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Post by LVF on Jul 26, 2021 10:54:40 GMT -5
Now that I know everything works on the Silvertone Twin Twelve recently acquired, I wanted to pull the amp chassis, do a bit of cleaning, make a mental plan for a minor modification to the amp/speaker connection and do an overall examination of the electronics in it. The minor mod I'm thinking of is removing the speaker wire connection which is hardwired between the amp amp and cab and adding jacks at both ends so I can use a normal speaker cord connection. Doing it in a way that it can be reversed to put it back to original. From the amp, it will be not problem. From the speaker cab side, it will be a bit tricky adding a jack and keeping the mod inconspicuous. As to the pic, checkout what it means to build an amp circuit without the use of the modern circuit board. That is a lot of wiring, caps, resistors and diodes and illustrates what it looks like when it 'contains no PCB's'.  not to mention that every piece of electronics in this amp was 'made in the USA' (with no 'PC' reference to 'global parts'). When I looked at the circuitry for the first time, I was happy to see that after more than 50 years, everything looked 'bright and shiny' with little dust. It was easy to clear off what was their. Also, only two of the vacuum tubes [6GC7's] had been replaced with the rest being original 'Silvertone' valves. This amp is really put together. I can't believe this amp ever got much use the way it looks.  |
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Post by Peegoo 🏁 on Aug 16, 2021 8:51:32 GMT -5
That is nice and clean!
I'd solder a 24" speaker lead to the speaker and add a 1/4" plug on the end. Easily reversible to stock. Add a zip tie around the speaker lead and speaker frame to prevent damage to the connector card on the speaker in the event the lead gets yanked.
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Post by LVF on Aug 16, 2021 16:48:46 GMT -5
As of this moment, I've haven't done anything yet and I may have to just add an extension with a phone jack like you say. I have not found one issue with this amp so far and I still can't believe how pristine it is for something over 50 years old. Not to mention, all the electronics seem original except for the two tubes I mentioned earlier. I decided to add the same pic here because the first one came out on the small side for some reason. This may give you a better idea of it's condition. The only thing missing is the foot switch but, I tried my foot switch from my Twin Reverb and it fine.  |
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Post by LVF on Mar 24, 2022 14:38:31 GMT -5
This amp is now under repair as it 'let the smoke out' of one of the big red caps and also has a tremolo issue as it stopped working. I've done some repair but, I have on order, all the replacements for the big red caps and all the diodes as well. I've done some work on replacing components in the tremolo section consisting off caps and resistors that were out of spec. I'm now waiting on the new parts that should show up before the end of the month. I'd like to say that all the red caps had a year guarantee on each of them (it says so on the label ) but, the year guarantee expired 57 years ago  . On that note, my meager research into the age of this amp has led me to believe that this is a first year model 1484 as in 1964 and I base that on the manufacture date of the speakers which were built the 19th week of 1963. Assuming Jensen would not be holding on to these speakers for any length of time, I can only assume that this amp was built in 1964, the first year of production for this amp. That would be 3 years before my original amp of which I got, brand new, for my birthday in 1967. I'll have this amp up and running again in no time...maybe. |
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Post by funkykikuchiyo on Mar 25, 2022 11:03:58 GMT -5
No PCB, but also not a lot of eyelet boards! I remember the first time I opened an amp and saw TRUE point-to-point. It was messy and elegant all at the same time. Heh.
I wonder how those were made back in the day. Lots of sub assemblies maybe? I can't imagine one person just sitting and soldering them one by one. That would take forever. Manufacturing was so different.
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Post by LVF on Mar 25, 2022 14:01:33 GMT -5
I'm learning some things about the different 'styles' used in the electronics of amps. Diagnosing and working on amps in general are not something I do in general. I should probably send it off for repair to someone who doesn't need a learning curve like Uncle Doug but, I like doing things myself so, I'll work on it to success or...failure, at which point, I'll send it off to a pro. But for now, I'm having fun attached to a learning experience. So, far I've learned a lot about this stuff and have at least, the competence to order the correct parts replacements. I have no problem doing the soldering required to change out the parts and I am learning to 'section' the different areas of the electronics. It doesn't seem all that difficult to do. My experience in automotive electrics is helpful. It probably comes to no surprise that there would be issues like this on such an old amp but, I can't help feeling that replacing all the tubes started the issues I'm having. Before that, It worked perfectly but, I wanted to put new tubes in so I could preserve the originals. I'm guessing the old hardware didn't like my new tubes.  |
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Post by LVF on Apr 3, 2022 10:32:50 GMT -5
Here is the result of my 1484 amp 'letting the smoke out'. After almost 60 years, it needs a repair. Actually, it was already under repair for a non functioning Tremolo. The big red cap on the left decided it had enough and let loose, spewing oily substance (PCB's? ) on the inside of the amp. Doing a check of the other caps, I discovered the one above the exploded cap was not working as well plus, all the diodes you can see were taken out. Time for a major overhaul...  ...I ordered enough caps to replace all the red ones and diodes as well. If those blue ones look like they are crammed in their place...they are. I had no idea the the replacements would be even bigger the the big red ones. They're probably one fifth larger. It was necessary to insult some of the wire connections from each other as they are pretty much, butted up against each other.  I was surprised I was able to fit them in place of the red ones but, fit they did...just barely. This particular repair actually improved the amp performance very well. It doesn't break up as soon and it is so quiet! Now, I'm back to were I left off figuring out the trem problem.  |
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Post by LVF on Apr 29, 2022 19:32:48 GMT -5
Looking at the last date posted about this, it's been a while. That's because I had to go over what I've done so far to repair the tremolo circuit which was the original issue and diagnose what I did to continue its disfunction all the while, waiting on parts to show up. With that, I discovered that I had replaced some key resistors in the tremolo circuit with the wrong values. This happened because I didn't pay attention to what was sent me for replacements. I had ordered resistors with kilo ohm resistance but, received ones that had a value of just ohms. I should have had, for example, resistors that were 560K ohms but, was sent resistors that were only 560 ohms. Several of the replacement resistors were this way and I didn't catch it until I had put them in the circuit.
As I've said before, I don't really have any experience repairing amps especially, this one that's nearly 60 years old but, I do have years automotive electronic/electrical experience so some of that experience didn't make me a complete moron about this. Regardless of these issues, I've had a really good time doing this stuff. Anyway, after the discovery of this debacle, I got the right resistors, having replaced many of the caps involved already and I now have a fully functioning tremolo in the 1484 which means this amp is fully functional, everything works again! Job done! 👍
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Post by LVF on Apr 30, 2022 10:47:12 GMT -5
As a follow up, I thought I'd try to show what the tremolo circuit is in the 1484 with before and after shots of the repair. As it turns out, I replaced all the caps in this circuit because I found too many of them out of spec and those green ones had carbon burn marks on the bodies of a few. That resistor I have featured in the mirror image has 'smoke' marking. That is a 330k resistor. Moving on to the next image...  As you can see, all the caps are different now with new ones and the resistors involved are replaced with the right valued resistors (heh!  ). When I looked at doing this work, glancing at the entirety of it was quite intimidating. However, after studying the schematic, I was able to isolate the tremolo area, both on the schematic and the the circuit area itself. It makes it much easier if you can do that. As you can see in this pic, the tremolo circuit has all new caps and resistors. It also shows partially, a couple of the big blue caps that replaced the big red ones after a couple of those blew halting progress on the tremolo circuit for a time. I have to tell you that one of the caps in the tremolo circuit that was replaced is a different value. In the first pic, you can see the value of that green cap on the right side of the pic which is .05 micro farads. It's replacement is the blue one, behind the black cap in the second pic. It's value is .1 micro farads. Twice the value. I found later, that this did not affect the operation of the trem circuit in anyway. One of the things I found trying to gather these caps and resistors was finding places online to buy these things. It's not like you can go out to the local Radio Shack to get this stuff anymore. They don't have any around here or places like them. It's a whole new world!  For a rookie like me, looking for this stuff, it took considerable time and a few different companies to gather what I needed. Amazon, Parts Express, Stew Mac, Mojotone among others, were most of the sources for these parts, along with a few shipping debacles along the way. Having experienced the shipping end before, I was sure to order 'extras' to ensure I would have parts on hand should I have to do this again down the line. This whole experience has led me to acquire a fair amount (heh, I first spelled 'amount', amoount, which I think may be proper Canadian...maybe  ) of knowledge and a bit more confidence in doing my own repairs, along with acquiring some new tools and equipment. I love doing this kind of stuff anyway. Keeps me busy and out of trouble.   |
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Post by LVF on Apr 30, 2022 13:01:06 GMT -5
Here is a demonstration of this amp as I recorded a sound clip that demos the amp itself and the tremolo in a few speed levels. I'm playing the LP standard and the 'noise' is just BS...basic BS right here |
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Post by pcalu on May 1, 2022 7:10:10 GMT -5
Here is a demonstration of this amp as I recorded a sound clip that demos the amp itself and the tremolo in a few speed levels. I'm playing the LP standard and the 'noise' is just BS...basic BS right here Nice very Nice... Tonality wise, that Silvertone Twin Twelve isn't influenced by Fender's move to a scooped tone stack in the mid 60s. Has a mids up front focus, yet a clean detail.. almost a Fender Brown sound. Like it! |
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Post by LVF on May 1, 2022 9:34:01 GMT -5
I'm just glad I could get this amp back in proper working condition but, the sound and tone it has is one of my favorite. Having a working trem makes it that much better. It really is a joy maintaining it. I wanted to add something I keep forgetting to do. One of the other parts replaced in this amp was the 12 AX 7 tube socket for the trem circuit. The old one had a broken connector. So, it was more than just caps and resistors. |
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not to mention that every piece of electronics in this amp was 'made in the USA' (with no 'PC' reference to 'global parts'). 
. On that note, my meager research into the age of this amp has led me to believe that this is a first year model 1484 as in 1964 and I base that on the manufacture date of the speakers which were built the 19th week of 1963. Assuming Jensen would not be holding on to these speakers for any length of time, I can only assume that this amp was built in 1964, the first year of production for this amp. That would be 3 years before my original amp of which I got, brand new, for my birthday in 1967. 
). When I looked at doing this work, glancing at the entirety of it was quite intimidating. However, after studying the schematic, I was able to isolate the tremolo area, both on the schematic and the the circuit area itself. It makes it much easier if you can do that. 
For a rookie like me, looking for this stuff, it took considerable time and a few different companies to gather what I needed. Amazon, Parts Express, Stew Mac, Mojotone among others, were most of the sources for these parts, along with a few shipping debacles along the way. Having experienced the shipping end before, I was sure to order 'extras' to ensure I would have parts on hand should I have to do this again down the line.
) of knowledge and a bit more confidence in doing my own repairs, along with acquiring some new tools and equipment. I love doing this kind of stuff anyway. Keeps me busy and out of trouble. 
