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Old 7th Dec 2023, 4:55 am   #1
1valve2many
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Default Old Philco A3756 hi-fi amp safety question.

Hi, I have an old Philco valve record player with the deck undone but not removed yet. My plan is to make a small guitar amp out of it, or use some of the parts to make a champ copy.

My question is, as I understand it, the capacitor (death cap) at one end of the small amp, will have a charge in it where it has been tested before sale? Is it safe to just touch the chassis to remove it from the record player?

There is a 3 cored flex on it, and as far as I can see, the three cables are connected. I assume that its safe, as it has an earth wire attached?

After removing, I plan to use an alligator clip with a resistor at the other end, to remove any charge from the capacitor to the chassis. Am I correct, or am I missing something?

Many thanks in advance.

Tony.
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Old 7th Dec 2023, 9:03 am   #2
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Default Re: Old Philco hi-fi amp safety question.

Hello and welcome to the forums.

I've never heard the term "death cap" before. I assume you mean the smoothing capacitor/s? They're unlikely to have retained a charge, but if you're concerned discharge them via say a 10k resistor.

You need to make absolutely sure that this is not a live chassis player which would be unsuitable for use as a guitar amplifier. What's the model number or name? Are all three wires of the mains flex connected at both ends? What valves are fitted? U series valves are indicative of a live chassis. Does the player have a mains transformer?

I'll leave our guitar playing members to advise you on whether it's a good idea to use a record player amp as a guitar amp.
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Old 7th Dec 2023, 9:39 am   #3
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Default Re: Old Philco hi-fi amp safety question.

hi and thanx for the reply.
yes, the aluminium can capacitor to one end of the oblong amp.

i can't say wether its a live chassis, i wanted to know if i can get the thing out in the first place to see if theres a number on it before i can look it up.

i was thinking, i have a heavy duty pair of rubber gloves for handeling electroplateing chemicals and drain cleaning acid. i was thinking of wearing them and unbolting it from the record plaver and draining the capacitor to make it safe.

im aware that some amps are not suitable for guitar amp use without being made safe with an isolation transformer. there called widow makers i believe.
i was just going to use it as the chassis for a fender champ clone.

untill i get the amp out the back of the player, i coulden't say if the chassis is earthed or not.
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Old 7th Dec 2023, 9:41 am   #4
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Default Re: Old Philco hi-fi amp safety question.

You are opening yourself to a lot of problems if you are thinking of repurposing the record player and selling it.
I have never heard of ‘Death Cap’, if you have lots of experience in this field then apologies, if you have little I would not embark upon the project.
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Old 7th Dec 2023, 9:50 am   #5
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Default Re: Old Philco hi-fi amp safety question.

Given your obvious lack of technical knowledge I respectfully suggest that you do not embark on this project.

Quote:
Originally Posted by 1valve2many View Post
hi and thanx for the reply.
yes, the aluminium can capacitor to one end of the oblong amp.

i can't say wether its a live chassis, i wanted to know if i can get the thing out in the first place to see if theres a number on it before i can look it up.

i was thinking, i have a heavy duty pair of rubber gloves for handeling electroplateing chemicals and drain cleaning acid. i was thinking of wearing them and unbolting it from the record plaver and draining the capacitor to make it safe.

im aware that some amps are not suitable for guitar amp use without being made safe with an isolation transformer. there called widow makers i believe.
i was just going to use it as the chassis for a fender champ clone.

untill i get the amp out the back of the player, i coulden't say if the chassis is earthed or not.
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Old 7th Dec 2023, 9:56 am   #6
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Default Re: Old Philco hi-fi amp safety question.

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Originally Posted by Nuvistor View Post
You are opening yourself to a lot of problems if you are thinking of repurposing the record player and selling it.
I have never heard of ‘Death Cap’, if you have lots of experience in this field then apologies, if you have little I would not embark upon the project.
I would never sell any electrical device.

no real experiance, i've been reading up on capacitors and guitar amps, perticularly repurposeing the record player/reel to reel into a fender champ amp. and how to use an isolation transformer to make it safer, or leaving the record player moter in the amp, as it's purpose in the record player is as an isolation transformer, so i have read

do you think im better off getting an old radio chassis and useing it for an amp.
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Old 7th Dec 2023, 10:20 am   #7
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Default Re: Old Philco hi-fi amp safety question.

The only Philco record players that I can think of are the Philco "Duet" (2 x ECL82) and the Philco "Trio" (2 x ECL83). Both of these are mains isolated, but they do not make the basis of a good Guitar amp unless it was to be a very low power pratice amp. I don't think that the OP has fully thought this through.
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Old 7th Dec 2023, 11:00 am   #8
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Default Re: Old Philco hi-fi amp safety question.

is there a model number then we could look at its circuit and advise more
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Old 7th Dec 2023, 11:06 am   #9
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Default Re: Old Philco hi-fi amp safety question.

Quote:
Originally Posted by Station X View Post
Given your obvious lack of technical knowledge I respectfully suggest that you do not embark on this project.

Quote:
Originally Posted by 1valve2many View Post
hi and thanx for the reply.
yes, the aluminium can capacitor to one end of the oblong amp.

i can't say wether its a live chassis, i wanted to know if i can get the thing out in the first place to see if theres a number on it before i can look it up.

i was thinking, i have a heavy duty pair of rubber gloves for handeling electroplateing chemicals and drain cleaning acid. i was thinking of wearing them and unbolting it from the record plaver and draining the capacitor to make it safe.

im aware that some amps are not suitable for guitar amp use without being made safe with an isolation transformer. there called widow makers i believe.
i was just going to use it as the chassis for a fender champ clone.

untill i get the amp out the back of the player, i coulden't say if the chassis is earthed or not.
MANY THANX FOR YOUR REPLY, SAFETY IS NUMBER ONE WITH ANTHING THAT WILL EVENTUALY BE TURNED ON. ( extreamly unlikely at presant) bar simple circuits at low power, I.E battery

I'm jumping ahead realy, number one on my list of to do things, is unsoldering / soldering and testing componants from old equipment.then on to then on to recapping maybe.

i want to make sure i understand the capacitors first and how to discharge them safely with resistor and crocadile clip on a length of wire
I was thinking i could wire up a plug with just the earth wire in place to earth anything im takeing apart, even on old dead equipment

i was thinking of makeing any complex projects out of old dead componants, mocking up a project for the practice.

I first want to make sure i understand the capacitors (death caps/widow makers.

as there the only thing that holds enough power to hurt/maim or kill as i understand it.

there are some great radios/record players/reel to reel to name a few. and the price is climbing ever higher all the time, so i wanted to gather up usefull parts for projects while the price is on the low side.

i would apreciate your input on this idea. many thanx tony
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Old 7th Dec 2023, 11:11 am   #10
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Default Re: Old Philco hi-fi amp safety question.

Quote:
Originally Posted by Edward Huggins View Post
The only Philco record players that I can think of are the Philco "Duet" (2 x ECL82) and the Philco "Trio" (2 x ECL83). Both of these are mains isolated, but they do not make the basis of a good Guitar amp unless it was to be a very low power pratice amp. I don't think that the OP has fully thought this through.
i thank you for your honest answer. pleasre read my last post. many thanx tony
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Old 7th Dec 2023, 11:13 am   #11
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Default Re: Old Philco hi-fi amp safety question.

Quote:
Originally Posted by FIXITNOW View Post
is there a model number then we could look at its circuit and advise more
yes, i have just found it on a small label. it is an (A3756). i believe it maybe a two stage amp
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Old 7th Dec 2023, 11:57 am   #12
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Default Re: Old Philco hi-fi amp safety question.

2 x ECL82's in push pull apparently:

https://www.vintage-radio.net/forum/...89&postcount=1

Lawrence.

Last edited by ms660; 7th Dec 2023 at 12:01 pm. Reason: link added
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Old 7th Dec 2023, 12:04 pm   #13
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Default Re: Old Philco hi-fi amp safety question.

Yes, well that sounds like the 1956/57 Philco "Duet", 2 x ECL82 plus EZ80. This will give 6-8 watts so could be re-worked into a practice amp.
I will help to advise what experience the OP has of working with vintage, mains-powered valved equipment.
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Old 7th Dec 2023, 12:04 pm   #14
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Default Re: Old Philco hi-fi amp safety question.

Quote:
Originally Posted by 1valve2many View Post
Quote:
Originally Posted by FIXITNOW View Post
is there a model number then we could look at its circuit and advise more
yes, i have just found it on a small label. it is an (A3756). i believe it maybe a two stage amp
Thread title updated.
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Old 7th Dec 2023, 12:16 pm   #15
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Default Re: Old Philco A3756 hi-fi amp safety question.

There are some audio valves which are still in production for audio and guitar uses. ECL82 is not one and they are no longer being made. Remaining stocks of them are low. You'll be committing yourself to using a dwindling resource with the inevitable rising prices.

David
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Old 7th Dec 2023, 2:04 pm   #16
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Default Re: Old Philco A3756 hi-fi amp safety question.

A "death cap" is an American term often used in relation to older USA guitar amps where the mains cable was un-polarised with no earth. Essentially it was a cap between one mains voltage & ground. So the same as used on UK live radio chassis's.

Andy.
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Old 8th Dec 2023, 1:11 am   #17
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Default Re: Old Philco hi-fi amp safety question.

Quote:
Originally Posted by ms660 View Post
2 x ECL82's in push pull apparently:

https://www.vintage-radio.net/forum/...89&postcount=1

Lawrence.
many thanx, my search engine wont find things, don't know whats up with it
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Old 8th Dec 2023, 1:15 am   #18
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Default Re: Old Philco A3756 hi-fi amp safety question.

Quote:
Originally Posted by Diabolical Artificer View Post
A "death cap" is an American term often used in relation to older USA guitar amps where the mains cable was un-polarised with no earth. Essentially it was a cap between one mains voltage & ground. So the same as used on UK live radio chassis's.

Andy.
is that to do with there plugs?, i read that they can be put into a wall socket either way, so with no earth, the power can reverse . very dangerous

thank you for your reply
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Old 8th Dec 2023, 1:16 am   #19
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Default Re: Old Philco hi-fi amp safety question.

Quote:
Originally Posted by Station X View Post
Quote:
Originally Posted by 1valve2many View Post
Quote:
Originally Posted by FIXITNOW View Post
is there a model number then we could look at its circuit and advise more
yes, i have just found it on a small label. it is an (A3756). i believe it maybe a two stage amp
Thread title updated.
thank you tony
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Old 8th Dec 2023, 1:22 am   #20
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Default Re: Old Philco hi-fi amp safety question.

Quote:
Originally Posted by Edward Huggins View Post
Yes, well that sounds like the 1956/57 Philco "Duet", 2 x ECL82 plus EZ80. This will give 6-8 watts so could be re-worked into a practice amp.
I will help to advise what experience the OP has of working with vintage, mains-powered valved equipment.

i have no hands on experiance bar soldering and unsoldering, as i mentioned in my earlier post, safty is no 1 on my list. i plan on practicing soldering and unsoldering and testing before i even attempt anything bar simple circuits with a battery. so lightbulbs, switches and resistors.

i plan on useing worn out/dead componants and things to build anything just for practice. but thank you tony
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