This will be good.  I hope I dont report back with tales of falsely accused to-220 voltage regulators 

Lord I was born a rambling man (below):

I tried to find a source for the relay(s) even contacting one established high volume vendor and they didn't have an exact match.

Also some of the Internet lore indicates this PS works on a "break before make" (or vice versa) and is somewhat complicated. 

I had seen an advantage to having "the same" boards on each side" (remember working on drum brakes  ) but the two sides may not be identical)

Also the schematic (for the digital meter version) I don't see any test voltages anywhere  but maybe I missed them idk.

Anyhow I want to try and keep it simple and do some fundamental inspections without opening a can of worms. 

I have a topward dual power supply the left side doesn't get up to full voltage.
If you look in the swap meet section there is some discussion pictures and schematics.

I had an idea that maybe since there aren't that many parts just order some stuff and shotgun it.

However after reading about these units I saw a few instances where some transistor replacements fixed the problem(s).

So for the sake of clarity the focus of this discussion is to simply focus on transistors for the preliminary investigation.

Reading some old threads I saw where I can probe the collector and emitter of said devices in circuit and check for shorts. 
-if there is no short then move along
-if there is a short it may be good because of the circuit but remove and test

If I have interpreted this correctly I like this plan  because for starters the power is OFF. 

Also it will give me some experience discerning a voltage regulator from a transistor 

So if you like that then that is my plan nothing more or less.  Just check every transistor in circuit for C-E short and report back.

A major technological advance has been made.    Negative voltage has been achieved 
Thanks to G1 and Mick 

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So per instructions the (+) is connected to to ground on different power supply.

Pretty cool I confess I was fearful of some 🎆🎇 fireworks

I guess the important part is the negative of the power supply must not be grounded.  Then it would be the fourth of July 

So that's cool I have my chips and stuff on the way and it seems to be a common theme with these guys to connect V+ and V-

But then other ones had stuff like Vc and Vd but I'll worry about that when I get to it.

That's really cool looks like it would fit in the palm of your hand 

Thanks guys 

I have to go through my stuff and see which of these resistors and capacitaters  I have and don't have
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Shouldn't take more than a couple of weeks 

Hello sir welcome to the forum 

Being totally unfamiliar with either I watched a few videos they seem to both be nice amps but I would pick the Laney and also pick the lower wattage amp as well.  100w seems like a lot to me but I don't play out.

These days they have one and two watt amps that sound killer.

But whatever you do just enjoy the search lots of great stuff used out there as well.

I have a few items in cart at digikey I'm gonna finish my list tonight and get this stuff on the way.

This is some good stuff because I already have a problem 

So I'm looking at this diagram and getting stoked about doing it  but then I'm like oh no...
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How do I get a minus fifteen volts on the device   

So I had what I thought was a major epiphany and said ah ok just hook the neg of the power supply but make sure the neg is ungrounded
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Being proud of myself 💪 I said yeah I can test this and made the following circuit on breadboard.  And it didnt work (fortunately)

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Since it didnt work I figured ok maybe my negative is connected to ground so I checked for continuity and resistance and they are not connected.

To add to the confusion  as I type this I anticipate that perhaps the Op-Amp will show -15v because for lack of better words (maybe ?) it's not resistive.  Sorry for opening a can of worms.

But at least I'm getting out of the "dude...neg is ground" mindset.  Because sometimes it is.

I'm kinda glad I get to order a green 💚 jumper cord. 

Are they supposed to be insulated like with mica 

Quote from: g1 on November 26, 2024, 06:53:23 PMPlay it.

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Thank you sir

I just enjoyed reading about Burr-Brown I had actually never heard of them until now.

Btw happy holidays to all of you 

Good afternoon esteemed members and Mods

I want to begin some experiments in this book
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Right off the bat 🦇 I need a 741c

I have a stash of old ic but no 741 c

So looking at digikey there are many different ones (or same ones)

I was able to weed out about half because they are surface mount and I need eight legged DIP

Also there are some Kool TO-99B but they are $17 a piece

The ones that look suitable all have additional prefixes

LM741C-MWC

UA741CPG4

LM741CN

LM741CN/NOPB

UA741CP

maybe I need to compare pinout and data sheets 

10-4

Nice to hear from the big boss     

This has gotten way past my pay grade  but seems like there is an open somewhere maybe go back and check anything that was installed/removed/replaced and or pinouts of said components (?)

Good luck guys 

Just now after work I hooked a tuner to the amp and it worked but it had a bad hum.

I tried some resistors and capacitors between the tuner and amp and it didnt help. 

Kinda weird because after that I ran my sin wave through it again and it was quiet as a mouse.