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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 11th Apr 2017, 3:32 pm   #1
IvorBlister
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Default Philips EL3542 tape recorder problems

I have a Philips EL3542 four track tape recorder which has been working fine for the last few months. I sorted out the problems with the clutch pads and wind/rewind is fine. Recently it has developed a sound problem which is best described as a low rumble varying at random with occasional louder pops and clicks. This is present with both tape stationary and when playing. The magic eye responds to the pops etc even when not recording. The noises are recorded on tape and show up when played back on a second machine. Recorded music etc still plays back ok but with the background of the noises. I have cleaned valve pins/bases and switches and swapped valves with a working machine but no improvement. I have just received the trade service sheet but so far have not ventured to check voltages etc.
Any thoughts or help on where to start and look for the problem would be much appreciated. Thanks Nick.
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Old 11th Apr 2017, 8:25 pm   #2
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Default Re: Philips EL3542 tape recorder problems

Something in the power supply, like a failing smoothing capacitor or rectifier valve perhaps? Especially considering the magic eye is responding too without any input signal.
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Old 11th Apr 2017, 11:16 pm   #3
Michael Maurice
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Default Re: Philips EL3542 tape recorder problems

These were made in around 1960 and I think before the mustard type of capacitors were fitted. I'd check all the coupling capacitors (Philips didn't use Hunts) and replace on sight.
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Old 12th Apr 2017, 6:30 am   #4
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Default Re: Philips EL3542 tape recorder problems

The EL 3542 uses two relays. RE 1 and RE 2. RE 1 discharges 17.5
volts from a 125 uF capacitor, when a metallic tape leader passes over
SK 9 (guide post contact).

When RE 1 momentarily closes , it pulls in RE 2.

RE 2 pulls down a trip lever, which stops the tape motion.

Any leakage to earth in the coil, or an arcing contact of RE 1, which
operates at 220 Volts will be heard . This voltage feeds the anode resistor to
the second section of B2 (ECC 83) . It can fry and arc without stopping
the machine .

This relay did cause much trouble.

Here is a note I wrote ,Radio Electronics Jan 1966 page 98, about it.
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Old 12th Apr 2017, 10:38 am   #5
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Default Re: Philips EL3542 tape recorder problems

I bought one of those new, superb machine for the time. You have done most of the obvious things but you might try gently tapping the valves with the handle of a small screwdriver, they can go noisy.

Peter
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Old 12th Apr 2017, 12:29 pm   #6
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Default Re: Philips EL3542 tape recorder problems

I had something quite similar on a Grundig TK145

I have had this since my youth (15) it also had a rumbling with pops and bangs it would sometimes start even when the machine was idle but often started as soon as it was put into play.

Sometimes it would reach a creshendo and suddenly stop.

Gently tapping the machine would usually result in a rustling which sometimes developed into the rumbling.

I turned out to be dry joints on the PCB I never found out exactly which one it was but it went away after I resoldered virtually all of them!

That was more than 40 years ago though

Cheers

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Old 12th Apr 2017, 3:33 pm   #7
IvorBlister
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Default Re: Philips EL3542 tape recorder problems

Hi and thanks to all for the helpful suggestions. Have tried the valve tapping as well as replacing valves but no change. My first thoughts were to the power supply but the reference to the relays was interesting. Have checked playing a tape with metal strips and the auto shut-off works as expected but will check further.
I am more than happy with the mechanical repairs, even to the point of making small replacement components and although I have constructed several amplifiers in the past, valve and solid state, this is really my first adventure into trouble shooting and, hopefully, repairing. Was not sure about the 'mustard' capacitors - anyone help me out there? I have included a few pics of the inside - was it mustard in colour caps? From the cabinet the machine was made in 1961 and has been in the family since new so I know that no modifications or repairs have been done in the past. Still a nice machine apart from the rumblings.
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Old 13th Apr 2017, 8:27 am   #8
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Default Re: Philips EL3542 tape recorder problems

Most of the caps are 'mustards' - the creamy yellow colour - however there is 1 x Wima brown cap, 0.1 mfd, in the 3rd photo, that should be changed as they are not so reliable.
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Old 13th Apr 2017, 9:36 am   #9
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Default Re: Philips EL3542 tape recorder problems

Do you have an oscilloscope to hand? Looking at the signal present on each stage might indicate where the trouble originates. If you have eliminated the possible electro-mechanical items as indicated previously, my suspicion would lie with a noisy resistor - possibly the anode load of the first stage.

Les.
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Old 13th Apr 2017, 7:25 pm   #10
IvorBlister
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Default Re: Philips EL3542 tape recorder problems

Don't have a 'scope, just Avo 8. I hope to explore a few options this weekend and order replacement capacitors too. Thanks all for the help so far.
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