Schematic help please

[bluesguitar]

Anyone know of a good book or resource for learning how to get a grasp of schematic diagrams. I can understand many symbols, etc. but I can't transfer schematic diagrams into two dimentional layout locations. In other words, I don't know where to locate what I'm looking at on the schematic in the chassis itself.

[xtian]

Wow; made me think. This is an acquired skill. I don't know that there are shortcuts, but after tracing a few circuits, you'll get the hang of it. Start with what you recognize on the schmatic. For example, the tubes are pretty easy to find, right? On the schematic, what's connected to the plate (pin 6) of preamp tube number one? Usually a 100K or 220K plate resistor to supply high voltage, and a coupling capacitor that sends the signal to the next stage.

Use two chopsticks. Put the point of one chopstick on the schematic at a junction, and the other on the circuit. This may help keep your place as your eyes shift from paper to amp.

Of course, PTP and turret/eyelet board circuits are easy to trace by eye; PCP boards are much more difficult.

[NickC]

I don't know of a dedicated book for that purpose.

A good place to start would be studying Fender and Marshall circuits that are well documented, with readily available schematics and layout diagrams (Bassman, Deluxe Reverb, Champ, Princeton, Marshall JTM45). Once you understand the relationships between schematic and location on a layout you'll be able to apply that skill to more complicated beasts like the Dumble's.

[Phil_S]

+1 on what Nick says. In particular, the Fender files have very nice companion layout drawings to the schematics. Start with a simple amp and work up to the more complex. Print both the layout and schematic. Start at one end of the schematic and find the part on the layout. Cross reference them, maybe with a letter starting with A and then you can go to AA after Z. As you work your way up to the more difficult ones, you'll start to see the layout patterns. At first it will be slow. The pace will pick up.

[bluesguitar]

Thanks to all for your tips. I was having a problem with my tremolo and wanted to swap tubes as a 1st troubleshooting step. I needed to find the tube in my tremolo circuit but didn't know which it was. With your advice and some investigation I found the tube. I can see where this is one of those experience things. I didn't realize that they designated tube locations (V5, ect) on the schematic. That was my initial concern. I will just have to familiarize myself with more of the process. Thanks again.

[NickC]

Today, as I was rearranging some books-and-stuff I found this:

Beginner's Guide to Reading Schematics (Second Edition)
by Robert J. Traister and Anna L. Lisk

ISBN 0-8306-7632-5
TAB Books
Division of McGraw-Hill, Inc.
Blue Ridge Summit, PA 17294-0850

I had forgotten I had it. It's not bad, and it covers vacuum tubes.

The second eddition was in it's sixth printing as of 1991. Good chance it's still available.

Hope that helps.