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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 14th Jan 2020, 11:14 am   #21
DMcMahon
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Default Re: Grundig TK 819 Any Useful Info

Quote:
Originally Posted by Ted Kendall View Post
Do you mean the steel cap? This is part of the elecromagnetic clutch for fast wind.
No, sorry I did not explain it very well. In the photo, the underside of the top of the reel table is shown on the right, as looking at the photo (this is the part in question).

There is 3.5mm wide circular groove on the inside of the outer felt ring. the groove is a few mm deep. The outer diameter of the groove is around 68mm
and the inner diameter around 60mm.

The groove is filled with the grey substance, I assume it is something that had decomposed due to age ?
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Old 14th Jan 2020, 11:19 am   #22
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Default Re: Grundig TK 819 Any Useful Info

Quote:
Originally Posted by peterpixel View Post
It was worth asking the question to avoid reinventing the wheel.To improve access to everything it should be noted that the transport can be easily separated from the electronics.Peter.
Thank you Peter, it does not look easy to me, but I will have another look, not until tonight though.
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Old 14th Jan 2020, 11:39 am   #23
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Default Re: Grundig TK 819 Any Useful Info

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Originally Posted by DMcMahon View Post
No, sorry I did not explain it very well. In the photo, the underside of the top of the reel table is shown on the right, as looking at the photo (this is the part in question).

There is 3.5mm wide circular groove on the inside of the outer felt ring. the groove is a few mm deep. The outer diameter of the groove is around 68mm
and the inner diameter around 60mm.

The groove is filled with the grey substance, I assume it is something that had decomposed due to age ?
Someone had a similar problem:

https://www.vintage-radio.net/forum/...d.php?t=123169

Lawrence.
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Old 14th Jan 2020, 11:46 am   #24
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Default Re: Grundig TK 819 Any Useful Info

Looking at photos of the Mechanical and Electrical chassis's in the Service manual it does like it could be fairly easy/straightforward (as Peter said) to remove the top mechanical/transport chassis from the underneath electrical chassis below.

I have never seen a R2R that comes apart like this before.
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Old 14th Jan 2020, 11:50 am   #25
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Default Re: Grundig TK 819 Any Useful Info

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Originally Posted by ms660 View Post
Many thanks Lawrence, that old post will help me a lot.

David
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Old 14th Jan 2020, 1:14 pm   #26
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Default Re: Grundig TK 819 Any Useful Info

Hi,I'm making the assumption that your unit is very similar to the TK830.If so then the transport is supported on 4 vertical brackets.Each is held by 2 screws,accessible from above in my unit,so after removal of these screws and disconnection of the plugs and sockets the transport can be lifted out.Peter.
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Old 14th Jan 2020, 4:30 pm   #27
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Default Re: Grundig TK 819 Any Useful Info

Hi Peter,

Thank you for the extra inputs. I guess the TK 830 is very similar. With the 819 there are 6 brackets each held by 2 screws.

Prior to originally saying that it looked difficult take apart, I had removed all 12 screws but could not get anything to budge easily, so thought maybe that had to do more disassembling of some of the transport components (like the capstan motor).

Later I will have a fresh look, probably just needs a bit more gentle force.

David
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Old 14th Jan 2020, 5:25 pm   #28
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Default Re: Grundig TK 819 Any Useful Info

I have been having at quick look at sourcing new suitable replacements for the four RC snubbers and see that it may not be quite as easy as it might seem.

I see from last years "TK 920 Exploding caps" post that the poster sourced (and I assume used) some Kemet devices. One of the forum reviewers was not keen on the Kemet parts for a couple of reasons, one being that they have a paper dielectric and he recommended polypropylene. They are a metallized paper dielectric technology which I think is old and in better capacitors superseded by Polypropylene film.

Personally I am not so sure I would be too unhappy with the Kemet devices for the reasons given by the reviewer, but there are 2 (maybe small points) about the Kemet device that might put me off a little.

1.They are rated at 250 vac, at least one of the snubbers sees 260 volts (from the 260 volt tapping on the mains transformer) I think on motor start, so ideally it would be good to get a higher rated ac volts snubber. The Kemet device is X2 safety rated so probably is fine. Of course the original Frako snubber is only 220 volts ac rated ! and in those days unlikely to have any safety/impulse voltage rating .

2. The Kemet device is only rated at 630 vdc which in this application is probably OK, but is low compared to the 2,000 vdc Frako rating.
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Old 14th Jan 2020, 9:38 pm   #29
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Default Re: Grundig TK 819 Any Useful Info

Now have the top transport section separated from the lower electrical section, as Peter previously stated it is easy. Just had to use a bit more gentle force plus remove an extra 2 screws from the front frame, that secured down into a metal strip on the electrical section that the push button switches are fitted to.

Then after carefully removing the various connectors, the top section lifts off, giving great access to everything below, including the 2 remaining CR snubbers C34 & C35. I wish my other old Grundigs had this great feature !

Once I remove the snubbers, then the general area will need a good clean up, probably will be difficult to remove the tar like snubber potting compound, some of which has spread over one of the valve bases plus spattered various items etc.
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Old 14th Jan 2020, 9:55 pm   #30
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Default Re: Grundig TK 819 Any Useful Info

Looking at suitable CR snubbers a little more, I see that Kemet do a higher AC voltage of 275 (F409 series) but still paper dielectric, they also do a 275V polypropylene (F43 series), also see that Elko (I know that they are another brand that sometimes gets bad press) do a 275V polypropylene (also F43 series ?).

Still looking at these and others. Have not yet looked at prices, as this could be a deciding contributor if any of them are too expensive.
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Old 14th Jan 2020, 10:51 pm   #31
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Default Re: Grundig TK 819 Any Useful Info

Quote:
Originally Posted by DMcMahon View Post
Photos attached of the mains plug. Its height is 32mm, width 15mm and overall depth (including pins 25mm).
Prob no help to you but I have the same problem with mains inputs but with older TKs where the mains plug is a 3-pin affair. I have room to replace the mains socket with eg a kettle connector type plug and socket but you appear to have restricted space. If you don't want to go non-standard you try for size the 2 pin plug/socket you'll find on the cheapest portable radios. They are small enough I think. Also and drastically you could look at butchering your existing socket so as to sweat in two round pins to suit the same radio plug
TT

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Old 14th Jan 2020, 11:57 pm   #32
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Default Re: Grundig TK 819 Any Useful Info

Thank you for your inputs, its always good to get other peoples thoughts.

In the short term I am just going to hard wire a 3 core mains cable connection directly in. Then later if the rest of the unit looks hopeful, I will think about what I will do with the mains connector, as you say space is restricted.

I am not worried about changing the type of plug, i.e. I am not one of those people who for good reasons want to keep everything original & authentic.

I really would like to go 3 pin so that there is a safety earth connection, I am a bit maybe over the top when it comes to safety earthing. As soon as I get a 2 wire mains cable R2R (loads of them) I very soon convert to a decent 3 core UK cable + UK mains plug, normally leaving them hardwired if that is how they come.

If they come with a UK 3 pin plug, I remove the 13 amp fuse (it is nearly always a 13 amp) and replace with a 1 amp fuse for better protection, Very few R2Rs rarely get close to drawing anywhere near 1 amp in my experience. For ones that are borderline or above, I then would fit a 2 amp or higher if required.

One thing I am thinking about is to remove the Remote Control connector (which I would not use anyway) and fit a 3 pin mini Bulgin mains connector in its place. I think the mounting hole for the Remote Control connector is just about the right size for the Bulgin and there is maybe enough space behind to take the Bulgin.

I have the mini Bulgin on a couple of my TK 23s and before I brought the TK 819 I brought a couple of mini Bulgin connector mains cable assemblies for possible future upgrades of some of my other Grundigs and/or other makes.

The mini Bulgin is a bit Micky Mouse but is more than adequate electrically. I know nowadays with more recent electric specs that the mini Bulgin is not supposed to be used with voltages higher than 60 volts when the connector is accessible (and likely to be removed/replaced), but for my personal use, this is not an issue.

Note - I am not recommending mini Bulgin mains connector upgrade to anybody.
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Old 15th Jan 2020, 2:37 pm   #33
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Default Re: Grundig TK 819 Any Useful Info

Quote:
The mini Bulgin is a bit Micky Mouse but is more than adequate electrically.
Up to 3 amps to be specific.
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Old 15th Jan 2020, 3:23 pm   #34
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Default Re: Grundig TK 819 Any Useful Info

Removed the other 2 snubbers, both in a bad way, the outer case on one falling apart when removed fully.

Had to first remove a few components (well cut off at one end) to access & then untwist the strong metal tabs on the metal snubber hold down clamp.

To get access to the snubber wires to unsolder at the relay (temporarily cut them off, so will do later) had to remove the adjacent ECC 81 valve and its metal screening can.

The valve and the can were stuck solid due to the tar like compound all around the valve base, so had to use hair drier to free it up.

Lots of small tar splattering all around, much can be cleaned with IPA plus elbow grease but for the more stubborn large deposits I resorted to a bit of cellulose thinners, did not want to use anything too abrasive, so as not to damage the lovely gold paint, some of which is starting to pit/bubble up.

There are 4 non electrolytic capacitors on top of the lower electrical section, that I will replace as a matter of course. No suspicion that they are bad, but would be difficult to access/replace them later when everything re-assembled. There are 2 quite large Frako electrolytics on the top section, I will check them out more when I get power on.

Unlike the "Exploding caps" post, my motor start capacitor (C38/C39) assembly visually looks in good condition.

The underside of the electrical section needs a good clean and a couple of Wima capacitors that are starting to show signs of splitting will be replaced, plus 1 large Frako that is splitting.

Would not normally do a wholesale replacement of the Wima/Frako etc paper capacitors, but on this occasion may consider it, as a lot of them look relatively easy to access.

Really impressed with the German Service manual where it has drawings and photos showing all the main components and also has component listings, this is much better than most German Grundig Service manuals and probably as good if not better than the few UK Grundig service manuals (that show this sort of detail) and on par with the USA Grundig Majestic documentation.
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Old 15th Jan 2020, 8:17 pm   #35
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Default Re: Grundig TK 819 Any Useful Info

Various cleaning on-going. Gave the wooden box/case a thorough brush/hoover out, getting rid of years of dust, dirt and fluff buildup, particularly heavy in the circular plastic vents in the base.

A good sized Celestion loudspeaker in there.
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Old 15th Jan 2020, 8:39 pm   #36
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Having a few R-Rs mostly with black plastic bases I think you can't beat the genuine wood examples foe pleasing appearance. Always repay the effort in cleaning and restoring
TT
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Old 15th Jan 2020, 9:47 pm   #37
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Default Re: Grundig TK 819 Any Useful Info

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Originally Posted by DMcMahon View Post
There is a noticeable vertical gap between the top of the Magic eye and the viewing hole in the top panel (you can sort of see this in one of the photos in the first post), does anybody know if this is normal or could there be a surround/ infill piece missing from the panel hole ?
Interesting that most of the ones (including the 820 and 830) I see online all have a similar looking gap ?
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Old 15th Jan 2020, 9:52 pm   #38
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Default Re: Grundig TK 819 Any Useful Info

Should it have a shroud, it would be unusual to have an open gap.

Lawrence.
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Old 15th Jan 2020, 11:03 pm   #39
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Default Re: Grundig TK 819 Any Useful Info

I asked this question early on and one response was that the 830 does not and that in his 830 the Magic Eye is at top of the window. Subsequently I found that there is a height adjustable bracket but I have not yet tried it, to see how much of the gap can be reduced.

Still seems strange why so many have the gap, maybe the adjustment range is too small, I can see the possible need to file/elongate the slotted adjustments holes.
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Old 15th Jan 2020, 11:28 pm   #40
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Default Re: Grundig TK 819 Any Useful Info

Decided to have a look at converting the mains input supply arrangement.

This unit has a 2 pin mains plug but without a mains cable. Not easy to source a suitable 2 pin socket to make a mains cable, so decided would convert unit to a 3 pin mini Bulgin mains plug.

Original 2 pin mains connector plug will be left fitted but disconnected.

Unwanted (by me anyway) Remote Control socket to be removed and replaced by the mini Bulgin.

Removed the Remote Control socket, it was quite a struggle, in there really tight.

I had no spare Bulgin plug (do have spare Bulgin sockets on mains cables) so had to pinch/borrow one from another of my TK 23s. I had measured up the Remote Control socket area the best I could, before removing it and also measured the Bulgin.

But when I went to fit the Bulgin, its outer diameter was a tiny fraction smaller than the mounting hole, so I need to make some sort of washer to go between the mounting hole and Bulgin to stop the Bulgin pulling through the hole.

The remote control socket has a sprung loaded switch in its base, which I guess is actuated when the Remote Control external plug is used. Looking at the schematic it shows a link across 2 pins of the Remote socket, which once again I guess is the switch that is actuated (opened) when the external remote plug is used (but this may not be correct).

So I need to double check the wiring to the schematic and restore the link, also make safe the other wires disconnected from the remote socket that will not be used.

A couple of Wima capacitors had to be disconnected to get the connector out so will replace them during the tidy up after fitting and wiring the Bulgin.
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