TOS schematic values and BOM??

[67polara]

I don't think the BOM for the TOS is for the Schematic that is posted.  There seems to be multiple mistakes or it was made for something else.  Those in the know can you fix it please.

Tony

[tubenit]

Can you list the mistakes or incongruencies please that you see. If you will list the mistakes, I'll take a look at correcting them. I am not going to go over them again searching for mistakes.

I put alot of time & work in those and requested extra pairs of eyes to look over them early in this process.

If you are willing to put in a little time helping point out specific mistakes to add to the many hrs I put in to sharing this info,
I'll work with you and get it corrected.
 

I posted those PRIOR to putting them in the SCH library so anyone that was interested could have a chance to look for mistakes. I am not saying there isn't a mistake but I didn't notice any mistakes nor did anyone else report one.  

I'd also like to point out that over 1200 hits have been on the TOS schematic/layout file in the SCH library....... without someone stating there were problems between the BOM and schematic (IIRC).

AND that on the top of the BOM I listed (from the very beginning) to "check for errors and compare with schematic".  


With respect, Tubenit

[67polara]

Not trying to start anything here.  I haven't checked the whole thing but here just in the power supply is where I see problems.

The BOM Has these values:                                    Schematic has these:

2 X 47uf                                                             1 X 47 uf
2 X 22uf                                                             2 X 20 uf
2 X 8uf                                                               1 X 16 uf
                                                                         2 X 10 uf
1 X 430k 10 watt                                                  ???  can't find it on the schem.

I'm sorry I just got my parts and started to build the power supply then noticed I didn't have the right caps that's all.

Tony

[tubenit]

OK fair enough & thanks for listing that. I will correct that and repost it.

Any other mistakes or incongruencies that you see?  If so, please mention them so I won't have to continue correcting the BOM.

Out of curiosity ........ did you check the BOM with schematic (prior to ordering parts) as was mentioned on the top of the BOM?

I probably would opt for 10uf instead of 8uf and just use the two 47uf and two 22uf.    If you don't have 10uf, then I'd try the 8uf and see if you like the way it sounds prior to switching them out.

The BOM 430ohm 10 watt does match the schematic. It is the power tubes shared cathode resistor.



My power rail & cathode values in both of mine is signficantly  different than Geezer's which is "the" quasi-official schematic for the TOS. Plus mine are GZ34 vs. solid state rectification.

With respect, Tubenit

[67polara]

Ok thank you  No I did not match it up against the schematic I ordered the parts from work so my wife wouldn't see what I was spending money on and only took the printed BOM with me.  See there are so many really intelligent peeps on here I figured if no one brought up a problem is must be correct.  I've built a couple amps and stuff but I'm a noob when it come to this stuff.  I am more like a parrot I can copy but not that smart to design it my self.  Unlike you and Geezer that have this tweaking down to an art.

OK then the resistor value on the BOM is wrong it says 430K not 430R 10 watt.

Tony

[sluckey]

Using the schematic to put together your own parts list is an excellent way to become very familiar with an amp.

[Fresh_Start]

Using the schematic to put together your own parts list is an excellant way to become very familiar with an amp.

Amen to that.  Sitting down with the schematic, the layout, the bill of materials and 1 or more highlighters can be very illuminating.  Verify every connection & every component, starting at the input jack and working your way to the ouput transformer, confirming that the layout, BOM & schematic are all in sync.  Even if you don't find a single mistake (yeah, right!), you are going to be better prepared to build the amp and less likely to make mistakes (see note from PRR below).

Cheers,

Chip

[tubenit]

OK then the resistor value on the BOM is wrong it says 430K not 430R 10 watt.

Tony, with all due respect ......... please look again.  It says very clearly on the BOM 430R/10w.

No I did not match it up against the schematic

There was a reason that I put right at the top of the BOM to "check for errors and compare with schematic"   


With respect, Tubenit

[EL34]

It's really fun designing an amp, then compiling all the documents that go with the build

Right Jeff?

[Tone Junkie]

See Tony now thats funny I have to do stuff like that so my Wife doesnt know what im spending money on to. you will like this amp it has a lot of things going for it that no other can match. Bill

[67polara]

I have no doubt that I am going to love this amp.  It sounds so amazing on the clips and seems like the perfect set up.  I made a mistake and because I found problems with the BOM I am being crucified on the forum.  Please forgive me I will say no more.

Tony

[tubenit]

Bill of Materials is updated here:

http://www.el34world.com/Forum/index.php?topic=9636.msg87475#msg87475

With respect, Tubenit

[PRR]

> 22uf          20 uf
>  8uf           10 uf

Just FYI: 8 and 10 are "the same", 22 and 20 are "the same".

Power and bypass cap values are large but NOT critical. The radio (or amp) will work fine with a little less or a lot more.

The process for making these is NOT precise. Older caps were sold with VERY wide tolerances. A "8uFd" could really be 15uFD or 5uFd.

The original cap was 8uFd. Because the tolerance was large, the next size introduced was 16uFd then 32uFd.

But going this path you get to odd numbers like "256" which is a silly-exact name for a part which may really be 130 or 500uFd. Also decimal numbers are easier on a slide-rule.

For a lot of the classic era, filter/bypass caps came in a 10-20-40-100 sequence. Note the large gap from 40 to 100.

The real numerical problem is resistors; while a basic radio (even a guitar amp) can work with +/-20% values, for fussier stuff you may need a value within 10% or 5%. Hence the 10-15-22-33-47 sequence (with in-betweens for fussy work).

When we see 8-16-32 or 10-20-40 sequence nominal values on old plans but have to buy new-sequence caps, we use the nearest value. Because the old caps had WIDE tolerance (could be way off the marked value) and newer caps are more on-target, we can even round-down (15 in place of 16) and be sure the original design goals are respected.

> fix it please

Simple 1-stage effects-pedals, there seems to be a fad for "VERIFIED!" layouts. That's for beginners who are already at the limit of their skills.

Building a BOM is intensely tedious. And exponentially worse for more than a few stages.

I need to plumb a new 4-stage water filter system. I CAN'T come up short halfway through the job or we won't be able to drink or wash. I just spent 3 days between the corner of the cellar and the computer compiling a list of every elbow, nipple, tee and bushing and what sex each one had to be. (Electronics is easier!) After all the scrawled diagrams and tedious ordering, I leaned back and realized I had forgot the shutoff valve from the house! (There's a LOT of valves involved and I lost count.) Argh. (BTW: the installation sheets for filters also often omit key valves, because it depends on the site conditions.)

"Do I have ALL the parts??" is ultimately up to the technician. I'm going to lay out every bit and piece and stare at every hole before I break the old plumbing. Modding an amp before tonight's show, again you need to lay-out every piece and make your runs to the store before you cut into it. Building from scratch without a tight deadline, for me, has always been build a little then see what else I need.