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Help with AU-999 Redux

Yes I am talking about C609 in the phono stage. Is there anything you DONT know? Geez...

Anyhow, I have a vast variety of caps of all different values, just unfortunately no 33uf 6.3v. If there is a uf value (6.3v) that would work better than a 330uf just let me know and I might have it -

what is the goal here? To get as close to 33uf without going under?

Thanks so much.
 
The cap just provides an AC bypass for that emitter resistor. Size is not an issue, but I simply would not go for a voltage rating of 10V, and a capacitance rating of less than the stock 33µf. Like I said, if the 330µf cap fits, use it.
 
Okay great. Got a 100uf 6.3V in its place. Did the deoxit and new heat sink paste last night.

I am just about to plug it in. I will either post back with photos or a sob story in a few moments ;)
 
I found two Toshiba 2SC1079 in one channel and two Hitachi 2SC898 in the other. This combined with the two different driver boards in my unit makes me think that perhaps someone replaced an entire side of this unit a long, long time ago.

Is this mismatch going to be a problem?
 
Welp, here it is.

I took the "ambitious" approach.

1. Replaced every electrolytic cap with Panasonic FC
2. Replaced every .47uf mylar cap with Panasonic Metal Film Polypropylene
3. Replaced every single flying saucer resistor
4. Replaced mica insulators and applied arctic silver ceramique thermal paste
5. Replaced mylar caps on driver boards with vishnay/roederstein polypropylene caps
6. Place polypropylene bypass caps across the main power filter caps.
7. Removed protection board in its entirety
8. Replaced all fuses
9. Deoxited every knob and switch
10. Adjusted bias per service manual
11. Adjusted DC offset
12. Cosmetic cleaning with water and pledge for wooden case

999over.jpg

999under.jpg

999front.jpg

999corner.jpg

999corner2.jpg

999top.jpg


PS - sounds awesome! Letting it burn in with some Atom Heart Mother. Next up, Marantz 3300!
 
Pics showing for me - took a minute or two to load though - before that it did look like they were missing...

xoaphexox
That is such a clean looking Amp !!! - it looks like new - I take my hat off to you for the cleaning job and getting to grips with the electronics - but with EW in your corner for that, you can't loose :D

Everyone out here (me at least :D) can't wait to hear your impressions of how it sounds - so please keep us posted...

John
 
Thanks John.

You are right, I would not have been able to perform nearly as much surgery without EW helping guide me. Especially when it came to the whole transistor thing.

I listened to it for about an hour yesterday and about 10 minutes so far today. My initial impression of it was that it lacked bass but then I realized that I put the bass knob back one click off and was listening to it yesterday the whole time at -2dB bass!

I have yet to fix that. One other negative I noticed was that until I turn the volume knob up between 1 and 2, I only hear sound out of the right channel. I have had this same annoying problem with a Yamaha CR-2020.

When I turn the volume up and put it in L+R mono mode, I do not notice a difference in volume between the two channels, so I think its not an issue of one channel being louder than another, it just sounds like one channel does not "turn on" until it reaches a loudness greater than the other.

Aside from deoxit (which I have done several times) are there any other potential reasons/causes for this?

Aside from those two minor issues I think the sound quality is great - all the cliched terms I can use such as "warm, full, rich, deep, wide" apply to this amp.

It does not sound nearly as 'clinical' as the Pioneer SA-9800 I was running immediately prior, or as flat as the Yamaha CR-2020 in my office.

Unfortunately I have never heard a tube amp, so I cannot tell you how "tubelike" it sounds. I do know that it sounds much softer and warmer than the later model Sansuis I have, the AU-919 or AU-11000a.

I still have some tinkering to do with this unit. I am eager to determine what this volume issue is. If it means getting a new volume pot, I will just have to live with it.
 
Browser problems:sigh:
That looks great :thmbsp:

A couple of questions
Why did you
2. Replaced every .47uf mylar cap with Panasonic Metal Film Polypropylene
5. Replaced mylar caps on driver boards with vishnay/roederstein polypropylene caps
and why did you choose those particular caps?
Also are you planning on changing these
"I found two Toshiba 2SC1079 in one channel and two Hitachi 2SC898 in the other."?

thanks
I'm waiting for my Digikey order.
 
Thanks.

I replaced every .47uf cap with the metal ones because I read previously about people using orange drops in this situation with good results. I approached the orange drop question in this thread before it got deleted/recreated and EW had suggested I try the panasonics instead of orange drops, so I did.

There were 1uf mylar caps on each driver board, and I had a bunch of 1uf film polypropylene caps laying around so I decided to use them.

I have been toying around with the idea of replacing mylar caps ever since I saw http://amp8.com/english/eindex.htm but had never tried it. I figured now is a better time than any, since I had to place an order from Digikey anyhow.

I dont think I am going to replace the output transistors after all, because I dont notice anything audibly wrong with the functioning of the unit anymore (with the volume knob above 1).

If someone knowledgeable chimes in and says there is a technical reason for replacing them, I will certainly do so. I have a few spare OnSemi TO-3's laying around from an earlier restoration.
 
I think the volume pot issue seems to have gone away. I dont even notice it anymore. Probably just a pot that I did not deoxit well enough that has fixed itself now that I have been using it daily.

That's a relief!
 
xoaphexox,
I'm happy for you if only my 999 would behave.
I replaced the outputs, and the transistors on the headamp.
New ps caps and a few others.
I'm back to blowing the bias fuse, and very distorted low volume.
I'm about to give up.
I double checked my transistors and cap polarity. I'm at a complete loss.
Help!
banghead.gif

thanks
mdr
 
Have you checked the VR's on the driver boards? I didnt replace mine, but they are so old that when they dont make contact the bias fuse blew. I turned off the unit and used a tool to move the bias VR from end to end several times to "clean up" the traces with the wiper.

Then I was able to adjust bias without the fuse blowing because the VR was always making contact.

Also, I reflowed every joint in the unit. Did you make sure to replace the transistors with the proper ones? For each channel's ripple circuits? Do both bias fuses blow or just one channel?

If you want me to take a particular photo of a board I can do it this weekend (or sooner) and get back to you.

Also, did you have the protection board? Did you remove it? Maybe one of your SCR's are shorted?
 
xoaphexox
Thanks for getting back to me.
I measured the bias VR's and they seem to work fine

"Did you make sure to replace the transistors with the proper ones? For each channel's ripple circuits?"

I'll tripple check

I removed the protection board

A photo would be great.
I guess I'll recheck everything and reflow all of the solder joints.

"Do both bias fuses blow or just one channel?"
Just one bias fuse, but the other channel is at a very low volume and distorted.

thanks
mdr
 
Found the problem, now to find the solution

Woo Hooo!
I found the problem, now to find the solution.
That pesky 2SC281 dangling transistor!!!
I had replaced every transistor and cap even a few resistors, till I had a brainstorm, trade the 2SC281 with the one on the good board. POP! blows fuses.
Now where to find a replacement?
I searched and found them at Digitron, they have date codes 1984 and 1994.
Which one to get?
I also found them at ACME Enterprises of Orlando.
Is there a more modern replacemant?
thanks
mdr
 
Digitron is a parts-whore reseller/clearing house. They won't give you the time of day unless you're prepared to spend 2 or 3 grand, and will probably ignore your emails.

Consolidated Electronics may well have them, but he's got a $25 minimum order...

The problem is the metal case it fits into...you need to find something you can slip into there. The 2SC3526H (Panasonic) is a TO-92L device that might fit (or you may be able to make it fit).
 
EW,
Thanks for the headsup on digitron I still haven't heard from them:no:
So I guess I'm small potatoes to them.
I went ahead and ordered from ACME Enterprises of Orlando.
I hope I don't end up like Wile E. Coyote
Wile-E-Coyote.jpg
but I'll find out:D
 
Fixed!!!!!

:banana::banana::banana::banana::banana::banana:

WHOOO HOOOOOO!!!!!!
:banana::banana::banana::banana::banana::banana:
That Pesky dangling transistor!!

My shipment from ACME Enterprises of Orlando came in thismorning.
They pack the stuff in brown paper lunch bags!
Every thing was perfect, I'd use them again. Here's the link

http://www.acme-sales.net

Now does any one know how to get rid of scratches/gouges in the faceplate?
Thanks for all of your help:music::music::banana:
mdr
 
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