Schematics and knowledge sharing thoughts

[kidb]

Something thats been on my mind lately.. I'm a studio technician, repairing gear for people over the years has left me wondering why some companies dont share schematics. I live in a town where people would rather take it to a local tech than ship items for repair. It only hinders my ability to help out people with gear that I can't get documentation on. Several companies equipment I tend to turn away because I don't want to spend time or charge for time figuring out the circuit before getting into the repair. Stranger to me is that for seemingly all of the classics, RCA, Telefunken, Neve, API, Teletronix, Ampex, Studer, etc.. documentation is and was freely given. Often older units would come with schematics, RCA used to glue them in the lids of gear! I can't imagine buying a console or tape machine without documentation. So it strikes me as odd that the newer companies that are essentially just building copies of the older gear don't want to share any schematics. I personally don't buy the copycat fear, I've yet to see API or Neve go out of business with their classic products being copied many times over. And I believe in the Barbara Striesand effect, the more secret something is the more people will want to know/figure it out. Even gooped circuits have been reverse engineered.
I'm genuinely curious on this forum, with all of the diy community where people stand on this topic. It just doesn't quite make sense to me. Please share your take!

 

[OneRoomStudio]

So it strikes me as odd that the newer companies that are essentially just building copies of the older gear don't want to share any schematics.

I wonder if it's precisely because they're making their living by copying someone else's work that they're more afraid of someone copying theirs?

 

[JohnRoberts]

Something thats been on my mind lately.. I'm a studio technician, repairing gear for people over the years has left me wondering why some companies dont share schematics. I live in a town where people would rather take it to a local tech than ship items for repair. It only hinders my ability to help out people with gear that I can't get documentation on. Several companies equipment I tend to turn away because I don't want to spend time or charge for time figuring out the circuit before getting into the repair. Stranger to me is that for seemingly all of the classics, RCA, Telefunken, Neve, API, Teletronix, Ampex, Studer, etc.. documentation is and was freely given. Often older units would come with schematics, RCA used to glue them in the lids of gear! I can't imagine buying a console or tape machine without documentation. So it strikes me as odd that the newer companies that are essentially just building copies of the older gear don't want to share any schematics. I personally don't buy the copycat fear, I've yet to see API or Neve go out of business with their classic products being copied many times over. And I believe in the Barbara Striesand effect, the more secret something is the more people will want to know/figure it out. Even gooped circuits have been reverse engineered.
I'm genuinely curious on this forum, with all of the diy community where people stand on this topic. It just doesn't quite make sense to me. Please share your take!

It is good training to repair equipment without schematics. In fact many old hand drawn schematics have errors that require figuring it out in real life.

Equipment designers who do novel designs (not copycat clone makers) have a valid concern about getting their best ideas ripped off. I have even had patented design ideas ripped off.

JR

 

[pucho812]

As I have been head tech for companies as well as head engineer at studios I can offer some insight here.
From a company point of view we prefer you send in units for repair. Warranty or non warranty, we can assure that things are repaired to our standards. That the correct parts are used and that it’s done correctly. That doesn’t mean it wouldn’t happen at a local shop but I have seen some hatchet jobs in my time and even helped out a few folks around here to fix the hatchet jobs they purchased.
So a good company may do service centers so they are closer to where the unit is at. For example at an old tech job when I departed they turned my work into 2 U.S. service centers one on the left coast, one on the right coast and I still get calls to fix stuff. The other big concern is theft of design. Which now days is more rampant then ever.

On the studio side, nothing is more annoying than not being able to get a schematic. While I can make my own and often have to work on gear without them, it takes more time to get things sorted.
So I get that a company wants their own qc and they want to protect designs I can also see the other side and frustration it causes.

Perhaps you could sign an nda and see if that appeases the company and you get what you need.
Or the other option is to take what you know and apply it to what your looking at.

For example if I see regulators in the psu I know what to expect at the psu connections. The same goes for opamp pinouts and power on the opamps.
If I see a transformer, assume it’s not a custom part, I can use the turns ratio and determine any sort of gain setup or step down. The trick is to take the big picture and slice it into smaller ones that you can manage.

 

[JohnRoberts]

Back in the 70s as an arrogant technician I declared that I can fix anything.... I don't need no stinkin schematics.

Of course there were a few that I could not coax back to life, but most electronic failures were pretty straightforward. Often when power components release their magic smoke they leave visual evidence.

Active devices like diodes and transistors generally have predictable characteristics like junction forward voltage drops that can be tested for with a modern VOM. Back in the day we could test Vbe junctions using an old school Simpson 260 on low ohm's scale.

Often you can read part numbers off devices or ICs. Some use potted circuit blocks and/or scrape off the markings to give us a more of a challenge.

JR

 

[pucho812]

Back in the 70s as an arrogant technician I declared that I can fix anything.... I don't need no stinkin schematics.

Of course there were a few that I could not coax back to life, but most electronic failures were pretty straightforward. Often when power components release their magic smoke they leave visual evidence.

Active devices like diodes and transistors generally have predictable characteristics like junction forward voltage drops that can be tested for with a modern VOM. Back in the day we could test Vbe junctions using an old school Simpson 260 on low ohm's scale.

Often you can read part numbers off devices or ICs. Some use potted circuit blocks and/or scrape off the markings to give us a more of a challenge.

JR

I concur.

 

[Brian Roth]

Lexicon and Eventide published schemos. While some/many failures on their products can be traced to analog I/O or PSU problems, good luck doing anything on the digital sections without service info.

Bri

 

[zzzzz]

A company with a name related to heat refuses to share their schematics which is pretty funny.

Had a fairly new but noisy 76 from them in (which is maybe a rev D 1176 but with a BA283 style line amp? maybe?) -- turns out the BC184C transistors in the output stage were sketchy which is no surprise considering they've been obsolete for a long time (counterfeits? re-labeled mystery Chinese part?). Replaced with MPSA18 -- problem solved.

More importantly: the "Rubycon" capacitors in the unit looked preeeettyyy weird! The printed sleeves don't look remotely like any authentic Rubycon YXA caps I have ever received from Mouser or Digikey. Perhaps they should look into where their factories are sourcing these components.

When I contacted them for schematics or sevice info, they kind of just hinted at the fact that I should look up a stock 1176 schematic and figure it out from there lol... even though that isn't what their product is.

 

[scott2000]

More importantly: the "Rubycon" capacitors in the unit looked preeeettyyy weird!

I liked it more when they change a couple of letters in the name...lol

 

[mjrippe]

Back when I had my repair shop a manufacturer of powered monitors asked me to be their East Coast service center. BUT they would not provide me with schematics for component level repairs. Only determine which circuit board had the problem and order a replacement. I was not their service center for long.

EDIT: I forgot to mention, the company was in the U.K. so replacements took a while to obtain. Meanwhile, the customer has no monitors as the company did not offer me a "loaner" pair.

 

[Brian Roth]

Most everything made these days uses "Chinet Technology". No, not made in China, but:

https://www.mychinet.com/products/

Use it, throw it away,,,,,

Bri

 

[k brown]

What I always found especially puzzling was Audio Technica including schems with their mics/power modules, but with no parts values whatsoever (now, of course, no schems at all).

 

[Khron]

More importantly: the "Rubycon" capacitors in the unit looked preeeettyyy weird! The printed sleeves don't look remotely like any authentic Rubycon YXA caps I have ever received from Mouser or Digikey.

I liked it more when they change a couple of letters in the name...lol

Ah, the infamous "Rukycon", yes. There's also "Rulycon" floating around out there (or at least used to be)...

 

[BigPauly]

Something thats been on my mind lately.. I'm a studio technician, repairing gear for people over the years has left me wondering why some companies dont share schematics. I live in a town where people would rather take it to a local tech than ship items for repair. It only hinders my ability to help out people with gear that I can't get documentation on. Several companies equipment I tend to turn away because I don't want to spend time or charge for time figuring out the circuit before getting into the repair. Stranger to me is that for seemingly all of the classics, RCA, Telefunken, Neve, API, Teletronix, Ampex, Studer, etc.. documentation is and was freely given. Often older units would come with schematics, RCA used to glue them in the lids of gear! I can't imagine buying a console or tape machine without documentation. So it strikes me as odd that the newer companies that are essentially just building copies of the older gear don't want to share any schematics. I personally don't buy the copycat fear, I've yet to see API or Neve go out of business with their classic products being copied many times over. And I believe in the Barbara Striesand effect, the more secret something is the more people will want to know/figure it out. Even gooped circuits have been reverse engineered.
I'm genuinely curious on this forum, with all of the diy community where people stand on this topic. It just doesn't quite make sense to me. Please share your take!

At one point, as is reflected here, some stuff was proprietary and considered secret when that stuff was new technology. Over the years though, some of it leaks out to the public. For instance, there’s the mythical so called “missing Western Electric library of engineering docs”. Some of that has made it to the public, but a large portion has not. That portion is labeled “not for publication”. All I’ll say is that there is a staggering amount of it, lots of handwritten observations etc…

 

[BIASKING]

This is a good transistor sub search engine...

<https://alltransistors.com/crsearch....2&tj=150&ft=150&cc=5&hfe=240&caps=TO92&cf=on>

<https://alltransistors.com/transistor.php?transistor=22476>

 

[sahib]

Ah, the infamous "Rukycon", yes. There's also "Rulycon" floating around out there (or at least used to be)...

I mentioned this somewhere here before but many years ago (I mean many years ago) I almost bought a CD player that was branded SQNY.

 

[kidb]

It is good training to repair equipment without schematics. In fact many old hand drawn schematics have errors that require figuring it out in real life.

Equipment designers who do novel designs (not copycat clone makers) have a valid concern about getting their best ideas ripped off. I have even had patented design ideas ripped off.

JR

I totally agree, no issue fixing stuff without schematics if I have to. Mostly referring to the recognizable companies that make look alikes that are not the small designers - which I agree could be taken advantage of. If you have brand recognition copy cats are of little concern, it seems impossible to stop anyone from copying you, where there is a will there is a way..
That being said it sucks you were ripped off! I don't condone it one bit.

 

[kidb]

As I have been head tech for companies as well as head engineer at studios I can offer some insight here.
From a company point of view we prefer you send in units for repair. Warranty or non warranty, we can assure that things are repaired to our standards. That the correct parts are used and that it’s done correctly. That doesn’t mean it wouldn’t happen at a local shop but I have seen some hatchet jobs in my time and even helped out a few folks around here to fix the hatchet jobs they purchased.
So a good company may do service centers so they are closer to where the unit is at. For example at an old tech job when I departed they turned my work into 2 U.S. service centers one on the left coast, one on the right coast and I still get calls to fix stuff. The other big concern is theft of design. Which now days is more rampant then ever.

On the studio side, nothing is more annoying than not being able to get a schematic. While I can make my own and often have to work on gear without them, it takes more time to get things sorted.
So I get that a company wants their own qc and they want to protect designs I can also see the other side and frustration it causes.

Perhaps you could sign an nda and see if that appeases the company and you get what you need.
Or the other option is to take what you know and apply it to what your looking at.

For example if I see regulators in the psu I know what to expect at the psu connections. The same goes for opamp pinouts and power on the opamps.
If I see a transformer, assume it’s not a custom part, I can use the turns ratio and determine any sort of gain setup or step down. The trick is to take the big picture and slice it into smaller ones that you can manage.

Good points! I totally get companies wanting to QC their own repairs. Mostly concerned with the ones that have no service centers, and wont share schemos. I would sign an NDA, might be worth emailing a few companies about that. Haven't been offered that solution but I can inquire!
Totally agree most things are easy to get around in a block diagram sort of way. I don't have an issue repairing or figuring out circuits, just prefer having a schematic reference. I have run across errors in schematics for sure! nice to have the unit and schemo to compare!

 

[kidb]

At one point, as is reflected here, some stuff was proprietary and considered secret when that stuff was new technology. Over the years though, some of it leaks out to the public. For instance, there’s the mythical so called “missing Western Electric library of engineering docs”. Some of that has made it to the public, but a large portion has not. That portion is labeled “not for publication”. All I’ll say is that there is a staggering amount of it, lots of handwritten observations etc…

I am largely in support of sharing information, repair wise (right to repair), and keeping old equipment going that is no longer supported. Sad to know there is so much good info lost over the years.

 

[kidb]

Back when I had my repair shop a manufacturer of powered monitors asked me to be their East Coast service center. BUT they would not provide me with schematics for component level repairs. Only determine which circuit board had the problem and order a replacement. I was not their service center for long

I have experienced this exact thing... no longer do warranty work for companies, which is mostly test, make sure its deffective, and send them a new unit... or at best, board swapping..