Help diagnosing issues with a BSR TD2 portable

[HaddockLB]

Hello there, new member here. I'm posting here to ask for help regarding a vintage reel to reel tape recorder I picked up at a boot sale in summer last year. The machine is a BSR "Challenge, dual sound" single speed recorder dating from roughly the early 1960s using a mechanism that is shared with many other recorders. Since I got it I've been doing works on it to try and repair it to full working order.

The main and still unfixed issue is that when you turn the volume up to a regular listening level, the machine emits an awful howling/feedback noise that I cannot seem to diagnose.

Secondly FF and rewind don't work on the inverted T switch but all you need to do is give the reels a nudge towards the centre which will get them to engage with the rubber wheels that drive them forward/back.

I'm posting here mainly to ask for help on diagnosing and potentially fixing the howl. My first thought was capacitors so I went ahead, bought and installed some new ones that replaced the electrolytics, one across two terminals of the mains transformer/rectifier and three to replace a multi-section "can" type. All installed with no issue yet the howl persists!

I recorded a quick video on my phone to demonstrate the howling I'm on about. https://www.youtube.com/watch?v=nlhXpGfWhMQ

Also some pictures of the machine are attached. Please note that the inside pictures were taken prior to capacitor replacement.

[Paulus.d]

When I had one of these many years ago, it used to howl and feedback all the time ...... later on I discovered a pin had broke off of the ECL86 valve.
Replacing it fixed the problem .. I would look at the valve base to see if it has any loose pins or dry joints.

Regards Paul

[HaddockLB]

When I first took the machine apart I did get the valves out to take note of the numbers and if I recall rightly all the pins seemed to be intact and solid.

My main suspects at this point are either the ECL86 has gone bad internally or the ECC81 (presumably preamp) valve has gone bad. I know barely anything about valve electronics as this tape recorder is actually my first ever device that has them.

I didn't even know until I first openned it up when I began my fault finding and making repairs. Another thing of note when this machine is switched on and has been running for many minutes it gets a bit smelly presumably to be expected with 50+ year old electronics.

I also asked for advice on a R2R FB group and one pointed out that it could even potentially be the magic eye tube (presumably an EM84) that serves as a VU meter.

And yet another suspect that is on my mind are a few other small capacitors that are on the board along with old resistors that might have gone out of tolerance. But currently I'm going to bet the issue is from either valves or capacitors. I think I'll go browse tonight to order some replacement valves.

Unfortunately with my age I live with two parents who just think I'm just wasting my money on fixing up this "silly old piece of rubbish" to put it in their words.

[Welsh Anorak]

I notice in your first picture there is a yellow and red capacitor on a tagstrip - have you changed this?
Also clean the record/play switch with switch cleaner.
If new valves don't do the trick then we can help.

And it's not a piece of rubbish - if it is many of us own rubbish dumps!

[HaddockLB]

Originally Posted by Welsh Anorak

I notice in your first picture there is a yellow and red capacitor on a tagstrip - have you changed this?
Also clean the record/play switch with switch cleaner.
If new valves don't do the trick then we can help.

And it's not a piece of rubbish - if it is many of us own rubbish dumps!

Yep. That cap is one of the ones I replaced. I replaced that and the three caps inside the can on the main board. I'm going to take it to my gramps next week and hopefully give it a full service with his help. He knows his valves as he worked as a TV repairman in the 60s just before TVs began switching to transistors. Also ordered a replacement ECL86.

[ben]

That certainly sounds like a valve has gone 'microphonic'. If it were more high pitched I would suggest components around the tone control, but that does not seem the case here. A valve swap will help narrow this down.

The poor spooling is just sticky brown grease on the linkages that shift the reel tables into contact with the motor or idler. Also near the joystick. Look on the deck chassis udnerside too, there 's something there too to check, IIRC. A clean and relubrication (NOT WD40 - can be useful initially to free things up, but then clean off and use light grease)

Another thing to be wary of: blanket replacement of components at once. This is not a criticism of the OP, but unfortunately, the internet seems to be full of people with little or no knowledge whose only contribution to conversations like this is to say 'recap it!' Now, those of us who know this type of gear are well aware of certain problem capacitor types which are almost guaranteed to be leaky: Hunts moldseal, wax/paper types, TCC, Rifas, red/black plesseys, etc. But the average electrolytic is nowhere near as problematical.

The result is people new to the hobby being told this blind capacitor swap nonsense, then there's a deluge of threads with "I changed the capacitors and it still won't work/ it's now dead/ it's now worse/ it's now got a noise..." . Not only do people not learn anything this way, it wastes time and money and can introduce new problems due to solder splashes, excess pcb handling, wrong polarity, lifted pcb traces, wrong values fitted, etc.

It's best to first narrow down the fault, usually with the aid of a meter, then replace one thing at a time and note the results.

Anyway enough of my ranting and raving, we are here to help so ask any questions you may have!

[HaddockLB]

Thanks for all the advice. My family were at gramps' today as it was his birthday. I brought the recorder down to showcase it to everyone and to play a game of "name that tune" with the reel of tape that came with the machine. Contains songs ranging from between 1962 and 1978 presumably all recorded from the radio back in the 70s by the previous owners. I personally enjoy how lo-fi the music sounds coming out of this machine when its working right.

When I showed him the issue he agreed as well saying that a tube has probably gone microphonic. Will bring it to him again next Wednesday if all goes to plan and if the replacement valve arrives on time as well as some contact cleaner and isopropyl for general cleaning at the same time.

[HaddockLB]

Also before Weds I wonder if one could enlighten me on the true manufacturer/origins of this machine?

Looking on the underside is a plastic badge that presumably is this machine’s serial number. Again this machine seems to be obscure in that my google searches for “BSR Challenge” didn’t bring up much info.

Also there is a jumper underneath that connects terminals on the mains transformer. I haven’t touched it ever since I got the machine.

The serial badge reads “A46/62.01245” so I wonder if one who knows their serial formats could deduce a manufacturer or manufacture date of this machine?

[Station X]

Challenge were an Irish company who also made transistor radios.

Look at this radio and you'll see that the logo is similar to that on your tape recorder:-

https://www.radiomuseum.org/r/challenge_all_transistor_r18.html

[DMcMahon]

Originally Posted by HaddockLB

The serial badge reads “A46/62.01245” so I wonder if one who knows their serial formats could deduce a manufacturer or manufacture date of this machine?

I think possibly the A46/62 is actually A46/G2, which is a model of Sound. Sound were produced by TRE who were Tape Recorders (Electronics) Ltd of London. If so I am unsure how this would tie into the possible Irish manufacture origin ?

According to "A Guide to British Tape Recorders" book the Challenge Dual Sound used the BSR TD1 tape deck.

So I do not think it is a BSR recorder, although BSR did do some R2R's, the BSR identification is just the tape deck chassis.

As per this link I have a Challenge R2R but mine uses a Collaro Studio tape deck.

https://www.vintage-radio.net/forum/showthread.php?t=185575

David

[Tractorfan]

Hi,
I would be inclined to move the voltage selector to the higher voltage position.
UK mains voltage is nominally 240 volts, and the higher setting would be a little kinder to the circuitry.
Cheers, Pete.

[llama]

I think the voltage selector should be in the other position. Seems likely that a previous owner dropped the selector position down to a lower value to give the machine extra oomph - maybe to try and compensate for a failing valve.
Unless I've misconstrued the photo. Anyone?
Graham

[DMcMahon]

Yes well spotted, agree that for UK use with nominal 230/240 volts mains voltage, the mains selection link should be in the other position.

David

[HaddockLB]

Moved the link and briefly tested. Only noticable difference I think is the initial warmup time but maybe is the reason that when I had the machine running before for a while it would start to smell and some metal parts get pretty hot. I take it that they had links like this because the voltage tolerances on the secondary side and potentially for use in mainland europe where the voltages are quoted as 220V as opposed to the UK's 240V supply. I expect that voltage does not dictate tape speed as the BSR mechanism incorporates a "shaded pole" AC motor which if I did my research right is a synchronous motor whose RPM is tied to the 50Hz supply frequency.

[Ted Kendall]

Originally Posted by HaddockLB

Unfortunately with my age I live with two parents who just think I'm just wasting my money on fixing up this "silly old piece of rubbish" to put it in their words.

No experience is wasted. You might tell them that...

[DMcMahon]

Yes unless seriously abnormally low the mains voltage value will not affect the motor speed.

David

[DMcMahon]

Originally Posted by DMcMahon

I think possibly the A46/62 is actually A46/G2, which is a model of Sound. Sound were produced by TRE who were Tape Recorders (Electronics) Ltd of London. If so I am unsure how this would tie into the possible Irish manufacture origin ?

According to "A Guide to British Tape Recorders" book the Challenge Dual Sound used the BSR TD1 tape deck.

David

The book also states that the Sound A46 used the BSR TD2 tape deck.

Main differenence betweem the TD1 and TD2 tape decks being that the belt drive of the motor to flywheel in the TD1 was changed to idler drive in the TD2.

David

[HaddockLB]

Indeed, I say mine is a TD2 as it is all idler driven the only belt is from the main flywheel/capstan which was loose when I originally got it so of course I replaced that pronto also as luck would have it my replacement ECL86 just arrived as I was typing this reply. Will be fitting it on Wednesday with gramps.

[HaddockLB]

Another update. Took it to gramps and we stripped it down together and fully regreased the linkages. FF and rewind are now fully working. Also replaced the ECL86 but still microphonic issues. After giving them the tap test. The bad valve is the ECC81 preamp. So got one on order that should show up later this week.

[McMurdo]

Microphonic valves can be a problem in guitar amplifiers and some modern Chinese-made ones have to be selected for the least microphony in certain positions. In fact some suppliers will select them for you, I guess they do a tap test!