New member - looking for parts and advice, lots of advice

[Colday0]

Also, is it possible to get moderator bypass approval at all? Having to wait for a mod to process and approve my posts certainly slows the process down.

I'm a long time user of other forums (StarDot for old BBC computers etc) and am well behaved.

[DMcMahon]

Originally Posted by DMcMahon

I do understand why this Challenge machine has a Fidelity label ?

David

Typo above, it should have read - I do not understand why this Challenge machine has a Fidelity label ?

David

[DMcMahon]

Originally Posted by Colday0

Apologies for being a berk. The Challenge machine does not have any markings or names on the mechanism panel.

Ah ha, the mystery is solved.

David

[Analogue man]

The Collaro motors do tend to be slow if they are cold, dirty or lubricated by dried up oil, A clue to the need for a good service is to run them until they get warm then they will probably start up much quicker.

[Sideband]

Originally Posted by Colday0

Also, is it possible to get moderator bypass approval at all? Having to wait for a mod to process and approve my posts certainly slows the process down.

I'm a long time user of other forums (StarDot for old BBC computers etc) and am well behaved.

Those are the conditions of belonging to the forum. After 10 posts I believe the intial moderation is lifted. It was introduced in the early days of the forum to weedle out some of the idiots or time-wasters thus reducing the time the moderators wasted going through and deleting such posts. Bear with it! Soon you will have the freedom of the forums (within the rules of course)!

[MostlyHarmless]

Michael can give sage advice when it comes to reel to reel tape recorders.

I've only ever worked on my own AKAI 1710 but i would recommend that you are careful with the use of Mineral based machine oils and plastics and rubber as the two should be "Never the twain shall meet" at least if you don't want the plastic to disintegrate and the rubber to swell up!

I believe silicon based oils are ok if coming into contact with rubber and plastics though I'm sure other more experienced forum members can clarify

MostlyHarmless

Originally Posted by Colday0

That's nice to hear. I noted the direct drive motors, is there any service thoughts on those, other than a tiny drop of machine oil?

I've been looking at the nasty grease. Not a great problem to sort out.

I noted that the motors are slow to start up and seem to run a little slow, will cleaning the mechanism likely sort that out or is there a 'pot' on the board the would allow adjustment?

[Colday0]

I do note on the circuit board that there is a potentiometer that I've not really explored yet. I am curious as to what that could be for. I'll get some decent photo's of the 'manual' that came with the machine in due course and upload them here for other's reference if that is of any use?

Hopefully my posts will become 'free' shortly.

[Colday0]

I presume MostlyHarmless is an Elite referral? I played many many hours with that as a child, and not a few as an adult with the new iteration as well. And it seems my posts are now 'released'.

I really need to get organised with repairing this Challenge device as I have several tapes of my now very elderly uncle rehearsing with his band which I want to digitise.

[Cobaltblue]

Originally Posted by Colday0

I presume MostlyHarmless is an Elite referral?

More likely a nod to Douglas Adams The Hitchhikers Guide to the Galaxy where the entry for the Earth is "Mostly Harmless"

It was also the title of the 5th Book of the series in the so called "trilogy", the 6th and final book being written after his passing.

Cheers

Mike T

[Colday0]

Ah yes. Also true. I guess the Elite reference is a nod to the same. I'd have to look and see which came first. But I digress...

[DMcMahon]

Originally Posted by Colday0

I do note on the circuit board that there is a potentiometer that I've not really explored yet.

From the Challenge schematic if the potentiometer is R24 I think that is the Erase adjustment. It is not shown as a trimmer but I think C17 would be the adjustment for the Bias or vicer versa.

David

[Radio Wrangler]

In tape recorders, usually the erase head is just driven flat out at whatever amplitude the oscillator stabilises at, but the bias feed of some erase oscillator signal into the record head winding is usually adjustable. The adjustment is made for minimum distortion.

With a 2-head tape machine, you have to record a section, wind back and replay into your distortion meter and keep repeating until you achieve a satisfactory result.

Here's where 3-head tape machines pay back their extra cost! You can record and play simultaneously and so watch close to real time distortion readings, twiddle the bias slaightly and about a second later as the tape moves between the heads, you see the change in distortion come through.

Machines with three motors and direct drive to the spool hubs, lack a lot of rubber, so they are much easier to keep going long-term. The Revoxes go a step further with direct drive to the capstan. Their only rubber belts are two associated with the tape position counter.

David

[Boulevardier]

Originally Posted by Radio Wrangler

In tape recorders, usually the erase head is just driven flat out at whatever amplitude the oscillator stabilises at, but the bias feed of some erase oscillator signal into the record head winding is usually adjustable. The adjustment is made for minimum distortion.
David

I agree - I've never come across a domestic tape recorder circuit with adjustable erase-signal level - anyway I suspect that a standard pre-set wouldn't be able to cope with the power going to erase head.

I haven't seen the schematic of this one, but could the other preset be to set the sensitivity of the record-level indicator?

Mike

[DMcMahon]

The Challenge and its Sound A43/A44 equivalents do not have sensitivity adjustment for the EM87 record level Magic Eye.

David

[DMcMahon]

Many domestic machines I have worked on have separate erase and bias adjustments, particulary Grundig. One of many examples is the TK 14 where R37 adjusts the voltage across the erase head, C19 adjusts the HF Bias current (measured as a voltage across the Record head or a voltage across 100 Ohm resistor connected in the earth side of the record head).

David

[Boulevardier]

Originally Posted by DMcMahon

Many domestic machines I have worked on have separate erase and bias adjustments, particulary Grundig.
David

Thanks - I obviously need to get around more - I haven't worked on a Grundig. But I have seen recorder circuits of a similar vintage that have adjusters for the record-level indicator.

Mike

[DMcMahon]

Yes Mike, many of the Grundig (including the TK 14) have sensitivity adjustment for the Record/Modulation level, particulary the EM 84 machines.

David

[dave walsh]

Hi Mike. You weren't sure of your TR's make and model [post 4*] but just sorting that out has become a bit of a "challenge"
I was quite intrigued by your initial story about the reel to reel machine that you aquired at a very young age but then returned to the Jumble Sale, possibly with a recording of PInk Floyd's "The Wall" on the tape. We've all done things like that ie missed out on items we didn't fully appreciate or understand at the time.

A brief glance at the listings suggested a date of 1982 for the double vinyl masterpiece but I knew it would be wrong [it's the DVD!]. I remember the reccord came out in 1979 [November] as a very good friend [sadly now deceased] gave it to me for Xmas! By then I had managed to buy an Akai 4000DS tape recorder [much underrated in my opinion] from my brother. I tranferred all four sides of this classic album to a 7" reel of tape for convenience and I still have it I found, however, that being able to listen to to the whole thing without interruptions [as in live performances later] was a different experience altogether and people came round just to have a drink and listen to the whole thing-sometimes over and over! Happy Days!

Dave W

Perhaps surprisingly, I didn't do the same thing with the first exraordinary 4 sided
artwork [Dylan's Blonde on Blonde 1966] but that wasn't a single storyline. 4 sides, just one song on No 4 and a blurred fold out photo on the double cover. A new world!

[Colday0]

I have an original pressing of The Wall (and all other Pink Floyd albums) on vinyl. Was in a record shop last week looking at new pressings of these albums which are c£30-50, but they had an original of Piper at the gates of dawn on the shelf, in worse condition than mine which was up for £300! Has made me re-evaluate playing the vinyl now.

Either way, not sure what to do with them as if I'm not going to play them, what's the point of having them? I have them all on CD anyway.

[dave walsh]

Point taken ColdayO [sorry I thought you were Mike there for some reason]. Gen X, Z or whatever have been buying lots of vinyl for years now, often without not even wanting anything to play them on! The covers are intriguing enough as artefacts so, either way, vinyl remains in demand as it always has been, whereas the new "fashion" ie tape recorders-especially from the 1960's onwards didn't last in quite the same way!

So it's left to hobbyists and enthusiasts like ourselves. The biggest problem is making sure that there are machines available to playback various tape formats, either for direct enjoyment or digital transfer. Even CD Players are not so readily available these days but many DVD machines will play those so that's my [hopefull] backup It "sounds" like your restoration challenges will be met though and the results very worthwhile.
Dave

I have a friend who can't play DVD's CD's or accept my compilations as his parner won't allow any older hardware in the house. It's all streaming apparently! She's very nice though.