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Messages - Tassieviking

#61
Be very very careful in that amp, there is 444 volts DC going to the valves and the capacitors can still have voltage in them even when the amp is unplugged.

I have one version of the schematic only for the RG50.
Is there a reference number for that resistor on the PCB ?
You cannot view this attachment.
#62
If it already has sockets mounted for the IC's I would say go for it, as long as the new op-amps are compatible.

If you are after less noise then it might be better to check those 40 year old capacitors as they might have downgraded a bit over 40 years.
I would definitely test the main filtering caps for the power supplies, those big electrolytic caps can cause noise if they go bad.

There are better quality capacitors around now, a lot better then 40 years ago.
The biggest question is do you need it to sound clearer or do you just want to tinker, I would leave it alone if everything is working ok and it's not too noisy.
The amps were always a bit noisy back then, some more then others.
#63
I think it should have been marked, but then in the stomp-boxes I make up there is no room so my markings are under the components.
Once you mount a resistor you can no longer see what the part number is in most of my PCB's I make up.
But then my PCB's are for myself, and anyone I share them with on a forum.
#64
Nothing about a tweeter in the schematic that I could see.
#65
That looks like a standard audio transformer to me, i don't know what from as my background was industrial electronics.
It would be used to isolate the audio signal between 2 different circuits.

Why do you think the DV74HC132AN will not be the same as the 74132 you need ?
It can handle up to 7v supply and you have 4.8v supply in the scope.
If the chip can handle the voltage and signal then it should be ok.
Hopefully someone who knows for sure can jump in with an answer for you.

The LM358 dual opamps will come in useful in many projects, you could use one to buffer the sinewave output of the ICL8038 signal generator IC that you got there.
The ICL8038 has square, triangle and sinewave outputs and will make some great signal generators for you to build.
#66
Well F F F F Freak me out.
I wonder if there are any Bass amps in there, with 1000 watts D class powered speakers it would be great if there are several Bass models included.
#67
Light bulb on top sounds like a photo transistor of some sort.
The 4 lead SK3006 is a Germanium transistor that has an extra leg for the metal cap on top as far as I know, and the SK3004 is also a Germanium transistor.
Some Germanium transistors are becoming expensive since they are no longer available and are very coveted for Fuzz pedals.

You should test all the Germaniums individually and record the findings.
https://www.radiomuseum.org/tubes/tube_sk3006.html

Datasheet is too big to upload here so here is the link:
http://bitsavers.trailing-edge.com/components/rca/SPG-202Z_RCA_SK_Series_Replacement_Guide_1981.pdf

Look at page 26 for the SK3004 and SK3006

#68
Quote from: saturated on October 14, 2023, 10:25:03 PMI also learned that wires have two ends.  meaning all the while I knew to stay away from the wires on the end of the CRT.
I should have known that the ends of those wires are in the top middle of the following photo.

You will quickly learn to be careful if you touch those "hot" wires, but don't worry, it only hurts till you pass out.
You just need to worry about waking up after you pass out, it's not guaranteed.


#69
The first thing you should do is make sure the speaker is not connected to that output as it will most likely destroy it.
The next thing after that is a bit beyond me at the moment.
Best of luck with it.

Here is a later service manual :
#70
That potentiometer is meant to rotate fully around, it is made that way.
That one has no inbuilt stops on the shaft.
#71
Did you put a knob on the shaft before you tried it ?
Some of the older ones might need a bit more force to turn the last bit so it activates the switch.
#72
Amplifier Discussion / Re: Peavey Power Transformer ID
October 12, 2023, 08:53:34 PM
That part number is given as a substitute part for a Peavey Studio Pro 40 in this article:
https://www.ssguitar.com/index.php?topic=1593.0
I have no idea if it is accurate or not
#73
I am not sure if this is the same or if you can get it but its available in Italy.
https://www.folliemusicali.com/prodotto/fender-outlet-0057799000-pcb-udsp-micro-dsp-for-deluxe-90/

USA:
https://reverb.com/item/67584695-fender-dsp-board-with-processors-2002

If you think the fault is in U4 then see if you can get a new chip and have someone copy the program from the 100 amp into the new chip, it is only an Eprom.
#74
Here is the link to the other site pa911 mentioned :https://music-electronics-forum.com/forum/amplification/guitar-amps/maintenance-troubleshooting-repair/986153-fender-acoustasonic-30-dsp-with-very-audible-hiss

I can't help but someone might be able to.

And the schematic: You cannot view this attachment.
#75
If nothing else comes out of it, the experience you are getting out of this is priceless in the long run.
Keep it up.

Edit: And most likely cheaper then spending your time in the local bar as well.