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Sessionette 75 loud hum

Started by stax, September 11, 2016, 06:07:17 AM

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stax

My Retrotone modded sessionte 75 has developed a fault, very  loud hum which gets worse the higher the volume, I do have a signal going through.
I'm no expert but can do simple jobs so I replaced the two mosfets in the power module and also uppped the wattage on a 12k resistor that I read can fail, also as they are cheap and socketeted I replaced the 4 ic's.
I will replace the two filter caps next as they have been there for over 20 years so that won't hurt.
Any other tips or things to check out before I give up and take it to a tech  would be much appreciated.

DrGonz78

So you swapped out two mosfets, upped the wattage on a resistor, and threw in 4 new ic's. That did not fix the problem? It would be best to pinpoint the fault by using proper troubleshooting techniques instead of just throwing parts at it on a hunch. At this point you might as well change the filter caps and see if anything changes. If you have a multimeter you can set it to AC volts and measure AC ripple that might be caused by bad filter caps. 120hz hum will be the symptom if you have a bad AC ripple.

Plz post the schematic for all to help.
"A person who never made a mistake never tried anything new." -Albert Einstein

stax

The resistor change is recommended by the original designer on the Sessionette web site, the ic's cost pennies and the mosfets were something a few threads with similar problems kept pointing to, these cost about the same as half the journey in petrol to take to the only decent tech I know.
The average cost even for small jobs can work out £80-100 so yea I have thrown a few bits in and hoped for the best.
There is a schematic online of a Sessionette 75 but it's not very clear,I can't even make out the values of the filter caps so no point in posting the link, thanks anyway, sorry to waste your time.

DrGonz78

I could look right at the pick in the schematic, it includes pictures, and I could read it right off the schematic too. Two 2200uf 63v axial caps.
"A person who never made a mistake never tried anything new." -Albert Einstein

J M Fahey

Quote from: stax on September 12, 2016, 02:21:39 AM
The resistor change is recommended by the original designer on the Sessionette web site, the ic's cost pennies and the mosfets were something a few threads with similar problems kept pointing to, these cost about the same as half the journey in petrol to take to the only decent tech I know.
You mean the only Tech who can stand you  :lmao:

QuoteThe average cost even for small jobs can work out £80-100 so yea I have thrown a few bits in and hoped for the best.
Compare it to our cost, we charge nothing here for advice  :o ... but of course you must follow it.  ::)

There is a schematic online of a Sessionette 75 but it's not very clear,I can't even make out the values of the filter caps so no point in posting the link,
I see you are doing it again  ;)
Old dogs learn no new tricks, just keep repeating the old ones  ::)

Quotethanks anyway, sorry to waste your time.
You did it again !!!!!!!
This must be some kind of record, I guess, only guy with more negative votes than actual number of posts.

Don´t you feel sort of ... proud about it? :loco

Funny thing is that even so, very kind DrGonz78 gave you the answer, go figure.
Hope it works, because .....errrrrrrrr ....... I guess you already burnt all the good Karma points every newcomer gets.

Next time you´ll have to pay the basic consultation fee  :trouble




Naaaahhhh, just joking, you can ask again if you wish, just box the sandbag for a couple hours first so you work out all your aggression and get in the mood to ask and get answers  :tu:




stax

You nasty sad little man, what a knob, I asked a simple question just as I did once before and you bunch of twats start the crap again, jesus what a joke.

g1

You asked a question, got a valid response, then got all snarky ('sorry to waste your time').
On the off chance you were getting harsh treatment here for no reason (which never happens), I looked up your ONLY previous post, where you did the exact same thing.
sheesh  ::) .
http://www.ssguitar.com/index.php?topic=3603.msg27492#msg27492

galaxiex

#7
Doesn't take much to rile this guy up.

The slightest suggestion that he help us (by asking for a schematic) help him, and he takes it as an insult.

I'll bet he's a road rage type driver too.
If you put your signal on to change lanes he closes the gap and gives you the finger for trying to "cut him off".

Here's a suggestion stax.
Try taking a meditation class or maybe some yoga.
Perhaps you'll find some inner peace and calm to soothe the savage inner beast that keeps coming out.
You might even find out something interesting about yourself.

Just to be clear, the above is written WITHOUT any hint of sarcasm or anger.
I am very serious.
You need to find some help before you go postal and start killing people.
Ok, that last line was meant as humor.  ;)
I hope you can see it that way.
If it ain't broke I'll fix it until it is.

J M Fahey