Hi everyone, I went to this page Same problem as mine w/ a solution, and installed this.



All it did was act as a bypass to the on/off switch, now it's always on.

So, does anyone have a solution to popping noise when shutting down a SS amp?

Here's the schematic:
https://www.ampwares.com/schematics/marshall/masterlead_30w_5010.pdf

Quote from: phatt on June 21, 2017, 07:49:51 AM
Good on you  aaron. :tu:

Regarding Reverbs; you may have to live with the hiss as it's a common complaint. :grr
Reason; To save a buck they don't use a very strong drive circuit and just turn up the gain on the return PU circuit to compensate for the weak reverb drive circuit.
Result; is a lot of excess hiss and buzz is introduced.
Short of a complete redesign you won't get rid of the hiss completely.

How do I know this?  Cause I've experimented and built a lot of reverb circuits. 8|
Phil.

Well, that sucks!.....I'm a perfectionist!

That, ironically, brings us back to full circle where someone suggested I buy a reverb pedal !

Quote from: DrGonz78 on June 20, 2017, 03:51:47 PM

Quote from: aaron on June 20, 2017, 03:14:53 PMWhat I ended up doing was cannibalizing a small heat sink from another circuit board, applied thermal paste, attached it to the resistor, and voila!

I'd like to see a picture of that.

:cheesy:
It's already closed up.

Just imagine an Oreo cookie.
The bottom cookie is the ceramic resistor,
the filling is the thermal paste,
and the top cookie is the aluminum heat sink (it actually only had about 1mm of play on either side of the resistor)
:lmao:
YUM!

am I the only one who thinks that the large cap (to the right of C10) has a huge dome on top?

Does the white stuff on TR5 look suspicious to anyone?

Hi guys!

I would have sworn I posted a reply yesterday.....

What I ended up doing was cannibalizing a small heat sink from another circuit board, applied thermal paste, attached it to the resistor, and voila!  Now I sleep better at night. (I hope the amp appreciates my efforts!)  I put it on R94 b/c it sits right on the board as opposed to R95 that is elevated a 1/4" by it's own leads.

The reverb still has a hissing noise, but I'll leave that for when I get my strength back.

Thanks to all, I really appreciate your help!

BTW, my attitude is that not only are you helping me, but maybe somebody else in Google land will see the posts and it will help them too!

Hi Phil, thanks for your response.

I wrote "The VDC across R94 and R95 is 22.7-22.8".   

When I wrote across, that meant from one lead of R94 to the other lead of R94.  Ditto for R95.

I was just trying to provide additional readings (that made no sense to me)

The VDC across R94 and R95 is 22.7-22.8.

I cannot get a DC voltage reading when I put one DVM probe on the chassis and the other probe on either side of the resistor.  The meter runs between 40 to 373mVDC with lots of fluctuation.


Chassis to R94 either side = 8.3 to 8.5 VAC
Chassis to R95 either side = same thing 8VAC.

Chassis to either side of CR25 or CR26 = 8 VAC.

Chassis to CR23 35 VAC
Chassis to CR24 18.5 VAC
Chassis to CR22 8.3 VAC
Chassis to CR21 8.3 VAC

I'm doing something wrong, but I'll be damned if I know what it is.  I'm going to take a break from this, I'm too busy and it's driving me too crazy.

thanks to all

Yep, you're right
when you're thinking in your head, it makes sense b/c you know what you're talking about.

Unfortunately, nobody else does.

I'll get back to this tomorrow.

OK, after resoldering (applying the soldering iron) to the bad looking points, the amp sounded great on the overdrive channel, and the clean channel too! :dbtu:  I didn't get a chance to try the reverb yet...

but what happened was that the ceramic resistors I mentioned were so freaking hot, that it was creating a strong smell.  I didn't want the circuit board to go bad again b/c the resistors heating and reheating the solder, and have everything go back to the original condition again.

There's no way that those resistors should be that hot.  I was wondering what to do, and I decided to check out the voltage vs. what it's called for on the schematic.  I don't know why, but the AC voltage was less than half on one side, and like a fourth on the other side of what it's supposed to be

So now, I'm working on isolating the transformer to see where the breakdown in voltage is happening.

I really need to figure out why those resistors are overheating....

I'll keep you posted

off all the posts, including my own, I can only see the image two images of "mr. keep on trucking" from R. Cobb, and the Fender power transformer image below that.

Every other post shows only links.

thanks

Quote from: phatt on June 08, 2017, 09:09:14 AM
.

Regarding the *wierd noise* well most of those Amps do make a fair bit of excess hizz and buzz when the OD/ distortion channel is used especially if you crank the gain up high,, again normal. 
Worth a note;
**These amps are loud and intended for LOUD Venues**
A common mistake is using these amps at bedroom level and in that situation the Fizz is quite obvious BUT at Gig levels you don't hear it.
So crank the master Volume and if the fizz/hum/buzz is louder than your guitar then yes the circuit maybe faulty.

Having repaired a few of the fender amps from this era the players often NEVER use the Distortion Channel as it's not that good xP,, more often than not they just leave it on the clean channel and use pedals for all the OD/Dist sounds as pedals give you many more options. :dbtu:
Phil.

The noise/hiss/whatever is way beyond normal, so it's the circuit, not the amp's characteristics.

I don't see how not using half the amp's channels increases my options.

I was hoping for electronic advice....

In any case, I've resoldered all the usual suspects.  I'll report on the results as soon as I put it back together.

Well, I'm still not seeing any pics embedded.

:grr

I still can't embed images from google drive....
clicked on "insert image".....nope
clicked on "Insert Hyperlink".....nope

thanks for letting me know how to fix the pics......I was wondering why I couldn't see them :tu: