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91
Schematics and Layouts / Re: Ibanez TSA30 Schematic and PCB Layout
« Last post by phatt on February 19, 2019, 06:47:20 PM »
Yep a fair point. :tu:
As I don't have that Amp I'm only guessing.

One thing I should add is that the Schematic shows no Grid Stopper resistors on the power tubes and although you won't notice much at low volumes when the Amp is working at high volumes it will most likely spit,, sometimes called power stage choking.
I'd suggest at least 5k and right at the pin if possible. you may have to cut tracks to do it but worth it if you play with a lot of heavy loud distortion.
This very problem drove me nuts on some of my early valve amp builds years back as I only had 2k2 resistors. sounds gawd darn awful. :grr
I replaced them with 10k and bingo no more harsh blocking distortion.  <3)

Explained well here if interested;
http://ozvalveamps.org/choking.htm
Phil.   
92
The Newcomer's Forum / Re: Carlsbro Hornet (1970s)
« Last post by phatt on February 19, 2019, 06:29:24 PM »


What an eejit. It so clearly has.

Just goes to show I need those readers or a magnifying glass. Age has not only caught up but overtaken me this last year... 

Thanks, again, Phil.

Yep I know the feeling, my eyes also struggle to see fine detail. :'(
I don't even bother to try and fix anything that uses SMD's.  xP
I agree with *galaxiex* about replacing Electro's in old gear but I would add this;
Only replace the obvious first and get the amp working,,, then go back and replace the others.
If you shotgun the whole lot and it still does not work then you have no idea if you added yet another mistake. :-X
Phil. 
93
Amplifier Discussion / Re: Ampeg SVT450
« Last post by phatt on February 19, 2019, 06:09:10 PM »
Hum? That is not a definitive observation.
Try this, Plug your guitar into the *POWER AMP INPUT*
You should hear clear undistorted signal.
If there is still bad distortion then the power amp has issues.

To test the preamp;
(Assuming you have another amp?)
plug a lead into *EFFECTS SEND* and send that signal to another amp.
You should be able to engage the Graphic EQ,, but master will be bypassed.

If it's clean and all controls work (Except Master volume) then plug into the *PreAMP OUT* and send to another amp.
Now the master should work as well as all preamp controls.
Report results.
Phil.
94
Amplifier Discussion / Re: Ampeg SVT450
« Last post by aruption on February 19, 2019, 11:48:58 AM »
In that case, it's definitely the preamp. Changing the EQ settings or limiter/pad switches don't do anything to make the sound better or worse (although the pad will still reduce the overall volume). Engaging the other EQ section doesn't change anything either.
95
Schematics and Layouts / Re: Frontman 212r
« Last post by dlbraly on February 19, 2019, 09:05:46 AM »
Thank You,
I have not had a chance yet to call Fender to ask them.
I will let you know what I find out.
96
The Newcomer's Forum / Re: Carlsbro Hornet (1970s)
« Last post by psafloyd on February 19, 2019, 08:57:09 AM »
I have worked on quite a few SS amps from the 60's and 70's.

I've found in all cases those amps benefit from replacing ALL of the electrolytic caps.

I used to test them (caps) and leave them if they "seemed good" but the amp(s) would still have problems.

If that amp were mine I'd start by replacing ALL of those blue tubular electro caps.

Just my $0.02

Makes perfect sense. Nothing lasts for ever, after all.

Thanks for your tuppence worth.

97
The Newcomer's Forum / Re: Carlsbro Hornet (1970s)
« Last post by psafloyd on February 19, 2019, 08:55:57 AM »
C16 has popped,,so replace for sure.
What's the bet that is part of the trem circuit. ;)
Phil.

What an eejit. It so clearly has.

Just goes to show I need those readers or a magnifying glass. Age has not only caught up but overtaken me this last year... 

Thanks, again, Phil.
98
The Newcomer's Forum / Re: Carlsbro Hornet (1970s)
« Last post by psafloyd on February 19, 2019, 08:54:21 AM »
So you don't have this schematic, but if you can find other Carlsbro amps of the era, chances are the trem circuit is similar if not the same.

Thank you, Enzo. Struggling to find the same era.There seem to be plenty of the earlier and later valve amps or the later SS ones. But I'll take a look for the later ones and make a comparison.
 
99
The Newcomer's Forum / Re: Carlsbro Hornet (1970s)
« Last post by phatt on February 19, 2019, 02:37:49 AM »
C16 has popped,,so replace for sure.
What's the bet that is part of the trem circuit. ;)
Phil.
100
Schematics and Layouts / Re: Frontman 212r
« Last post by Jazz P Bass on February 18, 2019, 07:32:54 PM »
I don't believe that switch is available anymore.

Have you attempted to contact Fender?
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