Most common parts...

[Brad1]

I know it's impossible to list ALL replacement parts (resistors, caps, diodes, etc), but does anyone know where I can find or download some kind of a list for the "most common" tube guitar amp replacement and modification components of those?

A general list of something that a normal working repair shop may normally have on hand to repair or tweak a wide variety of amps?

Stuff like filter and signal cap types and values, resistor types, values and sizes, etc.?

I'm not thinking of trying to "open up shop", or anything. I just have a roomful of old amps of which some could probably use a little maintenance, and maybe even a little bit of experimentation. I also have a few yard sale organ, and tube stereo-amp/old PA amp projects to tinker with. Some of these things, I get to messing with them, decide I may want to try this...and can't just DO it, without waiting, and without spending time looking around for simple parts, and wasting postage on a very small order.

There are absolutely no local sources for 99% of this stuff, besides the extremely-limited selection of Radio Shack.

It would be handy to just spend a bill or two at once to order a "hobbyist list" of components to have on hand (a few of those filter caps, 10 of those resistors, etc.)

Anyone?

Thanks,

Brad1

[Enzo]

I have no idea how to search for this, but we have had any number of discussions about shop parts and what to stock. Go look back through Music Electronics section.


There is no simple answer, short of going through my shop looking at drawers. It all depends on what you work on. Get some old fender schematics of things you might see, then make up parts lists. Sure there are common things like 100k and 1.5k resistors, and 220k and and and... But then look up a coupler representative Marshall amps, and do the same exercise. You gonna work on both? Or just one more likely? Marshalls liked those dual can caps for filters, Fender liked axial lead individual caps. Tubes? There are only a few types we see over and over. 6L6, EL34, EL84 12AX7 12AT7 5AR4 5Y3. But you may or may not ever need some of those. Like old Sunn amps? Then a 7199 or 6AN8 might be handy.

Pots come in all shapes and sizes, I gave up long ago trying to stock them all.

[Brad1]

I have no idea how to search for this, but we have had any number of discussions about shop parts and what to stock. Go look back through Music Electronics section.

Thanks, Enzo. I tried a search, but the search function on here is....frustrating. I searched the internet, but maybe I'm just not using the magic combination of terms. I've looked at a bunch of parts suppliers, hoping maybe they'd have some kind of handy "Common amp repair components" kit.

I certainly don't expect anyone to take a bunch of time to look through stuff to create a list, or anything. I just thought it would be handy. Most of mine are Fender, with a sprinkling of Marshall, Kalamazoo/Gibson, Ampeg, Univox, etc.

What I probably ought to do is just go ahead and look at them all, make my own list of "official" parts and tubes, etc., and then add in some possible "experiment" parts of varying values and types to order.

What really brought this on was some recent yard sale "finds" that I got for next-to-nothing, and am deciding what to do with. I figure with a couple of bins full of common parts, I could experiment a tad here and there.

One of them is an old Merrell SA30 Hi-Fi tube amp. It has a pair of 6V6 (actually, 7408, installed) each channel, but the most intriguing thing is that it has separate bass and treble for each channel (with the ganged volume pot) and then to the two OTs. Kinda like two separate amps from one power supply.

I've been wondering about the possibilities for something like that. Add another volume, (and use the one for only one side), run a guitar through both sides, each channel tweaked slightly different, and to two different speakers? Maybe a handy funky harp and guitar amp in one, to two different speakers (even in one cab)?

Haven't been able to locate any readable schematics for that thing, yet...but it's all there...except someone already did some minor modifications to it. He had a couple of large 10-ohm ceramic wire-wound resistors tapped off the OT, and added a switched potentiometer...with part of it going to the convenience outlet?

Anyway, I picked this up and the guy had all kinds of stuff cobbled together and stuffed into two homemade cabinets that matched his homemade speakers. There were actually 32 external added-on RCA jacks on this thing, on 3 different switch boxes and the back panel of his "Master Unit".

One box had nothing but a funky, worthless old phonograph in it. The other had an old BSR R-R tape deck (with no electronics save the transport and heads I/O), something called a "BA Custom Adapter" going to that (and for which I can find no info), and an old Shure M65 Stereo Converter Adapter. That BA thing looks to be manufactured, but nothing can be found of it. It's a tube preamp of some sort, with level controls only...but it has some weird inductors in the circuit. I'm wondering if that isn't standing in for the "electronics" of the tape deck? The bigger inductor off the power supply is a 6.8mH, and the two off the 12AT7 tubes are 2.6mH. Weird.

No big deal. If nothing else, I could probably sell that Shure and recover my $20, and more.

Anyway, that's what I was wanting just a general list of that stuff...IF anyone had something like that handy, or knew where one was.

Thanks,

Brad1

[Enzo]

I think if you went through our Music Electronics section - and may have to go through quite a few pages now - look for thread titles that suggest this topic. I don't know that a search would pick it up from keywords. In other words search with your eyes rather than the search box. A title like setting up shop might be good, and not on your search list.

[g1]

the search function on here is....frustrating.

That's being kind!
Someone here (sorry I forgot who) suggested the following: use google advanced search. Where it says "Then narrow your results by..." there is a box for "site or domain". Enter music-electronics-forum.com in that box. Do your search.
In my experience this method works much better than the search feature of the forum.

[Enzo]

The problem I see with the search function is that it looks for words. Clearly we can't search for "resistor" or just about every thread would come up. But when one thread talks about a parts collection and another very similar thread talks about parts selection, no search will find them both. And also will miss the ones about sourcing parts and another on stocking parts. And every novice repair effort starts with this "can anyone tell me the common parts that fail when..." So so much for searching "common parts."

Might have better luck looking for opening a shop or stocking a shop.

[Tom Phillips]

That's being kind!
Someone here (sorry I forgot who) suggested the following: use google advanced search. Where it says "Then narrow your results by..." there is a box for "site or domain". Enter music-electronics-forum.com in that box. Do your search.
In my experience this method works much better than the search feature of the forum.

I believe that was me and that procedure has been very useful. Below is a link to the results for "parts to stock" OR "parts to order" with MEF specified as the domain to search using the Google advanced search page. A new requirement is that you need to search for the advanced search page first because the link to that page no longer appears on the Google home page. WTF?

- Google Search=

[g1]

A new requirement is that you need to search for the advanced search page first because the link to that page no longer appears on the Google home page. WTF?

If you do a regular google search, at the bottom of the page you can click on "advanced search".
I use Firefox browser and have google set as my default search provider. I can highlight any word or text, right click, and one of the options in the dropdown is "search google for [highlighted text]". I find this extremely useful and use it all the time.

[Brad1]

Thanks guys.

I'll use some of those search techniques to see what pops up.

Thanks again,

Brad1

[Jazz P Bass]

Just my opinion mind you.
Repair 100 different amps.
How many parts that failed (if parts failure is the reason) are the exact same?
The odds of the answer being 'Zero' are real good.
The answer that you seek (a list) does not exist.

[Mick Bailey]

No matter how many parts I stock, the next amp through the door needs something different. I use suppliers that can get parts to me quickly, and over-order if the parts are relatively inexpensive in the hope that if one fails I'll need another.

Stock is dead money unless you have turnover, and the warranty on most components (especially tubes) begins when you buy the parts, not when you fit them.

If you did have a list, you'd find that many of the components never got used. You'd be better off ordering parts as needed rather than going out with a shopping list. A component value alone is not always helpful - you need the lead pitch and dimensions too for a lot of repairs, especially with crowded PCBs. Finding the correct electrical characteristics is often easy compared to getting the correct size and layout, especially in a market where components are becoming increasingly smaller and leaded components are disappearing in favour of SMD.

[Enzo]

Commodity parts I stock. Ordering parts is easy enough, but shipping kills you. I can't just order a cap and a pot somewhere. And we all know about order-filler items, but if I order some stuff, and buy my fillers as well, that spreads shipping cost over a bunch of parts, but then two days later I need another thing, and no fillers. I can't buy a roll of solder every week.

Resistors are dirt cheap, and really, for a couple cents each, I just order them by the hundred. 180 ohms comes up? Fine, get 100 of them. 100k plate resistors in Fenders come up often enough, and 82k phase inverter resistors too. And I know I am goi9ng to use 22uf 500v axial caps and 22uf 25v axials as well.

[mikeydee77]

In my shop (which I have only set up in the past couple of years) I stock tubes which I buy in quads (3 quads at a time), common resistors (CC and MF), Diodes and Op Amps and very few caps (cathode bypass, and a few filter caps), A few transistors. I have hardware in terms of common screws, knobs and jack sockets (cliff, switchcraft and fender). I tend to just over order when I am confident the part isn't a one-off but it is definitely a balancing act that although I am not quite 100% right, I am finding that I am often able to complete a job without ordering parts more and more of the time. However a lot of my stock doesn't seem to be going down so there I am definitely not quite on top of it.

Here in the UK there are lots of small home based parts suppliers and which I find charge such small shipping charges (e.g. £2) which seems very reasonable. The bigger suppliers like Farnell, Rapid and RS Components typically charge £5 unless a minimum of about £30 is reached.

Also I would recommend that using a shopping list system to maximise shopping efficiency will save you time organising, ordering and shipping. I have tried things like evernote and google spreadsheets (which you can turn into an online form) and settled on Google Spreadsheets. I can just tap in shopping items on my phone (say when I am on the bus) and then once it is worthwhile to place the order I can usually get free shipping or minimal shipping. This is a good replacement for the old scraps of paper that I used to rely on; also keeps a record of where I bought stuff.

[Brad1]

Thanks for all the suggestions, guys.

I wasn't really wanting HUNDREDS of one particular thing...just a fairly good order of normally-used components, and tweaking stuff...5 of this, 10 of that, some of those, more of the others.

I just start messing around with something, figure out I'd like to try something...don't have a part, and have to either order just a small amount of parts, or wait until I mess around with another thing or two to maybe order a combination of more parts, or something. I just don't like the shipping costing more than the parts.

Plus, I put something aside...and it bugs me and makes me feel guilty if I'm doing something else while that thing is sitting there staring at me. I've got four "projects" sitting around deciding what to do, and I know some of my old amps could use some minor maintenance...and maybe even some experimental minor tweaks. I've finally gotten to the point where I can pay these things some attention after being unemployed/underemployed for 5 years until I got a good job a year ago. I found that working third shift seems to have given me more free time, as far as...there's not much to do in the hours I'm awake, and even have to keep through the weekend. (Do they still allow alcohol in bars?! Been a while.)

I've got schematics to almost all this stuff, so I'll just find time to bring each up, and maybe make kind of a cross-reference for amp model, input/preamp components, power supply, amp section, etc., add up parts, figure out possible alternative "tweak" values for those, and have an idea what I may want just to freshen up some things, and to try some things.

It's just me wanting to try to get things in good shape and sounding good, while learning more and more as I go.

I know some of you guys who do this day in and day out could probably tell anyone what a particular value of component in a particular amp is...or rattle off the circuit specifics right off the top of your head, but this isn't something I do everyday. I "understand" all of the stuff, and I can guess at some of it and be right, but I still have to confirm before acting.

That's all this is for. The stuff I have, the yard sale/thrift store "hmmm....I wonder" stuff I pick up for next-to-nothing, and the occasional pre-diagnosis/easy-fix (or "no...go ahead and take it to that guy) for friends.

I'll figure it all out.

Thanks,

Brad1

[eschertron]

I wasn't really wanting HUNDREDS of one particular thing...just a fairly good order of normally-used components, and tweaking stuff...5 of this, 10 of that, some of those, more of the others.

An alternative way of stocking for your specific needs might be to diagnose a handful of amps, and when you find a bad resistor or cap, write it down. Maybe at that point you cannot continue on that particular unit until the replacement part arrives - go ahead and start diagnosing another amp. You could find that soon enough you have a list of parts worth ordering, and possibly an idea of the parts that will be need for as-yet undiagnosed amps... the other 4 or nine of the "5 of this, ten of that".