Help to Identify Zonal 675 Tape vs Ampex 478 - UK Vintage Radio Repair and Restoration Discussion Forum

Humber888 · 16th May 2015, 2:08 pm

I've come across three 10.5" NAB spools of Tape. All three NABs are marked Ampex 478, but two of the boxes they came in are Zonal 675s and the third Ampex. So, is there an easy way of telling what the actual tape is (assuming the tapes are either Ampex or Zonal). All tapes are back coated but only two have leaders and, of these, one has a very short stub of leader which looks like it starts with a colour coded 478 and serial number on the splice. The other's leader is just plain yellow.

So, I've probably got one reel identified as 478, but the others are iffy. I don't particularly wish to try them yet on my Revox in case any Ampex ones are suffering from 'sticky shed'.

Any suggestions on identifying them?

Mike

bobreel · 16th May 2015, 5:41 pm

I have several spools of Zonal tape and they all have what appears to be original yellow leaders. If thats of any help.
Bob.

Restoration73 · 17th May 2015, 5:38 am

Most tape sheds brown or black oxide - genuine Zonal seems to shed a white dust.

Humber888 · 17th May 2015, 5:02 pm

Thanks to you both for your comments. Closer inspection suggests that two of the spools hold Ampex 478 (very matt black backing) and the one with yellow leader may be Zonal as its black backing is shinier than the other two.

Mike

Ted Kendall · 17th May 2015, 5:05 pm

Zonal 675 is black on both shiny and matt sides, and the oxide face is really shiny - very well callendered. Ampex oxides are generally brown and matt in appearance.

Humber888 · 17th May 2015, 5:35 pm

Well, Ted's comment stuffs my theory of having one reel of Zonal 675 as it is brown on the oxide side and has black vaguely-shiny backing. I am fairly happy that the other two tapes are both Ampex 478 as they appear identical and one has the remains of '478' on the joining paper splice to where the leader would be attached. Maybe I should just dump the tapes for safety and keep the NABs. My preferred tape is Agfa PEM368 anyway.

Mike

saxmaniac · 17th May 2015, 10:18 pm

Have you tried fast winding from one end and back to see if there resistance to winding? If they are sticky then it shouldn't mess up the machine too much?

Radio Wrangler · 17th May 2015, 11:08 pm

Seems a shame to dump tape that could be OK. Have you tried winding any over a cotton bud soaked in alcohol?

David

Humber888 · 18th May 2015, 9:38 am

No, I haven't put the reels on the Revox yet. I was trying to narrow down the make first before committing to spooling them through. I will take Saxmaniac and RW's advice and stop playing 'chicken'.

Mike

Humber888 · 18th May 2015, 2:15 pm

So, not the best results ever. The maybe Zonal tape spools OK but has loads of splices. The first Ampex 478 tape slowed down to a crawl during spooling and I had to clean crusty deposits off the tape guides. So, I think these tapes are toast.

More irritating is the fact that the Revox A77 has partially packed up since last use. On switch-on, the power lamp and tape detector bulb did not come on and the capstan motor did not start. The reel motors work, so sounds like at least one power supply has failed. I think the A77 is now due for a major refurbish when I get a chance, but I'm currently working on an HP3580A audio spectrum analyser as a priority.

Mike

SteveCG · 18th May 2015, 2:26 pm

When you do your refurbishment be on the look-out for skeleton preset resistors where the wiper arm has come away due to corrosion. There is one in the main PSU. Also the Rifa capacitors used in the motor circuits (often found with cracked casing); these fail short circuit and so cook the low value resistors in series with them.

Radio Wrangler · 18th May 2015, 2:42 pm

Ah, well, shame it's not useful stuff.

Some tape I acquired in the 80's and thought was zonal has blue matt-backing.

Rifas fail short but rely on mains power to blast the foil away to clear the short, but in applications with resistors in series, the resistor may cop it first.

My A77 hasn't been powered for some time. I need to swap the Rifas and I think I'll do all the presets before it sees power again (besides the mains cable is hiding somewhere in the attic)

I like HP3580s a lot. With an 8640 they make a good phase noise tester.

David

Ted Kendall · 18th May 2015, 8:10 pm

The blue stuff may well be Zonal, but more BBC type 102 than type 200 (675, PEM 368 and BASF SPR50). It will take about 6dB less level and needs different bias levels to 675.

Radio Wrangler · 18th May 2015, 11:26 pm

Thanks, Ken. I'll note that on its boxes.

David

16th May 2015, 2:08 pm	#1
Humber888 Heptode Join Date: Jul 2012 Location: Bromley, London, UK. Posts: 702	Help to Identify Zonal 675 Tape vs Ampex 478 I've come across three 10.5" NAB spools of Tape. All three NABs are marked Ampex 478, but two of the boxes they came in are Zonal 675s and the third Ampex. So, is there an easy way of telling what the actual tape is (assuming the tapes are either Ampex or Zonal). All tapes are back coated but only two have leaders and, of these, one has a very short stub of leader which looks like it starts with a colour coded 478 and serial number on the splice. The other's leader is just plain yellow. So, I've probably got one reel identified as 478, but the others are iffy. I don't particularly wish to try them yet on my Revox in case any Ampex ones are suffering from 'sticky shed'. Any suggestions on identifying them? Mike

16th May 2015, 5:41 pm	#2
bobreel Triode Join Date: May 2010 Location: Wrexham, Clwyd, UK. Posts: 20	Re: Help to Identify Zonal 675 Tape vs Ampex 478 I have several spools of Zonal tape and they all have what appears to be original yellow leaders. If thats of any help. Bob.

17th May 2015, 5:38 am	#3
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: Help to Identify Zonal 675 Tape vs Ampex 478 Most tape sheds brown or black oxide - genuine Zonal seems to shed a white dust.

17th May 2015, 5:02 pm	#4
Humber888 Heptode Join Date: Jul 2012 Location: Bromley, London, UK. Posts: 702	Re: Help to Identify Zonal 675 Tape vs Ampex 478 Thanks to you both for your comments. Closer inspection suggests that two of the spools hold Ampex 478 (very matt black backing) and the one with yellow leader may be Zonal as its black backing is shinier than the other two. Mike

17th May 2015, 5:05 pm	#5
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,675	Re: Help to Identify Zonal 675 Tape vs Ampex 478 Zonal 675 is black on both shiny and matt sides, and the oxide face is really shiny - very well callendered. Ampex oxides are generally brown and matt in appearance.

17th May 2015, 5:35 pm	#6
Humber888 Heptode Join Date: Jul 2012 Location: Bromley, London, UK. Posts: 702	Re: Help to Identify Zonal 675 Tape vs Ampex 478 Well, Ted's comment stuffs my theory of having one reel of Zonal 675 as it is brown on the oxide side and has black vaguely-shiny backing. I am fairly happy that the other two tapes are both Ampex 478 as they appear identical and one has the remains of '478' on the joining paper splice to where the leader would be attached. Maybe I should just dump the tapes for safety and keep the NABs. My preferred tape is Agfa PEM368 anyway. Mike

17th May 2015, 10:18 pm	#7
saxmaniac Heptode Join Date: Oct 2007 Location: Birmingham, West Midlands, UK. Posts: 618	Re: Help to Identify Zonal 675 Tape vs Ampex 478 Have you tried fast winding from one end and back to see if there resistance to winding? If they are sticky then it shouldn't mess up the machine too much?

17th May 2015, 11:08 pm	#8
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: Help to Identify Zonal 675 Tape vs Ampex 478 Seems a shame to dump tape that could be OK. Have you tried winding any over a cotton bud soaked in alcohol? David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

18th May 2015, 9:38 am	#9
Humber888 Heptode Join Date: Jul 2012 Location: Bromley, London, UK. Posts: 702	Re: Help to Identify Zonal 675 Tape vs Ampex 478 No, I haven't put the reels on the Revox yet. I was trying to narrow down the make first before committing to spooling them through. I will take Saxmaniac and RW's advice and stop playing 'chicken'. Mike

18th May 2015, 2:15 pm	#10
Humber888 Heptode Join Date: Jul 2012 Location: Bromley, London, UK. Posts: 702	Re: Help to Identify Zonal 675 Tape vs Ampex 478 So, not the best results ever. The maybe Zonal tape spools OK but has loads of splices. The first Ampex 478 tape slowed down to a crawl during spooling and I had to clean crusty deposits off the tape guides. So, I think these tapes are toast. More irritating is the fact that the Revox A77 has partially packed up since last use. On switch-on, the power lamp and tape detector bulb did not come on and the capstan motor did not start. The reel motors work, so sounds like at least one power supply has failed. I think the A77 is now due for a major refurbish when I get a chance, but I'm currently working on an HP3580A audio spectrum analyser as a priority. Mike

18th May 2015, 2:26 pm	#11
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: Help to Identify Zonal 675 Tape vs Ampex 478 When you do your refurbishment be on the look-out for skeleton preset resistors where the wiper arm has come away due to corrosion. There is one in the main PSU. Also the Rifa capacitors used in the motor circuits (often found with cracked casing); these fail short circuit and so cook the low value resistors in series with them.

18th May 2015, 2:42 pm	#12
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: Help to Identify Zonal 675 Tape vs Ampex 478 Ah, well, shame it's not useful stuff. Some tape I acquired in the 80's and thought was zonal has blue matt-backing. Rifas fail short but rely on mains power to blast the foil away to clear the short, but in applications with resistors in series, the resistor may cop it first. My A77 hasn't been powered for some time. I need to swap the Rifas and I think I'll do all the presets before it sees power again (besides the mains cable is hiding somewhere in the attic) I like HP3580s a lot. With an 8640 they make a good phase noise tester. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

18th May 2015, 8:10 pm	#13
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,675	Re: Help to Identify Zonal 675 Tape vs Ampex 478 The blue stuff may well be Zonal, but more BBC type 102 than type 200 (675, PEM 368 and BASF SPR50). It will take about 6dB less level and needs different bias levels to 675.

18th May 2015, 11:26 pm	#14
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: Help to Identify Zonal 675 Tape vs Ampex 478 Thanks, Ken. I'll note that on its boxes. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done