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Messages - nosaj

#91
Amplifier Discussion / Re: Fender AMPs problems
June 28, 2015, 10:30:53 PM
Quote from: Ace-of-guitars on June 24, 2015, 09:26:19 AM
Ok. So I have a weird problem. I was just going to play when I noticed no sound coming from my amp. I tried playing around with the volume knob and magic! The PRESET changed!

Please help!
I took it as a sarcastic post to as how the user fixed his own problem by fiddling with the vol knob..

nosaj
#92
What tubes does it have in it?  Is it stereo or mono?  If stereo maybe swapping the output tubes around?  to see if other side starts working?

First and for most if the filter caps are original you should probably be looking at replacing them first.

That schematic is pretty hard to find.  You might try PM'ing him.

Jason
#93
Tubes and Hybrids / Re: Amp Cradle
June 01, 2015, 11:47:44 PM
Here's the plans for that exact one. I cobbled one together from scrap wood. Works well.

http://www.trinityamps.com/ForumGallery/trinity/Amp_Cradle.pdf

nosaj
#94
i built a fender champ clone out of salvaged parts the only thing that was new were the caps. Everyone that has played it thinks it sounds great.

Start simple then work up, i started with a Pedal from Small bear, then did the Champ on tag board and then a Kalamazoo model one PTP to see if I could follow a schematic versus doing a layout.  each project advances you some more.

nosaj
#95
What is wrong with it?

nosaj
#96
Amplifier Discussion / General amp health checks
May 21, 2015, 09:13:26 PM
Does anyone have a generic checklist they do when checking the health of a solid state or a tube amp?

Thanks,
Jason
#97
ok power supply voltages look correct  24.7 +-  and 11.8 +-.

So the 25v and 12v rails look ok.

Amazing what happens when you loosen all the connections then put it back together.

Everything seems to be working just fine now. All that was done was clean pots and jacks. removed circuitboard( which meant loosing pots), taking measurements then putting it back together.

Jason
#98
Here's the schematic Randall sent it today.

#99
Yes rc235 ds.

Sorry
#100
There are several of the rc4558p chips so I switch one that looked to be in the chorus section for one near the input that is in the pictures.  No change. What I'm wonder now is if the normal channel and the overdrive channel are on the same rc4558 .  Normal uses one half of the rc4558 and overdrive uses both?  Either way normal channel vol seems way too low.
Tomorrow when i get a chance I'll start with the power supply where I should have started first. Cause if it isn't right nothing else will be.

Will update tomorrow if possible.

jason
#101
Will get those pics shortly. Just took measurements on rc4558p by input 
pin1 .13 vdc
pin2  .16 vdc
pin3 no voltage loud sqeel
pin4 -11.3
pin5 loud hum like touching a grid input on a tube
pin6 smaller hum like above
pin7 no measurement
pin8 10.5 vdc

Output transistors lm1875t
left channel
pin5 23.9
pin3 -16.1

right channel
pin5 24.1
pin3 -24.1

Pics attached. Looks like it ties the 2 ground planes together ??
#102
Was under the impression that electrolytics 20 years + should be replaced.

ok here's what I've found since yesterday.

on normal channel maxed audio with audio pumped in, on stereo output one measure .06vac in 8 ohm resistor.
on overdrive channel maxed audio with audio pumped in, on stereo output one measure 10vac in 8 ohm resistor.

Looking near inputs on board is a rc4558p opamp which I'm guessing handles normal and overdrive.

Output transistors are lm1875t  so it looks like 20 watts max?

Still in process of finding a schematic, near the rc4558p chip there are 2 leads which look like a component was clipped out.

Thanks,
Jason
#103
I just picked up a randall RG 235 DS head and 2 stereo spks for $60 output seem audibly low.  Does anyone have a schematic for it?

Caps are first thing to be replaced but just wanted to check values as I see some mods in there.

Thanks,
nosaj
#104
ljn wrote:
I'm pretty sure the part in question was a PNP germanium transistor. It only had two leads, though.


Then it isn't a transistor.
From another site same question......


U100... Isn't that the "Club", right? You know that Kasino amps are largely just Kustom amps in different cosmetic appearance. They recycle largely the same PC board modules. Club, according to my references, holds PC105 (preamp), PC803 (reverb & f/s control) and PC900 (power amp & +/- 8VDC regulators).

You can verify pretty easily what board numbers are of interest.

I can find a crossreference to 61088, which is a 1N3754 diode, but not a reference to 61008.

Another useful resource:
http://www.vintagekustom.com/literature/Tech/tech.html
#105
If you really want help post the schematic and quit yer B*****in.

jason