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Old 13th Feb 2018, 12:02 am   #1
muttley1984
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Default Help with Braun MT99R

Hello,
My 90year grandma has a Braun MT99R radiogram which actually belonged to her mother and has been gathering dust for a long time (probably 25+ years!!). My grandfather passed away recently so I would really like to get her radiogram back in working order to give her a little lift. She loves her music and being a family heirloom it would be great to get it working and back into her life

It is a Braun MT99R and uses the RC61B circuit (chassis?) however it currently doesnt have a record deck at all as someone has obviously removed it over the years. I have managed to acquire a cheap BSR UA8 with the intention of re-fitting this if I can do a good enough job of restoring it and replacing a few parts

When i switched the unit on it plays the radio without any noticeable issues so I have reason to believe that if I can work out how to reconnect a record deck to the ‘phono’ input, I am hoping I wont have too much to do on the radio side or with the amplifier and speakers but maybe that is a little presumptuous?

I have the RC61B schematic and purchased a braun MT99 user manual (all in German!) but am still a little unsure of my next steps. I am reasonably technical but have never done anything with vintage audio before and would really appreciate a steer in the right direction

My initial questions are……

Q1. How do I power the record deck? I.e where do i 'pick up' the power supply from the radiogram unit?

Q2. Where and how do I connect the output of the cartridge from the record deck?

I can see the ‘source selector switch' on the schematic and can appreciate that the position of this basically configures the circuit however I am not sure where the inputs are. As a complete novice I could guess that the phono input is connected to the ‘port’ in the middle you can see on the photos which has nothing connected to it but I would like to understand this properly and cross check it against the circuit. As you can tell I am struggling to make the link between the schematic and the photos I have of my grandmas radiogram. If someone could perhaps talk me through the basic design or even mark up the schematic and/or photo that would be enormously helpful and help me get started

As I say I am very new to all this but willing to learn and determined to get this working again for my grandma so would really appreciate any help and support you can offer me

Thanks

Chris
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Old 13th Feb 2018, 7:43 am   #2
Boater Sam
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Default Re: Help with Braun MT99R

MT99R is a USA export model. It is a late valve model, I'm surprised that it is not transistors.
https://www.radiomuseum.org/r/braun_mt99r_rc61c_us.html

https://www.radiomuseum.org/r/braun_..._rc61b_rc.html

The voltage of the motor on the record deck you have will determine if and where it can be connected for power to the turntable.

The black DIN socket in the centre is likely to be a tape in/out connection not pickup.
The EL84 valve is not in its socket fully.
This valve will most likely need its grid coupling capacitor - C69 on the diagram - replacing before you use the chassis if you are to avoid destroying the irreplaceable output transformer &/or valve.

Does the instruction leaflet not show the socket locations? If not you may have to follow the wires from the selector switch in the gram position.

Do you have a circuit diagram you could post?

I've found you the circuit diagram,

http://85.144.192.2/nvhr/Braun_TS2.pdf

the pickup is in the dotted box at the bottom. It would seem that the motor was a mains one and was connected directly to the mains.
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Old 13th Feb 2018, 11:28 am   #3
Edward Huggins
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Default Re: Help with Braun MT99R

The BSR UA8 will have brown and black wires going to the motor. These can be connected to the mains, or more elegantly, via the main radio on/off swich - maybe on the volume control? This is a mono radiogram so you only need 2 wires (signal + earth) going to the pick up socket. Is there a cartridge in the UA8? If there is, and if it works, do bear in mind that this will only be suitable for playing older Mono LPs unless you change the cartridge.
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Old 13th Feb 2018, 12:50 pm   #4
Audio1950
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Default Re: Help with Braun MT99R

I would measure the total height of the UA8 deck before going any further. It will probably too high to allow the lid to close.
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Old 13th Feb 2018, 12:59 pm   #5
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Default Re: Help with Braun MT99R

Good point, though the original Telefunken deck is not a low line model.

https://www.radiomuseum.org/r/telefu..._tw560_tw.html

Power bulge in the lid? Ha ha.
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Old 13th Feb 2018, 1:31 pm   #6
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Default Re: Help with Braun MT99R

https://www.vintage-radio.net/forum/...d.php?t=109268

Lawrence.
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Old 13th Feb 2018, 6:21 pm   #7
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Default Re: Help with Braun MT99R

I wonder if the pickup connections are the 2 (4mm?) sockets on the paxolin plate that carries that DIN socket, and that the 2 resistors and capacitor shown associated with the pickup on the circuit diagram are actually fitted to the turntable unit and not the radio chassis.
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Old 15th Feb 2018, 5:43 am   #8
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Default Re: Help with Braun MT99R

I would think that is the most likely arrangement. The 2 resistors and the capacitor should be close to the cartridge, in which case the OP does not have them. The tape socket is definitely the black DIN 3 pin, connected to resistors W31,W32 & W33. The pickup will be between chassis and switch contact B1.
Potentiometer W40 looks to be a very trick item with 2 taps.

The 4 sockets in line on the left of the chassis rear are from left to right, earth (signal, not mains), AM aerial, 2 for 240 ohm twin feeder FM aerial.
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Old 15th Feb 2018, 8:31 pm   #9
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Default Re: Help with Braun MT99R

In the OP's second picture, there is a brown and black wire to the right hand side along with a brown figure of 8 cable which I suspect is the mains feed. Could the brown and black be the remains of the turntable feed ?
The speakers all seem to be fed from the top of the chassis so they are all accounted for and the extension speaker socket looks to be the red and black wires going to the rear panel socket board.

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Old 15th Feb 2018, 10:43 pm   #10
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Default Re: Help with Braun MT99R

If I get chance on Sunday I will check how mine is configured with photos. I don't mind removing the back but I won't remove the chassis. It's working perfectly and I don't want to risk any damage or disruption taking it apart. I don't remember seeing any resistors etc on the turntable.
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Old 16th Feb 2018, 1:31 am   #11
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Default Re: Help with Braun MT99R

Is Muttley going to come back to his thread or are we talking amongst ourselves?
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Old 16th Feb 2018, 10:08 pm   #12
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Default Re: Help with Braun MT99R

Apologies for the delayed response, my broadband has been down this week and has just been re-connected!!

Thanks to all for your advice and suggestions. In the absence of internet I have been trying to translate various parts of the user manual to see if I can verify some of your comments. Unhelpfully there are lots of words and very little diagrams i'm afraid! If anyone can read German and is happy to help then I will get it scanned at work and will post it to the thread

Thanks for all your help. Its great I now know where the grid coupling capacitor is and where the pickup is shown on the circuit diagram. I have been looking at the circuit diagram and still cant get my head around how the 'piano keys' switch contacts work. Without this I dont think I have much chance of tracing cables. I will spend a bit more time trying to figure this out but any help is much appreciated.

I'm pretty confident about the deck height as Sobell1980 has a BSR UA8 deck in this specific radiogram

According to a very vague translation the DIN socket does appear to be something related to 'magnetic recording using a tape'?

Very eager to see a picture of sobell1980's set up as I am really hoping this will confirm the theory that the pickup wires go to the sockets on the paxolin plate that carries the DIN socket. If I can confirm this I can turn my attention to powering the motor

Boater Sam - are you suggesting that the "two resistors and capacitor" shown on the circuit diagram in the pickup box would have been integral to the original deck but will not necessarily be an integral part of the BSR UA8? If so will I have to install and integrate these somehow?

I live 1hr30min drive from my grandmas house and really dont want to transport the radiogram so when I do get there next I really want to make the most of my time so all your help and suggestions are most welcome otherwise I think this project could have gone on for years!!!
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Old 17th Feb 2018, 3:53 am   #13
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Default Re: Help with Braun MT99R

Quote:
Originally Posted by muttley1984 View Post

Boater Sam - are you suggesting that the "two resistors and capacitor" shown on the circuit diagram in the pickup box would have been integral to the original deck but will not necessarily be an integral part of the BSR UA8? If so will I have to install and integrate these somehow?
Yes, that's why they were drawn in the box.
The pickup goes between chassis and the contact on the selector switch, you should be able to id that with the switch diagram not the circuit diagram.
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Old 17th Feb 2018, 11:05 am   #14
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Default Re: Help with Braun MT99R

The DIN socket is for recording and playback of a reel-to-reel or cassette recorder. The specific pick up voltage reduction circuit components for the cartridge would usually be on the radiogram chassis and not the tag strip of the UA8.
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Old 17th Feb 2018, 2:06 pm   #15
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Default Re: Help with Braun MT99R

I bow to your superior knowledge Edward, let's see if Muttley can find them.
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Old 17th Feb 2018, 4:20 pm   #16
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Default Re: Help with Braun MT99R

Quote:
Originally Posted by muttley1984 View Post
I have been looking at the circuit diagram and still cant get my head around how the 'piano keys' switch contacts work. Without this I dont think I have much chance of tracing cables. I will spend a bit more time trying to figure this out but any help is much appreciated.
They look complicated but reasonably simple to work out the basics but not so easy for me to put down in words but here goes anyways....So far as I can tell so far based on this schematic:

http://85.144.192.2/nvhr/Braun_TS2.pdf

Looking at the switch drawing on the schematic sheet all the contacts are numbered (1,2,3,4 etc) for each section (A,B,C,D etc) Each section corresponds to a function, the switch contact numbers along with their A,B,C,D etc designations are all to be found in the schematics drawn circuit, it's easy to miss some of them but after the following descriptions you should be able to find them all if you haven't done so already. The switch bank is shown in the out position, eg: no switch buttons depressed, if a L (long wave) M (medium wave) or K (short wave) button is pressed then the contact bars for the switches in section A will remain as shown and the contact bars for the switches in the selected section will move upwards (as viewed in the switch drawing)

Section A: The switches are shown in the AM position (L,M & K) in that position the primary of the FM IF transformer (SP22) is shorted out by switch contacts A8 & A9 and the grid voltage for the tuning indicator is sourced from the AM AGC line via switch contacts A5 & A6. When UK (VHF/FM) is selected the contact bars for both A section switches move upwards, this releases the short across the primary of the FM IF transformer (SP22) because switch contacts A8 and A9 are no longer connected by the contact bar, and the voltage for the grid of the tuning indicator is now sourced from the FM demodulators -ve output circuit via switch contacts A5 & A4.

Section B: PH (phono) When this section is selected the receivers audio amplifier input is connected to the record players pickup output circuit via switch contacts B2 & B1, contacts B8 & B9 are also disconnected from each other, this disconnects the HT feed to the IF amplifier valve (the 2nd EF89) and also to the tuning indicator valve, when PH is not selected the input circuit of the audio amplifier is connected to the receivers demodulator circuits via switch contacts B2 & B3, the relevant demodulator output being selected by the position of switch A via switch contacts A5 & A6 for AM or via switch contacts A5 & A4 for FM.

Section C: L (long wave) When this section is selected the long wave RF coil (SP11) is switched in via switch contacts C3 & C4, the tap on that coil is connected to the medium wave coil (SP9/10) and the medium wave trimmer (C27) The long wave coil connects to the grid circuit of the mixer via switch contacts G2 & G3 and switch contacts K2 & K3

The oscillator inductance for long wave is made up of coils SP13 & SP14 connected in series, SP13 is the medium wave oscillator coil.

Section D & E: Fa-Ru....Not entirely sure yet what this sections function is, I tried Google translate based on what's in here:

http://www.radiodesign.de/museum/bil...super99bda.pdf

but I can't quite make sense of it, maybe someone else can, anyways from the switch descriptions so far it isn't difficult to figure out what connects with what when the button is out or when it's depressed. Unselected it introduces a +ve voltage to the FM demodulators -ve output rail that controls the gain of the last IF amplifier on FM (via its suppressor grid) and which also supplies the grid voltage for the tuning indicator on FM via switch contacts D8 & D9, contacts D8 & D9 can only supply this +ve voltage when UK (FM) is selected due to switch contacts H8 & H7, also switch connections E2 & E3 connect the antenna input circuit to a series combination of the short wave wave antenna winding of SP8 and the medium wave antenna winding of SP9/10. When the function is selected, the antenna input circuit is only connected to the short wave antenna winding of SP8 via switch contacts E2 & E1 and the +ve voltage mentioned above is disconnected.

Section F: M (medium wave) When this is selected, contacts F8 & F7 short out the longwave oscillator coil (SP14) The medium wave oscillator coil (SP13) is the only one left in circuit due to the action of switch contacts G8 & G9.

Section G: K (short wave) When selected, switch contacts G2 & G1 connect the short wave RF coil (SP8) into circuit, switch contacts G8 & G7 connect the short wave oscillator coil (SP12) into circuit.

Section H & K: UK (VHF/FM) When selected, switch contacts H8 & H7 connects HT to the VHF/FM tuner head, switch contacts K2 & K1 connects the output of the 1st FM IF amplifier transformer to the grid circuit of the mixer which also serves as the 2nd FM IF amplifier when the UK (VHF/FM) function is selected......Phew.

I hope this might be of some use.

Guilty as charged if there's any errors.

Lawrence.

Last edited by ms660; 17th Feb 2018 at 4:45 pm. Reason: rolling edit...spellin, gramma etc.
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Old 17th Feb 2018, 9:07 pm   #17
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Default Re: Help with Braun MT99R

Sorry for the delay. Been visiting mum in the New Forest. Just got back and caught up with the thread.
Here are some pictures of how the deck motor is connected to the brown and black wires that look like they go to the mains transformer. Mine are taped up and cable tied, but you can make out where they go. The other connections for the time arm audio wiring go to the din connection on the paxolin board shared with the tape player socket. Hope all this helps. Any further questions, fire away. Photos are taken by lifting up the deck out of the cabinet looking down into the radiogram.
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Old 21st Feb 2018, 6:10 pm   #18
muttley1984
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Default Re: Help with Braun MT99R

Thanks Sobell1980 for the pictures, very helpful indeed and I really hope your unit is still in fine working order!

I am still struggling a little working out the pictures and could do with some confirmations if you don't mind?

Can you confirm that the brown and black motor wires come down through the guide hole at the top of the picture and then just connect directly onto the transformer terminations? The picture shows a lot of yellow cable 'ducts' which I presume are nothing to do with the motor wiring, is that correct?

I think I can see four or five termination points on the top of the transformer? Am I correct in assuming that these points are the voltage levels referenced on the circuit diagram and so if I am connecting a 240V motor I should just use the outer termination points?

Regarding the 3rd and 4th pictures I believe these just show the reverse side of the paxolin plate that is shown on my original pictures and thus you are confirming that the two wires from the cartridge connect into the 2 x 4mm sockets on the paxolin plate shared by the tape socket?

Please forgive my ignorance and the novice question but can anyone advise an adequate termination method for terminating the cartridge wires into those sockets? The socket diameter and length appears vey large compared to the wire diameter. Is a length of bare twisted copper wire and some solder good enough or should I be looking to crimp a suitable connector to better terminate the wire into the socket?

When I get to my grandmas next I will take a picture from the same perspective as yours and will make sure I check that the circuit behind the paxolin plate is actually still present!

Can you confirm that you assumed the components referenced on the circuit diagram as part of the phono input dotted box i.e W55,W57 and C79 were just part of the chassis somewhere or integral to the cartridge?

Thanks also to MS660 for your very helpful explanation of the switch contacts. I am slowly starting to understand this now thanks to your explanation, much appreciated
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Old 22nd Feb 2018, 7:12 am   #19
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Default Re: Help with Braun MT99R

I will have another look this evening for you to clear all this up.
Regarding terminating the cartridge wires mine are simply soldered into place above the tape din socket. After all you are not going to be removing them again and eliminates poor pin connections.
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Old 5th Mar 2018, 1:39 pm   #20
muttley1984
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Default Re: Help with Braun MT99R

Hi All - I am now in possession of the BSR UA8 autochanger deck which came as part of my 'donor unit' which is a Pye black box. Now I have this at my house my plan is to give the deck some TLC using the service data info and make sure it is all working correctly in the Pye black box and then transfer it to my grandma's MT99R. I am now reasonably confident about what I need to connect and how to connect it thanks to all of your support

This first issue I have is the cartridge on the donor unit. It is an Acos GP67 cartridge. From a little reading this is not suitable and needs replacing. I have looked for a few weeks for an Acos GP91 3SC (as this is being used by Sobell1980 with good results) but without paying a lot of money I haven't found anything suitable so am looking for alternatives.

From my reading I believe I am after a ceramic cartridge rather than crystal and require a 'stereo compatible' cartridge to not limit the records I can play on the device without damage. I have come across the following options. Could anyone advise whether these are ok and secondly if I should have a preference? I am slightly concerned about the stated output being max 190mV, is this going to affect the performance in the MT99R drastically?

1. BSR SC12H
2. BSR SC5H
3. BSR SC-12M – stated as a replacement/upgrade to the SC12H. It states the sound quality should be better as it uses “diamond tip BSR ST20 stylus needle”?

https://www.maplin.co.uk/p/ceramic-s...e-sc-12m-hr10l

Would be extremely happy if anyone could advise/suggest a better available alternative

Thanks
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