My amp

5string5fingers · #1 04-30-2010, 11:12 AM

In light of my amp dying, and having to purchase a new one, I've decided to take apart my amp to see what exactly was the problem. In hopes to fix it someday. I just took off the grille cover and this is what i found.

More pictures as i get farther. Just thought i'd share for those of you who like old funky amps.

5string5fingers · #2 04-30-2010, 11:28 AM

Heres a picture of the back of the speaker. Maybe someone out there can tell me a little more about them.

There doesn't seem to be any physical damage to the speakers that I can see which keeps me believing it was the amp head not the speakers. Anybody know if this cabinet could handle modern speakers? I've always considered keeping the cabinet and then replacing the speakers with new ones and then buying a modern amp head.

5string5fingers · #3 04-30-2010, 12:19 PM

I found these,theres 4 of them screwed into the back of the head. No idea what they are,seem very corroded though.

The inside

Pilgrim · #4 04-30-2010, 12:34 PM

Be DARN CAREFUL around those gold-colored canisters. I believe those are capacitors, and they could easily be storing enough electricity to seriously injure you.

If you don't know anything about amps or electronics, I STRONGLY recommend that you close the top of it and walk away. You are playing in dangerous territory. Even a non-working amp can be dangerous.

KramerBassFan · #5 04-30-2010, 12:36 PM

UMM!

Those "really corroded" metal circular things are power transistors... the things with SK3027.... Do not mess with them. Transistors are Static sensitive..

What is the brand?

Looks like a Sear Silvertone type amplifier... but the speaker reminds me of a Magnatone.

And those big gold canisters that look like soda cans are Power Capacitors.. DO NOT TOUCH THEM!

5string5fingers · #6 04-30-2010, 12:40 PM

Quote:

Originally Posted by Pilgrim

Be DARN CAREFUL around those gold-colored canisters. I believe those are capacitors, and they could easily be storing enough electricity to seriously injure you.

If you don't know anything about amps or electronics, I STRONGLY recommend that you close the top of it and walk away. You are playing in dangerous territory. Even a non-working amp can be dangerous.

uhm..thanks for the info and saving my life

. I'm not messing with anything I just wanted to see if there was anything obvious that was broken,but i see nothing so I'll be leaving everything alone now.

The amp is a Sears brand amp.

KramerBassFan · #7 04-30-2010, 12:43 PM

That cabinet should do OK as long as you don't pump too much bass or too much power through it... but the amp may be shot, and hard to fix. Those old transistors can be a PITA to track down and identify. Trust me there.

I'd recommend getting a new amp to go on top of that big ol' speaker cabinet.

But pretty cool old rig you got there.. I'd rock it.

Most likely the amp has failed.

5string5fingers · #8 04-30-2010, 12:46 PM

Quote:

Originally Posted by KramerBassFan

That cabinet should do OK as long as you don't pump too much bass or too much power through it... but the amp may be shot, and hard to fix. Those old transistors can be a PITA to track down and identify. Trust me there.

I'd recommend getting a new amp to go on top of that big ol' speaker cabinet.

But pretty cool old rig you got there.. I'd rock it.

Most likely the amp has failed.

I was thinking the same..but I wanna see if anyone here might know more about the speakers and their power capabilites. This amp head is only 100W at 4 ohms and the smallest amp head i've seen is 200W and I dont wanna blow the speakers.

rbonner · #9 04-30-2010, 12:50 PM

Yes it is a sears silvertone. The transistors are probably just fine. If the amp worked good and then just quit it's not going to be very hard for somebody in the know to fix.

The voltage on those caps is probably around 40-50V DC not the kind of killer voltage, but there are places in the power supply that have line voltage and if you don't know what a transistor looks like you are looking for BLOWN UP parts and I don't see any.

The speaker is a FISHER brand, by the EIA CODE on the back.

The big transistors would only be blown if you shorted the speaker leads out. 2N3055's would probably plug right in and work. You can get those at radio shack. A quick search on those existing units could tell comparing specs. Earp .... SK is an RCA, if they are bad they are about $6.25 BOB

5string5fingers · #10 04-30-2010, 12:54 PM

Quote:

Originally Posted by rbonner

Yes it is a sears silvertone. The transistors are probably just fine. If the amp worked good and then just quit it's not going to be very hard for somebody in the know to fix.

The voltage on those caps is probably around 40-50V DC not the kind of killer voltage, but there are places in the power supply that have line voltage and if you don't know what a transistor looks like you are looking for BLOWN UP parts and I don't see any.

The speaker is a FISHER brand, by the EIA CODE on the back.

The big transistors would only be blown if you shorted the speaker leads out. 2N3055's would probably plug right in and work. You can get those at radio shack. A quick search on those existing units could tell comparing specs. Oh yeah SK is one of Sylvanias numbers, those are already replacement transistors.

BOB

Is there any place online i can find info on the speakers? Like specs,what they're rated for?

rbonner · #11 04-30-2010, 01:02 PM

Quote:

Originally Posted by 5string5fingers

Is there any place online i can find info on the speakers? Like specs,what they're rated for?

What are they two 10's and a pair of 15? I can't tell by the pic.

They are low power, low excursion speakers. The amp is fine for a garage band type practice amp and playing Suzi's birthday party.

They are probably good for 25W each. Finding details for stuff like that on the Internet is like combing through goo...

I already mentioned the EIA Code thats the 1056 and that indicated the manufacturer. Thta speaker built 14th week of 1972. You'd probably just tee off the secretary at Fisher if you called them.

Since sears doesn't build anything... I wouldn't doubt that Fisher actually manufactured the whole amp for them.

Just be glad you've got it, test the speakers to make sure they are OK and fix the head. Nice practice amp.

BOB

5string5fingers · #12 04-30-2010, 01:08 PM

Quote:

Originally Posted by rbonner

What are they two 10's and a pair of 15? I can't tell by the pic.

They are low power, low excursion speakers. The amp is fine for a garage band type practice amp and playing Suzi's birthday party.

They are probably good for 25W each. Finding details for stuff like that on the Internet is like combing through goo...

I already mentioned the EIA Code thats the 1056 and that indicated the manufacturer. Thta speaker built 14th week of 1972. You'd probably just tee off the secretary at Fisher if you called them.

Since sears doesn't build anything... I wouldn't doubt that Fisher actually manufactured the whole amp for them.

Just be glad you've got it, test the speakers to make sure they are OK and fix the head. Nice practice amp.

BOB

2 12s and 2 15s. I don't know how i'd fix the amp if i dont know whats wrong with it. Closest amp tech is 4 hours away in atlanta.

BassmanPaul · #13 04-30-2010, 02:12 PM

It's not too likely in my mind that the SK3027s are original parts. SK parts were a range of generic replacements. I suspect the amp has blown its outputs in the past. Although plenty of SS parts are indeed sensitive to static discharge those parts are not. They can be tested simply with an ohmmeter and replaced if needed. If one has gone replace all four. They should be refitted using heat sink compound and the mica washers they came with.

Please be careful with what you are touching inside the amp. The mains voltage and indeed the plus and minus rails can hurt you.

Paul

rbonner · #14 04-30-2010, 02:43 PM

OK took the time to look at your profile and see where you're at. You jam with a guitar buddy, does he have a head or is he a combo guy? If he has a head, or one of your other buddies, test our your cab and make sure the 4 speakers work. Even the 9V battery test will tell you the things are still there.

If they check out, you just need some sort of amp head to make them play and while the Silvertone cab isn't a work horse, it will get you by.. Something like an Acoustic 200 head or even a 600 would get you by while you save up for a larger cabinet.

Then when you and your buds are heading to ATL for some nice summer reason. My kid is your age and heads to Minneapolis to do evil things with his buddies a few times a year, call ahead to the amp tech and wheel the head in, or ship it to him in a box.

You'll get it back working... BUt when an acoustic 200 can be bought for a couple hundred used, why not just pick one of those up?

Check out the speakers first.

BOB

JMac4strngr · #15 04-30-2010, 02:51 PM

The only place in Atlanta that works on SS amps would be Wizard electronics. They will charge 80 bucks just to open it up. I am with rbonner with the acoustic 200 head..... Come to think of it I think I have an old SS head I would give to you if you were in the Atlanta area.

5string5fingers · #16 04-30-2010, 09:50 PM

I'll test the speakers. I no longer jam with that guitarist anymore,or at least havent in the past 8 months just because i no longer live 30 minutes away from him its not an hour and 30 minutes,and we've both been so busy and he just has a small 30W combo. I was looking at the b200 amp head,but wanted to make sure that wouldnt destroy my speakers.

JMac I might hit you up sometime soon if thats cool. I'll be in atlanta in may for my birthday.