did not power on
found an open fuse
replaced fuse
put on dbt looked good
powered on but has no trace

crt is glowing a little but not much

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the slide switches are extremely stubborn

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you practically need a hammer and chisel to move them

 

I am aware there are crazy high voltages in these things so I havent fooled with it   

this is how i had it...exception being I had grounds hooked up to the tab on top...idk 

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thanks for your help

alright guys I desoldered a resistor a d measured it at 1 kohm....seemed maybe too high.
I then made up some jumpers from odds and ends...hooked everything up..put my multimeter on each side of the resistor...8.05v....dang it 

so i am extremely interested in seeing if I can get a good ground on that center pin when the replacement is soldered back in circuit.

frustrating..but this has been a good experience...thanks for your help
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thank you sir that thought certainly did occur to me much like many things that test ok without a load and fail with one.
I am ordering a couple new 7808 but dragging my feet trying to assemble a large Mouser order to offset shipping.
I do not have any resistors on hand but def have some junk laying around where I can desolder one and use it.
thanks

hello ssguitar enthusiasts

I am ordering some components as listed in an old lab book for experiments.
Listed are transistors, scr, diodes, resistors and capacitors

I am familiar with electrolytic capacitors as most are polar and marked as such..seems like for a breadboard I would want capacitors that can be installed either way?
maybe film or ceramic?  maybe price will be a consideration idk

I am assuming the diodes and resistors will not need to be anything special or unusual.

thanks for your help I have some Jameco breadboards.

regards
Wesley

hello friends
Im thinking I made incorrect measurements or something..maybe there is an insufficient ground...(I dont know anything...just guessing with my limited knowledge)
anyhow since 7808 seems to test ok out of circuit I will put it (or replacement) back in and test more points.
I really have a feeling this is going to be something really stupid like a deficient contact....ground...switch...jack...idk.

thanks again you guys rock !!

hello ssguitar friends

since this device seems to test good out of circuit I am venturing that I did not measure it correctly in circuit....I dont remember where I had ground..I likely clipped it to the metal chassis...
anyhow my new rabbit hole is going to be learning about ground(s)

thanks again

well hell.....
I hooked everything up...wish I could post some pics

as soon as I turned the power supply on my meter was showing 8.03V
so I guess this little guy can work when its not soldered in the amp...idk smh 
so back to the drawing board...or schematic...
on the plus side this was lots of fun damn I learned a lot in the last few days....
just wish I had a different cadaver to pract8ce on because I really love this amp 

so thanks guys dont bail on me yet ha ha

thanks guys it is helping to actually do stuff in real life instead of just calculating current and voltage drops. 

just an FYI of my thought process....last night I had wondered if I could connect it to a 12v battery (automotive) immediately I was horrified imagining 650-700 CCA vaporizing the little device and kinda breathed a sigh of relief that I didnt do that.

so then this morning on the way to work I got to thinking...in my boat I have a big ass dedicated 12v deep cycle hooked to one thing...a Lowrance sonar.  and its not drawing hundreds of amps or glowing red from current. (lots of times I run sonar with the outboard off and so I have a separate cranking battery)

so I kinda came to my senses about this...I think my thinking got corrupted by imagining a variable power supply could dial in any current...maybe it can idk..

so anyhow I am going to take a 12v batt or power supply and connect to pins 1 and 2....then connect multimeter to pins 2 and 3 and see if it reads 8v.

also I plan to connect the DUT to a heatsink before testing

it also occured to me that this is precisely what Mr Tassie Viking instructed me to do while it was in the amp (thank you sir!) 

hey guys when people at Peavey dumped hot glue on components was that supposed to act as a heat sink?

thanks again
    

resistance across C58 about 3.5kohm

yes sir will def be checking that.  glad to see you recommend using mouser or digikey....was tempted to go elsewhere.
if there is anything else I should get from there let me know I hate to spend $7.99 on a $3 order.  maybe some of the other peavey-esque chips..just to have on hand.
I ordered a function generator today....that should make me learn the signal path
anyhow thanks for all of the help

hello all
I have a realistic power supply 13.8v 3A
I want to hook up and test an old 7808CT removed from my amp.  I dont know much but I am thinking 3 amps is gonna blow this thing up or melt it....
(I dont want to reuse it this is just me trying to learn some stuff...)
I also have a topwon 6303A that I havent unpacked yet maybe I can dial current down..
also I read the data sheet on some of the semiconductors...about a I could find was the output current.
I did some preliminary diode type tests per youtube...it seems to be good idk....if its good its good I will replace it regardless that dag blasted glue had to come off anyway.  Anyhow mucho beer and pizza to all I really appreciate it all the help I have gotten here.
regards
Wesley

well guys I kinda inadvertantly jumped the gun.  I wanted to remove the "silicon" blob encompassing 7808 only to discover it was armor piercing resistant hot glue.  so I resorted to some medieval methods ie soldering iron and picks etc to get all of that crap off and out of there.
meanwhile I wanted to short that diode and measure but it was getting late and it was so tiny I was trying to think of how I could achieve it....then I was wanting to lift those links as advised so I knew I would have to turn the board over...which I did...and then that poor 7808 had suffered so much abuse I just desoldered it and put the board back like it was. 
go figure in other places the hot glue just peeled right off.

anyhow the marking on the device is

"MC (MC logo)

7808CT
QQ8606A"

thanks for your help

thanks guys
I havent ordered any components yet but aside from the physical dimensions is something like this ok

Linear Voltage Regulators 3 Pin 1.5A Fixed 8V Pos Vltg Reg

I want to do as much testing as possible to learn

regards
Wesley

btw Happy Easter or whatever your endeavour

ok im back...the three transformer wires...red/yellow with red on each side...I get 13.6v a/c testing each side to center

on the big c57 I get 17.6v dc

on the little c58 I get 0.646v dc

then I tracked down cr24 and got dizzy trying to remember arrows and cathodes.... bands.

I messed with it quite a while got lots of different readings...but all under 1v...time for refresher course

hth btw I will look to subscribe or contribute as gratitude for the help I have received

regards
Wesley