AU-505 restore project

[ricksiri]

Hi everybody.
I am picking up an AU-505 tomorrow. I got inspired to aquire one after reading the positive opinion from qrxrestore.com. I want to attempt a full restoration. I don't yet know the shape of this unit. I got it from an online auction. I have found several really good threads here, regarding the AU-505. I have very basic electronic skills, but I have a good DMM and a Hakko soldering iron . I've replaced caps in some of my other vintage Sony stuff, (STR-6060F and TA-3200F), but haven't tried a full restoration. I'll post pictures as I go along and hopefully get advice from you knowledgable folks.

 

[smurfer77]

Good luck. The AU-505 is a wonderful machine. Here is my AU-505 thread - maybe it will be useful but just beware it was maybe my 2nd rebuild so there is some nonsense in there that I say.

 

[ricksiri]

Thanks smurfer77. Your thread is one I found earlier this week. Fantastic resource.

 

[stereofun]

Great amp to work on. You are in for a treat. I made the mistake of using power supply caps as coupling caps. So definitely get some coupling caps in there, dedicated to audio. A good candidate is Nichicon KG's. You can also use a KG for the supply cap. Imo it is not necessary to add polyprop bypass caps to either position. Those efforts are better spent on upgrading signal caps including an upgrade of the green mylar input cap.

Share some pics as you get going please and give us your listening impressions

 

[Shug451]

I didn't have the guts to do it myself, so I had a tech do it. He told me it was one of the easier amps he had ever worked on! Maybe I should have tried... Good luck with yours. I have to say it sounds superb after the recap.

 

[ricksiri]

I unpacked the AU-505 this afternoon. Aside from a little bit of rust on the transformer laminations and smudgy faceplate, this thing is really clean...AND it came with original box with original Sansui styrofoam inserts. I'm pretty stoked.

 

[usedto]

Here's a photo of my 505. I bought it in 2010 off of CL. It belonged to a kid who's dad worked for the garbage company, so I imagine he got it for free. I think I paid $45 for it and a TU666. I plugged it in, hooked up a source and some speakers, listened for a bit, then wrapped it up in plastic and set it on the shelf. Need to get a part or two for the tuner, but it works, too.

 

[ricksiri]

I took a chance and hooked it up to an old set of KLH's and ran an Ipod through the aux. input. Beautiful sound for a few songs...then a snap, crackle through the left channel started developing. I turned it off, deoxited all the pots and switches. Tried it again. Same thing. Snap, crackle from the left channel. Since I'm doing a complete restore, and since it does, technically work, I'm not going to chase this down. I'll just start with the restoration I'll start putting together a parts list.

 

[slimecity]

Yup - chances are you have the original "flying saucer' ceramic small-signal transistors in this amp. They breakdown and generally dont sound good anyway until they are replaced. They will be described as "8002" or "9002" types in the service manual.

Go to hifiengine.com, register & download the service manual for this amp.

Do some searches here as recommended subs have been discussed before.

 

[ricksiri]

Great amp to work on. You are in for a treat. I made the mistake of using power supply caps as coupling caps. So definitely get some coupling caps in there, dedicated to audio. A good candidate is Nichicon KG's. You can also use a KG for the supply cap. Imo it is not necessary to add polyprop bypass caps to either position. Those efforts are better spent on upgrading signal caps including an upgrade of the green mylar input cap.

Share some pics as you get going please and give us your listening impressions

Stereofun, Thanks for the tips. I think I'll try the bypass cap trick. I have a couple of sets of Klipschs', so it could work nicely.

I didn't have the guts to do it myself, so I had a tech do it. He told me it was one of the easier amps he had ever worked on! Maybe I should have tried... Good luck with yours. I have to say it sounds superb after the recap.

Shug451, I'm excited to try this rebuild. "no guts, no glory'

Yup - chances are you have the original "flying saucer' ceramic small-signal transistors in this amp. They breakdown and generally dont sound good anyway until they are replaced. They will be described as "8002" or "9002" types in the service manual.


Go to hifiengine.com, register & download the service manual for this amp.

Do some searches here as recommended subs have been discussed before.

slimecity, Looking at the service manual, it appears there are none of the dreaded "flying saucer" transistors in the AU-505. It seems, though, from what I'm reading, that most folks go ahead and replace the majority of the transistors. I'll probably go that route, too.

 

[ricksiri]

In looking at the PC boards, I'm noticing this brown gunk around the solder areas. Is that a problem, and if so, would a q-tip and a little alcohol be advisable?

 

[Hyperion]

Is that a problem, and if so, would a q-tip and a little alcohol be advisable?

Old flux, not really a problem, except in the most sensitive areas. I always clean it off for a better look at the joints and tracks as sometimes the flux can hide things you'd want to deal with.

 

[slimecity]

Dont worry about or anything minor like that - can you take a photo of the main board so we can see what small transistors you have on it?

Actually I dont think theres any in there which stand out as being in the "top 11 worst transistors" list. It may be best to shotgun them all with suitable replacements unless you are prepared to test them one by one with freeze spray (thats what I would do).

 

[stereofun]

If it bothers you - better than a q-tip that might leave material behind, I dip a soft toothbrush in rubbing alcohol, then gently nudge/scrub the board down. It's not necessary per se, but it is much easier to inspect joints and wire attachments after......and ok, it does look nicer.

 

[ricksiri]

Old flux, not really a problem, except in the most sensitive areas. I always clean it off for a better look at the joints and tracks as sometimes the flux can hide things you'd want to deal with.

Thanks Hyperion.

slimecity, I think I'll just replace them. Take the mystery away

 

[ricksiri]

If it bothers you - better than a q-tip that might leave material behind, I dip a soft toothbrush in rubbing alcohol, then gently nudge/scrub the board down. It's not necessary per se, but it is much easier to inspect joints and wire attachments after......and ok, it does look nicer.

Thanks Stereofun.

 

[ricksiri]

I'm putting together a cap list. I'm looking at Nichicon KG series for the the power supply and coupling caps. All I can find on Mouser site is "snap in" lugs. What are those types of lugs and does anyone know if they will work on this unit? I realize they may not fit exactly for the power supply mounting bracket, but what about going through the PC board? On trsnfrmr's recapping thread he mentions..."Note that the two big caps have 4 solder connections each and are a pain to remove."... Hmmm?
Maybe stereofun or smurfer77 will chime in here.

 

[slimecity]

Snap in will work - I just ordered some for my 555a - the pins of the output caps (for the new caps) will go thru the holes on the board but you will probably have to jumper one of the new cap plus or minus pins to the proper place on the PCB - you will see what I mean wen you get the new caps - new caps are generally smaller than the old ones so this issue is common.

4 lugs means that the old caps have 4 lugs soldered to the PCB, which you will need to unsolder. If you look at the metal traces under the board you will see that 2 are plus and minus, while 2 are not connected, they are just there for stability of the cap. Ignore those when you put your shiny new caps in (the right way around lols)

 

[ricksiri]

Thank you, slimecity, that really helps.

 

[ricksiri]

Recieved my package of parts. I think I'll start on the small filter board.