Little and Large (Grundig portables)

[DMcMahon]

The "Little" I think is a Grundig Cub, I also have 3 other littles (2 x Grundig TK 1 and a TK 2), all 4 are in pretty poor condition awaiting to be looked at, when time permits.

None of the 4 have the AC/DC power pack, so first job might be to rig up a suitable power supply rather than mess about with batteries at first.

[ben]

Someone brought me one of those Grundig Cubs to look at several months ago. Unfortunately, the motor is u/s. Which, in a rim drive machine is pretty terminal! It's a pretty crude unit anyway. The TK1 I think was the better one with a proper capstan drive.

The cub can be fed from a 9v(?) external supply via the phono socket on the side.

[DMcMahon]

Thank you Ben for the inputs, they are all poor condition so am not expecting too much, at minimum they will be fun to play with and attempt to get some life out of them.

David

[wd40addict]

How about some info on 'Large'?

[AC/HL]

Early Japanese miniature recorders were rim drive and PM erase, maybe the Cub was in competition (or vice versa)

[DMcMahon]

Originally Posted by wd40addict

How about some info on 'Large'?

Large is my Ampex ATR-700, an excellent 10.5" solid state stereo 4 track (this one is not 15 ips), out of my large R2R collection, it almost certainly is my favourite one.

A very heavy and sturdy well engineered machine, took a little time to get used to it, my first R2R experience with XLR connectors.

When I got it last May it was cosmetically and operationally in a bad way but after a big strip down, cleaning and a service it now works really well, luckily the only part that needed replacing was the broken tape counter drive belt.

More recently I replaced the thin white faced plywood side panels with nice solid oak panels that I made, which has improved its look.

Have not used it a lot yet but will do as time goes on.

Originally Posted by AC/HL

Early Japanese miniature recorders were rim drive and PM erase, maybe the Cub was in competition (or vice versa)

Excuse my ignorance Bill what is "rim drive" ? (I meant to have asked Ben the same question).

David

[TonyDuell]

Rim drive is driving the takeup spool in record/play mode to move the tape, rather than using a capstan and pinch roller. Rim drive, therefore, has non-constant tape speed (it speeds up as the takeup spool fills)

[DMcMahon]

Thank you Tony, that makes sense, I have never come across that before.

[TonyDuell]

Rim drive is not as common as capstan drive, but it does turn up :

Old and cheap reel-to-reel recorders, only really suitable for speech. I have a Toho 402, for example (I mentioned it here sometime back).

The minicassette (Philips-type) dictating machines. The (Japanese) microcassette is capstan drive.

Data recorders based on the minicassette, such as the drive in some Philips computers

Data recorders based on a modified minicassette such as the HP82161 HPIL tape drive

Some compact-cassette data recorders, such as the the HP9865 (and thus the built-in drive of the HP9830).

In the case of the data recorders they use a self-clocking encoding scheme (for example the HP9865/9830 has 2 tracks, a flux transition on one track is a '0', a transition on the other track is a '1' and a transition on both tracks together is a byte marker) so the actual tape speed doesn't matter too much.

[DMcMahon]

Originally Posted by ben

Someone brought me one of those Grundig Cubs to look at several months ago. Unfortunately, the motor is u/s. Which, in a rim drive machine is pretty terminal! It's a pretty crude unit anyway. The TK1 I think was the better one with a proper capstan drive.

The cub can be fed from a 9v(?) external supply via the phono socket on the side.

The only Cub documentation I can easily find is 2 sheets (schematic + technical description) from a "Radio Servicing" manual.

This shows that there is provision for 5 internal batteries, 4 standard 1.5 volt batteries (maybe D size) connected in series to provide 6 volts to the motor.

The fifth battery is a 3 volt (old Ever Ready No. 8 type battery) that connects in series to provide 9 volts to the electronics.

The external power supply socket is for a 6 volt connection this connects to the junction of the 2 internal batteries, so I assume you would have to remove the four 1.5 volt batteries, but leave the 3 volt battery in otherwise I cannot see how power would get to the electronics if the 3 volt battery was removed also. This does not appear to make sense so I think I am missing something ?

I assume that there must originally have been some Grundig documentation on it at least User instructions but am struggling to find any.

I think that the TK 1 and TK 2 are different to the Cub because they had an optional AC/DC power pack that could be fitted underneath the unit.

[Paul_RK]

Originally Posted by TonyDuell

Rim drive is not as common as capstan drive, but it does turn up :

Old and cheap reel-to-reel recorders, only really suitable for speech.

There was the Sound Belle, valved and mains-powered, which a tolerant ear might have found acceptable for casual music recordings in spite of the accelerating tape speed. It must have stayed in production a while, I'm harbouring a couple of them of different generations.

Paul

[TonyDuell]

I have a TK1, and the power input socket on that is a 2 pin DIN (NOT a DIN speaker connector!) with a switch in the socket. The recorder takes 6 1.5V cells, 4 off D size (motor running at 6V) and 2 off C size (in series with the 6V battery to give 9V for the electronics). The external power socket effectively replaces the 6V battery (disconnects the D cells and connects the external PSU in place of them) and I assume the 3V battery (2 C cells in the TK1) has to be fitted. I guess the motor was the main load on the battery, and that the C cells lasted long enough that it wasn't a big problem to keep using them.

I notice you asked about the Grundig Book in another message. I am pretty sure it has a couple of pages of 'Working Instructons in a Nutshell' for these machines. But it won't be technical.

[DMcMahon]

Thank you Tony, that is helpful. Maybe it was only the TK 2 that had the optional power pack ?

[TonyDuell]

I have no information on the TK2. My copy of the Grundig Book doesn't mention it.

It's always possible that the optional power supply had adaptors that fitted in place of the batteries and connected to the battery contacts. Like Philips did with the mains adaptor for the EL3585.

[DMcMahon]

The TK 1 Repair manual shows the power pack, the PDF document presently is too large to attach, but have pasted 2 screen shots in the attached Word document.

[DMcMahon]

The Grundig TK 1 Repair Manual is on hifiengine

[TonyDuell]

Thanks for that, I've now downloaded it.

It seems that I was right in a way. There is a 2 pin DIN socket (shown on the circuit diagram of the main machine) for a 6V PSU to replace the motor battery. If you use that you have to keep the 2 C cells fitted. The PSU that fits on the bottom has contacts that touch the battery contacts in the machine, replacing all the batteries.

[DMcMahon]

Yes you were right Tony, it certainly helps to understand it with an excellent manual like that one.

[DMcMahon]

Just purchased a second Cub, better condition than first one but like most of these portables has badly corroded battery terminals. Need to find/make some time to start looking at some of them.

[SteveCG]

I had a TK1 a long time ago. 3" spools, 3 3/4 ips, mono, half track, with AC bias but erase was a permanent magnet, and an exclamation mark style magic eye. Yes, it had a mains power unit which replaced the bottom cover of the tape recorder.

I thought it did a reasonable job of recording at the time. I still have a couple of tapes recorded at the time and they sound tolerable.