Jess Oliver lives on through The AMPEG PORTAFLEX CLUB - now up to lucky 7! - Page 14

JimmyM · #**261** 03-10-2012, 01:40 PM

Quote:

Originally Posted by beans-on-toast

Nice to have you back Jimmy.

Thx David...I knew the club would be in good hands with you here, though. BTW, I should say that I, as was hinted to earlier, hate Tom and his navy random flair stack.

Well I hate that I didn't go for it. Nicely done, bro!

FenderAmpeg · #**262** 03-10-2012, 03:48 PM

Quote:

Originally Posted by JimmyM

Thx David...I knew the club would be in good hands with you here, though. BTW, I should say that I, as was hinted to earlier, hate Tom and his navy random flair stack.

Well I hate that I didn't go for it. Nicely done, bro!

Scared me for a minute!

I was waiting for your return to do the full documentation.

Some cool news, the seller of the NRF B-15N contacted me on Thursday, they found the dolly and are going to send it to me for just the cost of shipping.

Ric Vice · #**263** 03-10-2012, 04:01 PM

Quote:

Originally Posted by John D

Try here: Fliptops

The main cap that I would be concerned about is the one in the top left corner of your picture, just under the fuse holder. You can only see the bottom of it from inside the amp. The remainder of it is up top, with the tubes. It is actually three or four caps inside one can.

However, the larger multi-section cans are not always a direct replacement fit. Maybe David or someone can give you a better answer.

John,
Did all B-15's have the Caps in a Can up topside or was that something that they added later? That's one of the things that my tech replaced when he replaced the caps. Until he showed it to me, I had no idea that's what it was.

Ric

deekay911 · #**264** 03-10-2012, 04:56 PM

Quote:

Originally Posted by Ric Vice

John,
Did all B-15's have the Caps in a Can up topside or was that something that they added later? That's one of the things that my tech replaced when he replaced the caps. Until he showed it to me, I had no idea that's what it was.

Ric

Mine is an early 63 and it has the 'caps in a can' on top, so I think it must have been that way from the start.

Has anyone used the fliptops capacitor kit? You know which caps it contains?

beans-on-toast · #**265** 03-10-2012, 05:03 PM

Quote:

Originally Posted by John D

I'm not sure, but I think the green ones are coupling caps. If I'm correct, they would be the least of my cap worries. The main cap that I would be concerned about is the one in the top left corner of your picture, just under the fuse holder. You can only see the bottom of it from inside the amp. The remainder of it is up top, with the tubes. It is actually three or four caps inside one can. Others you need to be concerned about are the bias caps. The Fliptops set should include all of them. However, the larger multi-section cans are not always a direct replacement fit.

Deekay, as John said, the green caps are coupling caps and normally do not need to be replaced. Those caps are like gold, people pay big bucks for them. The caps that usually need replacing are the power supply and bias caps.

On the early B-15N, the original cap can was 40/40/20/20uF. You might want to confirm this by looking on the cap can, they were always changing the values that they used. For instance on the 63 NA with the diode rectifier, they used a 40/40/40/40uF cap can. Fliptops lists a 40/40/20/20uF but they are out of stock. I would call and ask if they are getting more and ask what they recommend otherwise. As a substitute you can get a 40/40/40 @525V and then get a single 20-30uF cap and install it on the eyelet board. This single cap would be used for the first stage in the pre-amp. The 40uF caps need to be at the first stages of the power supply.

You should also order a new insulated washer to go with the cap can. Sometimes the old one can be reused but the extra cost is not worth the risk of not getting it. Using an insulator is a must as the cap can case needs to be isolated from the chassis to prevent creating a ground loop and the subsequent hum.

You should also order the 50uF 50V (or higher voltage) and 250 ohm 10W (or higher wattage) used in the bias circuit. These often go out of spec so it is good to change them. This is the pair of components connect from pin-8 of the 6L6GC power tubes to ground. It is a good idea to mount the 250 ohm resistor off the board a bit. It can get hot and scorch the board.

In general, if a component looks burnt, take the time to replace it as it is probably out of spec.

David

JimmyM · #**266** 03-10-2012, 05:14 PM

Quote:

Originally Posted by FenderAmpeg

Scared me for a minute!

I was waiting for your return to do the full documentation.

Some cool news, the seller of the NRF B-15N contacted me on Thursday, they found the dolly and are going to send it to me for just the cost of shipping.

SWEET! Nice going!

beans-on-toast · #**267** 03-10-2012, 05:17 PM

Ric, they always used cap cans at Ampeg as far as I know. The higher the capacitance and the higher the voltage, the bigger the form factor of the component. Because of the large size, they used to mount them on top of the chassis like a tube. They wouldn't fit under the chassis in a lot of cases.

The ones that Ampeg used were called Type FP and manufactured by Mallory in the US. They were designed to be plugged into a special socket, you would twist them and they would lock into place. No soldering was needed to change them. A lot of companies did not use the socket as it meant extra cost. So tabs on the can are twisted on the insulating wafer to lock the cap in place.

In the days of radio, it was common to have more than one cap in a can. Some had nice looking copper jackets and the radio chassis looked like a work of art as much as the fancy wood cabinets did.

John D · #**268** 03-10-2012, 06:03 PM

Quote:

Originally Posted by Ric Vice

John,
Did all B-15's have the Caps in a Can up topside or was that something that they added later? That's one of the things that my tech replaced when he replaced the caps. Until he showed it to me, I had no idea that's what it was.

Ric

Guys,

I worked in electronics for several years, before making a career change and going into the mechanical field. I still remember a good bit of electronics, and don't mind sharing. However, I always try not to lead anyone astray by stating something as fact unless I am 100% sure. That's why I prefaced my response to Deekay with "I'm not sure".

David is your man when it comes to Portaflex amps. I know enough about electronics to know that David knows what he is talking about, and I have never seen him "blow smoke" at anyone. Please, always take his word over mine. I always look forward to his answers, because I learn/relearn something from each of them. Meanwhile, I'll try to help when I can.

Ironically, I have never worked on a B-15. The answers I gave about the caps are things one learns in a general elcetronics course. These caps are found in most older electronics, and I have changed more can caps than I care to remember.

John

beans-on-toast · #**269** 03-10-2012, 06:14 PM

John, everyone's input is needed and appreciated. Your comments are always spot on. Don't feel that you need to defer to me. Besides, I need all the help I can get. I started going downhill when I turned twenty-one.

John D · #**270** 03-10-2012, 06:27 PM

Quote:

Originally Posted by beans-on-toast

John, everyone's input is needed and appreciated. Your comments are always spot on. Don't feel that you need to defer to me. Besides, I need all the help I can get. I started going downhill when I turned twenty-one.

Thanks, David. I do what I can, but it's been almost thirty years since I did any electronics work. I know all about that hill. I started on the downhill side at about that same age. It's been a long ride down, but I hope to ride it out for a long time.

GregT · #**271** 03-10-2012, 07:51 PM

Hey JimmyM,
Take a look at my signature. Is it possible to get a number?

JimmyM · #**272** 03-10-2012, 08:48 PM

Yes Greg, I'll give you a number 5 days ago...260.

Also, looks like I missed one:

#274 Boondog Reisbol

If I missed any others, let me know.

GregT · #**273** 03-10-2012, 09:07 PM

Thank you!! Not sure how i missed that. Good to see you back!

fuzzy beard · #**274** 03-10-2012, 09:25 PM

Well all pre 1967 Sb-12 owners take note! JJ 5ar4 rec tube is to tall to fit inside cage. I dont know what all years this goes for but i know the sb-12 was mostly unchanged till 67.

**ddbassGA** · #**275** 03-10-2012, 10:03 PM

Well I'll be. Go out and git you a $90 UK MULLARD.

fuzzy beard · #**276** 03-10-2012, 10:12 PM

Thanks!

I'll put that on my list. Right now i am restoring a Kustom tuck and roll so money is tied up. I am thinking about a copper cap.

**ddbassGA** · #**277** 03-10-2012, 10:20 PM

Yeah, might be SS time.

FenderAmpeg · #**278** 03-11-2012, 08:09 AM

Quote:

Originally Posted by fuzzy beard

Well all pre 1967 Sb-12 owners take note! JJ 5ar4 rec tube is to tall to fit inside cage. I dont know what all years this goes for but i know the sb-12 was mostly unchanged till 67.

Fuzzy, did you try it?
I've got one, they are pretty tall but just fit without touching. Although if there is much variance in the manufacturing process you could get some that are too tall. I've got two Sovtek 6l6's that vary in size by a quarter inch!!

fuzzy beard · #**279** 03-11-2012, 08:10 AM

I hate to keep buying and trying till I found one that fit.

Ric Vice · #**280** 03-11-2012, 08:31 AM

Quote:

Originally Posted by fuzzy beard

Well all pre 1967 Sb-12 owners take note! JJ 5ar4 rec tube is to tall to fit inside cage. I dont know what all years this goes for but i know the sb-12 was mostly unchanged till 67.

Fuzzy Beard,
Yep, that is a problem, as I used to own a SB-12 (well, actually it belonged to my wife

) The rectifier tube went and the tech solved it by putting rubber washers under the tube cage so the newer 5 AR4 would fit. Actually, it wasn't that noticeable.

Ric