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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 24th Oct 2020, 7:25 am   #41
cdm1christopher
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Default Re: Vortexion reel to reel tape recorder WVA series 5

This schematic shows a 25k variable resistor. Follow metre then bridge rectifier and along that bias circuit you will see a 25k resistor with an arrow through it. Like I said on mine there is no such resistor.
But this is for the cbl 5 not vortexion. Just to clear things up.
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Old 24th Oct 2020, 7:32 am   #42
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Default Re: Vortexion reel to reel tape recorder WVA series 5

12bh7 thats handy cheers Bill.
It will all be looked at Monday as I have a load of gear to pick up today then unload tomorrow and find out what works and what don't. There's the FET 50/70 vortexion amplifier think only one they built using the FETs to capture the valve sound as opposed to transistors in there so that should be a good feed for the reel to reel give a descent sound.
400 mile round trip ew.
Thanks for help guys always appreciated.
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Old 24th Oct 2020, 10:05 am   #43
DMcMahon
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Default Re: Vortexion reel to reel tape recorder WVA series 5

Quote:
Originally Posted by cdm1christopher View Post
This schematic shows a 25k variable resistor. Follow metre then bridge rectifier and along that bias circuit you will see a 25k resistor with an arrow through it. Like I said on mine there is no such resistor.
But this is for the cbl 5 not vortexion. Just to clear things up.
As per Post 22, the Bias Adjustment/Set Bias (pot/variable resistor) surely is the Bias adjustment shown in top left corner of your front panel photo Post 9 ?

David
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Old 24th Oct 2020, 11:03 am   #44
ms660
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Default Re: Vortexion reel to reel tape recorder WVA series 5

So far as I can make out the CBL 5 circuit so far as component placement goes in that area is the same as what's shown in the OP's photo's, especially the photo in post#32 where the bias control the limiting resistor and the meter selector switch are clearly visible.

The limiting resistor in the photo could be a 39k? which is the value that appears to be used in the WVA 4 schematic.

Lawrence.
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Old 24th Oct 2020, 12:34 pm   #45
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Default Re: Vortexion reel to reel tape recorder WVA series 5

Good eyesight Lawrence, I think you most likely are correct. With my eyesight is is just the first band orange (3) that is maybe in question.

David
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Old 24th Oct 2020, 12:39 pm   #46
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Default Re: Vortexion reel to reel tape recorder WVA series 5

I could be wrong given the resolution and the angle but I would say Orange White Orange and a tolerance band possibly Gold in that order from top to bottom.

Lawrence.
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Old 24th Oct 2020, 12:50 pm   #47
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Default Re: Vortexion reel to reel tape recorder WVA series 5

Very difficult to be sure, agree with the white orange but struggling with the first band that should be orange, I thought the final band (tolerance ) looked like brown (1%).

David
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Old 24th Oct 2020, 3:09 pm   #48
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Default Re: Vortexion reel to reel tape recorder WVA series 5

More likely Gold, (5%) given the age, I would think.
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Old 24th Oct 2020, 8:03 pm   #49
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Default Re: Vortexion reel to reel tape recorder WVA series 5

Iíve just pulled the top off a Series 5 WVB and that resistor in its meter circuit is 39k, which appears to be the same as the OPís WVA.

The other component values in the oscillator circuit appear to be the same as the CBL which is the only Series 5 circuit I can find.

This set will give a value of Ď200í bias with the variable resistor turned fully up.

Bill
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Old 24th Oct 2020, 8:15 pm   #50
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Default Re: Vortexion reel to reel tape recorder WVA series 5

Looks like Gold was a good call.
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Old 24th Oct 2020, 8:31 pm   #51
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Default Re: Vortexion reel to reel tape recorder WVA series 5

Of course the clue was the Series 4 schematic denoting that the 39k was 5%
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Old 25th Oct 2020, 7:13 am   #52
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Default Re: Vortexion reel to reel tape recorder WVA series 5

So basically the resistor between the signal bias switch and the bias pot might need changing. Interesting it only goes to 200 on the meter. I would of thought it would go all the way over. Especially on the wvb as you can you the bias to create different sound effects depending on the setting of bias. Unless I'm thinking of a different model. Anyhow it's certain there's not enough current getting through hence the low bias setting. I've got all this gear to sort out today. But I'll have a look tomorrow. That Vortexion 50/70 is immaculate got a good deal there. So I've got my kit the WVA, 50/70 and the first super 50 Vortexion 1946? So be some fun to have plus I got a load of mixing gear so be able to do some interesting recordings.
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Old 28th Oct 2020, 12:01 pm   #53
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Default Re: Vortexion reel to reel tape recorder WVA series 5

Well I've had to drop that 39k resistor down to 10k. So I'm now getting 200 on the signal/bias switch. Which is obviously what it should be. Not 50 max which is all I was getting. Initially thoughts where the 12BH7. But thats fine. Glad it is. Those replacement Brimar ones which I have cost a ****** fortune.
So all okay at minute. I'll run some tapes through later see how it sounds. Workman in at the moment so ****** chaos.
Mind you I'm baffled as having to drop 27k to get correct reading?
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Old 28th Oct 2020, 2:37 pm   #54
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Default Re: Vortexion reel to reel tape recorder WVA series 5

Unless my reading of the admittedly incorrect circuit is wrong all you have done is altered the calibration of the meter, not affected the bias level in any way.
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Old 28th Oct 2020, 4:45 pm   #55
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Default Re: Vortexion reel to reel tape recorder WVA series 5

If the components around the 12BH7 check out OK and you are happy that the valve is good, then I wonder if the bridge rectifier may have a partial fault and be dragging/reducing down the bias signal seen by the meter.

If you have a scope then check the bias signal at the Set Bias pot area and make sure it is a clean and stable sinewave and note its amplitude, the manual indicates frequency will be around 58kHz.
Also check the rectified signal going to the meter.
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Old 28th Oct 2020, 5:06 pm   #56
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Default Re: Vortexion reel to reel tape recorder WVA series 5

Em altered the calibration of the meter? I assume if you allow more current/voltage through the circuit I'm sure that would impact on the circuit. Don't quite understand that one! And if only the meter has been calibrated then how would the sound/signal on the tape have improved I.e the bass and treble are alot cleaner and crisper? I've come across quite a few circuits where the actual components listed are not always a true representation of what should actually be there.
Still good check tomorrow.
Yes I was thinking re rectifier as why would the mounting screw of the rectifier have been undone and not fully screwed back. Suggests someone has had a fiddle there at some stage. I'm sure it would not unscrew itself!
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Old 28th Oct 2020, 5:08 pm   #57
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Default Re: Vortexion reel to reel tape recorder WVA series 5

Got that wrong way round increase not decrease
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Old 28th Oct 2020, 5:47 pm   #58
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Default Re: Vortexion reel to reel tape recorder WVA series 5

I can`t remember quite how those meter rectifiers go together but if it had been unscrewed it may have affected the clamping of the plates.

I don`t think the resistor you changed is in the bias circuit, I think it is the meter series resistor, if it is in the same position as the 82k on the CBL circuit.

I would expect differences between the WVA / B and the CBL because the heads are totally different for the mono and stereo machines.
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Old 28th Oct 2020, 5:54 pm   #59
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Default Re: Vortexion reel to reel tape recorder WVA series 5

No need to reduce the value of the 39k resistor, just find the fault.

Lawrence.
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Old 28th Oct 2020, 7:39 pm   #60
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Default Re: Vortexion reel to reel tape recorder WVA series 5

Anyone know the exact spec of this diode like I say I've never seen one before its obviously a bridge vf rectifier so low voltage but as usual not having the correct schematic or parts list don't help.
Cheers Chris
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