10-16-2009, 12:05 PM
In addition to Chuck's excellent comments, I would like to add the following.
Too many people who are getting into this hobby or related fields, such as the restoration of vintage guitar amps, have the mistaken notion that replacing all of the tubes in the unit they are working on is a cure-all for everything. It isn't, folks! Here is the reality of what happens when you replace every tube in a radio, vintage guitar amp, or whatever:
1. You are spending money unnecessarily.
The chances are very good that most, and often all, of those tubes are still good! If you replace every tube without checking the old ones first, you are probably just wasting money.
2. You are driving up the cost of replacement tubes and, therefore, hurting the rest of us who know better.
This sort of thing is already happening with tubes such as the 35Z5. The shmendriks who insist on plugging in an old radio without first replacing electrolytic capacitors often end up blowing the 35Z5 rectifier sky-high. So, since there is a finite supply of 35Z5 tubes, the prices begin to go up. Supply and demand.
3. You are adding to our landfills for no good reason.
There is no good reason to toss out good tubes - especially if they are types that are no longer manufactured. If they test bad or are otherwise known to be bad, then yes, toss them, But don't throw them away if they are still good! Test them first!
Remember: It is the failure of the paper and electrolytic capacitors that causes the vast majority of the problems in an old radio. These must be replaced first before doing anything else if you expect that old set to last very long.
Rule of thumb: Replace all paper and electrolytic capacitors first. Check resistors and replace any that are not within 20% of rated values. Test the tubes and replace only if necessary.
I am not directing these comments to anyone in particular. But I do feel that everyone who is new to the hobby should keep these things in mind.
Sorry for the rant, but I felt these things needed to be said.
Too many people who are getting into this hobby or related fields, such as the restoration of vintage guitar amps, have the mistaken notion that replacing all of the tubes in the unit they are working on is a cure-all for everything. It isn't, folks! Here is the reality of what happens when you replace every tube in a radio, vintage guitar amp, or whatever:
1. You are spending money unnecessarily.
The chances are very good that most, and often all, of those tubes are still good! If you replace every tube without checking the old ones first, you are probably just wasting money.
2. You are driving up the cost of replacement tubes and, therefore, hurting the rest of us who know better.
This sort of thing is already happening with tubes such as the 35Z5. The shmendriks who insist on plugging in an old radio without first replacing electrolytic capacitors often end up blowing the 35Z5 rectifier sky-high. So, since there is a finite supply of 35Z5 tubes, the prices begin to go up. Supply and demand.
3. You are adding to our landfills for no good reason.
There is no good reason to toss out good tubes - especially if they are types that are no longer manufactured. If they test bad or are otherwise known to be bad, then yes, toss them, But don't throw them away if they are still good! Test them first!
Remember: It is the failure of the paper and electrolytic capacitors that causes the vast majority of the problems in an old radio. These must be replaced first before doing anything else if you expect that old set to last very long.
Rule of thumb: Replace all paper and electrolytic capacitors first. Check resistors and replace any that are not within 20% of rated values. Test the tubes and replace only if necessary.
I am not directing these comments to anyone in particular. But I do feel that everyone who is new to the hobby should keep these things in mind.
Sorry for the rant, but I felt these things needed to be said.
--
Ron Ramirez
Ferdinand IN
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