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Help with testing tools

A

akabek

Active Member
I did read a few pages on the So You Want To Repair Audio gear but a lot of the links don't work and maybe there is newer affordable gear to look at.

I have a some vintage amps and preamps I would like to go over and repair. I would like to get the tools I will need to test these components for damaged parts, safe slow power up and check factory settings like bias. I have limited electronics experience so I plan to do a lot of reading and watch YouTube videos. I am looking for assistance on what equipment I will need to maintain my gear and to tinker with.

I have hand tools, WES51 solder station, multimeters etc. My amps range from 100 watts per channel into 8Ω to 160 watts per channel into 8Ω.

For an oscilloscope I inherited my fathers vintage Eico 460 oscilloscope. I know it is basic and old and to be honest I am not even sure if it works. Assuming it does can I use it to track problems and check settings? If it does not meet my needs what should I be looking for keeping in mind I just need something that will not be used often. I would rather not use my PC so I would be looking for a stand alone unit.

I will buy a variac for slow power up. Will a 500va unit be enough? Do I still need to build a Dim-Bulb tester if I get a variac?

When I slowly power up an amp to check factory settings do I need a dummy load? If so how many watts do I need? Would it be beneficial to build a dummy load for 2 channels?

I assume I also need audio Signal Generator. Which entry level unit will work?

Is there anything else I need?
 
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avionic said:
For solidstate, not a must have , unless your troubleshooting underload issues.
Click to expand...

I thought a dummy load is used to load the amp and when diagnosing a problem. Or does this only apply to tube amps? When would you use it for solidstate?
 
Yes, welcome to AK!

Build a dim bulb tester.
Get both an analog and digital meter.
I also have two of the cheap digital meters from harbor freight to use when adjusting DC offset.
A tester that will do just about every solid state device.

Also something to discharge the filter caps. I use a old lava lamp with the plug removed and clips added. A lamp inserted will draw the juice when connected to the cap connections.




C9DD5729-A545-47C3-B46C-F066C2AFAC59-copy.png
tester trans!.jpg
 
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akabek said:
For an oscilloscope I inherited my fathers vintage Eico 460 oscilloscope. I know it is basic and old and to be honest I am not even sure if it works. Assuming it does can I use it to track problems and check settings?
Click to expand...

Welcome Aboard!

Being a 5MHz 'scope, it may be suitable for some audio frequency work, but may lack the resolution you could eventually want for observing distortion. If it works, it could be a siutable starting point. If it doesn't work, a little time spent analyzing/repairing it may be worthwhile, but it is probably not worth investing any significant resources to get it operational, expecially considering that a decent quality used/working 'scope can be had for as low as $100 if the buyer is patient and astute.
 
avionic said:
Highly recommend mini-grabber test leads for your multimeter.
Click to expand...
A must have. Can't get hot meter readings without them or you might be doing a lot more troubleshooting on a unit that just needed the bias adjusted. Ask the 100 akers that have had that happen if minigrabbers would have been a good idea.

I popped a resistor in a turntable before I got smart enough to get minigrabbers
 
Oerets said:
Yes, welcome to AK!

Build a dim bulb tester.
Get both an analog and digital meter.
I also have two of the cheap digital meters from harbor freight to use when adjusting DC offset.
A tester that will do just about every solid state device.

Also something to discharge the filter caps. I use a old lava lamp with the plug removed and clips added. A lamp inserted will draw the juice when connected to the cap connections.




View attachment 2068696
View attachment 2068697
Click to expand...

I plan to build a dim bulb tester. I found this great dim tester.
If I build a dim light tester do I still need the Variac?

Get both an analog and digital meter. Do you mean a multimeter?

A tester that will do just about every solid state device. I will look into the multifunction tester you posted a pic of

Also something to discharge the filter caps. I use a old lava lamp with the plug removed and clips added. A lamp inserted will draw the juice when connected to the cap connections. Good idea
 
Watthour said:
Welcome Aboard!

Being a 5MHz 'scope, it may be suitable for some audio frequency work, but may lack the resolution you could eventually want for observing distortion. If it works, it could be a siutable starting point. If it doesn't work, a little time spent analyzing/repairing it may be worthwhile, but it is probably not worth investing any significant resources to get it operational, expecially considering that a decent quality used/working 'scope can be had for as low as $100 if the buyer is patient and astute.
Click to expand...

What model oscilloscope should I be looking out for? Or what specs should it have. Do I need an audio Signal Generator?
 
I picked up some maxi-grabber test clips which are made just like the mini- grabbers, but about 5-6 inches long- excellent.
I also found a tektronix analog 2225 scope locally for $100. It’s only 50mhz, but is well suited for amplifier work. I have not had any issues making fm alignments with it either. Get a 10x probe. A cheap chinese one will work just fine.

I have used a function generator to produce analog sine waves. This works OK, but if you get a distortion analyzer later on, you will realize that those devices don’t produce a clean sine wave. Find an audio generator out there. The Leader described earlier is a fine choice and reasonably priced.

i don’t use a variac, but I do use a dim bulb tester. I would suggest you build a basic one and add more bulbs if you feel you need them.

I find I use a lot more test cables than I thought I would. I have 4 BNC to mini-grabber. Several BNC to BNC cables and lots of adapters- BNC to RCA, RCA to BNC, BNC T- splitters, several regular RCA interconnect type cables. Good lighting and a magnifying glass. I also keep a flashlight on my bench.
Oh, don’t store your hand tools above your work area. I dropped one in a powered up receiver once...once.
 
I decided to keep an eye out for a used analog oscilloscope locally rather than one of the new off shore units. I bought a used variac yesterday so I just need to assemble a dim bulb tester.

I have to find a used audio generator as well. I will check the auction site and local classifieds.

Where did you source your test clips and cables? Would amazon do or did you go through an electronics store.
 
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