fender bassman 60 humming

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Nigel Goodwin said:
As for bountyhunter, his generalisation isn't true - by FAR the most common fault is failure of the output stages, PSU may come second, but a long way behind.
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If you say so, but I was referring to consumer electronics in general and I can assure you, cheap elelcs that degrade over time cause more failures than any other single component.

A few years back one of the hot shots at Linear Technology did an expose article about how the Taiwan mother board makers cheaped out on the electrolytics since the mother boards and computers in general only have a one year warranty.....
 
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i agree 100% with that statement because i know 1 particular pc co. that cheaps out on their mother boards and power supplies ive had to repair many of them (emachine) is 1 of the worst for faulty mb and power supplies...

anyway back to what i was going to say (WE DID IT GUYS) its fixed the problem was in those new transistors i installed well 1 of them anyway the reverse test i mentioned above well i changed the 1294 out for a 3263 and changed out a diode at the output and now shes workin fine no humms no poping no smoking she sounds great thanks for all your help this is the best help forum i have ever found regarding electronic repair hands down!!!
 
maxs said:
i agree 100% with that statement because i know 1 particular pc co. that cheaps out on their mother boards and power supplies ive had to repair many of them (emachine) is 1 of the worst for faulty mb and power supplies...
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I am typing on an emachine. I bought it mainly to process audio tracks off CDs and create MP3 discs so I bought one with two disc drives since I figured one would fail........ it did, about a month out of warranty. The other one still works.
 
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yeah my uncle bought 1 about 2 years ago and 3 days after the warrany expired the power supply went out i fixed it for him then 6 months later the mother board failed i told him to go buy a different pc he got my next least favorite he got a dell although not as bad but not that good either i sorrta like gateway better but hp seems to be good and toshiba is another yeah emachine can be a good pc if you swap out the power supply for a better 1 and sometimes but not often you may not have to swap out the mother board ...good luck with it he he he !!!
 
Can you flipping believe it? I went to plug my scanner into the USB port on the front an hour ago and the port is dead. The one in the back still works....

It's like this thing is getting revenge on me.
 
bountyhunter said:
If you say so, but I was referring to consumer electronics in general and I can assure you, cheap elelcs that degrade over time cause more failures than any other single component.
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Quite true, but it doesn't apply to amplifiers like this one, which is what we are discussing.

You're talking about capacitors in switch-mose PSU's, which are definitely the most common cause of failure, bar none.

A few years back one of the hot shots at Linear Technology did an expose article about how the Taiwan mother board makers cheaped out on the electrolytics since the mother boards and computers in general only have a one year warranty.....
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Biggest problem was a batch of faulty electrolyte, the formula stolen by an ex-employee of another company, but before it was ready for production. This is very well documented, and caused massive premature failure over a huge range of items, with computer motherboards been a major user of the faulty caps.
 
Nigel Goodwin said:
Quite true, but it doesn't apply to amplifiers like this one, which is what we are discussing.
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Actually, I am referring to this amplifier. If it is as old as it appears, the electrolytics should be changed out if anybody plans to use it. Period. I know what life spans they have and how they fail. Even though they may not yet have suffered catastrophic failure, they degrade steadily with age as the electrolyte dries out and become less capacitive and more reactive. Maybe they are not causing the specific symptom here, but if I was going to use this amp, every elec older than five years would go in the dump can. They increase ripple in the power supply, increase voltage transients applied to internal components and can degrade amp performance specs. basically like driving a car with rotten bald tires. It may run, but.....
 
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Actually, the main problem is that Pacific Rim mother board makers cheap out the reference design that Intel gives them to save money. I provided some of those ref designs to Intels board division. They give them out but the clone board makers don't follow them. Reliable word is that they start with the ref design and start removing the most expensive caps (the large ceramic caps and tantalums) until the CPU malfunctions from voltage transients and put back in the last ones they took out until it works again. They also use poor quality caps with higher ESR than spec and they don't last as long. Anyway, the problem with garbage boards is certainly not confined to a bad batch of caps.
 
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Capacitors in something like this have a very easy life, by all means visually check them, but they are almost certainly perfectly fine - it's not old enough for the problems you are imagining. There's certainly no need to do a blanket change of them.
 
bountyhunter said:
Anyway, the problem with garbage boards is certainly not confined to a bad batch of caps.
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Not entirely confined, but certainly the vast majority of such problems were - and it's a VERY well documented problem, with millions of duff capacitors been supplied to the board manufacturers.
 
all the caps looked fine but i did replace the two large caps with pc grade caps the rest looked good but they may show problems in the future but as for now the amp is working fine with no problems what so ever im happy with the results and thanks again for all the help here ... great great forum good ppls here
 
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