvious problem that is not expensive to correct.

I'll keep you posted.

The good side: I got out my brand new, new style Epiphone Valve Junior head and rigged it up to my Epi So. Cal. cabinet that the Blackheart had been driving. Pure beauty. Ibanez ART300, "Swamp Water" plugged straight into the VJ produces incrediblely beautiful tone and goes into overdrive very nicely a little past half way open. Then I plugged in the Fender Am. Std. strat and it replicated the beautiful tone, similarly to the ART300, producing tones far superior to the more complicated blackheart.

I had relegated the VJ to placeholding status. I forgot how great it sounds and it certainly sounds fantastic. It is staying in my amp wall, regardless of what happens to the Little Giant.

I plugged a Boss tremolo pedal and an overdrive OD-3 pedal, along with my new Digitech Hardwire reverb pedal in between the guitar and the VJ, much to my delight. Awesome sounds coming out of this rig now. Very awesome.

So my bedside set up is real good for now: the newly hooked up VJ rig with the four by twelve cabinet plugged into one guitar, and my Delta Blues plugged into another guitar with a Bad Monkey in between it and the guitar.

This provides me with all the charm necessary to quickly put me and my fiance asleep with the guitar laying across my chest, eagerly awaiting to be reignited for yet another sleepy rock and roll.

 

[oldguy]

I hear ya..... I plugged the old modded V.Jr. into my 4x12 Sunday. Ran my Agile LP and then my Agile AS1000 semi hollow through my pedalboard, which includes DVM's original ZYS (actually the second one he ever built, I believe. He kept the first one for himself!), and it sounds great still to this day. Cranked it wide open, and let the tubes do their thing...... pure sonic bliss.

 

[jim p]

try over at Sewatt

You could post over at Sewatt.com and see if anyone there has a response to your problem. If you are going to get in there with a volt meter you may want to make a light bulb current limiter to help you trouble shoot the problem. If the power tube did go soft and draw high current it could have changed the value of the cathode bias resistor from excessive power dissipation. The resistor would usually increase in value so a new tube would draw low current but maybe it went the other way or the cathode bypass cap could have shorted that would cause high current from near zero bias on the tube.

 

[kiteman]

Wow Duffy, I'm really surprised that the amp blew. They're supposed to be overbuilt and really heavy duty at that but I don't know about the OT though. Sounds like the OT shorted, just my guess though.

Hope you get 'er back on the road.

 

[Duffy]

Blackheart

It is a cool amp and especially cool looking. I'm going to look inside and see if anything looks obvious.
Paying someone to fix it doesn't seem cost effective considering it was only 139 to begin with.

Maybe there is a service bulletin out on these or something. It is definitely out of warranty.

Maybe I can fix it or have it fixed inexpensively, otherwise it is not worth it.

 

[marnold]

Sounds like a job for Tung or DVM!

 

[duhvoodooman]

I really don't consider myself qualified to start giving amp troubleshooting advice (pedals, yes....amps, no). But I have put out an all points alert for Dr. Tung! I'm sure he'll drop by forthwith....

 

[tunghaichuan]

It is hard to diagnose these types of problems over the internet, so posting pictures would be a big help.

Before poking around inside the chassis, you want to make sure you drain the filter caps, you can get a nasty shock if you don't. The easiest way is to leave the amp on and unplug it. Play through it until the sound dies out. Then let it sit for a while.

It could be a lot of things, so post some hi res photos of the PCBs and anything that looks like it might be toasted.

 

[duhvoodooman]

It is hard to diagnose these types of problems over the internet, so posting pictures would be a big help.

:thwap I should have known enough to have posted that comment myself! Over at the BYOC Forums, photos are the first thing we forum mods ask for. And like we always say, make 'em "big, well-lit, well-focused closeups"....

 

[tunghaichuan]

Forgot to add:

The Blackhearts use the lead-free RoHS solder, so they can be difficult to work on. The PCB is double sided and there are joints on both sides of the board on some of the components, so that can make it a challenge to work on them as well. In addition, if you use too much heat, the traces will lift so watch out for that.

I've been meaning to open my amps up and do some mods, but after hearing a few horror stories about working on those amps, I've been kind of reluctant.

When you're looking inside the amp, look for any burned components, black or carbon deposits or any components with discoloration.

 

[Tig]

When you're looking inside the amp, look for any burned components, black or carbon deposits or any components with discoloration.

Also look for any components that are not "normal" shaped or appear "bloated".
I haven't actively T/S'ed component level boards since the 80's and 90's (you wouldn't believe how crude and ancient the systems at NASA used to be!), but I still remember a few things, kinda', maybe...

 

[jim p]

They have the schematic in the FAQ section over at SEwatt.com the amp has a bleeder resistor in the power supply so the caps should be discharged by it. If the pentode/ triode switch shorted to chassis it would cause a problem so it would be one thing to look for. The cathode bypass cap for the EL84 is 50 volts so not so sure it could have overvoltaged and shorted but you never know. If it comes to needing to replace the output transformer you have a lot of choices that could lead to better tone. Musical power supplies OT8 or OT10, a couple over at Triode Electronics to choose from, a 15 watt model at Ted Weber some as low as 19 bucks without shipping.

 

[Duffy]

Blackheart

Almost opened it up today.

Tomorrow I may open it up and take some pictures with my Nikon DSLR after I try to identify possible culprits.

The only other indication of a problem prior to the blow out was a few days before the blow out when the red power up light failed to come on when powering up. After minimal switching back and forth on the wattage toggle it came on and stayed on in each instance. This may be linked to the short or wiring problem. Never before had the light not come on when powering up.

The replacement Epiphone Valve Junior, new style, sounds so much better than the Blackheart that I am not putting the Blackheart back in the amp wall if it gets fixed. I will use it as a portable, stand alone unit with my other cab.

The Epi VJ sounds incredible with a pedal line up in front of it; overdrive OD-3, Digitech Hardwire reverb, and Boss tremolo. Using one or more of the effect pedals, or none at all, the VJ sounds incredible with sss single coil strats as well as high quality humbucker guitars. I'm going to use the VJ a lot because it is great and should get used, as such. I hope I don't have a reliability problem with it that even comes close to the Blackheart's record. That Blackheart has only a few hours on it, never abused.

Possibly opening it up will reveal a simple problem causing the blow outs. That would be nice. The Blackheart is such a simple amp to begin with I wasn't expecting problems any time soon.

Now that I'm a bit paranoid I'm hoping that the new style VJ's have an outstanding reliability record, and that it will stand up to heavy use, because I am definitely going to use it heavily, as one of my main bedside amps, to see if it holds up really well.

If it doesn't hold up either, I have a Peavey JSX Mini Colossal that I will use as the head for the cab and see how that stands up. The attenuator on the Mini Colossal is okay, but it definitely sucks tone when turned down significantly. I like the tone with the attenuator wide open.

I wonder how that cheap Kustom 99 dollar one knob five watt head sounds and holds up? Maybe I should consider an Egnater fifteen watt Tweaker or that twenty watt Ibanez tube screamer tube head.

Anything known about these? Might as well check them out while I investigate the problem with my Blackheart.

Tools and camera later today. That is if I can tear myself away from playing the VJ So. Cal. strat and HP Signature EXP superstrat HB connection - this is very fun and doesn't look or feel like work.

I will try to get on this and get some pictures up along with a couple new guitars I have been reticent in posting.

 

[kiteman]

I have that cheap Kustom 99 dollar one knob five watt head.

I haven't been using it but it's because it's too loud. Yea, a 5 watter that puts out like a 15 watter. Sounds good though.

 

[Duffy]

Trying

Additional info.

I took the amp apart and looked it over real good. Three more fuses inside, side by side, all good. No burn marks on the board or anywhere else. No swollen caps or resistors, etc. No evidence of any burn out.

I'm going to try to get some more small three mm fuses that go into the little door under the power cord and try plugging it into a different jack. It has been blowing this fuse IMMEDIATELY upon plugging in the amp, so there is no way I can use my digital multimeter to trace the current to a possible culprit, unless I can get it to stay on; and if it stays on I'm checking to see if it outputs to the cabinet and produces sound.

Very strange that this power cord fuse is blowing right there at the input point of the power cord. No evidence of messed up wires or burned components at the power cord input point - all wires going from it look good. Very strange.

Today I'm going to try to get some fuses - two amp three mm mini buss type cylindrical fuses, hard to find.



Anyone have any ideas what this could be?

Everything looks pristine inside the head chassis. Just blowing that fuse at the input point for the detachable power cord. Tried switching cords and immediately blew that fuse too.

I plugged in my Epi new style V Jr head and hooked it up to the same cabinet. Worked great, for a few minutes then the volume faded fairly quickly and came back in after a while then faded again.

Much checking it out to now avail until I finally noticed a couple days into checking it out, that there is an opaque white two piece coupling buss fuse container between the wires coming out of the inside of the amp and going to the power supply, a very short distance. This white fuse container was cock eye'd, I thought it was something else; it was not straight and rigid like a usual fuse holder.

Close examination revealed that the two locking tabs on the male cylinder that inserts into the basket female fuse holder receptacle were broke off, how I don't know.

This loose, unlocked fuse holder was allowing the cylindrical glass fuse to make intermittent contact inside the holder, resulting in the fading in and out of the amp as I played, much to my confusion.

Well, I finally figured it out and taped it shut with electrical tape, ineffectively I must note becasue the heat must have loosened the adhesive on the electrical tape and the fuse holder slipped apart again. Last night I fixied it semi permanently with duck tape strips that hold the fuse holder together way better. The wires at this point are so short that replacing the fuse holder would be difficult to do correctly unless I added wire, which I'm not hot on doing. I will see how the improvised solution holds up.

Just tried two slow blow fuses on the Blackheart - both blew immediately and I heard a slight buzz coming from the area of the transformer type large black box'y type thing on top of the amp chassis across from the Power Supply. The one that says 4, 8, and 16 ohms on it. This must be the component that allows you to switch impedance when you plug into the various impedance jacks; the wires from the speaker out jacks go into it. A slight fizz and then nothing. I didn't even see the power light come on. Very confusing.

How does an amateur fix something like this? The Crate engineer told me I could probably figure out what the problem is and fix it myself. I can't do this without help, especially since I can't check where my power halts in my circuit. If I had power in the circuit I could isolate the component causing the problem.

I think the power supply is shorted and that's why none of the secondary fuses are blowing.

The on off switch says On/On on the top and bottom of the case by the spade connectors and is just like the 3/5 watt power switch, exactly - same part number and exact appearance. Just two more wires attached to it. Seems like it should say on and off. It is definitely not obvious what this switch is but it looks pristine.

I may have found two hot solder spots on the pcb board where two wires attach saying they are "B" ac taps or something like that. Possibly these feed the impedance transformer or whatever the box is I heard fizz shortly.

Any insight is appreciated if any of this rings a bell.

 

[kiteman]

I suspect the power supply transformer, most likely on the primary side.

 

[tunghaichuan]

I suspect the power supply transformer, most likely on the primary side.

That's what I suspect, too. If your amp is blowing fuses on the IEC connector, then something on the primary side of the PT is shorted, most likely.

 

[jim p]

The transformer that was buzzing was the one with a 4, 8 and 16 ohm label on it? If so that is your output transformer I would think and not your power supply transformer. I think in a previous post you said you had to toggle the pentode / triode switch to get the amp to work so if the switch went bad and was shorting to chassis that would short the plate supply and draw high current through the output transformer causing the buzz. You can try removing fuse 1 and fuse 2 inside of the amp then replace the line fuse and see if the amp blows fuses then. If the line fuse does not blow then you have a short in the plate supply to ground, maybe at the pentode triode switch.

 

[Duffy]

Blackheart

Jim P-

Email me if you can. I would be willing to take you up on that offer to help me out on fixing this amp. It is in perfect shape, outwardly. Just can't figure out what is wrong with it and don't have the expertise to identify and correct the problem on my own. A repair shop would be more expensive than a new amp.

I'd like to save this one. This job is beyond my abilities.

Email me and let me know if you still want to help out. I will be responsible for all incurances.

Thanks for the offer.

 

[jim p]

e-mail sent

If you click on the name of the person posting a menu should appear with a link to send an e-mail. So you should be able to contact me that way. I also sent you an e-mail with my e-mail address.

 

[Duffy]

Jim P

Your name on the fret has the email and private message drop down options disabled. Didn't know if you knew that. On mine they show up.

 

[jim p]

Thanks I checked the box so I can receive e-mail now.

 

[jim p]

If a transformer is bad

If the power supply transformer has a bad primary Ted Weber has one for the stand alone reverb that has enough current capability for 25 bucks without shipping. On the output transformer there are some replacements that are also approx 25 bucks without shipping. The lower price ones will not have all the taps as far as 4, 8 and 16 ohms. Just looked into it because over at Sewatt someone posted about having there primary go bad on the power transformer.

 

[Duffy]

Little Giant

On the output transformer I only need 8 and 16 ohm outputs. I could get away with a 16 ohm only if I had to, both my cabs are 16 ohms but some amps have 8 ohm speaker inputs.

I will look into the shipping and get the show on the road.

An onboard reverb mod would be really cool if a good one is possible.

I need to get a pickup boost pedal or a treble boost pedal. Do these boost pedals mess up your preamp if you overdrive them too much? Thought I read that they could have a harmful effect on the amp if the level was turned up too far.

Thanks for the info.

 

[jim p]

Well if you will need an output transformer with 16 ohms the OT8SE or the OT10SE (see here http://musicalpowersupplies.com/2.html ) would work. I have not used either one but I would get the OT10 bigger is usually better for bass response. But you may not need one anyway. On the reverb there are sound clips of the Belton digi reverb here http://www.thefret.net/showthread.php?t=9379&page=21 post #388. If I still have all the parts and PCB it would be approx 50 bucks to add it. The main issue would be the location of the reverb level pot on the VJ amps I have played it safe and installed them on the back panel. On the overdrive not sure you will harm the tube using one you would need to cause a high control grid current to do that. You could have blocking distortion if the output of the box is capactively coupled with the high input impedance of the amp. That is where the Fender style high and low impedance inputs would come in handy. You could make a low impedance jack to plug the box into then plug that into the amp or modify the overdrive box maybe.

Just going through the posts at Sewatt there is this output transformer at Triode Electronics http://www.triodeelectronics.com/40-18031.html that everyone is happy with.

 

[ZMAN]

He Duff don't get me wrong. I have been reading this thread and I still can't get my head around these little 5 watt amps. 138 in amp dollars is a set of tubes for a good 25 watter. I would think that these are disposable after the warranty is up. When I see numbers like 50 for this and more for that I see you wasting money for little gain. I know you are trying to find an easy fix to the problem but how much workmanship and parts can be put into a 140 dollar amp?
Not to say that I haven't wasted money on gear, but I would cut my losses and scrap it!

 

[jim p]

approx cost of parts to repair and price of amp

The amplifier costs 200 bucks at MF new. If you replace an output transformer it should upgrade the tone of the amp for approx 30 bucks. The 50 to 60 bucks is to add reverb to the amplifier. If the power supply transformer is bad the one at Ted Webber to replace it should cost approx 30 bucks. So to repair the amp the parts should be approx 30 bucks if you need to replace a transformer less if just a short, bad switch or bad cap.

 

[Eric]

I also feel that, in cases of modding, repair, etc., frequently the owner does those things as part of a learning experience.

I see your point, ZMAN, but the counterpoint is probably that getting advice on a message board is free, and if nothing else, this is helping bolster Duff's knowledge of this sort of thing.

 

[ZMAN]

I also feel that, in cases of modding, repair, etc., frequently the owner does those things as part of a learning experience.

I see your point, ZMAN, but the counterpoint is probably that getting advice on a message board is free, and if nothing else, this is helping bolster Duff's knowledge of this sort of thing.

I know what you are saying is true no doubt. My whole issue is the 5 watt thing. I think that these tube amps with such low wattage are being cranked to the max to get them to distort. I am pretty sure that if you took a 25 watt amp and ran it full out you would end up with problems pretty quickly as well. I have owned several small practice amps both SS and tube and I have had NO problems with them. Of course they are 15 watts.
I use a pedal to get the distortion.
I am a huge believer in help from message boards. They are an invaluable source of information and help. I guess I should not have said anthing that isn't really helping Duffs problem.
I have a pretty good relationship with Duff, and I was really trying to save him some money.

 

[Eric]

I am a huge believer in help from message boards. They are an invaluable source of information and help. I guess I should not have said anthing that isn't really helping Duffs problem.
I have a pretty good relationship with Duff, and I was really trying to save him some money.

I wasn't trying to say anything about your comment -- it was just to offer up a possible explanation.

I try to remind myself when I see people modding the life out of a piece of gear and sucking any resale value out of it that they are probably doing it to hone their skills, not to increase the value of the item. It's a different way of thinking.