For or against establishing a sticky thread with a basic methodology, the necessary tools and the basic rules before any intervention, troubleshooting, upgrade, recapitulation, massacre, for noobs?
Like many here, I like to help with repairs but I'm more and more annoyed to see beautiful devices massacred or even destroyed following a "simple" recap.
We could first lay the foundations (for those who wish to participate), then gather the right information and then put them in their order of importance and create a sticky thread as a reference guide.
I'm very busy in "real life" but if we get together, we should be able to create this in a few weeks.
Tell me .
Like many here, I like to help with repairs but I'm more and more annoyed to see beautiful devices massacred or even destroyed following a "simple" recap.
We could first lay the foundations (for those who wish to participate), then gather the right information and then put them in their order of importance and create a sticky thread as a reference guide.
I'm very busy in "real life" but if we get together, we should be able to create this in a few weeks.
Tell me .
Good idea! Some suggestions (for amps):
-minimal equipment necessary
-Recap necessary?
-Opamp/component swapping necessary?
-Bulb lamp tester: how to
-How to check/setup output bias
-Check DC on output
-ground loops
...
-minimal equipment necessary
-Recap necessary?
-Opamp/component swapping necessary?
-Bulb lamp tester: how to
-How to check/setup output bias
-Check DC on output
-ground loops
...
Excellent idea.
Inexperience and randomly reading here and there makes many cause way more havoc than the original one, complicating repairs.
There is also the strong compulsion that "since I have it open" they needlessly mess with things.
First solve the basic problem, then improve, roll parts, whatever.
Inexperience and randomly reading here and there makes many cause way more havoc than the original one, complicating repairs.
There is also the strong compulsion that "since I have it open" they needlessly mess with things.
First solve the basic problem, then improve, roll parts, whatever.
Ok, nice, where do we start?
The basics of tooling?
Safety rules?
The rules according to what the person wants to do? (troubleshooting) (upgrade) (recap) (revision)?
The basics of tooling?
Safety rules?
The rules according to what the person wants to do? (troubleshooting) (upgrade) (recap) (revision)?
Well, I reckon , ppl asking help here already have almost all basic tools (eg. soldering iron, DMM, few of main sized screwdrivers) with some luck they might have desoldering suction or copper bride, so I think that part would be covered.
About safety... we might warn them what part of device is 'safe' to touch, relatively safe, and where not to poke fingers.... (personaly I would start with that).
BLT, next topic, mandatory!
After that you might to cover what one want (need) to do with device (repair/recap/upgrade).
😉 👍
About safety... we might warn them what part of device is 'safe' to touch, relatively safe, and where not to poke fingers.... (personaly I would start with that).
BLT, next topic, mandatory!
After that you might to cover what one want (need) to do with device (repair/recap/upgrade).
😉 👍
Sounds like more of an article than a thread. But it could still be a sticky. There have been inquires about doing the same thing with other subjects.
This 100%. This will turn into something very ugly if it is a thread. Sticky all the way.
I partly agree with you but it is not because the person has a DMM that he knows how to use it (sometimes we have to explain which scale of which function to use to make a measurement ) not to mention the DMMs from Wich or aliexpress which can be dangerous.
Without going too far into the trick, just the basics of good equipment.
Seems like a good idea to me - the basics of troubleshooting, actual repair techniques, rework and selection of suitable tools and test equipment to start.
Appropriate places to find replacement parts and avoid counterfeit parts and modern subs for some vintage parts would be bonus.
Appropriate places to find replacement parts and avoid counterfeit parts and modern subs for some vintage parts would be bonus.
Oh yeah, this one too, still with so many semis around I think this should be limited to explicit parts questioned...
Think you'd be surprised at how many don't have a scope at all. You can't do much without one.
Hey, I resemble that comment 😉
Change. Test. Change. Test. Rince & repeat.
Maybe more important - understand what it’s doing.
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- Ground and how it save my life but also kill me
- Where not to shove your probes or your fingers (not only the joys of ground clips, but also using passive when an active probe or differential probe should be used)
- aftermarket 30V DMM probe clips on 100+V rails, what could go wrong?
- AC/DC and the art of capacitor ratings (and the banging sounds getting it wrong)
- Why poorly designed switching on/off switching power supplies/torroids/inductors/relay coils are fun.
- Why following any internet fad thins the gene pool
- Why a USB scope isn't the best starting point.
Ok the serious list
- Ground, a definition, referencing ground and class 1 power and ground of the chassis..
- Ground loops - both inside and external with power.. (note Merlin and Rob Elliot cover these)
- Why before you get the probes out.. it's better to reverse engineer and understand what it's doing and why (there may be more than one concept/purpose in the same circuit).
- switch on for the first time. (ie variac/controlled power, use of load resistors instead of speakers)
- stability? is it really stable? (oscillation)
- frequency response - square wave and bode plot
- measuring THD requires very clean signal generation and sampling
- spectra, using a signal generator, harmonics and different types of noise
- start with off, then power, then I/O, clocks etc.
- Capacitors - test, bleed, test, short whilst working (ie electrolytic behaviour of climbing back up)
Rather than say what equipment is good - say why and what it provides:
- Multimeters x3 (at least one good)
- DMM probe kit with clips etc
- Osciloscope (2 channels good 4 channels can be very useful)
- Bench power supplies (at least two channels and both being able to be referenced separately)
- Signal generator (2 channel)
- Spectrum analyser (even a adequately protected/scaled signal for a sound card/ADC)
- soldering iron/desoldering.
The equipment list is where I'm at currently as a beginner. Each is very very useful for handling specific issues however each piece of kit has it's negatives (bit-depth, phase noise, etc etc).
So far I have designed and built one channel of a tube-bjt hybrid circlotron, assembled parts for a ADC measurement device, repaired a A220 and about to recap an old CDP, finish the clock board for the ADC, the power supplies and then get back to the circlotron.
The issue is upgrading is really redesigning vs repairing like for like. If the person doesn't understand the basic starting point for the design (although not everyone knows everything) then upgrading is going to be bad.
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In addition to trying to drive home the risks of surgery, I think it would be a flowchart logic that helps navigate the troubleshooting of a typical transistor amp.
Whooooa Nick great list m8 but also much much more than beginners stuff 🙂 👍 tho 1st of your group seems fine to explain to begginers 😉
