Hello,
I am in the middle of creating a parts list for several receivers from the late 70's. My questions are:
1. If I were to replace some of the electrolytic capacitors with non-electrolytic types, what type of the latter is best suited for this application? I hear film of some sort...Is there a brand/line that you have successfully used?
2. If I were to replace the ceramic capacitors, what type should I be replacing with? Same as in question one: Is there a brand/line that you have successfully used?
3. If I were to replace the resistors, what type would be the best to use?
Keep in mind that since the receivers are from the late 70's, these should be through-hole components.
Thanks in advance.
I am in the middle of creating a parts list for several receivers from the late 70's. My questions are:
1. If I were to replace some of the electrolytic capacitors with non-electrolytic types, what type of the latter is best suited for this application? I hear film of some sort...Is there a brand/line that you have successfully used?
2. If I were to replace the ceramic capacitors, what type should I be replacing with? Same as in question one: Is there a brand/line that you have successfully used?
3. If I were to replace the resistors, what type would be the best to use?
Keep in mind that since the receivers are from the late 70's, these should be through-hole components.
Thanks in advance.
If you want to replace a component with a different type of component then you need to carefully consider how the original is used and how the replacement could be different. Do this separately for each component. This is especially important for any components in the RF stages - changing these could quickly make the receiver unusable unless you have the necessary knowledge and test equipment to re-align it.
Why do you want to change these components?
Why do you want to change these components?
Thank you for your reply DF96.
Actually, I am starting with an experiment: I have two identical receivers, both Harman Kardon 330C. Both of them in original condition, one has a bad transistor in the phono stage. My goal is to do "upgrades" in increments and evaluate if there are improvements to the music material if any.
I plan on replacing all, including the malfunctioning transistors in the phono stage and evaluate the performance against the untouched one. If seeing improvement, do the same to the preamp and power amp stages.
Next step is to replace electrolytic capacitors and quantify the improvements (if any). Next replace the ceramics and evaluate and finally the resistors...then I would like to apply the knowledge gained to the rest of my broken gear...
I am just curious and I guess have too much time on my hands...
P.S. Last, but not least...My curiosity is driven only by the idea of seeing how much change new components with tighter tolerances would make and which change would have the most (if any) effect on sound reproduction.
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Often the worst problems with these receivers are worn out switches and controls.
If both of them seem to work normally, have fun. I would listen to the phono stages
via the tape out jacks to a system of known sound quality.
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Sorry, for the confusion, here is a clarification: With the exception of the faulty phono stage of one of the receivers, they both sound identical. The intent is to change parts in one of them only and compare to the other as I go along.
Unless the original designer was incompetent (or overruled by management) you are unlikely to improve the sound by swapping components. The most likely outcome is no change. The second most likely outcome is that the unit stops working.
Start by fixing faults - at least you can be sure that this will improve things.
Then change components which are likely to fail in the future - such as some old electrolytics, if they have reduced value or raised ESR. Any carbon comp resistors (and any which have significantly changed value) should be changed.
The way to genuinely improve equipment is by upgrading the circuit, not the components.
Start by fixing faults - at least you can be sure that this will improve things.
Then change components which are likely to fail in the future - such as some old electrolytics, if they have reduced value or raised ESR. Any carbon comp resistors (and any which have significantly changed value) should be changed.
The way to genuinely improve equipment is by upgrading the circuit, not the components.
My 197? FM radio became fuzzy and insensitive. The Sony replacement I bought in 2006 had lousy sensitivity. So in the 197? radio I replaced almost all of the electrolytic capacitors. It became sharp and sensitive again. No alignment was required. It still gets fuzzy at low room temperatures probably because there were some .47 and 1 uf capacitors in the front end (RF) I didn't have replacements for.
In the RF area, ceramics are quite useful, IMHO. Use COG if you can get them, X7R varies a lot. No old ceramic cap should need replacing unless they installed one where the foil shows (fairly common in non-mil-spec ceramic caps).
In the audio areas, polyprophylene film caps are respsected by J Curl etc. The polyester caps I instead used in the PAS2 preamp surely made it harsh and trebly.
There should be no reason to replace resistors from the seventies unless the manufacturer found some extremely bad vendor. (Like an Airline TV I worked on once, even the resistors were **** in that). Resistors can be cheaply measured. Cleaning of dust off high value resistors can improve performance, dust causes electrical leakage over a few volts, especially in high humidity.
I find measuring electrolytic caps with a meter a total waste of time, measure them with a calender. The atlas ESR meter doesn't charge the capacitor over a few volts and measure leakage, which is another problem. If an audio or video product has performance problems, over 10 years old, throw the electrolytics out. No consumer product had long life epoxy sealed forever electrolytic caps, except one brand of guitar amp that had green CDE's.
Replacing 1 or 2 parts at a time then testing to see if you made performance worse is good on any electronic project. That way if you made a bad solder joint or used a problematic component, you know right where your problem is without a lot of functional debug time. What you just did is the problem.
Besides that radio, I've replaced e-caps in several dynaco devices, some peavey devices, and a couple of 30-50 year old electric organs. They perform like new devices except when something else is wrong like *****y new vacuum tubes I bought. Tube sockets have also been a problem. Sockets not a problem in a 197x receiver. As previously stated, volume pots and switch contacts are often a problem from that era. I've changed several volume pots.
In the RF area, ceramics are quite useful, IMHO. Use COG if you can get them, X7R varies a lot. No old ceramic cap should need replacing unless they installed one where the foil shows (fairly common in non-mil-spec ceramic caps).
In the audio areas, polyprophylene film caps are respsected by J Curl etc. The polyester caps I instead used in the PAS2 preamp surely made it harsh and trebly.
There should be no reason to replace resistors from the seventies unless the manufacturer found some extremely bad vendor. (Like an Airline TV I worked on once, even the resistors were **** in that). Resistors can be cheaply measured. Cleaning of dust off high value resistors can improve performance, dust causes electrical leakage over a few volts, especially in high humidity.
I find measuring electrolytic caps with a meter a total waste of time, measure them with a calender. The atlas ESR meter doesn't charge the capacitor over a few volts and measure leakage, which is another problem. If an audio or video product has performance problems, over 10 years old, throw the electrolytics out. No consumer product had long life epoxy sealed forever electrolytic caps, except one brand of guitar amp that had green CDE's.
Replacing 1 or 2 parts at a time then testing to see if you made performance worse is good on any electronic project. That way if you made a bad solder joint or used a problematic component, you know right where your problem is without a lot of functional debug time. What you just did is the problem.
Besides that radio, I've replaced e-caps in several dynaco devices, some peavey devices, and a couple of 30-50 year old electric organs. They perform like new devices except when something else is wrong like *****y new vacuum tubes I bought. Tube sockets have also been a problem. Sockets not a problem in a 197x receiver. As previously stated, volume pots and switch contacts are often a problem from that era. I've changed several volume pots.
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