Dodgy amp needs repair

sbattersby 115 · 15th April 2005, 12:56 PM

Hey guys
I have a fender frontman 15watt amp thats giving way too much fuzz. I am not using any effects or pedals just playing the guitar straight through the amp. The fuzz and crackling drowns out most of the actual playing and I was wondering if anyone knew why or if I could fix it myself.

Enzo · 15th April 2005, 11:40 PM

These amps are not complex, isolate the problem. COnnect the amp to a different speaker to see if hte speaker was blown. Headphones sound OK? Look for DC offset on the output pins of the op amps, a sign of failure. Got a scope to look at the waveform through the amp? COUld be a bad output amplifier chip.

And of course American amps must be upside down for proper operation in Austalia.

mastertech · 15th April 2005, 11:54 PM

Hi guys did you know that the fault could originate at the guiter electrical
part only and the amp could be fault free
sounds like bad input connections

Enzo · 16th April 2005, 08:39 AM

Well, that is certainly true.

thedoctor · 22nd April 2005, 07:53 PM

Enzo got the first test perfect. Try the headphone jack. If it sounds good with headphones, you know a lot more about the problem's probable cause.

sbattersby 115 · 25th April 2005, 11:54 AM

hey its me again. when i use headphones it sounds exactly the same. and when i plug in a mic it gives the same fuzz. When nothing is plugged in it doesn't sound just as bad but you hear it a bit. I have never repaired an amp or really anything much before so like keep it simple english please

Centauri · 26th April 2005, 01:13 AM

Most likely cause with these is output chip - it is the square plastic thing with 5 legs bolted to an aluminium bracket - type number TDA2050. These devices run hot, especially when playing at high volume, and the aluminium bracket / heatsink is not really big enough to keep the chip cool.

Cheers
Graeme

sbattersby 115 · 27th April 2005, 09:42 AM

Thanks for the advice guys. could it be something simple like the input jack? something tells me its the problem, if so would it be hard to repair?

Centauri · 27th April 2005, 11:33 AM

In your original post you said "fuzz" - do you mean buzz? Hum/buzz/crackling, especially when the input jack is moved, could mean cracked solder joints on the circuit board - very common in later Fenders.

Cheers
Graeme

sbattersby 115 · 27th April 2005, 01:44 PM

I could well be meaning buzz because I dont much know the difference

Anyways it makes noise when it isn't supposed to like when a guitar is plugged in but you haven't played on it yet. Its strange because sometimes when you play on it the volume seems to increase itself and the pitch goes into an earpiercing scream. not nice

15th April 2005, 12:56 PM	#1
sbattersby 115 diyAudio Member Join Date: Apr 2005 Location: bushmills NI	Dodgy amp needs repair Hey guys I have a fender frontman 15watt amp thats giving way too much fuzz. I am not using any effects or pedals just playing the guitar straight through the amp. The fuzz and crackling drowns out most of the actual playing and I was wondering if anyone knew why or if I could fix it myself.

22nd April 2005, 07:53 PM	#5
thedoctor diyAudio Member Join Date: Apr 2005 Location: So. Illinois	Fender fuzz Enzo got the first test perfect. Try the headphone jack. If it sounds good with headphones, you know a lot more about the problem's probable cause.

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15th April 2005, 11:40 PM	#2
Enzo diyAudio Member Join Date: Sep 2004 Location: Lansing, Michigan	These amps are not complex, isolate the problem. COnnect the amp to a different speaker to see if hte speaker was blown. Headphones sound OK? Look for DC offset on the output pins of the op amps, a sign of failure. Got a scope to look at the waveform through the amp? COUld be a bad output amplifier chip. And of course American amps must be upside down for proper operation in Austalia.

15th April 2005, 11:54 PM	#3
mastertech Banned Join Date: Mar 2005 Location: Australia	Hi guys did you know that the fault could originate at the guiter electrical part only and the amp could be fault free sounds like bad input connections

16th April 2005, 08:39 AM	#4
Enzo diyAudio Member Join Date: Sep 2004 Location: Lansing, Michigan	Well, that is certainly true.

25th April 2005, 11:54 AM	#6
sbattersby 115 diyAudio Member Join Date: Apr 2005 Location: bushmills NI	hey its me again. when i use headphones it sounds exactly the same. and when i plug in a mic it gives the same fuzz. When nothing is plugged in it doesn't sound just as bad but you hear it a bit. I have never repaired an amp or really anything much before so like keep it simple english please

26th April 2005, 01:13 AM	#7
Centauri diyAudio Member Join Date: Jul 2003 Location: Newcastle, Australia	Most likely cause with these is output chip - it is the square plastic thing with 5 legs bolted to an aluminium bracket - type number TDA2050. These devices run hot, especially when playing at high volume, and the aluminium bracket / heatsink is not really big enough to keep the chip cool. Cheers Graeme

27th April 2005, 09:42 AM	#8
sbattersby 115 diyAudio Member Join Date: Apr 2005 Location: bushmills NI	Thanks for the advice guys. could it be something simple like the input jack? something tells me its the problem, if so would it be hard to repair?

27th April 2005, 11:33 AM	#9
Centauri diyAudio Member Join Date: Jul 2003 Location: Newcastle, Australia	In your original post you said "fuzz" - do you mean buzz? Hum/buzz/crackling, especially when the input jack is moved, could mean cracked solder joints on the circuit board - very common in later Fenders. Cheers Graeme

27th April 2005, 01:44 PM	#10
sbattersby 115 diyAudio Member Join Date: Apr 2005 Location: bushmills NI	I could well be meaning buzz because I dont much know the difference Anyways it makes noise when it isn't supposed to like when a guitar is plugged in but you haven't played on it yet. Its strange because sometimes when you play on it the volume seems to increase itself and the pitch goes into an earpiercing scream. not nice