Philips/Norelco EL3302

[toshik1]

Hello everyone, got an EL3302 in my hands. Restoration seems to be a pretty simple thing just a clean-up and replacing dry electrolytic caps. How can I make sure the tape speed is correct?

[Restoration73]

Ideally if you could obtain a calibrated test tape this might have a tone around 3kHz
that you could check on a scope or frequency meter. Failing that, if you could play
back a tape with some 60Hz ac hum you could adjust the speed to zero beat with
some live hum from your house current supply.

[Jimmyhaflinger]

i'm usually able to adjust the speed fairly accurately by listening to a song i know well

Also keep in mind that the original blue Philips capacitors are very reliable, i think i had to replace just a couple of them in all of my Philips tape recorder collection, and i have tens of them

[toshik1]

Thank you! Right now I have a major problem finding a pre-recorded music audio cassette!!! They are off the stores shelves for a while and everyone I know seemed to put them into the garbage a while ago.
I have four EL3302s so far.
One was making a loud humming noise due to dry power filtering 100 uf cap. Anyway the original axial blue Philips (today's name BC components) are still widely available.
I have another one making a loud buzzing noise, increasing when I put my palm next to main PCB but I did not fix it yet.

[paulsherwin]

Do you have a cassette recorder with a known accurate speed? If so, do the following:

1. Generate some 1kHz tone on a computer using readily available free software.
2. Burn the tone onto a CD.
3. Record the CD onto a cassette using your known good cassette deck.
4. Play back the cassette on the suspect deck while playing the CD on a player (a ghettoblaster is fine).
5. Adjust the deck speed until you null out the beat between the cassette deck and the CD player.

[toshik1]

Great idea!
However since I didn't have any cassettes I don't have a recorder also... All four 3302s are not guaranteed to have correct speed.
Teak and similar test tapes are $50+ on ebay, I can buy a whole vintage Pioneer CT-F500 tape deck for around $40 but again who guarantees it has a good speed?

[julie_m]

I've seen a clever circuit for testing the speed of a tape recorder, that deserves to be shared more widely.

It works by comparing the frequency of the output of the machine under test, as it is playing back a recording of the mains made using a machine whose speed is known to be correct, to the frequency of the actual mains.
[click for bigger version]
This is done using a thyristor to switch a filament lamp. It switches on when the input reaches the gate threshhold voltage during the positive half-cycle (which depends on the output frequency and thus, the tape speed), and off at the reversal of the supply. If the time interval between switch-on and switch-off is constant, i.e. when the two frequencies are the same, then the brightness of the lamp will be constant. But if the time interval is different, then the brightness of the lamp will vary. If the turn-on point is late and getting later because the machine is running slow, then the brightness will decrease (then rise to full and begin decreasing again); whereas if the turn-on point is early and getting earlier because the machine is running too fast, then the brightness will increase. The worse the mismatch, the faster the brightness will change.

How to use it:

Connect the input(s) of a known good recorder to socket "R" and record several minutes of mains frequency onto a blank cassette (you may as well fill the side, if you have the patience). This can be used over and over again, so save it with the test rig.

Connect the speaker output of the player under test to socket "PB" and adjust its volume so the lamp is at roughly half brightness. Now adjust its speed until the brightness of the lamp remains steady. When the lamp is neither getting brighter nor dimmer, then the playback speed matches the speed of the machine on which the test tape was recorded.

(Yes, it's right for a 6 volt lamp to be powered from a 12 volt transformer. The thyristor only conducts on the positive half-cycles, so the supply is half-wave rectified.)

[ricard]

So, in effect, an audio version of a stroboscope. Very clever!

[Jimmyhaflinger]

Originally Posted by toshik1

One was making a loud humming noise due to dry power filtering 100 uf cap. Anyway the original axial blue Philips (today's name BC components) are still widely available. I have another one making a loud buzzing noise, increasing when I put my palm next to main PCB but I did not fix it yet.

that 100mf cap is the same one i had to replace in one of my recorders!
apparently the hum was electrical noise from the motor and was getting into the preamp circuits due to that dead 100mf decoupling capacitor

the problem you're having with the other recorder may well be due to an o/c grounding somewhere in the preamp, look for fine cracks in the print and also make sure the grounding screw is tight

also, a good way to get a tape recorder that's guaranteed to run at the correct speed is to get one with a mains powered motor, such as many Akai machines from the early-mid 70s or a Philips EL3310 / EL3312

[toshik1]

Originally Posted by Jimmyhaflinger

that 100mf cap is the same one i had to replace in one of my recorders!
apparently the hum was electrical noise from the motor and was getting into the preamp circuits due to that dead 100mf decoupling capacitor

Yes Sir! Marked "732" on the circuit diagram.

[llama]

You could cut a spare cassette so that there is a known length in inches of tape. Then time it. The tape should run at one and seven-eighths of an inch per second.
Graham

[toshik1]

Originally Posted by Jimmyhaflinger

the problem you're having with the other recorder may well be due to an o/c grounding somewhere in the preamp, look for fine cracks in the print and also make sure the grounding screw is tight

Did not find lose ground so far but sounds right. As soon as I put my finger onto the chassis it goes away.

[radiotechnician]

The 3300 series came out a time when there were few cassettes
around with music, so if it was a tad slow, the owner wouldn't know
if he was playing his own recordings.

The 3301 service manual had several options, new motor, add on board, another
add on board, These versions were the 3300/52,
3301/52. 3301/52T, 3302, in Canada.

The speed test was a cassette tape modulated every 4.75 meters
which were checked with a watch and should have been from 95 to 103
seconds between bleeps.

By the time the 3302 came about, Philips had decided the bleeping test
for speed wasn't adequate. They proved a strobe disk and test stand and
instructed that a cassette be prepared with a knife and file so the tape
could exit side right, and loop around the strobe.

The thumbnail is from the 1967 3302 service manual.

[toshik1]

Thank you! I have the service manual and read this.
Interesting that the schematics and PCB layouts in two versions of EL3302 service manuals I have (4 and 12 pages versions in German) are different from the actual EL3302s I have and the schematics paper sheets inserted by the motor.

[Jimmyhaflinger]

there were a few different versions of EL3302s, early ones had germanium transistors, then in 1968 the amp was redesigned to use silicon transistors in the preamp stages, then in 1969 the amp was slighly modified again with subtle changes in the print layout

[toshik1]

OMG! Yesterday I got another one Holland-made EL3302/94G s/n 291556 Norelco branded, it has no spring-loaded latch on the battery compartment cover. Also hard case logo is right above the grille logo, not above the microphone compartment like every other one I have. However I have another 3302/94G s/n 176309 clearly earlier with the spring loaded latch, also similar 00Gs and one 3302A/15P - apparently later model with clear cover, decontenting inside (self-tappers, same color pots wheels), simplified hard case with no microphone pocket and no case material over the clear cover. But with spring-loaded latch.
I don't know how schematics affected PCB layout, but all mine have crossed large caps (470 mf and 680 mf) terminals in the far end of the PCB

[mitajohn]

Following the thread I remembered that at 70s I had got a PHILIPS cassette test set for adjusting the tape speed and azimuth of the EL33XX. I found it in the attic in good condition. Its the PHILIPS cassette service set 801/CSS. I tested it and worked fine. Here are pics of the user guide as well as of the test cassette. The circuit inside is similar to the one posted earlier.

[toshik1]

Originally Posted by Jimmyhaflinger

Also keep in mind that the original blue Philips capacitors are very reliable, i think i had to replace just a couple of them in all of my Philips tape recorder collection, and i have tens of them

I'm sorry I don't have faith in those caps any longer!
4 out of 5 players I have (completely cleaned and rebelted) output extremely low hard to hear volume.
Only one seems to be nice and loud. So more caps are on the way to garbage soon.

[Jimmyhaflinger]

Originally Posted by toshik1

OMG! Yesterday I got another one Holland-made EL3302/94G s/n 291556 Norelco branded, it has no spring-loaded latch on the battery compartment cover. Also hard case logo is right above the grille logo, not above the microphone compartment like every other one I have. However I have another 3302/94G s/n 176309 clearly earlier with the spring loaded latch, also similar 00Gs and one 3302A/15P - apparently later model with clear cover, decontenting inside (self-tappers, same color pots wheels), simplified hard case with no microphone pocket and no case material over the clear cover. But with spring-loaded latch

the spring loaded latch came out later in 1968 about the same time the new circuit with silicon transistors came out

earlier units with germanium transistors didn't have the spring loaded latch

the clear cassette cover and the simpler (and more durable) carrying case came out much later in about 1973

you can tell the year and place of mfg. of your recorders by looking at a sticker in the battery compartment, it it reads WR it means it was made in Philips' Wiener Radiowerke plant Austria, AH means it was made in Hasselt, belgium (marked as "Made in Holland) and SV means it was made in Singapore

the date is in a ww-yy format in earler units (ie 35-67) or in YWW format in later units (ie 935 where 9 stands for 1969)

[Jimmyhaflinger]

Originally Posted by toshik1

I'm sorry I don't have faith in those caps any longer!
4 out of 5 players I have (completely cleaned and rebelted) output extremely low hard to hear volume.
Only one seems to be nice and loud. So more caps are on the way to garbage soon.

that's strange as i rarely had problems with original Philips capacitors... maybe that's because you live in Florida which has a much hotter climate than i have here in Northern Italy.

i usually avoid complete recaps on philips machines because the printed boards are extremely fragile and the tracks are incredibly easy to damage even for a skilled technician with professional soldering tools

And also because i avoid modern chinese capacitors at all costs, i've seen many of them going bad by just sitting in a drawer unused for a few years and many capacitors with reputable brands on them are actually counterfeit