[Jukebox-list] LPC1 amplifier rebuild.Do the mylars needreplacing...TESTING

[Don]

Hi J.C.

No, don't bother changing the mylars or ceramics.  Anything else, change it 
(wax papers, plastic caps of any colour).

If you doubt a mylar or any cap (EXCEPT ELECTROLYTICS, use an ESR meter for 
them) for that matter, here is a simple test circuit I always use to clear 
up a doubt...

TEST EQUIPMENT:
 0 to 400 volt DC power supply
analogue voltmeter
capacitor under test is OUT of circuit (unsolder one end)

TEST CIRCUIT:
just a simple series circuit...
left end of capacitor to NEG of power supply
POS of supply to NEG of meter
POS of meter to right side of capacitor

TEST PROCEDURE:
check capacitor voltage rating and keep test voltage below that    ;-)   say 
it is 400 to 600 volts
with meter set at a range above 400 volts
slowly dial up the power supply voltage and watch the analog meter needle 
deflect, then return to its "zero" position
at full voltage the meter needle should return to its "zero" position or 
very nearly to "zero" IF the cap is NOT leaky.
IF the cap is leaky the voltmeter's needle will show you the voltage across 
the METER caused by the leaky current flow from the cap and through the 
internal resistance of the voltmeter.  TOSS that leaky capacitor.

Try this test on some of your mylars, if they are in frequency sensitive 
areas of the circuit.

Have fun.
Cheers,
Don










----- Original Message ----- 
From: "Ron Rich" <ronnnrich at yahoo.com>
To: "Jukebox mailing list" <jukebox-list at lists.netlojix.com>
Sent: Monday, September 04, 2006 7:25 PM
Subject: Re: [Jukebox-list] LPC1 amplifier rebuild.Do the mylars 
needreplacing.


> Just a hint--the original TSA-1/3 amps and speakers are 16 
> ohm--replacements are hard to find--I suggest a re-cone job. (TSA-4's up 
> are 5 ohm) Ron Rich
>
> Jjmscf at aol.com wrote:  I finally got the LPC1 running and selecting after 
> near full
> dissasembly,unsticking stuck parts,cleaning and relubing.The mech works 
> great after some
> contact setting and some needed readjusting.Thanks to Ron's tip in his 
> book on
> the adjustment of the RSR-LSR and RR contacts I cured the problem of the 
> arm
> not moving over before the record came back up when I tried to play both 
> sides
> of a record.I had to clean the mute relay contacts in the amp like Jackie
> did to get it to reject and mute reliably.I had 1 cap shorted in the write 
> in
> circuit which I soldered in the replacement temporarily while I got all 
> the
> contacts and mech working.Every selection works.Even the coin mech works. 
> I
> have 0 speed problems with this LPC1 and the mech runs great.Gets right up 
> to
> speed on 45s every time.I couldn't believe it with all the horror stories 
> I've
> heard about the speed problems on these.I even took apart the motor and
> cleaned the shaft and bearings and the little ball.I liberally lubed it 
> with 3 in
> one motor oil.New motor bushings and a new plug underneath.The coupler was
> still in great shape and soft and flexible on mine.I guess one tip to is 
> that
> everything must be as free as possible.The motor,turntable shaft bearings
> ,everything.Get that old improper lube out of there and use the 3 in 1 
> motor oil
> Ron recommends or Seeburg oil if you can get it.Also the autospeed hum is
> gone.
>
> So now I have disconnected everything again to rebuild the Tormat control
> center,auto speed and amp to replace the old paper and electrolytic 
> caps.My
> question on the amp is that this amp has mylar caps rather than paper 
> caps.Do
> they have to be replaced or are they ok because they are mylar?I already
> bought all the electrolytic and paper caps.The kits are kind of pricey.I 
> can get
> the caps cheaper myself.The sound is ok.Nowhere near as much power and 
> bass
> as my 222.The highs are nice and clear if the volume is up loud.The highs 
> seem
> kinda muffled at low volume.I tried an unrebuilt TSA4(couldn't connect the
> muting circuit) and it sounded about the same.The woofers rattle a bit 
> with
> low bass notes so I'm gonna have to get replacements or reconing.Then it's 
> time
> to work on cosmetics.
>
> J.C.
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