Grundig TK14

[ex 2 Base]

I am about to revive a Grundig TK14 reel to reel tape recorder, its been in our loft for 60 years. Also, will the tape have deteriorated, any advice will be much appreciated. Ted

[theredhouseinn]

Hi Ted.
Don't switch it on.
I have just done mine.
All the caps will need changing, especially any dark brown Wima's, which will probably s/c.
Check all resistors for value, and change any that are out of tollerance.
The switch contacts will need cleaning.
You will have to take out the relay and clean the contacts carefully.
The tape may still be ok, look at the edges of the tape to see if there is any crinkling.
That will do for starters Ted.
John.

[DMcMahon]

I do not agree about changing all the capacitors, if Ted has the experience to do then it is not a bad thing to do but most of the capacitors could still be good.

In my expereirence the TK 14 and similar TK range at that time did not normally use the black/brown Wilma paper capacitors (said to look like toffees) which potentially can have electrical leakage problems.

All the ones I have seen either have yellow/gold coloured Wilma Tropyfol (TFM) Polyester film/foil capacitors (which generally are very reliable) or yellow/brown/orange ERO FOL II capactors which are another Polyester capacitor, generally very reliable again.

Would certainly recommend checking out C10 0.1uF grid coupling capacitor to pin 8 of the ECL 86 output valve (actually goes via C13 0.047uF which also should be checked) to be on the safe side or just check for no +ve voltage at pin 8.

If Ted has the equipment and required experience of doing it, certainly would recommend a controlled power up using a lamp limiter or better still a Variac.

First do a thorough visual of the components to check for any obvious ones that have any signs of having overheated, are burnt, are leaking etc.

If can safely do it, would recommend that the main DC HT voltage be measured once powered up, schematic shows a value around 256V in Playback mode.

Attached is a typical Wilma TFM example and a typical ERO FOL example (actually the C10 and C13).

Not aware of any relay/removable relay.

David

[Techman]

Originally Posted by DMcMahon

I do not agree about changing all the capacitors, if Ted has the experience to do then it is not a bad thing to do but most of the capacitors could still be good.

Not aware of any relay/removable relay.

Exactly.

Also regarding the relays - probably thinking of something like the TK35, one of which I've just been working on.

[DMcMahon]

Originally Posted by DMcMahon

All the ones I have seen either have yellow/gold coloured Wilma Tropyfol (TFM) Polyester film/foil capacitors (which generally are very reliable) or yellow/brown/orange ERO FOL II capacitors which are another Polyester capacitor, generally very reliable again.

David

I was primarily referring to the coupling and de-coupling capacitors. There are other makes/types for the electrolytics etc.

[Techman]

As you say, it's always worth checking and possibly replacing the grid coupling capacitor to the output valve - I've just replaced it on that TK20 I was given the other day.

[Katar83]

I dont think TK14 has brown wima capacitors, at least I couldn't see any on the pics and videos I've seen while restoring my TK5. That said I'm not sure I'd feel comfortable powering up 60 year old caps myself. Only single cap was still within spec on my TK5 so I'd probably replace them if that was an option, if not then cross your fingers and hope for the best?

[Uncle Bulgaria]

I always think the 'Steps To First Power On' is a good reference for those like me who need a crib sheet!

Bring it up gently on a lamp limiter or variac and check the current draw, after checking for obvious damage as DMcMahom says.

[DMcMahon]

Yes the TK 5 is a different kettle of fish being manufactured around 7 years earlier. Similar applies to the many other TKs manufactured around that earlier period including TK 7, TK 8, TK 9, TK 12, TK 16, TK 20, TK 25, TK 30, TK 35, TK 819, TK 820, TK 830, TK 919, TK 920 and not forgetting the earlier Reporter 300, 500, 600 & 700 series.

These did use many Wilma paper capacitors that can be troublesome sometimes, less common but there can also be a few Frako & Hunts paper capacitors also which can be potentailly troublesome.

In my TK 5 after checking/measuring I renewed most of the paper capacitors (majority were Wilma), some were were very leaky (effectively short circuit at DC working voltage), some were just very poor cosmetic condition so replaced them as well for good measure.

David

[ex 2 Base]

Many thanks chaps for the information given. I have a circuit diagram from Paul above, and have located those possibly iffy caps. I have Variac and lamp limiter and several meters so OK in that area. The recorder is have a few happy days in our airing cupboard with the top and bottom removed, I notice the belt are broken, can any one suggest a belt supplier. I'm busy at the moment hoping to fix our son's Ebac dehumidifier. Ted

[DMcMahon]

For Wilma paper type capacitor identification purpose attached are some typical examples from my TK 5. The yellow mustard was as nearly always no problem, apart from being the incorrect value fitted (obviously fitted as later replacement but wrong value used).

The single black Hunts was quite leaky.

David

[Katar83]

If all fails eBay will find you belts for your TK14, they are ~£20 from Germany for a set.

[DMcMahon]

My previous references to Wilma capacitors of course should have read Wima !

David

[DMcMahon]

TK 14 PCB component layout/connections drawing.

[DMcMahon]

Ted,

Due to ongoing serious health issue with my wife and time consuming care work with my elderly father and my wife's elderly parents I am largely off line in terms of doing much Forum work, so have posted your PM to me here.

I've got the recorder out of the airing cupboard and on the bench. I'm an absolute novice here, re tape recorders or radio repair. Anyway I've got the circuit board out and have disconnected one end of C10 & C13. C10 is .1 all OK. C13 a Wima is high .096 (according to the circuit diagram should be .047) as I have some used, but tested .047 Y2 type, would one of those be OK in this location. I don't want to buy a packet of 5 and use 1. I still need a set of belts, have you an address in Germany, from where I can buy a set, nothing available on ebay.

It is always good to open up your questions to a wider audience to get best responses.

The Y2 capacitor is normally used as a mains filter/suppressor from one line of the mains to earth, but should be OK to use as your coupling capacitor. The fact that C13 is a Wima and nearly twice its value could well mean it is leaky.

For C10 the fact that its capacitance value is correct does not necessarily mean it is good, although in my experience increased/higher capacitance often goes hand in hand with leakage. Insulation resistance check (at rated voltage) or DC voltage measurement at output side of capacitor would better prove its leakage state. If it is not a Wima or other waxy/paper capacitor then it probably will be OK.

Link here to Grundig drive belt dimensions-

http://www.taperecorders.nl/RIEMEN-nw.htm

Here is one eBay TK 14 belts link-

https://www.ebay.co.uk/itm/Belt-Set-...IAAOSwzhVWqjLj

David