Salvaging Hammond A043 L100

[HommeMarrBuckley]

Hello


I saw Steves post about the Plexi/Huss build and thought I would check out getting a Hammond online.  I was able to get two poweramps and thought of using them for the plexi and perhaps Deluxe Ab763 circuit (still unsure)
Anyway, Im all about reusing as much as I can and had some questions.


http://i.minus.com/iIJ2hWBrkEygU.JPG


This thing is dusty as all get out.  (spider webs)  Is it wise to take a vacuum to it?

After everything is taken out, what can I use on the chassis to clean it? steel wool and some kind of rust remover?

The Pt has some rust--what to remove like the above and is it possible to repaint then black as long as bottom/wires are covered?

I can imagine that I can keep the strips, wires and test the resistors for drift.  How can you determine wattage/measure diameter?

http://i.minus.com/iLMivCM8G4SWR.JPG

The capacitors?  Should I chuck them out?  The black was described online as pretty worthless--dunno about the others.  I will probably remove the electrolytics but as you can see in pic, the cans/covers are into the chassis.  Best method to remove them?

http://i.minus.com/ibsf5UFeeVtW2i.JPG

Tube sockets are riveted in.  Should I keep those that I might use and cut remainder or just cut all out?

Told from working organs.  How to test the PT, OT, and choke?  Wish the OT was a multi tap--laugh.  Is the choke compatible for these type 18-20 watt projects?

Have read about the high B+ and will look into the Hammond documentation.

Will take me awhile to get there but reconditioning will be a good indoor activity in lieu of the bitter cold outside.
Any input is appreciated.
Thanks
Matt


just if asked--they were $50 each

[TIMBO]

Hi HMB, I have an AO48 similar to yours it has a reverb as well a tremolo and an AO63 running some bigger power tubes.
The workmanship that went into these is awesome and a shame to trash it, but that is entirely up to you and the condition of the amp.

My thoughts on mine is to use as much of the existing circuit a that is typical to guitar use or try to tweak what is already there.
In most cases, these old buggers the Ecaps are at there useby date and the CC resistors are all over the place value wise.
If the tube sockets are loose and can't be tightened replacing is a pain and this leads to other hacking and at the end of the day, just pull all the good bits and start from scratch.

[eleventeen]

1: dusty as all get out.  >> Better: Find a pal with a compressor and and blow it out best you can, more forceful than a vacuum. WEAR SAFETY GOGGLES!! Stuff, sometimes abrasive stuff blows back into your face! Vacuum is OK if no compressor is around.


2: The Pt has some rust--what to remove like the above and is it possible to repaint then black as long as bottom/wires are covered? Sure. Optional.


3: At 10-20 cents each, IMO you are better off replacing resistors. All of them. The older Carbon comp ones impart noises into the circuit. It's basically an issue of how much your irritation at hard-to-chase-down noises and the time req'd to mess with them is worth. If you're gonna take the time to (for example) paint the tranny (which affects nothing) out of concern for the esthetics....it seems like you would want a lower noise floor. I say about the same for the caps, really. SOMEtimes I will reuse such parts if I am making a junkbox queen and the idea is to spend ZERO, but if you want it to turn out nicely, IMHO you do not reuse R's and C's and the case can be made that you don't want to reuse the tube sockets. I mean....you can surely try to reuse the tube sockets, but you have to ask the question...how are you going to find out if you CAN'T reuse them? Ans: By wiring up the amp. OK, now you have all your components in place and are wired up, but now you have to drill out the rivets and rewire. If you can do that neatly, and it is not that hard if you have done it....have at it. Some folks will prefer to have as much new as they can; it depends on your own valuation of your time vs the $$ req'd to buy the stuff new. That said: Those tube sockets look decent quality and they probably only had one tube in the their whole life.


My way of getting those E-caps out: Suck the solder out of the soldered ones. Get a lineman's pliers or a set of large jawed pliers. Not any kind of needlenose. Grip the twisty-tabs AS CLOSE TO THE CHASSIS as you can. Untwist them and get the unsoldered ones as straight as you can so it looks like they will pull out of slots in the chassis. Try to get them all flat, in one plane. Sometimes you just have to break off one or even two of the tabs. Ultimately, you should be able to wiggle the caps off the chassis.

[HommeMarrBuckley]

1: dusty as all get out.  >> Better: Find a pal with a compressor and and blow it out best you can, more forceful than a vacuum. WEAR SAFETY GOGGLES!! Stuff, sometimes abrasive stuff blows back into your face! Vacuum is OK if no compressor is around.

I was thinking maybe a can of compressed air and perhaps a rag to wipe away.

The Pt has some rust--what to remove like the above and is it possible to repaint then black as long as bottom/wires are covered? Sure. Optional.

What to use here to remove the rust.  I read to try steel wool and high percent alcohol (on chassis too).  Some said the steel wool can leave particles.  I was thinking maybe a toothbrush then.  I aint looking to scrub to get showroom but a little work should help it look better.  Main concern was using a product that would ruin whole project due to its makeup.

At 10-20 cents each, IMO you are better off replacing resistors. All of them. The older Carbon comp ones impart noises into the circuit. It's basically an issue....... 

I guess when time comes will weigh these pros/cons.  Hardest will be the sockets because they look pretty good--will have to evaluate as well with what tubes I will use for the circuit.

My way of getting those E-caps out: ...

I thought pliers route too because doesn't seem any other way of bending those tabs to slide out.  Looks easily breakable so will get gingerly and not hectic.

Thanks for your input.

[HommeMarrBuckley]

Could these transformers be suitable for Tweed Bandmaster 5E7?  Would 6L6GC tubes be an issue from it being made for EL84/6BQ5?

[sluckey]

Stick with EL84 or 6V6 based amps.

[Toxophilite]

Though a rank amateur here,
I've done a couple strip and rebuild and a few conversions rewiring the preamp signal path, both have worked well.
The simple conversions are easier but you are restricted by the capabilities of the existing power amp etc which could be okay
The strip and rebuild option allows you to build whatever is possible with the existing main components(transformers etc)
In this instance particularly I think replacing resistors and caps is a good idea .
I believe part of the reason for replacing the tube sockets is that taking the usually mechanically attached components and wires off of delicate tube socket pins is can be time consuming, a little frustrating and sometimes you have to replace them anyway.
Pprobably easier if you have the $$ to drill them out and pop in fresh new ones
You can snip the old can caps out too


I guess deciding what you really want to end up with and how much work you want to do is the key.

[trobbins]

Your photos are not viewable at the moment.

If you are keen to learn, and have some time, then that sounds like a great start as any old valve gear can become new gear - and there-in lies the adventure for many of us.  Best not to rush in, but get to understand what you have, and what you could do, and how to do it.

This may be of some help in a general way:
http://dalmura.com.au/projects/Renovating%20PA%20amps.pdf

[TIMBO]

Hey Tim , Welcome aboard, lots of good stuff here.

[Willabe]

Welcome trobbins!


                  Brad   

[HommeMarrBuckley]

Steve, for one of them, I was looking at your Deluxe Lite build.  (Right now, I see Toxo- is doing a verb/trem.)  Anyway, real short, on the scematic you have a 10kA mid pot but on the layout it's 25kA.
Remember Im not real deft here, but that negative feedback red arrow on the layout---does that signifies a ground?  Also, the grounds are listed on the layout by number 1, 2 but on filter cap page they have letters.  I should be able to figure them out if I go with the schematic. 


I saw that it's on your drawing board and from 7 years ago so I understand.  I was just looking to source parts is all.

[sluckey]

on the scematic you have a 10kA mid pot but on the layout it's 25kA.

10K is the correct value for all AB763 amps with a mid pot.

but that negative feedback red arrow on the layout---does that signifies a ground?

No. Connect that wire to the hot lug of the speaker jack.

Also, the grounds are listed on the layout by number 1, 2 but on filter cap page they have letters.

Ground "1" and "D" connect to a chassis ground lug mounted very close to the input jacks. All other grounds connect to the same chassis ground lug that the PT center taps are connected.

[HommeMarrBuckley]

Thanks.
I think you mentioned it but with this chassis, would the JJ 40 20 20 cap can be a good option here along with one other 20 cap?

[sluckey]

All you need is the JJ can.

[HommeMarrBuckley]

Dont want to frustrate you but I don't understand.
If there are five 20uf caps, doesn't the can leave one 20uf missing?


Also, would you put the two 10k/1 watt resistors on the can itself or on the board/tag strips?

[sluckey]

Dont want to frustrate you but I don't understand.
If there are five 20uf caps, doesn't the can leave one 20uf missing?


Also, would you put the two 10k/1 watt resistors on the can itself or on the board/tag strips?

The first two caps are tied together. They are in parallel, acting as a single 40µF cap. So, the 40µF section of the can serves as two 20µF caps. I would mount the 10K resistors directly on the cap can lugs.

[HommeMarrBuckley]

Yep, pretty dumb.
Sorry--should have checked before posting.  Laugh, the image is scrolling across the top.
Thought it was 40/20/20


See now its 40/20/20/20.

[HommeMarrBuckley]

Steve,


For your Deluxe Lite, in terms of the Hammond A043  OTs impedance, is 8ohms about right?


What rectifier tube would you recommend?


And no choke needed, correct?

[Toxophilite]

Steve will undoubtedly chime in with more accurate info but I've built a couple of deluxe lites based on his design
The last one I just finished is in a AO-43 Chassis using the original transformers, it's sounds great!
Output impedance is 8 ohms for 6V6
And there is a choke in the power supply.The one on the AO-43  is just right for the job
though moving closer to the PT might be a good idea


Please correct me if I'm wrong Steve

[sluckey]

I'd use a 5AR4/GZ34.

[Toxophilite]

ooops I forgot about that!


5AR4's/GZ34 don't have much voltage drop do they??


Are they similar in B+ supplied to a straight SS rectifier setup?

[sluckey]

5AR4 voltage drop is somewhere between a NOS 5Y3 and SS diodes.