Help Reading Schematics

[FragMe!]

1 kc as he puts it = 1000 Hz, he is probably refering to 1000 Hz tone.
Also good thing you have others to haunt, because I think my going to be haunted list may be long, nothing of my doing though.

[ShadowHawk]

I will find a way. muhahaha *cough* *cough*!

Now the fun part. I know a lot of these components are outdated like the RCA31C. Is there a place that has a cross-reference to equivalent and updated parts?

BT, happy new year.

[FragMe!]

Happy New Year to you too.
The interweb great place for info just typed RCA31C cross reference as the search and it came up with TIP31C.

[ShadowHawk]

You know, it never occurred to me to add "cross reference" to the search query. Definitely call that a duh moment.

Well another component I could not find:


Unless I'm blind, I didn't see it on the symbol list or anything similar.

I'm also using multisim to clean up the schematics. Do you have access to a similar program that could read it's format for project files?

[FragMe!]

Chances are that is a neon bulb or bulb of other type given the date of 1981 on the drawing, leds weren't popular back then and it is also 120 or 240 volts across those points.

And sorry no I do not have any electronics schematic program.

[ShadowHawk]

Guess I'll have to submit my test to the professor the hard way, PDF. Hey, this amp is yours anyways for the help in designing it. I'll just be a proud owner of a Fragme! SH-250 Guitar amplifier.

1) I was reviewing pots and I was wondering if these specs would work:
• Tolerance: ±20%
• Rated Wattage: 0.05
• Rated Voltage: 50V AC
• Rotational Life: 15,000 Cycles
• Rotation torque: 20 to 200g/cm
• Insulation resistance: 100MΩ @ 250VDC
• Breakdown voltage: 300VAC for 1 minute
• Value: 50kΩ

I like this pot because a T1 LED fits in the shaft and would give the knobs a nice glowing effect. Will need your help on applying that though.

2) Would this work as the zener? It's closer to 4v.
3) What kind of transformer is being used? Looks like it has 7 leads, 4 on one side, three on the other.
4) What is the difference Gain and Trim on pots? I just noticed two on the schem, the Gain is rated at 50kΩ and the trim is 250Ω.

And you should be proud of me, I am actually learning . Q3 and Q4 are showing that they are RCA31Cs. Now the problem is, Q3 is a PNP while Q4 is a NPN. an RCA31C is a NPN, so Q3 is incorrect. Now an RCA32C is a PNP, and since it is in Channel B in the equivalent spot (Q16) then the schematic maker made a mistake and incorrectly placed the wrong part name in Q3. Unless Q3 and Q16 are supposed to be NPN RCA31Cs, then I'm totally wrong on the assumption. But I doubt they would make two mistakes in the same circuit location, drawing Q3 as a PNP and making Q16 the completely wrong part.

[FragMe!]

Transistor question, I believe it is a labeling problem channel "B" The drawing is correct as it shows the flat side of the arrows on the transistor pointing towards the more positive rail.

The pot should be okay (didn't the guy who gave you the schematic for free include the free parts list as well? ) Adding an LED should be easy, just need to find a properly voltaged one add in a current limiting resistor and then you have glowing.

That Zener should be find
The transformer he has shown can work on either 120 or 240 volts and that will determine how you wire the primary but I am guess you will be using 120 volts.
The secondary is 120 Volt center tap, and the way it is wired to the bridge rectifier it works as a 60 bolt half wave rectifier. Can explain more if you want.

Since is has a 10 amp fuse on the primary it is a beefy transformer.

Will add more later work is getting in the way.

Back
Difference between the gain and trim pots is, the trim pot is used to balance out the 2 halves of the circuit to make up for component variations and the gain is just the go to 11 and leave it there pot. Well okay it is the main level control if you want to put it that way.

[ShadowHawk]

First qestion I asked and they said they didn't have one since it is so old and they don't sell them (a.k.a, we're giving you enough freebees as it is bud, don't push it. ). So basically, it is thier basic layout, but I'm going to have to find the parts myself. Since most are not made anymore and have been replaced with newer, enviromentally Frendly types, (RoHS) I'll have to cross reference labled parts and figure out the unlabled ones.

Need more explaination on the transformer, went over my head on that one. I am primarily wiring it as 120V, but if you can show me how to dual it like an ATX Power Supply does, then that would make it more production savy (I may visit europe one day and need to switch between the two, never know).

So, I was right on the transistor, yay! . I've corrected it in my cleanup schematics to make better sense. Already had to do that for a few parts (the 1 and I prob). Makes me wonder how the heck they built anything with schematic makers like this one.

Had to take Faith to the Doc for a check-up. She had an ear infection last month so we followed up. Ear infection is pretty much gone, but now she has viral tonselitis. If it's not one thing, it's another. Keep bouncing back and forth on these two illnesses with her. One clears up, the other comes back.

[FragMe!]

Sorry to hear about Faith hope she is better soon.
Here is a high quality picture of how to make your transfor dual voltage.
Using a DPDT switch. Yes I am lazy the rectangles are the transformer coils.

[ShadowHawk]

Well, back to the job of parenthood. Faith is better, still got tons of questions, but just got a new ixa-w404 receiver for my 07 Optima that needs installing. One particular device I'm using is a PAC SWI-JACK that is being a pain to install (controls my receiver from the factory steering wheel controls). Think I figured it out though (will post instructions here in case anyone runs into my problems). Then I have a back up camera that needs wiring from the camera on the trunk to the receiver. Nice thing is, some of the things you taught me actually helped with this. Thanks.

Since I'm a perfectionist with little time to work on extensive projects, I'll be back in about two weeks (maybe longer) with more questions and a schematic I made of the amp from what you helped me on. Since you helped me and this updated amp is half yours, would you like me to PM the schem and parts list or post it here for public domain?

[FragMe!]

May as well post it as public domain, I have no time to build anything and oh I don't have a guitar anyway so no real need for an amp.