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Advent 300 Rebuild: Let the jaws hit the floor, let the jaws hit the flooooor!

patfont said:
You can check Dave Eaton's site he lists the important updates.
Addition of grounding wire on bottom of chassis.
Mica and new thermal grease for the outputs, if yours are the older style.
If tuner is drifting once warmed up, there is a cap swap that can help.
Click to expand...
I've found that the cap in question is only a problem on CERTAIN build versions of the 300. The N470 value in place of an N750 only works on the older style non-ceramic filter versions. Otherwise, leave the N750 be as it works best for the ceramic filter versions.
 
I bought a tuner drift upgrade & the -15v kit from Dave; I saw another post about the 300 that covered new grease & mica.... just wondering if I missed anything as Dave said the updates should be in the service manual. I downloaded one from HiFi Engine and there were no updates mentioned- but there were several mods on his site that I think are part of the updates.
 
Let me know what mods you are thinking of/gonna do, I have done them all.

I have rebuilt many, I always add new Bourns trimmers for the bias adjustment, I do replace the -15V reg. if it is inop. If I am doing the tone control bypass I do my own (hard wired) version.

You can:

Add gold plated RCA's
Add film cap upgrades in coupling/phono/preamp positions
 
Besides replacing all the electrolytics, I usually replace both the 15v + and - semiconductors. That would be RA100 (IIRC) and there were three transistors for the - side down by the tone controls on the main board (can't remember the Q#s off the top of my head right now) that always cause the noise in the preamp. The rest is the usual cleaning the switches & pots and applying new heat sink paste to the output transistors, cleaning the RCA jacks, etc. Of the ones I've restored, I think I've been lucky that there have been no blown outputs.
 
Which caps are most critical for the signal path? I do like to do a bypass on important caps - in cramped quarters like this I would use the Vishay 1837's.
Parts Connexion has 10 uf Black Gate's in stock and I ordered a bunch of those, they are getting so hard to find now.
I also ordered the mica to replace the plastic on the transformer heat sink, in addition to some new bias pots.
I have some Audio Note RCA & 5 way binding posts coming.
I put Nichicon Super Through caps in for the old filter caps 4,700 uf.
All the switches and dials have been cleaned with Deoxit.
My hope is that I can get this performing well enough to replace my Nelson Pass designed Nakamichi CA5 pre.
 
another bump on this fine older thread! I am curious as to why no WIMA caps were used on this rebuild?? Is there a reason as to not use wimas in the 1uf and 10 uf locations??
 
I use Sonicap Gen II at the coupling locations. Some of the SP locations have axial caps and leads would be too short, the stock 1uf/10uf lead spacing is very tight It could be done with the "tape" part number for the Wima's
as the leads are longer. You could also mount the Wima films on the back of the board.
 
patfont said:
I use Sonicap Gen II at the coupling locations. Some of the SP locations have axial caps and leads would be too short, the stock 1uf/10uf lead spacing is very tight It could be done with the "tape" part number for the Wima's
as the leads are longer. You could also mount the Wima films on the back of the board.
Click to expand...
Ahhh. Yes ! I forget many caps were axial leads.... Totally makes sense.
Would it be possible to get your cap list for this build ? If you still have the info??
 
Sorry, really don't have a cap list just keep everything in stock here.

My rebuild/list is based off the "Sound of the Wood" rebuilds, and then adding my upgrades and doing some listening and swapping out in critical locations.
I also do: depending on the unit:
-15V regulator upgrade
Hard wire tone control bypass
I always replace the bias trimmers
etc...etc...

They used Black Gate caps, they were a little dark sounding compared to the Silmic II once they are broken in.

http://vi.vipr.ebaydesc.com/ws/eBay...descgauge=1&cspheader=1&oneClk=1&secureDesc=0
 
When replacing Q401, Q402, and Q403 with the -15V regulator, are there any other changes to be made other than the removal of Q402, Q403, and installing the 7915 regulator as shown? I've looked at the schematics and it doesn't seem like any added links are necessary, but I'm no expert, so any comments would be appreciated.

Also, I am assuming any 7915 negative 15V power regulator can be used? I've installed a 1.5A that I had on hand.
 
Last edited:
MPSU52 was effectively dead base to emitter. I got another one then noticed I could just add the real -15v regulator. I pulled Q402 and Q403 but haven't had a chance to test them yet. Where does the jumper get placed? Can you let me know?
 
Last edited:
Look at post #33 pic:

Q403 jumper across the 2 locations cut out of the picture and your good.

Hope this helps
 
If i was gonna hard bypass the tone controls, would I jump from C204/C205 to R242/R243 or would i skip the resistor and wire straight to the preamp out jack?

Cheers,
Jake
 
If you are using the preamp section only and then hooking up to a high end amp and speakers then I would do the bypass. Otherwise leave it as is.
I do a hard bypass and take the bass/treble out of circuit. However the loudness switch is still in circuit.

Pat
 
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