[kstuart]

I do see the Wiki for the DIY Beginners Guide which has recommendations for tools, solder and so forth.
 
My question - is there anything that needs to be different for working on Vintage electronics (eg replacing capacitors), as opposed to constructing a new amp from a kit ?
 
Is a different solder used, for example ?
 
Thanks !

 

[wuwhere]

I found this.
 
http://www.ebay.com/gds/What-you-need-4-recapping-your-vintage-stereo-equipment/10000000008102766/g.html

 

[kstuart]

Quote:

I found this.
 
http://www.ebay.com/gds/What-you-need-4-recapping-your-vintage-stereo-equipment/10000000008102766/g.html

Surprised to see that on ebay, of all places ! 

 
Looks helpful, thanks.

 

[wuwhere]

I have read some excellent tips on ebay about buying used vacuum tubes from experienced tube sellers.

 

[duncan1]

Kstuart- No 1--replace ALL non electrolytic caps  with quality polyprop film caps[no cheap mains ripple versions] audio only . Change all electrolytics. . If tube check tubes for gain and output for balance. Check  tube sockets [usually have dirt film on them. Both SS and tube check power supply output check  bias adjustment in SS. Check for dry joints. check every resistor  for increase in value and change if more than 10% out.with metal film [or better] ---Tools DMM--analogue MM--soldering iron plus HIGH quality solder--DONT skimp on buying cheap stuff. long nose pliers side cutters --set of QUALITY screwdrivers --NO not the $1 set in the "buy here cheap" shop.Nut removers/small spanners.Good lighting to work with.--Old circuit diagrams can be found on the web.--If I have missed anything I am sure somebody will say.

 

[kstuart]

Quote:

check every resistor  for increase in value and change if more than 10% out.with metal film [or better]

Thanks for the helpful info.
 
If you are checking the value of a part that is soldered into the board, doesn't that affect the reading somewhat ?

 

[duncan1]

Thats correct unsolder one end  of the resistor to test small value caps   and using your analogue MM you should get a small swing on the highest range of the meter and it should go back to zero if it does not its probably faulty. A capacitor should really be tested on a capacitor tester but that gives an indication at least. Large value electrolytics should  have the positive/or negative  in a negative supply connection disconnected[check first for any  high voltage still held in the cap] and again using the highest setting check for a swing on the meter it will not go back down to zero like a small value cap but that doesnt mean its faulty unless it registers a low ohms reading.Very small values of caps --IE--500PF or 1NF shouldnt register on the top range of the meter if they do they could be faulty. BJTs [transistors] can be tested with an analogue meter if you dont have a transistor tester]  --NPN=base to neg  lead and keeping it there test the other two legs  on the transistor you should get a low ohm reading--NOT a S/C--test using the X1 ohms range--PNP the positive lead to the base and test the other two legs.  

 

[wakibaki]

There's no point in testing semiconductors in a piece of working equipment. Every time you lift a pin you run the risk of breaking it or lifting the pad it's attached to.
 
There's a lot to be said for not doing any work at all on a piece of working equipment, particularly complex equipment, particularly if you're a novice. More equipment has been destroyed by unnecessary 'maintenance' than by any other cause. Been there, done it. That's why we say 'if it ain't broke, don't fix it'.
 
If you want to get some practice, build a cmoy and work your way up building and learning to debug more and more complex stuff.
 
w

 

[Fred_fred2004]

Quote:

There's no point in testing semiconductors in a piece of working equipment. Every time you lift a pin you run the risk of breaking it or lifting the pad it's attached to.
 
There's a lot to be said for not doing any work at all on a piece of working equipment, particularly complex equipment, particularly if you're a novice. More equipment has been destroyed by unnecessary 'maintenance' than by any other cause. Been there, done it. That's why we say 'if it ain't broke, don't fix it'.
 
If you want to get some practice, build a cmoy and work your way up building and learning to debug more and more complex stuff.
 
w

Absolutly spot on - could not agree more

 

[wuwhere]

Most of the old boards would be through hole not just lifting pins.

 

[duncan1]

I disagree with the "pat" line --start on a CMOY--How do you know the IQ of the poster???. In the 50s I bought old 1930s radios and stripped them down -changed tubes /checked mains transformer voltages/heater voltages/changed old caps/bought exWD signal generator and put modulated signal through them . Checked output stage--  and so on. I bought the Practical Wireless mag[UK] and read up on that. I didn't start on a "one valver{tube] radio. I bought exWD communication receivers and repaired them.In 1960 I built from "scratch" a communications receiver called the "Night Rider"anybody my age in the UK will know it about-8 tubes as well as BFO . I still have the instruction book! So don't patronize him! If he WANTS to take apart a working amp -- Then LET HIM --its HIS not yours. He will learn more that way . Don't try to curtail his enthusiasm. If he wants to take it down to the last screw then he should its HIS. I gave PRACTICAL--DOWN to EARTH advice. I see NO fault in what I told him. --Judge not that you may be judged.in the same manner  

 

[jcx]

isn't encouraging anyone with unknown ability (actually asking for advice in this case) to "just go for it"  without any guidance, offers of perspective equally irresponsible - just because it worked for you doesn't mean its the only way either
 
and I must say from your posts in Sound Science I'm not sure how well your approach really worked

 

[duncan1]

Just because it "worked" for me?? Worked has nothing to do with it neither has "luck" its all down to intelligence and the ability to understand what you see and read.I ask again--How do you know the IQ of any poster   on Head-Fi-??? Intelligence isn't something that grows as you get older. The  tests in schools for young children  to establish their IQ is relevant to the level they achieve as they get older. In other words   their IQ doesn't go from say-120 and then up to 140 or more. You are born with the level of IQ you  live with. So how can you judge young posters  without knowing it ? They might have a higher one than the people giving advice.I treat everybody equally and have done all my  life. Don't care about the color of their skin whether they are-long-short-fat slim. And I certainly don't patronize people as I cant stand anybody doing that to me.---Sound Science??-Didn't even know I was on it. Because I take the side of Head-Fiers rather than business and tell them ways of upgrading their equipment  that must upset some but that's the point of being here. If you spent enough time --as I said on a post you can upgrade a 717 to a 727-11 . It isn't magic just down to earth PRACTICAL experience . Does saving a large sum of money upset some[not in business interests] Well you might as well close down Head-Fi because a lot of people here are telling you how.Are you going to dispute that the mother boards as far as the basic operational circuits on the 717/727-11 are different?? Then tell me how remember the negative feed back  can without any problem be changed back to the original global feedback. Perhaps you can tell me which of the contacts for the two channel boards -and I mean the SOCKET CONTACTS are DIFFERENT in both versions. The original copper runs go to the same components. showing the BASIC circuit is the same. just the volume control and relay cut-off have moved. Stax aren't unique many manufacturers  save money by only modding small parts  of their boards. 

 

[ssidyEvelyn]

Check for dry joints. check every resistor  for increase in value and change if more than 10% out right or not

 

[duncan1]

SSidyEvelyn-- Every circuit design is built to a standard that the EE designs it is up to him/her to which standard they apply That's why some companies bring out various  versions of the same product along the lines of---The more you pay the higher the fidelity. Some altruistic designers give you the top circuit straight off.There are also designers who achieve dis.of 001%THD and make a point of saying .Quote-I achieved this using cheap components[DS]. 10% is the limit I put on components in a used/old amp and that was the international standard using a color  code -Gold=silver etc .With modern production  this has changed to say-brown 1% -One of the first things I learned as a kid was the resistor color code its a great start you don't have to keep referring to a chart.. If a design is using resistors more than 10% out [new design] then I don't think much of it .because they don't care about the customer.    Thankfully they are in the minority  and will hopefully disappear.  Over time components change value depending on in resistors case the current traveling through them . Capacitors large value lose efficiency and develop resistance. If a resistance  marked as 1% changes value to say 5% then change that too. This might seem OTT but you must keep to the design specs. that the original designer has put forward  and if components change value the the designers specs. will be out  adversely affecting the performance of the amp.