Aragon 47k Schematics?

[Jim Leach]

Hi guys.

Does anyone have a schematic for the Aragon 47k? I know it is simple (I own one) but I am too lazy to go through and identify every part in there.

One channel is a bit down in gain it seems (about 3dB) so I am going to gut it and rebuild it with 'boutique' parts for 'gits and shiggles'. It might even function when I get done with it... Seems like a simple enough project for my skill set (or lack thereof).

I would also appreciate any tips or tricks I should know if you were going to undertake this project. Such as replacing any component values etc. Otherwise, it will be a straight rebuild. (just better quality and tighter tolerance)

Anyone?

 

[Jim Leach]

Bumping this up because this project might actually happen soon!

I acheived this by having someone else do the work for me...

He will match and replace all components in each channel, but a schematic (and any tips on improvement and/or specific suggestions for replacement components) are greatly appreciated.

Thanks guys!

 

[normo]

Let me know how it turns out. I have one sitting around, currently not in use. It had sounded kind of lean and clinical, and I wonder if that is the typical sound of the unit and if the work you are going to have done on it will change it. I hope it sounds great. Thanks Norm

 

[palma2007]

Let me know how it turns out. I have one sitting around, currently not in use. It had sounded kind of lean and clinical, and I wonder if that is the typical sound of the unit and if the work you are going to have done on it will change it. I hope it sounds great. Thanks Norm

HI.I´m also looking for the schematics.Found one of these but the XLR conector on the power supply is missing and I don't now which cable goes were ( red,black and white).

 

[trans192]

I'm interested in this as well - I have one lying around and under utilized. I'm curious - which power supply are you using - I have the baseline PSU and was wondering about the value of upgrading to something like IPS or maybe even something DIY.

 

[geraldfryjr]

I have one as well!!!

I have had it for about 15 years.

Actually I think mine is the 24K but probably use the same power supply.

I got it with a open transformer primary, I need the schematic so that I can make sure that there wasn't anything that made the transformer go out as it had a fuse built in to it.

It came from Florida, so it could have been just a power surge or it could have been lightening, Who Knows!!!

I don't think the output voltages are marked on it either and may be why I haven't fixed it yet.

It has been a very long time since I have even looked at it as it has just been sitting on a shelf ever since I got it with my Apogee Duette's.

Any help would be appreciated!!

Cheers!!

jer

 

[palma2007]

If anyone as a power supply ILDK-19 Ill appreciate directions on which cable goes into which pin on the XLR.

 

[Jim Leach]

Well, it's been YEARS and still no schematic is found...

Mine is still working, poorly, and I'm ready to just buy something else!

I assume now that components could/should be upgraded anyway due to age. Maybe newer, quieter better op amps could be substituted as well?

I'd really rather just invest a little money in this, as opposed to a lot of money on a new preamp- I'm thinking Musical Fidelity by the way, which is a few hundred dollars. If I can get in the same ball park for ~half the money, why not?

So, has ANYONE found that schematic yet?

 

[Jim Leach]

Found something:

"The actual audio circuit was a Dan D'Agostino design (Krell) and was rumoured to be very similar to what was in the old KPS" Which I think this poster from Canuck Audio Mart meant the KSL preamp, which Dan designed fro Krell.

Let's see where this leads.

 

[leadfinger]

Hello Jim,
The Aragon 47K phono does not use any integrated circuits, all discreet semiconductors and high quality resistors and capacitors.
I would check the gain and load jumpers. Re-seat the jumpers and make sure both channels are set the same. The only part that might need replaced would be the electrolytic caps but I doubt if they are bad. I would check the voltages going to both channels and make sure they are the same. If you need more detailed information I can get mine out of storage and do some tests.



I tried to attach an image but it may not show...
Hope this helps a bit..

Dave

 

[adason]

I found 28K schematics, may be it helps.

 

[Jim Leach]

Thank you adason. That appears to be line stage only, but I appreciate the effort. I may end up creating the schematic, even though I don't know what I'm doing...

Hello Jim,
The Aragon 47K phono does not use any integrated circuits, all discreet semiconductors and high quality resistors and capacitors.
I would check the gain and load jumpers. Re-seat the jumpers and make sure both channels are set the same. The only part that might need replaced would be the electrolytic caps but I doubt if they are bad. I would check the voltages going to both channels and make sure they are the same. If you need more detailed information I can get mine out of storage and do some tests.

View attachment 745707

I tried to attach an image but it may not show...
Hope this helps a bit..

Dave

All the jumpers are good. In fact, since I'm using a Benz-Micro Silver cartridge, I've been all over the loading and capacitance; including determining loading with various combinations of more than one loading resistor... Bottom line is the jumpers are not the cause of the problem, unfortunately. I think I'll try to get exact replacements for components and replace them. Maybe go with fancy copper foil/Teflon for the big capacitors (if they'll fit inside).

Supposedly these were built with "military grade" components. Some might be harder to get now, so many years later, but on the other hand, the military generally demands spare supplies for many years. I need to crack it open and see what I can figure out I guess.

I think it has a lot of potential, and has received good reviews over the years from the "pro" and amateur reviewers alike. I would think that a nicer power supply and "boutique" components (where it counts) could step it up a notch. Plus, I already have it, and getting to "47k modded" status from scratch will be expensive. Certainly more than modding will cost. At least I think so anyway.

 

[Jim Leach]

OK Here's an update.

I did find one jumper was loose on the gain of one channel, so hopefully that does it. I'll have to give it a try and see. I wish I had the schematic because I may want gain somewhere between the three possible choices... it would be great if I could match the output to my digital output for example, to avoid changing gain at the preamp all the time. I'm not sure if running two of the (apparent) resistors would give me intermediate resistance and hence intermediate gain...

I was thinking I would replace components with "better" stuff... the problem is, this thing is a veritible "who's who" of high-end components. Check the pictures! The only ones I'd consider are the two large capacitors.

Anyway, someone was also interested in the pinout for the A/C input, and I have that as well. See the pictures (in the next post), but I STRONGLY suggest you open your unit and inspect the power supply to verify input voltage and pinout for your specific unit.

 

[Jim Leach]

Power input connections

See photos:

 

[Jim Leach]

So, can anyone help me identify these caps properly?

10K250V doesn't make sense to me. 10K what? Not 10,000 mF, or is it? I'm thinking 1.0uF, which may be the same (i'm not an electrical engineer, if you hand't noticed) and that cap (from V-cap) has the same 250V rating as well.

But those V-caps are 1.65" diameter by 2.5" long, so it might take some "engineering" to get them in there, if it's even worth the $736.00 upgrade... Though I do know the value of good caps in the signal path, when necessary.

HELP!

 

[PH104]

Only a guess but it looks like the two TIP transistors and associated parts are part of the power supply. The capacitor, which might be some filtering on that power supply, appears to be a 10 uF/ 250 DC polyester cap. Here's an example of that cap:

10 Ea TI - 18 Uf 250V 10% Axial Lead Mylar Capacitor Speaker Crossover | eBay

Phil

 

[Jim Leach]

Hi Phil.

I didn't show a "zoomed out" view, but the bridge and caps for the power supply are under an RF shield to the left. There are six or so stubby fat caps and the rectifier, plus a few other bits (I did not remove the cover). Post #14, above, shows the cover in the second photo.

The second photo in post #13, shows the input from the 'table directly across from those big caps. They might be power supply filters too (power supply is off to the left)- I'm not sure. I'd have to pull the board out and draw it from scratch, and then determine what is what.

 

[analog_sa]

10K250V doesn't make sense to me.

10uF/250v 10%

They just used what they had available. The voltage rating is of course excessive but similar caps are seldom available with lower ratings. The capacitance is also excessive and determined by the input impedance of the following line stage. A 4.7uF is usually fine. If you use a high impedance line stage you should be able to get away with a much smaller cap.

Both circuit and PS regulation seem quite basic. I would not go crazy with upgrades.

 

[PH104]

Hi Jim -- analog_sa is very likely correct in that those are output coupling caps. You can measure resistance from one of the RCA outputs to an end of one of those caps to verify. Also try measuring from R27B (or A) to the corresponding 10uF cap.

It's such a pretty unit that I also agree not to go crazy with upgrades or try to shoe-horn in great big caps. I saw one such disaster on the internet. You should be able to find metallized PP caps - at a lower voltage if necessary - that would fit nicely to replace those 10uF's.

If you don't mind another measurement - turn the unit on and measure the voltage with repeat to ground on the tab of each of those TIP31 and TIP32 transistors. Then measure the voltage on each end of the 4 blue 10 own resistors. Just to satisfy my own curiosity. Thanks

Phil

edit -- It looks like there's input caps on each channel also: the WIMA cap and that gold electrolytic whatever it is.

 

[analog_sa]

edit -- It looks like there's input caps on each channel also: the WIMA cap and that gold electrolytic whatever it is.

You are quite possibly right. The input pair, same as all other transistors is bipolar. And cannot find any other purpose for those two caps... The bottleneck appears to be here, rather than at the output.