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Messages - Enzo

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Be more specific about the complaint.  DO you mean it works well sometimes and not others?  Or never really works well?  And what exactly does it do or not do that is the issue?

If it does something wrong, if you whack the top of it with your fist, will that bring it back?  At least temporarily.

Reminds me, in my shop days, when I had a speaker sitting out and wanted to test it with music.  Just a brief test.  They sound awful sitting on a table, so I would reach over and hold the speaker facing up over my trash can.  That enclosed space under the speaker gave it enough of an enclosure to see if it sounded halfway decent.

Low end from tiny speakers?  Not likely.  To make bottom, the speaker cones have to move sufficiently to make the wave fronts.  That is hard for a speaker to do with a movement of a millimeter or so.

Preamps and Effects / Re: Fender STC1 Chorus Pedal
« on: January 14, 2022, 06:06:51 AM »
The parts involved are also less common than they were, but Peavey made a chorus circuit for the Mace and some others, not using a BBD chip.  They made a delay line with discrete stages.

Amplifier Discussion / Re: Marshall 5005/Lead 12 Hum Source?
« on: January 09, 2022, 10:17:52 PM »
Well, I don't mean to be unkind, but one problem I see - and that is in many many threads - is people assuming that hum (the most common amp complaint there is) will be caused by the same thing.

DO you have that same "hum is less in the middle rather than the ends" on the volume control?  Are you sure your hum is 60Hz and not 120Hz?

There are a zillion sources of hum in amps.

Amplifier Discussion / Re: SWR Workingman's 12 combo- Hummmmmm
« on: January 06, 2022, 12:31:37 AM »
OK, then the ripple?  You have a positive and a negative supply in there.  Are both up to about the same voltage and free of ripple?

Amplifier Discussion / Re: SWR Workingman's 12 combo- Hummmmmm
« on: January 05, 2022, 07:40:52 PM »
How did you check the caps?  Just because the value is close doesn't mean it i well connected.  Sounds like DC on the speaker to me.  If so TURN IT OFF or the speaker will be destroyed.

Does the speaker cone move one direction and stay when you power up?  Take the wires off the speaker and measure for DC voltage between them.

Otherwise check the solder on the main filter caps.  Check the main power rails for ripple.

Amplifier Discussion / Re: Yamaha G100
« on: January 05, 2022, 02:19:48 AM »
This doesn't sound like a transistor issue.   They don't age like tubes.  My favorite example of transistor life:  NASA's Voyager satellites.  They run on transistors, and have been running now for 40 plus years in the cold of outer space.   They are way past the edges of the solar system, the temperature is a few degrees above absolute zero, and the little thing keeps sending back is working.

Amplifier Discussion / Re: Heathkit TA-16 Tripping Breaker
« on: January 05, 2022, 02:15:06 AM »
SO when the fuse/breaker blew, you were playing through teh amp?  Did it just stop in an instant?  or was there any sort of momentary lean up to the blow?  Like a moment of distortion or something?

Amplifier Discussion / Re: Heathkit TA-16 Tripping Breaker
« on: January 05, 2022, 12:07:50 AM »
You replaced a 2 amp breaker with a 1 amp fuse?  Well that doesn't tell me much.  Please tell me it was at least not a fast blow 1A.

Actually weak breaker was my first thought too.  You are throwing parts at it based on possible current surges.  But how about if the breaker is weak, then it doesn't care about peaks.

A fuse isn't a bad idea, but at least use a 2A SLOW or even a 2.5A.

Amplifier Discussion / Re: Yamaha G100
« on: January 04, 2022, 11:59:30 PM »
My first reaction would always be check the FX loop jacks.  But I don't think you have them, do you?

I love these amps.  The power amp is on the heat sink assembly hanging from the chassis.  A couple large bolts and it unplugs from the interior board by a 6-pin connector.   Just my guts hunch, but pull that assembly off and check the pins on the connector.  Any cracks on the pin solder?  or just simply resolder them anyway.  Likewise, inside, I think it is the power supply board has the mates for the six pins, resolder those.

It could be anything, of course, but caps don't come and go.  You have a symptom that does come and go.  I'd be looking for a failing connection.  A weak solder joint or a jack with poor contacts.

You have two channels, do BOTH channels act the SAME way?

And just a thought, you have hi and low jacks for each channel.  You likely use just the HI.  Plug into the LOW jack on a channel.  Does that sound like the "problem" condition?  If the cutout contacts in the LOW jack are dirty, the amp will stay in the low condition even using the HI jack.

Perhaps if you told us the make and model of what these parts are in, we could look on the schematic?

You have a good board?  Stick your ohm meter probes on the good one and see what it measures.

Resistors don't burn up on their own, something caused the excess current.   Very often a semiconductor.

CAp, hard to say.  Replacement cost well under a dollar.  WHy take chances?

Amplifier Discussion / Re: newbie question about cranked amp overdrive
« on: December 25, 2021, 05:56:04 PM »
Did I miss something?  The transformer you link is for a tube amp.  It has a 6v winding for heaters, and a high voltage winding for the B+.   Not suited to a solid state amp.

Amplifier Discussion / Re: newbie question about cranked amp overdrive
« on: December 24, 2021, 12:59:01 AM »
Doesn't matter, we read them all.

I don't have any solid state Wards drawings.

Amplifier Discussion / Re: newbie question about cranked amp overdrive
« on: December 23, 2021, 11:42:38 PM »
Is there some thing?  No.  One sets out with a gain structure in mind.  One then decides what sort of voice it wants to have.  Consider the tone stack.  I link below to Duncan Amps page.  They have this really cool "tone stack calculator", a bit of free software you can download.  It sets up several common tone circuits, and offers graphic frequency response in real time as you adjust the controls.  If you look further into it you will find you can even change component values.  And that is ONLY the tone circuit.  Amp designers have to balane MANY factors.

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