Rockometer Amp
Call us: 434-987-2804
Rockometer Amp Services
Basic Tech Services:
Any vintage amp should be properly serviced to be reliable, and more importantly, safe. If your Silvertone hasn't been serviced, we highly suggest the following if you're getting a new cab:
1. Install a 3 prong power cord and removal of death cap.
2. Recapping. The 1482, and almost all Silvertones and Danelectros from 1963 and up used a 3 section cap can in the power supply. The 1484/85's also used a stacked voltage doubler power supply utilizing 4 100mfd/150V electrolytic capacitors in series. The 1483 also used a separate 16mfd capacitor for the rectifier tube, but all used the 20-10-5 mfd 450 Volt multi section cap can. This cap can is not currently available.
The good news is there are multi section cap cans that are close enough in value to use, and are a good idea in the 1484/85's, as there is not a lot of room to use separate caps. These cap cans are larger in diameter, and require opening up the hole in the chassis.
The 14872/82's have enough room to use separate caps, so the replacement is easy, and the original can be disconnected and left in place for a vintage look.
It is also possible to "rebuild" an original cap can, this is done by opening them and removing the original caps, then installing new ones. I haven't done this yet, but it can be done easily with todays modern electrolytics.
Antique Electronics makes the modern cap cans, and for a short time was stocking a 20-10-10 mfd/450 volt cap can, which was dimensionally correct. If we can convince them to make them again, we will stock them.
One other set of caps that should be replaced are the 25mfd/25 volt caps on the preamp tube, and on one of the reverb tubes.
3. Resistors. All resistors should be checked for being within spec, these amps used Carbon Comp resistors, but they weren't the Allen Bradley 5% like you seein old Fenders. Danelectro used a 20% resistor, meaning a 100K resistor was still good if it measured 120K, or 80K! Resistors should also get checked for signs of burning, and the power supply resistors should be switched to a 2watt rating, minimum.
4. Coupling caps. these should be checked for DC leakage, they're usually fine. Don't replace them just to replace them,as long as they're not leaking, they're fine.
5. Tremolo circuits. These occasionally quit working properly, and it's usually a .5mfd cap that goes bad, try switching out the tube first, but it's probably the cap. Some of the early 1470 series amps used a less than great coupling cap, the circuit may need more work here. VERY IMPORTANT: THE 1484 AND 1485 SCHEMATICS ARE WRONG FOR THE TREMOLO CIRCUIT! THIS CIRCUIT SHOULD BE COPIED FROM THE AMP ITSELF, NOT THE SCHEMATIC! These two amps, and their Danelectro DM25, DM50 and DM100 all used a "light operated tremolo", also called a roach. A replacement optocoupler is available, but is a little different from original, and works fine. sometimes they go bad, I highly suggest you don't try taking an original apart, unless you know what you're doing.
6. Input jacks. We highly recommend installing shorting input jacks, they really do help reduce noise, and also give you a high/low input.
7. Cleaning. Yes, the amp should be clean, the newest ones are almost 50 years old! Blow out the dust, clean the pots and tube sockets with DeOxit, and retension the tube socket pins.
Taking the time to do all of this will keep your amp in top shape, it'll be safer, and it will sound better. Especially in one of our new cabs.
8. And finally... REVERB! Oh yeah, the infamous Silvertone reverb. These amps used a really less than crappy "reverb tank", the circuit is capacitor driven, like an Ampeg, and uses 1-6CG7 and 1-12AX7 for drive and recovery. The tank uses piezo transducers, and besides the fact that they didn't sound that good new, they go bad over time. I've taken apart several, and can get them to work A LITTLE better about half the time.
The only way to really improve it is to rip out the original circuit, and completely redo it. I've got a circuit that works pretty good, light years better than original. It's basically an Ampeg circuit, and it uses 1/2 of the existing 6CG7 and 1/2 of the existing 12AX7, so you can use those tubes. Once I get a few more tweaks to improve it more, I'll offer the conversion for you, or provide a schematic for you to follow. I'm doing one for a customer now, and will then try a fender style circuit in my personal 1484. Either one requires using the smaller Mod/Belton/Accutronics tank, as it is the only thing that fits inside the head cab. If you don't mind running a longer reverb cable, you could house a long tank in a small head box made for that purpose. Stick with the smaller one, it's easier. One more thing here on reverb, the Fender circuit requires a reverb transformer.
9. Oh yeah, tubes. If you've done all this and the amp sounds weak, or makes some noises that don't seem right, check the tubes. And before you run out and buy "new tubes", odds are very good that the ones that were in the amp originally are still in there, and they are likely superior to anything you can go out and buy. Except for NOS tested tubes. Seriously, a lot of these amps were played for a short time and put away, and have perfectly good tubes in them already.
Although they can be a pain in the ass to work on, we don't mind working on them, if you aren't in a hurry. A lot of shops don't like working on these, as they are a true "point to point" wired amp. Call your local tech and ask them, as our time is very limited for services.
Call anytime with questions.
DISCLAIMER! TUBE AMPLIFIERS CONTAIN HIGH VOLTAGES AND CAN KILL YOU, IF YOU DON'T KNOW HOW TO PROPERLY DISCHARGE THE CAPACITORS, TAKE THE AMP TO A QUALIFIED TECH!
