Yamaha B100, what needs fixin?

**~Ethan~** · #1 10-17-2011, 10:27 PM

Hey guys back when I was working for Lowes, I came across a Yamaha B100-115 bass amp just sitting by the trash can, so naturally I picked it up and brought it home! It looks fairly old, and it's missing a wheel. I tried plugging it in and it turns on but when I tried to play through it nothing came out. I know next to nothing about amps so I can't even begin to know what the problem might be.
I want to see if anyone here might know what may need replacing/repair or just whatever it will take to get it working again. I'll try to give as much info as possible but I'm afraid you may not have much to work with.

Here's a few pics I took, sorry for bad quality, the lighting just wasn't that good.

**~Ethan~** · #2 10-17-2011, 10:50 PM

Oh and side question, my local gc has a Kustom 810 for $400 and a Peavey 410 for $200. First, which company do you prefer, and should I sell/trade my GK goldline 210 to go towards one of the two? If I get another amp I'd be selling it anyways but my question is Kustom or Peavey better than my GK? Thank you!

James Hart · #3 10-17-2011, 10:51 PM

Quote:

Originally Posted by ~Ethan~

I came across a Yamaha B100-115 bass amp just sitting by the trash can

common fate for those.... I threw one out a few years back.

**B-string** · #4 10-17-2011, 10:56 PM

Quote:

Originally Posted by ~Ethan~

Oh and side question, my local gc has a Kustom 810 for $400 and a Peavey 410 for $200. First, which company do you prefer, and should I sell/trade my GK goldline 210 to go towards one of the two? If I get another amp I'd be selling it anyways but my question is Kustom or Peavey better than my GK? Thank you!

The Peavey 410. If you want a 810 go for a better brand IMO.

T-Bird · #5 10-18-2011, 01:28 AM

Hi.

Quote:

Originally Posted by ~Ethan~

It looks fairly old, and it's missing a wheel. I tried plugging it in and it turns on but when I tried to play through it nothing came out. I know next to nothing about amps so I can't even begin to know what the problem might be.
I want to see if anyone here might know what may need replacing/repair or just whatever it will take to get it working again. I'll try to give as much info as possible but I'm afraid you may not have much to work with.

Congrats on the find. Sort of

.

The missing wheel may just be the easiest and the only thing that an average Joe can do for such a find. Unfortunately.

If I came across one, and if I had the time (which I don't), I still wouldn't try to fix it if a 30 minute diagnosing wouldn't reveal the problem.

IIRC some of these came with hopeless to replace hybrid chips, but judging by the pic, there's TO-3 discretes in the power section in this one.

I'd start with the fuses, followed by testing the speaker and trying with another one, after "cleaning" the footswitch contacts with a plug.

Some Yamaha's I've worked with in the past show the TP readings on the PCB(s), as well as component values, so if You feel confident enough to work inside a live amp, I'd start from the PSU and work my way towards the power section.

That said, IMHO, this is as close as it ever comes to polishing a turd without actually taking up the hobby, so donating the amp to someone who's better equipped to repair it would be my choice of action.

Regards
Sam

**~Ethan~** · #6 10-18-2011, 02:25 AM

Quote:

Originally Posted by B-string

The Peavey 410. If you want a 810 go for a better brand IMO.

Ok thanks, I'll look into the peavey then.

Quote:

Originally Posted by T-Bird

Hi.

Congrats on the find. Sort of

.

The missing wheel may just be the easiest and the only thing that an average Joe can do for such a find. Unfortunately.

If I came across one, and if I had the time (which I don't), I still wouldn't try to fix it if a 30 minute diagnosing wouldn't reveal the problem.

IIRC some of these came with hopeless to replace hybrid chips, but judging by the pic, there's TO-3 discretes in the power section in this one.

I'd start with the fuses, followed by testing the speaker and trying with another one, after "cleaning" the footswitch contacts with a plug.

Some Yamaha's I've worked with in the past show the TP readings on the PCB(s), as well as component values, so if You feel confident enough to work inside a live amp, I'd start from the PSU and work my way towards the power section.

That said, IMHO, this is as close as it ever comes to polishing a turd without actually taking up the hobby, so donating the amp to someone who's better equipped to repair it would be my choice of action.

Regards
Sam

Hmm, I guess I'd better donate then lol. Oh well it was worth a try, I just let myself leave an opportunity like that go by. I figured I'd rather have it and it not work than wonder if it did work and have it get thrown away. Thanks for the info guys, I guess I'll look into putting it on craigslist or something. What would you recomend for a price?

1n3 · #7 10-18-2011, 03:00 AM

I played through one of these back in the late 70s. It was a decent amp for the time; above-average volume for 100w/115, and a beefy tone. On the other hand, these haven't acquired any collector interest that I know of, and it's large and heavy. If you know a tech who can give it a quick look for cheap, it might be worth going that far. In good working condition, it might be worth $100 or more. Otherwise, it's just a project for someone else. If the speaker works... $20?

**~Ethan~** · #8 10-18-2011, 01:23 PM

Hmm ok, I might ask around town first to see about pricing a repair then maybe craigslist if its not worth it. Thanks!

Monkey · #9 10-18-2011, 04:57 PM

I also played one of those in the early 80s and it sounded surprisingly fat and loud for a 100 watt amp. It was heavy and unwieldy, though, and I I had a problem with it making a strange hissing sound that my local repairman couldn't track down. I wouldn't put much money into it, but I enjoyed mine back in the day. Don't miss it, though......

Blue · #10 10-18-2011, 06:29 PM

These are great old school boxes - but way heavy / bulky. Keepers while you're young.

Blue · #11 10-18-2011, 06:31 PM

[quote=~Ethan~;11631663]Ok thanks, I'll look into the peavey then.

I took the dead amp off one - and kept the cab (with working speaker) as a second 1 x 15" ... but I was a lot stronger (and poorer) in those days.

Lowbrow · #12 10-18-2011, 08:30 PM

I had the separate head and 2x15 cab version. Sounded great, and the head on its own stayed in service long after the speakers went bye-bye.

lesliegl · #13 10-19-2011, 02:43 AM

Hi this was my first real bass amp when i bought it in 1983..very haevy and bulky but it had a great tone to it..after a while it developed a fault in that the volume kept going down..i had it looked at but no one could find out what was causing it..so i sold it on commission at a music shop in Alice Springs and it sold for more money than i bouht it for which i was quite happy with..lol i bought a Peavey Combo 300 to replace it although a better bass amp didnt have that sound to it ..i later played thru a later model Yamaha B series in 1985 and it had that ''tone'' so whatever they had in em' electronics wise i wish i could find it again

Leslie

T-Bird · #14 10-19-2011, 04:18 AM

Hi.

Quote:

Originally Posted by ~Ethan~

Hmm, I guess I'd better donate then lol. Oh well it was worth a try, I just let myself leave an opportunity like that go by. I figured I'd rather have it and it not work than wonder if it did work and have it get thrown away.

Just to clarify my last post.

If I led You to believe that I wouldn't have snagged it as well, nothing could be farther from the truth. I'm totally hopeless case when it comes down to dumpster-diving, even at the ripe age of 40

. It's just that I wouldn't put too much effort in it, but to pass it along to someone who's learning amp repair, something like that could be a gold-mine.

Regards
Sam

**~Ethan~** · #15 10-20-2011, 02:32 PM

Quote:

Originally Posted by T-Bird

Hi.

Just to clarify my last post.

If I led You to believe that I wouldn't have snagged it as well, nothing could be farther from the truth. I'm totally hopeless case when it comes down to dumpster-diving, even at the ripe age of 40

. It's just that I wouldn't put too much effort in it, but to pass it along to someone who's learning amp repair, something like that could be a gold-mine.

Regards
Sam

No not at all. I just have no knowledge of electronics or amps and no confidence in myself to do it is all. lol

lowend1 · #16 10-21-2011, 03:16 PM

I happened upon the head version a few years back that was on the fritz as well. Turned out to be an output transistor. I actually made money on it!