Sound Belle reel-to-reel heads
I have an old Sounds Belle tape recorder - a very neat design from the late 50s - but it unfortunately doesn't produce any sound. There is a button labelled P.A. (I guess for Public Address) which connects the microphone input straight through to the amplifier section and to the loudspeaker, and this works fine.
But nothing at all from the tape, so I suspect the play/record head may not be working. I don't have a signal injector but I managed to wire up an old ceramic record player cartridge to the wires to the tape head (as I believe the signal levels are similar) and miraculously this worked. The tape player is only mono, of course, but the tape head has 4 connectors. Two of these are soldered together and the other two carry the signal. I'm wondering if the other two connectors are for a second channel and if I use those 2 connectors and short out the ones that are currently used, maybe this might work? Any suggestions? Or any ideas where I might find a replacement head at a price that would make this worth repairing? |
Re: Sounds Belle reel-to-reel heads
Tape heads have two coils which are normally connected in series. Sometimes this connection is external, as appears to be the case here.
A crystal cartridge gives several times the output level of a tape head so your replay amplifier may be low gain, equally the head may be faulty. If you have a multimeter check it for DC resistance, assuming there is a reading (out of circuit) the head is probably O.K. Ideally you should demagnetise the head after passing DC through it but at this stage don`t worry. I assume you don`t have a tape with a known recording on it to try. |
Re: Sounds Belle reel-to-reel heads
There is scant information about this recorder as the tape-deck manufacturer may need some researching. To help your searches, your machine is a SOUND "Belle" (not Sounds) made by Tape Recorders (Electronics ) Limited. I have the original 1959 sales brochure for this rare model - but not readily accessible at this time.
|
Re: Sounds Belle reel-to-reel heads
The service info is up top:
At any rate for serial 35000 up. Apparently earlier version had ECC83 instead of EF86 front end. https://www.service-data.com/section.php/7622/1/a15935 It's actually a Sound Belle according to the service sheet. |
Re: Sound Belle reel-to-reel heads
I have found a circuit diagram: https://www.service-data.com/section.php/7622/1/a15935. It's a bit hard to follow but seems accurate. I do have a tape but I don't know if there is anything on it. I tried recording on it from the microphone and playing it back, but nothing. Whether it is not recording or just not playing back - or maybe both - I don't know. I was wondering about making a coil with the lead from a jack plug and bringing it close to the head. Would this work? Would it work the other way around to check the recording?
I can't find any replacement heads on ebay unfortunately. |
Re: Sound Belle reel-to-reel heads
I was reading that the Sound Belle does not use capstan drive, that is fairly unusual, I guess it uses a form of rim drive ?
|
Re: Sound Belle reel-to-reel heads
Have you checked the heads for continuity readings as advised above ?
If you had access to another recorder (working) you could check if the tape you have has any existing recordings on it and if the new recording attempts are actually being recorded to the tape. |
Re: Sound Belle reel-to-reel heads
I think this is a badged Incis (Italian), as were many budget machines of the 1960s.
|
Re: Sound Belle reel-to-reel heads
Yes, it has a rim drive and although the motor is really quiet the drive to the spool via the rim is very noisy so I will have to dismantle that.
Unfortunately I don't jave another tape recorder so need to fimd other ways of testing. |
Re: Sound Belle reel-to-reel heads
Quote:
Paul |
Re: Sound Belle reel-to-reel heads
Presumably without a capstan the tape speed will vary as the diameter of tape on the right hand spool changes. This would make it impossible to play a tape from another machine that did use a capstan for constant tape speed. An unusual design!
Checking the signal at the record/playback head, when set to record it looks fine with the bias at about 47kHz. Similarly the erase head shows the right signal. So it seems that the tape recorder is certainly working as far as the r/p head. The tape head does show a reasonable resistance of about 230 ohms so I think I now have to find a way of sending a magnetic signal through the head to see if that gets through or finding a bit of tape that I'm sure has something on. My model also has Daly and ERO capacitors so it sounds like the same model and probably UK made. Surprisingly, the capacitors test out as still withing spec but I will be replacing them once I can sort out the R/P head. Apologies if I seem a bit clueless but this is the first time I've worked on a tape recorder. Record players and amplifiers have been more my thing up to now but this seemed like a challenge. |
Re: Sound Belle reel-to-reel heads
Are you measuring the Record Bias/Erase signals using an oscilloscope ? If you have a scope then you could monitor the record signal and make sure it is getting through to the head.
At the head itself the record audio signal is modulated onto the much larger record bias signal so can be difficult to see. Similarly when replaying a tape (that has a recording on) you can monitor the playback signal. David |
Re: Sound Belle reel-to-reel heads
Yes. On the scope I can see the bias signal and with the microphone connected I can see the overlayed voice frequency. So all seems to be fine recording and previously I injected a signal there from a ceramic cartridge and that played fine. So from the R/P head back through the recorder it all seems to work fine but when I try to record onto the tape and then play it back I get nothing at all.
|
Re: Sound Belle reel-to-reel heads
It sounds like it has got a very dirty head.
|
Re: Sound Belle reel-to-reel heads
Quote:
|
Re: Sound Belle reel-to-reel heads
Thanks for the interesting information, Paul. Do you happen to know why 2 of the connections on the head are just connected together?
|
Re: Sound Belle reel-to-reel heads
Ensure that the tape has not been wound on back to front.
|
Re: Sound Belle reel-to-reel heads
2 Attachment(s)
Quote:
|
Re: Sound Belle reel-to-reel heads
Quote:
|
Re: Sound Belle reel-to-reel heads
The tape needs to be in intimate contact with the head face. Is the felt pad in good condition to make this happen?
|
Re: Sound Belle reel-to-reel heads
Quote:
|
Re: Sound Belle reel-to-reel heads
Rim drive if designed well didn't produce much wow even on music. The Stenorette was one example and the Philips dictation machines another. The later Philips mini cassette was also rim drive. I have an old Stenorette which only has speed issues now because the rubber parts have hardened over time. The older valve based Philips dictation machines using 3" reels in a cassette were particularly well made in my opinion.
|
Re: Sound Belle reel-to-reel heads
You seem to have shown that the playback amp is working by connecting your ceramic cartridge to it. I think you should now test whether the R/P head is actually generating any signal. The simplest way of doing this is by holding a tape-head demagnetiser against the front of the head. If you haven't got a demagnetiser, you could wind a coil of enamelled copper wire (say, from a junk transformer) onto a large nail, and feeding (briefly) ac from the valve heater chain into the coil. If the head is working, you will get a good 50c/s hum from the amplifier when the demagnetiser or the magnetised nail is held against the head.
Mike Edit - sorry I'm not familiar with this machine, but I've assumed that it's a valve machine and that it has a 6.3V ac heater chain. Obviously, if it's a mains-fed heater chain, don't connect to this. |
Re: Sound Belle reel-to-reel heads
Schematic shows 6.3VAC heater supply from transformer winding.
|
Re: Sound Belle reel-to-reel heads
Sorry, Barry. I did see your post but I didn't understand the 2 coils bit. I was wondering if the 2nd coil was useable as the one being used is clearly defective. Without the wires connected to the head I can see the correct signals on my scope showing the bias at about 48k and sound from the microphone superimposed. With the wires connected to the head - nothing. So I'm sure the head is faulty.
|
Re: Sound Belle reel-to-reel heads
1 Attachment(s)
Very interesting posts, thank you all. Paul, your picture is exactly as mine (photo attached).
|
Re: Sound Belle reel-to-reel heads
Quote:
The drive to a record head is normally more or less constant current so you would expect a big drop in level when you actually connect the head to the amplifier / bias signal though you should still see something unless the head is dead short, which would be unusual. |
Re: Sound Belle reel-to-reel heads
Yes, you are right. Each half measures as 340 ohm, 680 between the points the 2 wires connect to. I don't really know if this is reasonable though.
|
Re: Sound Belle reel-to-reel heads
Sounds plausible so the problem is probably not the head itself so as mentioned above, is the tape in proper contact with the face of the head - then try the induced hum from a demagnetiser or other field source as also mentioned above.
Remember, the output from a crystal (ceramic) pickup cartridge is many times the expected output from a tape head, so do not assume the replay amplifier is working properly. |
Re: Sound Belle reel-to-reel heads
I'll try a coil from a sound source. I saw a video on how to do that on youtube!
The pressure pads seem ok and the tape does make good contact as far as I can tell. |
Re: Sound Belle reel-to-reel heads
Some progress - the coil induced a very small voltage on the head. I've decided to change the capacitors next as they can't be still good after 60+ years, No problems with the electrolytics but there are 4 capacitors of a type I don't recognise made by EAR with values of 0.001(x2), 0.002 and 0.005 uF. That is 1, 2 and 5nf. 2 are rated 250v and the other 2 are 750v. Can anyone suggest what to replace them with?
|
Re: Sound Belle reel-to-reel heads
1 Attachment(s)
Here is a picture of them
|
Re: Sound Belle reel-to-reel heads
Are they ERO ?
|
Re: Sound Belle reel-to-reel heads
Yes, ERO brand
|
Re: Sound Belle reel-to-reel heads
I do not think ERO are particularly known for going bad, but like most makes when they get to this grand old age they most likely are not at their best.
I personally would go for Polypropylene, they are often yellow and often rated at 630 volts, they will probably be physically smaller than your 250 volt ones. Depending upon where the 750 volt ones are used, the 630V rated ones maybe fine, I have used 630V ones in place of 1,000V rated ones on output transformers with no problems. Often they have to be brought in minimum quantity of 5 or 10. Loads of sources like Farnell, RS, Cricklewood to name just 3, as well as many eBay sellers etc One eBay seller example is (I am not connected) - https://www.ebay.co.uk/itm/Axial-Pol.../253063259761? ssPageName=STRK%3AMEBIDX%3AIT&var=552134715900&_tr ksid=p2057872.m2749.l2649 David |
Re: Sound Belle reel-to-reel heads
Many thanks
|
All times are GMT +1. The time now is 7:59 pm. |
Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.