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337alant
13-09-2015, 19:46
Recapping the Studer A810
The studer decks are beautifully built decks but are still getting on in age and mine is 30 years old.

https://farm6.staticflickr.com/5821/21093181816_634dc24220_c.jpg (https://flic.kr/p/y8W55y)IMG_2531 (https://flic.kr/p/y8W55y) by Alan Towell (https://www.flickr.com/photos/69508926@N05/), on Flickr


Looking at the plug in circuit boards there are capacitors that although were very good quality Capacitors in their day can fail short and can take out other components or worse still the microprocessors which may be very difficult to obtain now.
The electrolytic capacitors are mainly from Frako and Phillips with non polar Bakelite caps from Roe roederstein. The frako and Phillips caps have a reputation for failing short and the Roe caps get leaky crack and dry out. At this age they have also generally drifted out of spec so are worth replacing with good modern alternatives. For this I chose the Nichicon Muse KZ, Fine Gold and Bi polar ES series and Panasonic FC.
http://www.hificollective.co.uk/components/nichicon.html
Here are a couple of shots of the boards before recapping generally these boards use all metal film resistors and good quality solid tantalum, Wima and Phillips Film capacitors that have a good reliability reputation.

https://farm1.staticflickr.com/519/18987138945_332f861af2_c.jpg (https://flic.kr/p/uVQ3Uz)20150620_150633 (https://flic.kr/p/uVQ3Uz) by Alan Towell (https://www.flickr.com/photos/69508926@N05/), on Flickr
https://farm1.staticflickr.com/720/20767994414_f58282c78d_c.jpg (https://flic.kr/p/xDcpcd)IMG_2389 (https://flic.kr/p/xDcpcd) by Alan Towell (https://www.flickr.com/photos/69508926@N05/), on Flickr
https://farm1.staticflickr.com/719/21202815268_b823e01e07_c.jpg (https://flic.kr/p/yiBYhu)IMG_2388 (https://flic.kr/p/yiBYhu) by Alan Towell (https://www.flickr.com/photos/69508926@N05/), on Flickr


After recapping here are a couple of shots of the same boards. Re capping isn’t easy but the board have quite robust tracks but tight holes. The Roe and blue Phillips caps in particular measured quite different to their intended values and showed signs of cracking in the case.

https://farm6.staticflickr.com/5703/21380097542_f057c406a0_c.jpg (https://flic.kr/p/yzhA8q)IMG_2488 (https://flic.kr/p/yzhA8q) by Alan Towell (https://www.flickr.com/photos/69508926@N05/), on Flickr

https://farm1.staticflickr.com/592/20769842603_28f9ef49e0_c.jpg (https://flic.kr/p/xDmSAx)IMG_2487 (https://flic.kr/p/xDmSAx) by Alan Towell (https://www.flickr.com/photos/69508926@N05/), on Flickr


This is just the start of recapping the full recorder will need to be done and I will post my progress as I remove other boards
After a replacement I listened to the deck and TBH I thought it didn’t sound as good as before :eek::scratch: but after a few days and now weeks it is sounding noticeably better :eyebrows:;).
I would like to leave it switched on for a long period but the capstan motor turns all the time on this deck and I don’t want to damage that so I switch off when not in use. There is supposed to be a way of switching off the capstan so I will check the manual.
Anyway happy days so far and a worthwhile exercise

Alan
Ali Tait
13-09-2015, 20:02
Good job Alan, it'll take a while to finish!

Need to do the Tandberg also.
PaulStewart
13-09-2015, 23:07
Great job Alan, I don't have time or space to do this sort of thing DIY at the moment, so I PSE (pay someone else). Henry Dukat has recapped all my Revoxes :)
337alant
02-02-2016, 21:56
Recapped the Basis Board on the A810 the other day
This is the main interface board for all the plug in boards but contains a load of 470Uf & 1000uf Phillips electrolytics that can fail short so best replaced.
Not a simple job to get this board out and De-solder these caps and the tracks are really fine so you have to be careful not to lift them, anyway it all went OK and its back up and running.
The old caps had high ESR and high uf values so were off spec.

https://farm2.staticflickr.com/1462/24780078795_9f31bb0fe4_c.jpg (https://flic.kr/p/DKJo6R)IMG_0589 (https://flic.kr/p/DKJo6R) by Alan Towell (https://www.flickr.com/photos/69508926@N05/), on Flickr

https://farm2.staticflickr.com/1572/24484542030_141ed31af0_c.jpg (https://flic.kr/p/DiBFjo)IMG_0588 (https://flic.kr/p/DiBFjo) by Alan Towell (https://www.flickr.com/photos/69508926@N05/), on Flickr

Alan
337alant
10-02-2016, 22:54
I replaced the 3 electrolytic in the stabiliser board, I didn't have an Axial 220uf cap so I used a radial on the back of the board which just fits, not happy doing this as its a bit of a bodge but it works fine.

I also replaced the Rifa and phillips caps in the Motor control board

https://farm2.staticflickr.com/1450/24623605210_abb688bc20_c.jpg (https://flic.kr/p/DvUpXq)20160204_184841 (https://flic.kr/p/DvUpXq) by Alan Towell (https://www.flickr.com/photos/69508926@N05/), on Flickr

https://farm2.staticflickr.com/1530/24825745931_51a9bbdc42_c.jpg (https://flic.kr/p/DPLrmg)20160204_175320 (https://flic.kr/p/DPLrmg) by Alan Towell (https://www.flickr.com/photos/69508926@N05/), on Flickr

Alan
337alant
11-02-2016, 00:31
Today I changed the battery on the MP Board along with changing the 3 EPROM chips to the 25/91 software version.
I didn't make a back up so I had to start again with the audio parameters
One strange thing is my ongoing problem with slow rewind speed is mysteriously cured by this upgrade?? its now working fine *bigthumbup*

https://farm2.staticflickr.com/1718/24920359636_47b3f90a3f_c.jpg (https://flic.kr/p/DY8mH3)IMG_0614 (https://flic.kr/p/DY8mH3) by Alan Towell (https://www.flickr.com/photos/69508926@N05/), on Flickr

Alan
danilo
11-02-2016, 03:50
Interesting. Did it actually help?
Years Ago whilst employed by the Canadian Broadcasting Corp. We had an an ongoing maintenance ritual with Our 1/2 " tape machines.
ALL tapes had to be reverse wound (by Decree) after ..each.. play.
And there was a Logged time/hours use on the Tape heads.
Which required regular replacements.. because the damned things wore out quickly.
Caps "servicing' was Very low on the maintence schedule. Simply because there were so many.. other.. items to maintain before caps became problematic.
Explaining Why I regard tape machines as goofy /unreliable contraptions 40 + years on.
Firebottle
11-02-2016, 08:22
Ooh, a 6803 microprocessor, that take me back a bit to designing industrial instrumentation :D
The Black Adder
11-02-2016, 09:03
lol... 6803!? - it's a bloody pinball machine. :lol:
337alant
11-02-2016, 18:27
Interesting. Did it actually help?
Years Ago whilst employed by the Canadian Broadcasting Corp. We had an an ongoing maintenance ritual with Our 1/2 " tape machines.
ALL tapes had to be reverse wound (by Decree) after ..each.. play.
And there was a Logged time/hours use on the Tape heads.
Which required regular replacements.. because the damned things wore out quickly.
Caps "servicing' was Very low on the maintence schedule. Simply because there were so many.. other.. items to maintain before caps became problematic.
Explaining Why I regard tape machines as goofy /unreliable contraptions 40 + years on.

Danilo
Nice to hear from someone who used these machines when they were new.
Its an unfortunate fact now though the electrolytic cap in these old machines are coming to the end of there life time and the Frako's in particular have a reputation of failing short and taking out other components such as microprocessors that aren't easy to find so its worthwhile changing them all out if you can.
The little blue phillips caps measured the worst of all removed and some of the red Roe rodestines where visibly cracked.
So its all just peace of mind now and the machine is working / Sounding better than when I first got it.
I do worry about head replacement when that time comes around as they are not easy to find and are expensive.

Alan
Arkless Electronics
11-02-2016, 18:37
Watch out for shorted tants on older ReVox/Studer gear ;)
337alant
11-02-2016, 23:44
Watch out for shorted tants on older ReVox/Studer gear ;)

HI JEZ,
I agree with you on the tants and have changed nearly all out on my Revox A77 and will do the same on my PR99s
However I have it on good authority from a Tech on tapheads.net that the tants on the A810 are very good and dont need changing?, I guess in reality you cant say that about any cap after 30 years.
I will put together a list of Tants and see if I can get some relabel replacements
I note that Nagravox on the internet recommend changing them all with electrolytics ?, what do you think

Alan
Arkless Electronics
12-02-2016, 01:53
HI JEZ,
I agree with you on the tants and have changed nearly all out on my Revox A77 and will do the same on my PR99s
However I have it on good authority from a Tech on tapheads.net that the tants on the A810 are very good and dont need changing?, I guess in reality you cant say that about any cap after 30 years.
I will put together a list of Tants and see if I can get some relabel replacements
I note that Nagravox on the internet recommend changing them all with electrolytics ?, what do you think

Alan

Hi Alan. Those caps on the A810 boards look like they could be solid aluminium type electrolytics... Philips at a glance. Not a problem.
Shorted tants is one of the most common faults on older ReVox stuff in general though.
I often replace tants with top quality electrolytics with good results myself so agree with Nagravox on that.