Coomber 393 Cassette Player/Recorder No Playback Sound
 

Early 1990' s vintage solid state mono cassette recorder with SofTouch logic solenoid control.

It can be used with up to 6 headphones for group listening such as in schools/colleges.

I purchased very recently and it was sold as "fully working".

Mechanically everything works well, but there is no playback sound when playing tapes, the same on internal loudspeaker, external loudspeaker, line out and headphones.

There is hiss sound but not tape hiss, because the hiss stays the same when tape playing back is paused or if no tape is present when play is selected.

The volume of the hiss can be varied with the volume control, but the level of the hiss can be different for the same volume setting, e.g. with volume set to mid position the hiss may be quite loud or quite quiet at different times.

Apart from the User instructions was not able to locate any other documentation so posted a documentation request here -

https://www.vintage-radio.net/forum/...d.php?t=196526 and received some very helpful and useful information.

David

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

Did a test recording using the internal microphone, just the same hiss on when recording played back. This version of the 393 only has automatic recording level control.

Trying the tape in another cassette machine the 393 recording had erased the previous recording on the tape but no new recording.

So looks like Erase works, will need to go inside to investigate further.

David

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

That is the first 393 model dating from 1990.

First thing is check the leads are soldered on the head.

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

After checking head wiring continuity, also check that the rec/playback switch has contact continuity in both modes. Might possibly be a dirty switch contact, exercising the switch will prove that and if so hopefully a case of cleaning it.

Dave

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

Got inside, without further stripping cannot see let alone access the PB/Record head wiring, looks like black frame plus maybe the metal bits below as per photo 3 would have to be removed.

Did a good visual of all the various wires connecting to the 2 main boards, including the board on the mechanism itself. Nothing untoward seen.

Decided to power up and try flexing the various wires and lightly taping the various items to see if could get playback sound to work.

But low and behold without doing anything else, it now is working and cannot get the sound to stop working.

Will give the Record/Playback switch a spray of contact cleaner and clean the heads (which look pretty clean already) and reassemble to see if it then still works.

David

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

While you're in there, check the soldering on the output sockets. I have worked on dozens of these and in most of them there were cracked joints.

The no audio problem that resolved itself rings a bell, I think I had one with a capacitor in the amp that had turned into a resistor and muted the audio. Will see if I made a note. Oddly enough the rec-pb sliders rarely gave trouble in my experience.

Another thing to check is the condition of the belt. Ensure there is no slipping when you put the deck into record as well as play - a loose belt will not manage to drive the flywheel under load, or will do so intermittently. Likewise, there should be full auto shut off in all transport modes - if it doesn't happen, new belts are needed.

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

Hi David! I actually happen to own this exact model. It's actually my very first tape recorder I got about three years ago from our local thrift store. I have repainted it since I got it and added some extras like an on/off switch and a custom speed knob with a switch between stock and custom speed so I can actually go back to normal playback/record speeds

When you engage playback, does the volume knob make any difference on the hiss, does it adjust the levels at all if you have to judge? I would ask the same about the tone knob - does that change the hiss frequency at all? SInce I can actually shut the motor off on mine, even with the motor off, there is still a hiss coming out from the outputs which is being affected by the volume/tone knobs. Even with the volume knob all the way down, I can still hear a bit of it and the tone knob affects it if I listen carefully. so maybe check the pots I guess?

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

Cleaned the heads (pretty clean already) and general tape path area, also sprayed contact cleaner on the Play/Record switch and exercised it by selecting Record (selecting record also automatically selects Play).

Reassembled and it is still working well on playback, sounds pretty good actually with a fair bit of volume available.

Did test recording using the internal microphone and it worked fine. Still to check external microphone and line recording.

Cannot explain why the original problem, can only assume a bad connection somewhere that went bad during shipping, hopefully it will stay good now, time will tell.

It was all reassembled by the time I read Ben's post 6, next time I look inside I will check out his suggestions.

David

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

Now it is working correctly there no longer is a hiss issue.

When I had the problem of just hiss on Playback (even when tape was paused) the volume control did affect the hiss level (no hiss if volume fully ACW) and the tone control did have some affect on the hiss frequency.

David

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

A few extracts form the Jan 1992 catalogue.

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

They're cheaper than I would have expected given that, presumably, it was a limited market and that 'educational' items always seem to be overpriced.

I'd wondered why the speaker was mounted on the back of the cabinet, now it makes sense.

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

I wonder if it's possible to actually add a knob to control the input level? Would it be as easy as adding a audio pot between the input line and the circuit 🤔?

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

I wonder if it's possible to actually add a knob to control the input level? Would it be as easy as adding a audio pot between the input line and the circuit 🤔?

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

The 393 has automatic recording level control, so simply attenuating the input signal probably won't do what you want.

Take a look at the sevice manual, in particular the added circuitry for the 395 (which has manual level control as well). It adds a level control potentiometer, 4 LEDs + comparators to judge the level and a switch to disable the automatic level circuit. Needless to say this is not a trivial additon but you might not need all of it (e.g. the level LEDs and drivers)

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

Was this a Coomber specific catalogue? i.e. their own catalogue.

David

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

What is the reason for wanting to do this?

David

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

Well, so I can have control over the input signal. Mainly concerning the line input. Coming to think of it, I can probably just adjust the output signal I am feeding in I guess? Is that what you're on to?

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

Yes.

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

I have yet to test line recording with the Coomber.

Personally, normally all I use for line signals are either the Tape/Rec Out phono's on Hi-Fi amps or the Audio Out phono's on CD player, normally these are fixed level line level signals. I would assume the Coomber auto recording level control should be able to cope with line level signals.

With some manual recording recorders that have DIN line inputs I do find that sometimes the phono line level signals are too strong, in that case I fit fixed resistor droppers in the phono to DIN cable.

David

Re: Coomber 393 Cassette Player/Recorder No Playback Sound
 

On these first and second versions of the 393, The DIN socket on the front is switched. When a plug is connected the internal mic is muted.

This DIN was replaced in later versions (393/7) by a quarter inch jack socket which was line input in rec and line output in play. Last time I saw that setup was in a Grundig dictaphone!

The ALC is quite gentle in these, acceptable results with music can be obtained. Mono, of course!