AU-517 vs AU-719 - a post-recap comparison
- Thread starter pete_mac
- Start date
pete_mac
Super Member
Some more tweaks (when will it ever end?)
The old binding posts have now been replaced with a single set of solid copper CMC binding posts, as I only ever use one set of speakers at a time. This has also allowed me by-pass the original speaker wiring and speaker selection switch entirely, with heavier-gauge wiring coming directly off the boards instead now. Neater, simpler, less resistance. I hear the purists gasping in horror! Don't fret though, as this is 100% reversible if required. I have kept all of the original wiring in place (albeit disconnected) and the wiring is taped up and tucked out of the way in an inconspicuous location.
I also repainted the lid using Rustoleum Oiled Bronze paint which is a good match for the paint used on the AU317, 517 and 717. Even though the 719 originally came with a black, I like the look of the earlier lids.
Overall, I'm really happy with the result and I'm looking forward to having a good listen. First impressions are that the output does sound a bit cleaner and 'meatier', but this could well be all in my head
The old binding posts have now been replaced with a single set of solid copper CMC binding posts, as I only ever use one set of speakers at a time. This has also allowed me by-pass the original speaker wiring and speaker selection switch entirely, with heavier-gauge wiring coming directly off the boards instead now. Neater, simpler, less resistance. I hear the purists gasping in horror! Don't fret though, as this is 100% reversible if required. I have kept all of the original wiring in place (albeit disconnected) and the wiring is taped up and tucked out of the way in an inconspicuous location.
I also repainted the lid using Rustoleum Oiled Bronze paint which is a good match for the paint used on the AU317, 517 and 717. Even though the 719 originally came with a black, I like the look of the earlier lids.
Overall, I'm really happy with the result and I'm looking forward to having a good listen. First impressions are that the output does sound a bit cleaner and 'meatier', but this could well be all in my head
pete_mac
Super Member
Thanks mate. The last thing that I'm considering doing is fitting some new RCA jacks - whether for the AUX input only, or the whole lot. The standard items are soldered onto a board rather than having flying leads so it complicates things a bit. I may end up spacing the board off the rear panel via poly spacers and then running wiring from panel-mounted RCA jacks to the board itself. Either that or I fit a new AUX jacks only and run new dedicated wiring straight to the preamp board.
Let's hope you never need to use your headphones !!!
Yep, that's a sacrifice I've had to make. I guess I could run some thinner dedicated wires to the headphone jack if required. I'm not a big headphone listener anyway, particularly given where my amp sits relative to my listening/seating position.
LeeS
Member
Hey Pete.
Quick question if I may? When you replaced your weedy "figure of eight" power cord with the new three core Belden cable, where did you attach the earth core to inside the amplifier? I have just run a single cable from the earth pin of my mains plug to the "Ground" terminal on the back of the amplifier, but was just wondering where you put yours to and if there was a "correct" location for it.
Thanks.
Quick question if I may? When you replaced your weedy "figure of eight" power cord with the new three core Belden cable, where did you attach the earth core to inside the amplifier? I have just run a single cable from the earth pin of my mains plug to the "Ground" terminal on the back of the amplifier, but was just wondering where you put yours to and if there was a "correct" location for it.
Thanks.
pete_mac
Super Member
I didn't affix the earth core to anything. I looped it so it wouldn't foul on anything and cable-tied it out of the way until I decided what to do with it.
I recapped a AU-417 a few weeks ago and it had a three core power cable as standard. The earth core on the 417 had a ring crimp on the end. The ring crimp was secured by one of the screws which holds the brackets on the power supply/protection board to the chassis. This suggests that it should be fine to attach the earth core anywhere where a secure connection to the chassis is achieved.
cheers
Pete
on this amp was
I recapped a AU-417 a few weeks ago and it had a three core power cable as standard. The earth core on the 417 had a ring crimp on the end. The ring crimp was secured by one of the screws which holds the brackets on the power supply/protection board to the chassis. This suggests that it should be fine to attach the earth core anywhere where a secure connection to the chassis is achieved.
cheers
Pete
on this amp was
LeeS
Member
Well, last night I bit the bullet and went in for a big PSU cap change on my 719. I have replaced the 33 year old Nippon Chemicon 10,000uF 71V 85C caps with some multi-terminal Mundorf M-Lytic AG+ 10,000uF 80V 105C caps.
I have had to add some double-sided, spongy tape around each cap to pack them out and have also added a piece of cut drain pipe for the clamps to work on (thanks for the idea Skippy). Bit of a bodge but it works. Holds them tight and looks OK (sort of).
I quite like these multi-terminal caps (+ in, +out and - in, - out). It meant I could solder all of the original wiring to the + in and - in and then still have 2 terminals left for adding bypass caps of choice. In my case some mkp Wimas. I don't think these Mundorfs are like the BHC T-caps where the two terminals are connected at the start and end of the foil, but the terminals are just internally connected together to allow for larger, neater wiring jobs.
I fired it up afterwards and to my ears, it sounded cleaner in the mid to highs, with more detail, slightly tighter bottom end and also quite a bit smoother and less spitty if that makes sense?
Anyhow, I will leave it on again tonight for a couple of hours and recheck and reset bias and offsets etc and have a good long listen again. I am happy, even if there were no audible differences, that I now have some half decent caps in there to complete the whole re-cap exercise and hopefully let the 719 live for another 30+ years or more.
A post is no use without pics, so even though they are not very good, I will post some pics I took a little later on so you can all see what I am talking about.
Cheers.
I have had to add some double-sided, spongy tape around each cap to pack them out and have also added a piece of cut drain pipe for the clamps to work on (thanks for the idea Skippy). Bit of a bodge but it works. Holds them tight and looks OK (sort of).
I quite like these multi-terminal caps (+ in, +out and - in, - out). It meant I could solder all of the original wiring to the + in and - in and then still have 2 terminals left for adding bypass caps of choice. In my case some mkp Wimas. I don't think these Mundorfs are like the BHC T-caps where the two terminals are connected at the start and end of the foil, but the terminals are just internally connected together to allow for larger, neater wiring jobs.
I fired it up afterwards and to my ears, it sounded cleaner in the mid to highs, with more detail, slightly tighter bottom end and also quite a bit smoother and less spitty if that makes sense?
Anyhow, I will leave it on again tonight for a couple of hours and recheck and reset bias and offsets etc and have a good long listen again. I am happy, even if there were no audible differences, that I now have some half decent caps in there to complete the whole re-cap exercise and hopefully let the 719 live for another 30+ years or more.
A post is no use without pics, so even though they are not very good, I will post some pics I took a little later on so you can all see what I am talking about.
Cheers.
LeeS
Member
As promised, here are the photos of the fit. Please excuse the poor quality of the photos.
Original Caps
Original Cap close up
From above
From below
New Mundorfs
Nw Mundorfs compared to old caps
New caps all fitted and connected
New caps from above
and finally with bypass caps fitted to spare terminals
Cheers.
Original Caps
Original Cap close up
From above
From below
New Mundorfs
Nw Mundorfs compared to old caps
New caps all fitted and connected
New caps from above
and finally with bypass caps fitted to spare terminals
Cheers.
LeeS
Member
Thanks for the kind words Pete.
Just got to re-replace some 1% tol Rs on the driver and head-amp boards (thought the (F) on the schematic was "Fusible" - Doh !!! :stupid
and swap the 4 black flags out for some silver micas, fit some "proper" speaker binding posts and a new, decent mains lead and that will do. She should last me another 30 odd years hopefully. 
On a side note (and a slight hijack - forgive me), could someone else with a 719 please check the colour banding/values of R29 and R30 on the head amp board for me please? It says that it should be 5.6K on the schemo, but the actual resistors are 56K. Just want to make sure that they are right.
Also does anyone know where one could get hold of an operators/user manual for the 719? I have the service manual but would be interesting to see what was in the user manual (if there was one).
Cheers.
Just got to re-replace some 1% tol Rs on the driver and head-amp boards (thought the (F) on the schematic was "Fusible" - Doh !!! :stupid
and swap the 4 black flags out for some silver micas, fit some "proper" speaker binding posts and a new, decent mains lead and that will do. She should last me another 30 odd years hopefully. On a side note (and a slight hijack - forgive me), could someone else with a 719 please check the colour banding/values of R29 and R30 on the head amp board for me please? It says that it should be 5.6K on the schemo, but the actual resistors are 56K. Just want to make sure that they are right.
Also does anyone know where one could get hold of an operators/user manual for the 719? I have the service manual but would be interesting to see what was in the user manual (if there was one).
Cheers.
Last edited:
Lee, I think you will have to accept the standard line - "what is in there now is correct" i.e. 56kΩ, the schematic confusingly indicates 5.6KΩ, and the Parts List says "56kΩ ½W 1% M.R." In our discussions on the subject I think you say they measure as 56kΩ which bears this out.
I think I am correct in saying this resistor is in the RIAA equalisation circuitry, so only in play if using the Phono inputs.
:thmbsp:
I think I am correct in saying this resistor is in the RIAA equalisation circuitry, so only in play if using the Phono inputs.
:thmbsp:
LeeS
Member
Ahhhhh... Thanks John. I didn't even look at the parts list. :sigh: That's confirmation for sure I think. A schematic cock up. Yep, I agree that they are part of the RIAA circuit too. Thanks for the assistance. Much appreciated. :thmbsp:
I have just received some new 1% 3.9Ks, so they will replace all the ones I stupidly downgraded in the first place and have also just got some 22pF silver micas to replace the black flags with. I will fit all these and check the bias and offset and do some probing about and make sure all the voltages are correct....
Thanks for your help.
I have just received some new 1% 3.9Ks, so they will replace all the ones I stupidly downgraded in the first place and have also just got some 22pF silver micas to replace the black flags with. I will fit all these and check the bias and offset and do some probing about and make sure all the voltages are correct....
Thanks for your help.
pete_mac
Super Member
Another piece in the puzzle... a pair of new-old-stock faceplates! 100% brand new, never fitted. Talk about finding the needle in the proverbial haystack! Big thanks to Dad (skippy124) for his efforts. Legend!! :thmbsp:
The 719 has quite a few minor nicks on the sides of the faceplate, and some little marks on the top edge. The 517 is much cleaner with only one minor scratch on the very top edge of the faceplate. With these new faceplates installed, both the 517 and 719 will now look a million bucks!
The 719 has quite a few minor nicks on the sides of the faceplate, and some little marks on the top edge. The 517 is much cleaner with only one minor scratch on the very top edge of the faceplate. With these new faceplates installed, both the 517 and 719 will now look a million bucks!
Betomon
Active Member
Very nice restoration! I've been following the thread, as I am in the process of re-capping my 719 as well. Can you tell me how the increase in the main filters' capacitance affects the amplifier or its performance? I've seen various replacement caps for these, but not too many comments on how they compare (i.e. pros and cons). I'd like to hear your opinion on it and anyone else with experience, as it seems that you have a very fine sense of experience and workmanship, as many others in this forum.
And also, care to share where you ordered your parts from? In the past i've always used Mouser ONsemi and dijikey.. seems like they have an excellent selection. Thanks for sharing this beautiful work!
And also, care to share where you ordered your parts from?
In the past i've always used Mouser ONsemi and dijikey.. seems like they have an excellent selection. Thanks for sharing this beautiful work!