Champion 30 troubleshooting

[pzelchenko]

Thanks in advance for helping with this. I am trying to get a Fender Champion 30 operating for my 8th grader here in Chicago. He just bought a Starcaster with (mostly) his own money, $60 from Craigslist, from a kind-hearted pro musician who adjusted it for a customer who never picked it up. I just found him a couple of effects boxes from a rummage sale for $2 each. I had this amp lying around from an old tenant. He's already pounded on my crappy classical guitar for two years and so he's really excited about this. He knows more rock history, discography, and riffs than I ever knew and he's having fun. A $64 guitar rig is a great deal, especially for a kid who obviously enjoys this so much.

Except the Champion 30 is blowing its fuse. He downloaded the schematics; I really appreciate the care that these Fender engineers put into documentation even on these cheap products. I'm now a big Fender fan despite zero experience with electric guitar gear.

The first time I powered this up a few months ago, I think the fuse blew; I replaced it and saw the AC light glowing yet I vaguely recall I wasn't getting any speaker output. This time we powered it up and saw AC light glowing, and also the reverb LED glowing when kicking in reverb (meaning that there must be some DC), but still no sound out of the speakers even with the guitar plugged in.

We opened it up and were seeing about 52V between TP3/TP4 and about 32V between TP5/TP6. This happens to be exactly twice normal (should read 25.9V on the former and 15.1V on the latter), so I guessed a possible short in the transformer secondary. I suppose I could take it out and test it either powered or through an ohms calculation. Next, I partway pulled up the lugs at P3 and P5 to get at TP1 and TP2, but when I powered back on, the fuse blew again before I could test. Not sure how I did that.

What is the most likely diagnosis? I'm glad that this probably originates on the AC power side of the board, but if I replace the transformer am I likely to spend the next two months sourcing the rectifier diodes and other AC parts, then in turn moving down the circuit and finding IC's blown and other things? Or is this a typical problem and no headache? Or is it impossible to say?

Also, out of curiosity, what's involved in the so-called "reverb pan" in the cardboard box? How does the delay work in there?

Thanks again in advance for your help, guys. If you need any other information, please don't hesitate to ask.

Peter from Chicago

[J M Fahey]

Champion 30
The first time I powered this up a few months ago, I think the fuse blew;This time we powered it up and saw AC light glowing, , but still no sound out of the speakers even with the guitar plugged in.

We opened it up and were seeing about 52V between TP3/TP4 and about 32V between TP5/TP6. This happens to be exactly twice normal (should read 25.9V on the former and 15.1V on the latter), so I guessed a possible short in the transformer secondary.

No, what they state as voltage in those TP is relative to ground/chassis , which sits exactly in the middle , that´s why some are indicated as positive and the others as negative.
Ground is neutral, neither positive nor negative.
So end to end it´s correct, both voltages will add and you´ll measure double.

I suppose I could take it out and test it either powered or through an ohms calculation.

Your transformer is fine.

Next, I partway pulled up the lugs at P3 and P5

You shouldn´t have messed with them.

when I powered back on, the fuse blew again before I could test. Not sure how I did that.

Now we have more doubts than before.

What is the most likely diagnosis?

Dead TDA1514 .

I'm glad that this probably originates on the AC power side of the board, but if I replace the transformer am I likely to spend the next two months sourcing the rectifier diodes and other AC parts, then in turn moving down the circuit and finding IC's blown and other things?

Well, you won´t replace the power tranaformer.

Or is this a typical problem and no headache?

It looks like a typical problem, but I don´t discard the posible headache because we don´t know what happened when you pulled and reseated those wires.

Or is it impossible to say?

It depends on how accurately you follow instructions.

Also, out of curiosity, what's involved in the so-called "reverb pan" in the cardboard box? How does the delay work in there?

Basicallym a spring with a "speaker"  in one end and a "microphone"  in the other.
Sound takes from 20 to 50 milliseconds to travel end to end, so that little spring is equivalent to a 10/30 yard long tiled passageway .... very clever.

Peter from Chicago

[pzelchenko]

Great information about the voltage, JM. I get it now.

Can you explain why it was bad form to slide those lugs up? I did it with the power off and the box unplugged, and it looks as if from there it is just going straight into the bridge rectifier. Is there an easier way to read that voltage without unmounting the board? The leads from the transformer are jacketed all the way into the coil wrapper and the lugs are fully sealed, so I can't put the probe anywhere unless I either move the lugs up or unscrew the board.

I ordered two of those amplifiers over eBay for $3.40 each including shipping, a pretty good deal. That brings the project cost up to $67.40! They are on a slow-boat but should arrive in a couple of weeks. When I get it in I'll let you know how it goes. I'll also check for bad solder joints since I read that this has been a problem. Thanks.

[Roly]

Hi pzelchenko and welcome.


Since you appear to have okay voltages we can forget about the power supply, it seems to be working correctly and a short on the transformer secondary would give you little or no voltage, instantly blowing fuses, or eventually a smoking transformer.

As JMF says, most likely a dead power amp chip.

Typically if you carefully replace that you should be out of the woods (and still be well ahead of the curve with your canny purchases  :dbtu: ).

You should also test the speaker by unplugging it and flashing a battery across the plug - should produce a loud splat if it's okay.

[J M Fahey]

It's not "bad manners" unplugging those connectors, just that sometimes they are plugged the wrong way (the door or phone rings, the cat jumps in your lap, "honey" has something *important*  to tell you, etc.) .
We've had a couple horror stories here

2 details:
1) build a lamp bulb limiter and use it.
It's on a thread here.

2) TDA1514 have been out of production for a long time.
I'd trust one bought at, say, Farnell or Mouser or similar supplier .... "an E Bay Hong Kong seller" not so much.

So "just in case" search for a respectable supplier.

Hey !!! the EBay one might work, so don't hurry to buy another, wait until you test  it.

[pzelchenko]

Wow, JMF and Roly, I really appreciate your ready knowledge. I would have had to pay $50-$100 for this advice if I'd reached out to someone here.

I slid those lugs up on the stanchions a couple of mm but did not remove them (a trick I learned from an old TV guy who long ago left us for hell or worse). That way I know where they need to go. But then it's AC so it shouldn't matter. Thanks for the advice, though. If that is all, then maybe it didn't cause the problem. But then the fact that the fuse has blown twice without obvious provocation makes me wonder what else is wrong. Can a short in that amplifier SIP cause it?

Already tested the speaker, it works fíne. And I hear you on the China problem -- I worked in Beijing and HK for Apple (I was Apple's first "white guy" or 老外 in China). But I asked a friend of mine at Intel who says that it's never a bad gamble, considering on the one hand that it is likely to be OEM stock (boards are all stuffed there anyway now), and on the other that China's rogue fabs, at least for simple SIPs and DIPs like these with very few devices, are as good as ours by now. The one problem is that some of these things for sale seem to be waved off of old boards. That is one reason I bought two.

[J M Fahey]

Wow !!!
So did you work for or meet Terry Gou ?

AS of chinese semiconductors, the factories set up there are run and controlled by the original people, under strict quality norms, so, say, a transistor or IC by, say, Fairchild or ST or whatever is guaranteed the same no matter where the plant is set up.
Same machinery, blueprints, secret sauce, you name it.

FWIW I have glued to the top of my bench a National Semiconductor label stating

"Semiconductors made in one or more of the following countries ... >list of some 15/20 countries< ...the exact country of origin is unknown"

And just found in a ruling by United States International Trade Commision a plea by AMD, the famous makers of microprocessors running many of our computers, about the impossibility of labelling individual chips with *all*  the data,because:

AMD's semiconductor devices are typically made in China, Korea, Malaysia, and Taiwan from wafers that are diffused in Germany, Singapore, Taiwan and Japan.

AMD has its semiconductor devices diffused in Germany or Singapore. After these semiconductors are diffused, they are shipped to Malaysia where they are cut. When the cutting of the wafers is completed, the dies can be handled in two distinct processes. In Malaysia, the chip capacitor will be attached, testing will be performed, and the lid will be attached. Then the processor will be shipped to Singapore or Suzhou, China for testing, marking and packing. After the testing, marking, and packing operations are completed, the processors can be shipped directly to customers or to an assembler, who will pack them into trays.

:loco   :duh

[Roly]

How much trouble would it be to put the full production record of that particular assembly, on the chip itself as accessible ROM?  Unique self-serial for every dice/assembly.

Ooops?   


So do we have lift-off?  Or more fault-finding to do?

[J M Fahey]

I guess that particular operation (ROM) is done when the original salami is made.
If it's later sliced in another Country (Continent  ), put inside the bun in yet another, mayonnaise in another, lettuce and tomato in another, packed in another, and so on, it's sort of hard to say where that sandwich was made.
That said, some of the operation splitting is ridiculous, I can understand that very critical and advanced diffusion is made in one place and all other simpler/cheaper operations somewhare else, but all that *presumed*  Country hopping (while maintaining sensitive dies CLEAN) stinks of Tax evasion, taking advantage of every Country's particular advanced Industry promotion Law.

Sounds very fishy to me.

[Roly]

Quite so.  Somebody is getting ripped here for sure.

Dead TDA1514 .

Are we there yet?   8|

[J M Fahey]

Some movements of delicate parts across the World simply do not make sense.

Just this mornig while sipping my wake up coffee I saw a program on a special VERY flashy Mercedes Benz model SLS on Discovery Channel.



The car is assembled in Stuttgart in the World's largest car factory, with some 28000 employees but that flashy red body is made and painted in Graz, Austria.

They explained the pains they took to move it 650 Km without scratching, staining, blemishing it.

We are talking a product which if touched with a bare hand can then be wiped with a handkerchief to remove fingerprints ...... and even so that worried them.

And it can be loaded on a truck and unloaded next day in the other factory, just travelling by (excellent) roads.

Yet Semiconductor makers want us to believe that raw unencapsulated chips, which are produced under these clean room conditions:

are cut in one country, sent to another to be tested, to another to attach wires, to another to encapsulate?

Yea, sure, I bet they also hired this Transport airline to do all that moving around:

[pzelchenko]

Quite so.  Somebody is getting ripped here for sure.

Dead TDA1514 .

Are we there yet?   8|

Sorry for the belated reply. Yes, we are there. It is election season in Chicago and I do political campaign consulting; with contract problems and other fires to put out there was little time for play. I received the amplifier chips from China in under 10 days, and they had the Philips logo on them. I didn't have any thermal paste for the heat sink, so I scraped as much as I could off of the old one and re-used it. I hope it is enough. After replacing the chip and the fuse, I switched it all on and plugged in the guitar; it worked great for a few minutes outside of the cabinet. But after carefully remounting the board to the chassis, it stopped working. Had I done something stupid? Had I already burned that chip out?!

I saw voltage at the external speaker jack, thank heaven. But no speaker output. When I removed the board, I was relieved to see that the foot-pedal and external speaker jacks had bad solder joints, another victim of wave soldering, just like with our Kurzweil keyboard. I'd estimate that one in five or six retail electronic devices go to an early grave because of such problems. Anyway, I showed my son how to fill those in. He is ecstatic. For under $70, this cheap Fender rig of his has a rich, satisfying sound and lots of dynamic tunability. Is the slight hum on both channels normal?

I've never used an electric guitar in my life, and I'm certainly no expert at acoustic. That said, it seems that after 30 years of not knowing, it turns out I could always do pretty fair blues licks and solos. It seems to do with the special tone that you can get with subtle pickwork on a fine steel string, amplified. And for this we don't need "11"; even with the volume at 2 this thing is much louder than my classical guitar; being able to focus in on that detail leads to the joys of the electric guitar. I never quite got that until sitting down alone with this rig and experimenting.

Thanks so much, especially to JM and Roly!

P.S. No, I never knew Gou. We may have met at banquets in Beijing or Hong Kong. I certainly know him by reputation, though. My former girlfriend is one of China's most sought-after HR consultants. Former, because I'd never see her: my time in Beijing was spent sitting around while she'd jet off to Foxconn, Hua Yi, Goertek, etc. to rescue them from expansion woes. They open a factory and add 5,000 employees, she camps out for weeks with her team building colossal databases and thick employee handbooks. The human toll is well-known: high suicide and divorce rates, suffering children, cities and regions buffeted by the economic effects, environmental fallout. If you want a fascinating read, try China Shakes the World by James Kynge. Among other fascinating facts, Kynge relates the story of a massive bankrupt German metal foundry, of hundreds of acres, that in 2003 was essentially labeled, disassembled down to the screws, and shipped on barges to the Yangtze Valley.

[J M Fahey]

Thanks for all your "insider" data

[Roly]

Thanks for the great report.  Very good to hear.   :dbtu:

I'm a little worried about the heatsink compound.  Old stuff drys out and may become less effective.  Just about any electronics store worthy of the name will sell you a tiny tube of white heatsink or thermal compound gunk like "Unik" (that basically behaves like acrylic paint and will get all over everything if you let it).  It would put my mind at rest if you went back inside some time, cleaned off all the old gundge (I find toilet paper is good) and apply a thin even layer to the IC pad, then whack it back - a little should ooze out around the edges.

And interesting about China (from an Aussie "high carbon" perspective  :grr  ).