Fender 25R frontman loud hum

[Slobrain]

Hey Enzo,
I figure I would ask you this question, a buddy brought me a fender 25R frontman amp1x10 combo. Its got a loud hum so I checked and its got DC on the speaker out.

My question is its got a TDA1514A output chip, do these go bad and take out any other parts or just the chip itself? He asked me if I would fix it and its a simple amp and trying to keep repair cost down so I was going to order the chip but wondered if you see anything that causes them to burn out other than cranking them up too loud.

Thanks

Slo

[Enzo]

Most of them don't burn out, so I don't worry about it. On the other hand using the little amp at stage volume is tough on it.

Usually I see the power amp IC fail with rarely anything else bad.

[Slobrain]

Thanks Enzo,

Ill probably order that chip from Ebay to keep cost down, I need to order him a speaker too, the speaker coil burned. Yes, I believe he did a gig with the amp so that probably caused this issue.

Thanks

Slo

[olddawg]

I've seen several of the frontman series have the main filter caps become completely unsoldered. It causes a helatious hum and can damage speakers. Also diff amp pair problems. In this lower wattage one the D.C. On the output most likely means the output IC... but it never hurts to check.

[DrGonz78]

Ill probably order that chip from Ebay to keep cost down

Wasn't there an issue with the TDA1514A chips being faked?

http://music-electronics-forum.com/t36372/

[Slobrain]

I just read those threads and they were from 2008 and 2014. I sure hope the China makers are making the real ones now, I just bought one from EBay... I guess I'll find out when it gets here... So the TDA1514A are not made anymore? Doesn't Fender still uses these in their frontman25R combos that sell at GC. I seen a bunch of TDA1514A on EBay, cheap too. Is there something I'm missing here?

[Enzo]

One thing ebay is missing is my purchases, I never buy parts on ebay. Even if most of them are real, it only takes one purchase of fakes to wipe out any savings I get on all the others.

My Frontman25 schematics are all from 2002 or thereabouts, 15 years ago. Not sure what Fender puts in them now.

Even if someone in China makes real ones, China isn't generic, there will be fakes of most anything until something major changes.

[Slobrain]

If anyone knows where to get a real TDA1514A fairly cheap could you please let me know. The one I bought from Ebay wasn't any good.

Thanks

Slo

[Jazz P Bass]

The 'real' TDA1514A is no longer in production.

I would go with the NTE7118.
TDA1514A NTE Equivalent NTE7118 IC - 50W AUDIO POWER... - Wholesale Electronics

[Enzo]

Fender won't sell direct, but you could call customer service there and ask if the part is still available through their distributors, and if not what replacement is recommended. Make sure to get any exact part number for ordering.

[J M Fahey]

Obsolete for 20 years, unavailable for 10 .
I do not even *try* to find them.

In Marshall 40W I replace them with LM3886 , a few mods are needed.

In a "25W" amp you might get by with a real TDA2050 (which are also discontinued but since that happened about 1 year ago you can still get them from small/local vendors, forget Mouser and such which were swept off and even less EBay) and might even use an LM1875 which are still made.

Please post schematic here or at least rail voltges and speaker impedance.
If you want to play it safe, use an LM3886 but youīll have to redrill heat sink (pins do not match and itīs single hole), wire leg stubs with short wire links and add a different mute RC network.

Not as hard or long to mod as it sounds and more robust than original.

Personally I trust that WAY more than an NT so called "equivalent".

EDIT: OUCH!!! $43.92 + postage for a dubious "replacement"????
Go straight to amp modding, please post schematic here.
An LM3886 is U$7 + postage at Mouser, guaranteed good and availble.

[Jazz P Bass]

Yowza!
I failed to take notice of the NTE price.

Well, I guess if your the only game in town, you ask what you can get.

An LM3886 bolted to the heat sink (with a mica isolator), connected to the proper pcb pads through flying leads, would not be that difficult of a project.

[glebert]

Is this amp super special to him? Seems odd to put this much trouble into a $50 amp. And this is coming from a guy who should have a statue of St. Jude on his bench.

[J M Fahey]

I find that $ to $ comparison all the time, which I find flawed.
$50 where?
At his garage/rehearsal room?
Perfectly working as his original one? After replacing the dead IC, of course.

Or "somewhere else", another City or State, needing packaging , freight and waiting?
Where probably it works (note the "probably" sticker) , but perhaps pots are scratchy, jacks/switches are worn/iffy , speaker may buzz, etc.

Personally Iīd rather repair a known properly working device which developed *one* problem, a repairable one of course, and inexpensive to boot (thanks to having a generous friend like Slobrain).

Even if not, Iīd rather spend, say, $70/80 and have a guaranteed piece of equipment than $50 + freight + wait for an untested one which might still give me a nasty surprise.

Of course, if somebody in same town has one in good working condition and will sell it for $50, then thatīs a non brainer.

I am writing this on a Toshiba netbook.
It failed one year ago, dead motherboard.
Replacing it with a new one, work guaranteed for 6 Months, was $200, I would have to wait 7 to 10 days.
I was in a hurry and wanted to be able to straight plug in my old hard disk with all data and installed software and instantly continue working so I bought a used one, exact same model, apparently in good state, for $250.
A new one at a shop costs some $600 .

After really using it at home, found hinges were broken and repaired with Loctite (could only be seen from inside, after disassembly), coloured streaks appear at random on the screen, some keys are "weak" and have to be hit *hard* or some "A" and "E" are not printed, etc.
Battery dies after 1 hour , now I am using my old one with it which lasts 3-4 hours ... like it did on the old one.

Why didnīt I plain buy a new one at a shop, with warranty and all the trimmings?

I would, but then I would have to reinstall a ton of software, some of it would have to be tweaked a lot (a path I already went through) ,copy all data ... not impossible but for me this is a working tool, I canīt stop.

I would have been WAY better if I had repaired my old one, which was immaculate otherwise.

Pity is the original straight out of the bubble wrap motherboard is no longer available, and I canīt trust a refurbished one, so I WILL have to buy a new notebook and slowly reinstall all software , lots of it unavailable in an installable form, and finally transfer all working data, including shop workflow, Bank statements, customer data, etc.

EDIT: as a similar comparison, customers should say their pusher: "hey dude !!!! what are you charging me???? this stuff is 1$ a gram !!!! .... in a small mountain village in Bolivia of course"

[glebert]

I find that $ to $ comparison all the time, which I find flawed.

If the amp owner was paying for the repair or the OP wants this to learn how to do the mods suggested then whatever, knock yourself out. It sounded to me like this is a "fix it as a favor" situation. I think it is important to value your own time.