A&R A60

[Pinky]

Thanks Radfordman, I hadn't noticed that. Have now put them back into position.

It's funny how tastes differ but I've always preferred the black finish although I seem to be in the minority on that. The pair are actually subject to sale to another pfm'er soon so they won't be around here much longer. I will miss them but they just aren't being used so at least someone will be able to make good use of them.

As you probably noticed, the A60 is 'only' an '85 model and was upgraded to A60+ in '87. I remain intrigued as to whether this brought about a sonic improvement or just optimised the gain through aux for cd (and relabelled it accordingly). AFAIK, the phono input was RCA's on the '85 models as standard so that wouldn't have needed changing here.

 

[Radfordman]

Of the three A60's I've got, the latest, 1986 one sounds the best.

 

[archfield1]

Looking for some quick hints for reapiring my SA60.....
It's the left channel thats causing me problems... Sounds very distorted (and possibly lacking in power). Not able to get any proper measurement off RV2 0.5mv I think.

Am I right in thinking the Left channel is Q21 etc and the right channel is Q121 etc?
What should I be checking next (Q21, Q20 appear to be OK at least at with basic meter testing).

Thanks
Steve

 

[Analog addict]

Looking for some quick hints for reapiring my SA60.....

You are correct in your orientation assumptions. Have you checked the power supply cap on the faulty channel? They were a known point of failure on early A60s and your symptoms are similar, voltage rails should be about 35-36 volts if memory serves. If you check out Retro Hifi webpages, they have a free to download service manual for the A60, including procedure for setting quiescent current.

Regards,

Frank

 

[archfield1]

voltage rails should be about 35-36 volts if memory serves. If you check out Retro Hifi webpages, they have a free to download service manual for the A60, including procedure for setting quiescent current.

Thanks Analog addict!
Have now replaced the big capacitors and the voltage rails are measuring OK. replaced the TIP3055s and the ZTX753s! However still no joy on the left hand channel.

So I've been voltage checking between the channels and the service manual. Here are the problem areas but can anyone help me with the cause?

Workng from left to right accross the circut diagram for the power amplifier section....
All voltages are OK until I get to:
Q18 - base-emitter should be 0.55v - measures as 2.5v
R65 - should be 0.55v - measures as 0.1v

this in turn also throws out incorrect voltages for R64 and R63...

Also the voltage across R61 should be 0.55v - measures 15mv!

Have tried measuring component values in-circuit but could't find anything obvious.
Any help would be really useful

Thanks
Steve

 

[Analog addict]

Thanks Analog addict!
Have now replaced the big capacitors and the voltage rails are measuring OK. replaced the TIP3055s and the ZTX753s! However still no joy on the left hand channel.

So I've been voltage checking between the channels and the service manual. Here are the problem areas but can anyone help me with the cause?

Workng from left to right accross the circut diagram for the power amplifier section....
All voltages are OK until I get to:
Q18 - base-emitter should be 0.55v - measures as 2.5v
R65 - should be 0.55v - measures as 0.1v

this in turn also throws out incorrect voltages for R64 and R63...

Also the voltage across R61 should be 0.55v - measures 15mv!

Have tried measuring component values in-circuit but could't find anything obvious.
Any help would be really useful

Thanks
Steve

Did you wind off RV2 after replacing the output trannies?
Q18 is the driver for Q20 (and Q19 drives Q21). You can test any transistor out of circuit using a multimeter and the following steps:
1. Base to Collector should act like a diode and conduct one way
2. Base to Emitter should act like a diode and conduct one way
3. Collector & Emitter should be open circuit in both directions

A&R Cambridge recommended replacing Q13 to Q21 (and same for other channel) as part of service and to be honest given the low price and access difficulties, in my opinion a worthwhile venture.

Voltage across R63 (8mv) is also a useful way of ensuring quiescent current is set up correctly once the amp is up & running. (http://myweb.tiscali.co.uk/nuukspot/decdun/a60mods.html)

 

[clamnell]

Do you reckon a60 would go well with royd minstrels? have to donate an a60 to a 14 yr old neice, struggling a bit with the speakers but hope to have some minstrels soon. Thanks!

 

[Simon Dawson]

Do you reckon a60 would go well with royd minstrels? have to donate an a60 to a 14 yr old neice, struggling a bit with the speakers but hope to have some minstrels soon. Thanks!

I think that would work very well, so long as she does not turn the wick up too much or too often. I've got an Arcam Alpha 6 running Minstrels for the TV and it sounds great.

Simon

 

[Martyn Miles]

Arcam... Ah yes, A & R Cambridge. Did you know that when John Dawson was at Cambridge, he belonged to the ( if I recall correctly) Cambridge Tape Recording Society? Cambridge ( and Oxford where I am ) is/was full of Societies. John Williams, the famous classical guitarist, came to play and John and his 'compatriots' mic.'ed up John's guitar through an amp. (Mic and amp make long forgotten) into a pair of BC1s. It was so well done many didn't notice it was amplified. As a person now involved in semi-prof audio I understand the subtlety of the combination of the correct microphone, replay level and quality of a loudspeaker with low coloration, unlike a typical studio monitor. People thought J D would be successfull. He was... In the words of a certain Presenter on Strictly Come Dancing. "Didn't he do well!" Martyn PS Apologies for any forgotten details. It was along time ago...

 

[clamnell]

I think that would work very well, so long as she does not turn the wick up too much or too often. I've got an Arcam Alpha 6 running Minstrels for the TV and it sounds great.

Simon

thanks very much for this. bit surprised - minstrels can't be played loud??

 

[Simon Dawson]

thanks very much for this. bit surprised - minstrels can't be played loud??

I suppose it depends on wht you mean by loud! I've never had any problem with mine and they are used at realistic levels, but there are stories that the mid/bass drivers are a bit fragile.

Simon

 

[anotherA60guy]

Greetings everyone.

A pleasant surprise to find this thread. Thankful that there's another source that I can refer to to prolong the life of my A60.

It was Tiscali's and around '05-'06 that I did a replacement exercise with the help of a friend with electronics/ical background and nifty with the solder.

Recently, my A60 has developed some minor problems. But, I'll hold the questions till later.

For now, to 'induct' myself into the 'fellowship of A60 enthuthiasts' , I'd like to share a fleabay gem in the from of a piece of (I think) a rare A60 plug in/gadget....

the MC60

-Red.

 

[Robert]

very nice

 

[Analog addict]

Moving coil boards don't appear on the market very often, but I've always stuck with high output MC cartridges and the discrete MM input on my oldest A60 works fine with the succession of Dynavector carts I've used.

 

[Mothman]

I have recently acquired an early A60 serial number 35XX. I would like to use it in my office system to drive a pair of 'Heco 120S Interior series' speakers which have a nominal impedence of 4ohms. The speaker manual says that they are OK to use with 8ohm amplifiers as long as only one pair are connected. They run fine with my 8ohm 1980's Sansui amp but I was worried about connecting them to the A60 as it states 8-16 ohm on the amp back panel. Has anyone any experience of using 4ohm speakers with one of of these old amps? My amp is in its original unmodded state and I usualy listen at about 25% volume if it helps

 

[Robert]

It should be fine.
One of the much touted benefits of the A60 over the then largely Japanese competing amps was the ability to drive more difficult loads. The amp has speaker fuses, so if your speakers pull too much current the fuses will blow.

All I'd expect is for the heat sink to run a little warmer. You can't do any damage at the listening levels you indicate.

 

[Mothman]

Thanks Robert, I'll give it a whirl and report back how the A60 compares to the Sansui.

 

[Robert]

Which sansui?

If its a 217 or 317 which were contemporary with the early A60 it'll be no walkover.

 

[Colinlp2000]

I ran some Alison 6s on mine many years ago, they were 4 ohm. I had no problems as long as the volume was kept under the 12 o clock position, after that it would pop the 1.6A internal fuses. At 25% volume you should have no problems at all.

Really nice amp the A60!

 

[Mothman]

Which sansui?

If its a 217 or 317 which were contemporary with the early A60 it'll be no walkover.

AU-G30X is what I'm running at the mo, I think this circa 83-84 so one of their later offerings but still a bloody good amp IMO. In a few days I also hope to pick up an AU-505 circa 72 which is also supposed to be a capable performer.