Got a Barn Fresh Silverface Pro AA165 in to Restore(Filter cap job done)

[Platefire]

Well the pro has got it's 3 conductor cord sluckey method. Works fine!

[jojokeo]

Of course it does but now it's just a useless plug in the chassis at this point w a few extra solder connections. I thought you were thinking about ideas to make use of the hole there. Regarding the ground, "many people" have attached it to the tranny bolt but if it were a new production amp leaving the factory then UL wouldn't approve it is all. It must have it's own dedicated chassis connection as close as possible where it enters through the chassis. Using tranny bolts or socket screws is not allowed by their standards.

[PRR]

If you expect to apply for UL/IEC certification, the power cord green goes to a *dedicated* chassis bolt, so it won't be lost if some fool changes the transformer.

Agree that in restoration, where added holes are distracting, a good connection to the PT is probably the best way to go. Hopefully your work holds-up many decades, and the next tech in there is also no fool, remembers to do something with the greenie flopping around. (Unlike the fools who wired my last house.)

Yes, abandon the 2-pin outlet. I'd be inclined to chop-off the wires, so a mis-plug or impact which shatters the brittle plastic does not leave live wires bouncing around inside.

> a simple 6-outlet strip is a $3-$5 thing

And often a piece of crap. However by now any serious electric musician has outlet-strips.

When I worked with younger dudes, and non-mint combo-amps, a couple times I got a wall-box, two duplex outlets, mounted down in the bottom of the cab. Gave it a high-grade long wall-cord. Tied-up the amp power cord so it just reached the box. Left three outlets for bass and pedalboard. Sturdy, handy, abuse-resistant. Working-man's hack, hardly collector-grade.

[Platefire]

Well-------I like the idea of those old fender parts remaining live. The customer even mentioned, he would like to keep the ground switch and now he gets to keep his accessory plug also. Got a plug on my Bogen CHB50 and used it to plug in a wal wart to power my delay. My house is old and wired with only two conductor wiring. When I was testing the amp with the new cord I tested the ground switch and noticed some static one position and when I switch the ground, it was gone. Platefire

BTW-I just imagine you could get into some major discussions regarding ways to hook up a three conductor cord on vintage amps.   

[DummyLoad]

two duplex outlets, mounted down in the bottom of the cab

something like this? my go to power tap for the lab and garage and PC servicing...rock solid & reliable. it's survived me for over a decade. the plug was replaced a couple of years ago.

great work on that amp plate.

--pete

[jojokeo]

Yes, nice work Plate as always. Guys are in good hands when they see you up North of the border.

Here's one for a different situation but something else people may want to consider? I have a couple of these wired with a switch and also incorporating a GFCI with the unit. I'm using mine in this situation on a reef tank set-up for pump control (when feeding or servicing the tank I need to "quiet" things down). But in a crazy bar or similar situation, it isn't out of the realm of possibility for a beer or two to be spilled (or thrown, lol). Hopefully people aren't throwing beer around 'cause the music sucks so badly, lol.   But you get the picture.

[Platefire]

Opened up the Dog House and what a surprise! Things are not like my schematic. The Tube data sheet on inside of amp says AA165. There are no 220K resistors on the first stage filters prior to the standby switch like on schematic. Also after choke, the next filter stages use a 4700 and 10K resistor, not a 1K and 4700 like on the AA165 schematic but like on the AB668 schematic. Attached is a sketch of that part of the power supply like it is on my amp. Also attached are pixs of existing caps/resistors and also a comparison of size to old Mallorys and new SPRAGE. I guess I'll change it out as is, because it is working. I just wasn't prepared for the 10K 3W, maybe I can find one in my inventory. Anybody know what power supply schematic matches this setup??? Thanks, Platefire

[jojokeo]

Plate, you got your drawing wrong on those resevoir caps' polarity. If it was me, I'd install the resistors on the series caps and change the 4k7 to 1k like it's supposed to be per spec of the AA165 and make it what it's supposed to be.

[Platefire]

Understand the drawing is whats in there now from the fender factory. One cap -is tied to the + of the other on the 70uf caps. The best fender example I can find is the Bandmaster aa763 schematic. The first filter stage before standby is just like this attached schematic--kinda rare! Plate

[jojokeo]

Your drawing has the + side of the bottom cap going to ground which is incorrect. B+ goes to positive of 1st cap, first cap "-" goes to lower cap's "+". Lower cap's "-" goes to ground. Do you see it? In both cases this is the proper way to use two caps in series. Do it the other way and watch out for the explosion when you hit them with power. Then after the choke is has the 1k followed by the 4K7 to drop B+ lower for preamp tubes.

[DummyLoad]

There are no 220K resistors on the first stage filters prior to the standby switch like on schematic.

i'll bet you a 6V6 smokey glass RCA that they're under the first two filters to the right in the photo's you posted. lift

IMO, i'd just replace the caps and any resistors that are out of spec.

--pete

[Platefire]

DummyLoad Har! I'm keeping my smokey glass 6V6 rca's(no wanta bet) because your absolutly right. I pulled the cap over with my finger and sure enough, there they are down on the board between the caps!

jojokeo is also correct in the I got my netatiive and positive backwards on that bottom cap.

So I missed it all the way around on that!     but glad to be proven wrong so now I can be on the right track again. I appreciate your help very much!!   Platefire

BTW-Isn't a good idea to replace all those power resistors with metal Oxide 3 watt while your in there??

[6G6]

Fender probably used 1 watt, so if ya wanna go 3 watt it will be cheap insurance.
If they aren't getting brown from being hot, leaving the old ones won't likely hurt anything.

[Platefire]

Yep, I'm going to replace the two main power resistors with 3 watt. It's a shame I didn't look a Doug's information first because he had a perfect discription of my filter cap situation and recomendations on what to replace and not to replace under Filter Caps/Fender amps. Just like Doug instructs, you/I need to look/research before posting questions. I'll try to do better on my next issue    Plate

BTW-Don't take me wrong! I love the interation and help from all the other forum members and depend on it desperatly, but at the same time I just need to remember not to panic with a quick post question and do a little more research through Doug's info and other available on the net first. Thought I should clairify that!

[Platefire]

I had thought that I could just remove all the old paper caps with the board in place and just desolder the leads but I'm finding the leads are not letting go as if they are mechanically attached to something under the board. I even cut the leads loose from the cap, removed the old cap so I could get a good grip with the needle nose pliers on the leads and even bent them around to other positions but they will not come out of the eyelet in the board. Yes the leads  have been desoldered from the eyelet. I have just tried removing the larger 70uf cap on the end just to get the feel of  how it would go. I haven't tried removing the others yet until I'm sure of the best proceedure of proceeding.

I beginning to believe that the board will have to be removed to change the caps but it seems to me that shouldn't be required but I don't know how else to get the old cap leads out. Need some experianced hands advice who know the ropes on this. Would appreciate some advice so I can continue. Thanks, Platefire

[sluckey]

I beginning to believe that the board will have to be removed to change the caps but it seems to me that shouldn't be required but I don't know how else to get the old cap leads out.

To do it properly you'll have to remove the screws so you can access the bottom of the board. The component leads ain't just poked into the eyelet with solder globbed on. The leads are poked thru the eyelet then bent over the rim to make a proper mechanical connection. Then solder is applied.

Sometimes, (and I hate this) if two adjacent eyelets need a jumper, a component lead will be inserted thru one eyelet, then turned up to pass thru the adjacent eyelet.

So, just pop the screws so you can see under the board. A dental mirror is handy. Suck all the solder out of the involved eyelets then you'll be able to tell what you need to do. Don't 'strong arm' them.

[DummyLoad]

I beginning to believe that the board will have to be removed to change the caps

on more than one occasion, i've seen lousy workmanship with fenders where the tech will have snipped the caps out as close to the body as possible, then use the remaining lead to strap new caps to. this saves time but looks like $#!t.

proper way:
- take pictures FIRST! GOOD quality pics with close-ups - draw the circuit. AND pics of the bottom too after you pull the board but before you dismantle! if you have to step away for a while, then you'll have pictorial reference.

- pull the leads out of the eyelets, then remove the board. now the insulator board on the bottom should come off as well. carefully unsolder the old caps from underneath.  note that some of the eyelets are pretty full so it helps to remove as much solder slag as possible with solder sucker and/or solder wick. with the caps out, measure the dropping resistors to see if you have to replace any. some techs replace the dropping resistors anyway with WW or metal types including the 220K divider network.

- replace board, solder leads back into eyelets, then check for short from A rail to ground with ohmmeter - you should see some resistance to ground but not "0". if you read "0" check your work and make sure none of the insulation of any of the leads hasn't been compromised.

- fire it up with a lamp limiter.

all ok, then reassemble amp, drink beer & play geetar.

--pete

[jojokeo]

Psycho - you may want to also consider focusing on the grounding system here, many times Fender wasn't the best in this regard. You should at least try to run the resevoir & screen caps back directly to the main ground seperating them from the preamp grounds. Fender always tied everything together, then with other things wondered why there were oscillations & parasitics and then "fixed/remedied" those maladies with tone sucking caps...just sayin'...if it were mine I'd definitely correct these issues as found.

[Platefire]

Thanks! I pulled the board. The big first two big 70uf caps had their leads running under the board to the 220 resistors. Thats why the leads wouldn't budge. I removed everything from the board including the 220 resistors, since I've got some new ones I'll go ahead and replace them too. Don't worry, I drew a sketch of it all before taking it apart! I was wanting to make a quick change over but that's not going to happen so I'll just go ahead and redo it all and do a good job of it. I've got pictures of it all and will post later. Platefire

[Platefire]

Here is some pixs on the cap job. Since this is my first Dog House Renovation I thought I would document it. The old paper 70 uf caps leads went under the board and were tied into the 220 resistors
for the first resivor prior to standby switch so there were no easy way to remove those caps & leads and just easily install new as I had hoped. I completely removed the board and rebuilt it in a way that I think you could now just change the filter caps out without removing the board--next time. I'll probably be on the other side of Jordan by then

[Platefire]

Mow cap progress

[Willabe]

Very nice Plate.


             Brad     

[plexi50]

Looks like it should be singing pretty soon Platefire.

[Platefire]

Yow, customer got it back today and was real happy. Repaced missing upper backplate, replaced all the missing tube sheilds on the preamp tubes, new three conductor power cord, new filter caps and re-installed his re-coned original fender speakers. Platefire