So I got this bag of fuses (1A 250V) and they looked good but I thought hey why not check one of these things 

So I came up with a plan....put the fuse in circuit with a 10 ohm fuse and run it up to 10v
while keeping an eye on it.

Well I started at 7.9v and the smoke show started quickly
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So I did some calculations wow I was going for one amp I never dreamed I would be cranking out some watts
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That resistor is like a quarter or half watt.
 

Btw the fuse survived 

But as I type this now it makes sense why I see these big ceramic wire wound ? resistors and they are low resistance

 
 

Ok this is what I did

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So I hooked everything up

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Then did some requested calculations

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Seems like a lot of trouble for nothing but I did get the "right answer" the book said for the 741c Op-Amp the typical value for the input offset voltage is 2 mv. 

I'm not yet running through the streets shouting eureka but hopefully later the significance of this will become apparent.

 

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.

Big thanks to Mick for encouraging me (almost a year ago) to try and get something out of this ancient artifact 

I wanted to put on my big ugly dim bulb tester but was kinda perplexed by the results.

60w bulb unscrewed and 43w bulb screwed in
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Now 60w bulb screwed in and 43w bulb unscrewed
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And both screwed in
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I didn't know if this was good or bad...they both glowed but more pink and orange not like a bright light.

So I figured ok might as well try something but maybe it's got blown outputs (?)

I grabbed a speaker and not having the slightest idea where to attach I picked two terminals and attached them and when I plugged it back in I was stunned to hear some noise 

I grabbed my cable to attach a signal and I can't believe it works           

But when I increased signal output it got really ugly sounding like it was in a blender 

So I removed some jumpers that had been there probably forty or fifty years and tried it again this time nice and clean 

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Also I saw the bulb would get brighter when I increased signal 🚦

If you are wondering there are no controls or power switch. 

It came with another piece that had knobs and level controls and one medium sized speaker.

Btw attached to the power cord were a couple of tags like instructions how to attach speakers
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So wow I'm really glad that I tried it and got sound thanks again Mick 

If I can get it set up to listen to ball games from a tuner or maybe even some music man that would be awesome 

Hey guys do you think that is a transformer and a choke or two transformers 

I ordered some 10 and 15 mh inductors off da bey.

No big deal but they measured IIRC like 8.8 and 13.2

I'm just using them in my experiments for my lab text. And will make sure to use the actual values in my calculations.

They don't have color codes so no tolerance I like em enough the leads are right for breadboard  and they were cheap no indicators of manufacturer.

Just more stuff I'm learning I reckon time to look for or start paying attention to specs    or if I actually need or want the primo to pay up.

Btw all good my house isnt los alamos these are great for my mickey mouse 🐭 🐁 setup. 

Check it 

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Briefly looking through it it has tons of experiments where he has you make little circuits to make and do cool stuff.

Like....make an op amp differentiator.  And integrator.

Or how not to 

I needed to make my transformer bread board friendly things are getting Rube Goldberg enough around here.

So I soldered some jumper wires to the primary and secondary transformer leads.

For your entertainment 

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The finished product

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And some okrer gumbo with shrimp 🦐 and fake 🦀 crab
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I think 

I need a transformer for an upcoming chapter in the book I have been working through
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I remember this artifact having 12v outlets on the back
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Open it up looks good  You cannot view this attachment.

But testing is disappointing
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But there are two 12v outlets on the back right gotta be a way to get 24v but I look and they are wired in parallel (?) 

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Have I been defeated by decepticons 

Practicing some desoldering trying out my new toy
I have extracted a few TO-220 (?)
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Pretty cool they have these clips to help hold them fast to the heat sink ?
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I like the solderpullt it seems to work good I like braid too but some times it drives me bananas 

I'm going after these capacitaters next

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I'm kinda worried about the plastic tip on this tool melting I suppose I need to get on with it and do not tarry 

If you are wondering what this artifact is I can answer that question....it's a GR5D Digital Convergence Board
(why of course... )

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This old Paco B-10 battery eliminator and charger has two outputs
One labeled as special low ripple output

So I turned it on and connected my scope to check it out

On the special low ripple terminal
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Now on the normal terminal

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I think 

Seems like people could make bad stuff look really good with a few different settings...or vice versa 🐱

Man I was pretty stoked they threw this in at the pawn shop    it's like twenty foot long 

Unfortunately it always hummed like crazy    so I did a little testing and I didnt see any shorts etc
Also I tried flexing it along the length of the cable like maybe it had a break idk

Apparently after further review....it's not the same as instrument cable ?   

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So....dude...it's not a guitar cable...

When I was wiring up and putting fuses (a good thing  ) in my ugly variac I had a power cord plugged in and a multimeter attached to the stripped ends of the power cord.

Over and over I would get normal readings on the voltmeter gauge on the variac but much reduced voltage through the power cord

I wondered that maybe the ammeter gauge was to blame checking polarity and bypassing it ect...so I kept checking and disconnecting and reconnecting until finally I suspected the cord so I did continuity checks and sure enough the positive prong had no continuity.

So I stuck meter leads into the socket and it worked correlating with the voltmeter on the variac.
Turning to the cord wondering why I had wasted like two hours and a couple awg fuses
It wasn't some old relic either it was from a cheep Walmart box fan that had a melted switch
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So I continued on with the continuity test but while flexing etc never could get it to work.  So then I started stabbing it with meter lead prongs piercing the insulation there was a looks like crimped in grommet but even right behind the plug there was nothing.

Even now I still find it hard to believe it doesn't work 

I present to you my ghetto redneck ridiculously ugly and heavy variac

So yeah 3/4 inch plywood isn't always a good thing 

Also a quick note...if you need a hole saw to insert an object that is two inches in diameter...don't use a two inch hole saw 

Also....solid core wire seems all primo and all but it's a pain   

Oh yeah also if you are using scraps of wire that are different colors it makes everything more interesting.
 
And....if you can buy a variac with gauges and outlet and switch etc it's probably cheaper and ergonomically compact and easier on the eyes 
Anyhow here it is running a box fan and old lamp with two bulbs

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And the inside
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I started with an ancient object called an Adjust-A-Volt and could not find anywhere on the web old forums anywhere the pinout save for one pic and thread so I tried it and it worked

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After all this I don't really have a need for it except I do want some bonding posts only so I can use it for the experiments in my book like when I need five volts ac or something for a breadboard.

One weird thing trying to be cautious for some reason I took a voltage measurement on the three mounting bolts and too my horror got like 27v ac  so after yet more world wide web forum etc I connected it to ground with a resistor then measured voltage across the resistor which was basically zero.

So...could be I'm measuring stuff wrong    or there is a phenomenon called stray voltage ⚡ 

 

I have a 15w tube amp.  It sounds great but I need more gain..not cannibal corpse gain but yeah I'll take back in black or travers snortin whiskey gain.

So what's the big deal  go buy a pedal /end thread 

But when I had my 5150 combo  I could max out one volume and put the other one on low and with an Ibanez chorus pedal be happy.

To cut to the chase I guess it's gonna be more than "dude...just change a resistor or add a capacitor"

 

I have on hand a forty year old boss heavy metal pedal I've never been crazy about it does an ok job and a pod500x and it too is ok but I'm not really happy with either one and the thing is dude I'm not that hard to please.

We have a good shop in town that has managed to survive good guys lots of used and new pedals let you test drive em etc

It's either do that or just order a mxr 5150 pedal from eBay or reverb....

Kinda ridiculous because I love my Peavey audition chorus that you guys fixed and play through it 99.9999 % of the time.

And I could kick it down a flight of stairs and it would still work whereas I'm on tip toes with this tube amp omg is it warmed up omg is it cooled down 

Sorry I guess I'm rambling.

Another new toy yay

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It's guaranteed to work because there was a sticker on it that said "checks ok date 1968"

I didn't have much luck with it it did power on I ran a sin wave thru it to my scope and when I turned knobs and flipped switches all it did was flip back and forth from a flat line to a sin wave.  Turning the knobs affected the rate.

Then I ran it into an amp and just got Morse code. 

Help is otw though....I couldn't find a manual for this exact manufacturer model but did find a manual for a similar model gen rad.

Also I ordered some BNC to BNC cables to make life a little easier.   

There is not much info I could find out there about these devices apparently they were used to test stuff that now they do the same testing with stuff that made these boat anchors...idk. 

I just want to get some cool looking stuff on my scope.   

And it's a biggun 

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There used to be a song on z-rock called "don't call me dude "

So I encountered a device that looked like a transformer or a choke.  I didn't see enough wires for a transformer so I immediately concluded that it was a choke.  For some reason I decided maybe I can start out simple and measure resistance (hey why not  )
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My ultimate plan was to run a sin wave thru it and start filtering like I read about in those books yay 
But then I ran into a problem
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Dude...is this the same as a choke ?!?!!?!?
 
(Btw looks like we have some cool upgraded emoticons  )

Oh well on with the experiment....dialed up some sin wave and connected it paying attention to Vp-p and RMS etc

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I then altered the frequency  checking the scope for any changes....I did see a
reduction in amplitude but my generator only went up to 3 Mhz
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At higher frequency I found this adjustment helpful 
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I also connected my multimeter across the DUT to monitor voltage drop wrt frequency and it did increase directly proportional to it but maybe my meter couldn't handle it when it got too high idk because it just got bigger then dropped to zero.

So at the end of the day perhaps I was seeing an attenuated (?) signal that was left over after the voltage drop (?)

At a certain frequency I did some maths and determined RMS from the scope and added it to my multimeter RMS but they didn't quite add up to what I had started with.

 

The "results" were not what I expected I thought I would be able to vary frequency and there would be a range or ranges or a cutoff where no signal was getting through but I didnt see that at all.

Oh yeah btw if it helps....I did test it with this as well
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Newly acquired Savage Rohr 15

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When I got it it seemed to work ok both channels four inputs...

I thought it didn't seem to have much gain but figured it was what it was.

I guess it had/has a problem because later it seemed to get quieter and quieter and finally one channel appearing inop and the other both volume knobs can be max and strumming a guitar 🎸 can be heard at low volume.

I worked up enough courage to take a look and perhaps see something.

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I looked at the chassis but did not touch or 🥢 chopstick anything.

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Also I reconnected the speaker before powering on.

Btw here is the tubes

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When I powered it on I noticed one 12ax7 was not glowing as well as the uncovered tube on the end which I presume to be a 12at7 (?)

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I guess I made a big mistake by not swapping a preamp tube to see if it was the tube or the chassis.

I carefully put everything back together and not too eager to further investigate until I can watch hours of reruns on YouTube about at least some basics of working on and around these units.

I also have read a bunch of the threads in this section so I'm expecting to be told check voltage ⚡ on pins xx on vx.

 

But alas I think this is gonna be on the back burner for a while.  I just don't yet have the stomach for poking around this amp.

Thanks

 

Saw this today...never heard of them.  Not much info out there.

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Looks pretty nice..kinda like a red 5150 combo

 

I saw this today and tried to leave it alone
went home and watched football
about 1630 called the shop to see if the owner was still there
he was 
so I went and offered $40 for it
i own it now 

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I just finished making a bunch of noise with it.  Im pleased.

I was surprised how loud it can get I had to keep it low.

also maybe its brand new idk but the pots are squeaky clean usually when i drag an old amp home its static city and rice crispies for a while.  all good elsewhere no hiss squeals or hum.

I admit I only bought it because its orange.