Studer / Revox etc BiPolar PROMS! Question and concerns! - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

jascha · 23rd May 2020, 1:35 pm

Hi again,

I have extracted the relevant pages from the Service Manual that will cover both boards, hopefully in pdf format they are clearer.

Thank you once again for all your expert advice, help and patience.

Much appreciated

jascha · 23rd May 2020, 1:42 pm

Hi guys,

I have taken out sections of the relevant parts of the SM for your attention. I hope that the website does not reduce the image quality since it's in pdf format this time. As I mentioned please look out for ICs 15 & 18 on the Spooling motor board and IC9 on the other board.

I thank you for your help, patience and generosity once again. This beyond my understanding of how these Ics work and that's why I'm a bit concerned in case they go faulty as they are not so easily replaced.

Regards
J

jascha · 23rd May 2020, 1:43 pm

oops the message came out twice thinking it was not uploaded. Apologies

SiriusHardware · 23rd May 2020, 1:47 pm

Quote:

Assuming Siriushardware's programmer links to a PC

Yes, it's a PC-connected Hi-Lo Systems ALL-07A programmer so I can read device contents and save them as files, as well as writing the code into new blank devices of course.

Of those you mention, it may not program the Harris or MMI devices, but I am almost certain it does the AMD, Nat Semi, and Philips / Signetics devices.

If the original devices do happen to be Harris or MMI devices, not a problem as I can read them as though they are any of the other types.

jascha · 23rd May 2020, 1:50 pm

Thanks again,

I will attempt to get into the machine and lift off the stickers covering the ICs so we can get to the bottom of this issue and curiosity

It would be an absolute shame if one such device would fail on us making such a machine useless. They sound amazing.

Best regards

SiriusHardware · 23rd May 2020, 1:55 pm

jascha, thanks for the service manual upload, always interesting to read.

Unfortunately the parts list only refers to the PROMs by their proprietary part numbers which is not unreasonable, as only that type of chip programmed with that specific code will do.

You can either carefully lift the labels to read the chip numbers, or we can make assumptions about compatible types based on the pin connections on the circuit diagram. We appear to have narrowed it down to several types which could be used as replacements even if we never read the numbers under the labels on your devices.

jascha · 23rd May 2020, 4:01 pm

I opened one of my machines and luckily the label must have come off from the IC on the Capstan motor board. I attach a photo of the IC. I would imagine that they used the same type of ICs on the other board? I managed to peel off part of the label and it looks like it’s the same chip.

We are getting somewhere it seems

Thanks again

SiriusHardware · 23rd May 2020, 4:23 pm

One is certainly a Phillps / Signetics 82S123N, the other might be, it would be good if you could be absolutely sure.

I'll just fire up my programmer software and make sure it definitely does do that device or one of the others which are pin compatible. Back shortly.

Make sure those labels don't get separated from their chips, fix them back on afterwards by whatever means necessary.

SiriusHardware · 23rd May 2020, 5:20 pm

After looking around in the programmer's software, these are the pin-compatible, read-compatible devices which I can do, starting with the type which is already fitted in your machine.

Philips / Signetics
82S123
82S123A

AMD
27S19
27S19A

National Semiconductor
DM74S288

Harris
7603

While my programmer does support some MMI PROMS it does not support the 6331.

If the chip has 'N' on the end of the number as yours do, that usually just means that the chip is in a DIP package. The 'A' suffix on two of the devices above signifies a version which has a faster access time but is otherwise no different to the plain non-'A' version. For your purpose either will do but the 'A' version may be more expensive.

Also note that there are quite a few 'Tesla' branded clones of the National Semiconductor 74S... series PROMs with an 'MH' prefix instead of 'DM' as per National Semiconductor. If you go looking for '74S288' you may well be offered Tesla MH74S288s, if so, avoid.

Despite the similarity in the part numbers the Tesla devices, while read compatible with the Nat Semi versions, are hardly supported by any current or historic programmers. My programmer can't programme the Tesla devices either.

jsantoro · 23rd May 2020, 6:04 pm

Hi Folks,

Pardon me for jumping in, I new here and usually hang out on the tapeheads forum. I work primarily on Studer/Revix machines.(and any tube gear). Jascha and I were speaking about this offline for a bit
The Proms in question provide the sequencing for the drive transistors for the motor phase switching for the spooling and capstan motors. Bipolar proms were the one that could provide really fast access times back then, 50ns access I believe.
I've never seen one go bad but they are getting old..
I'm working on an A807 right now with a 2802 calibration EEPROM failing before my eyes, so anything is possible.
I will probably try to make a copy of them in the coming weeks from my personal 807 so between SiriusHardware and I we should be covered on both sides of the pond.
Jim

jascha · 23rd May 2020, 6:21 pm

Thanks again sir. Do you think that the partially uncovered chip might be different to the one that lost its label? To me they seem to look identical but as you say it would be worth removing the label for your reference and peace of mind.
When it comes to purchasing blanks I will only purchase exact replacements unless I am told otherwise if there are equivalents I can use.
I feel very positive that there is light at the end of this tunnel and a sigh of relief as these ICs have been on my mind causing some concern if they failed and am stuck without them. I shall try and remove the label and come back to you.
Thanks

jascha · 23rd May 2020, 6:33 pm

@ricard: I found the adapter on eBay you mentioned earlier so they do exist:
https://www.ebay.co.uk/itm/164101688490
Cheers

SiriusHardware · 23rd May 2020, 6:42 pm

I would not like to assume they were the same - the fact that every visible part of the number including the '8749' highly suggests that they are the same type of chip from the same batch but it is up to you.

Now that think we know what type of chip the original ones are I can assure you that any of the alternative types I say I can programme in #29 will work equally well, but by all means obtain the original 82S123 type if you can. Looking around, none of them are especially cheap apart from the MMI 6331, the one I can't program of course.

Do you have some kind of label making machine, maybe you can print new labels for both chips with the correct numbers on?

jascha · 23rd May 2020, 6:51 pm

I think printing the label is the least of my worries and I am sure I can find a way to print a nice label with similar fonts like the original.

I will search everywhere for them and will purchase 6 blanks so I can have reserved for both my machines. I will check a few stores also in my home town in Malta and when I go back on tour (as I’m a musician) I will search for them in local electronic shops. You would be amazed what you would find in multi storey electronic centres in China... I have been there a few times and brought back every possible component I needed at the time. I bet they would even have these in stock in boxes of thousands and costing next to nothing!

.

I will pull out the label and be 100% sure and will come back to you.
I did search on eBay and found the 6331 which was the cheapest option but I’m pleased and thankful of your warning that your programmer doesn’t do the 6331 version! I shall stick to the originals and play safe

Thanks again

SiriusHardware · 23rd May 2020, 7:02 pm

If you do go to China and find boxes of PROMs for a few cents each be sure to bring us back a few National Semiconductor DM74S571s, as they are often needed, in pairs, for a different type of unit (not a tape recorder).

Good luck!

jascha · 23rd May 2020, 7:16 pm

I shall keep that in mind for sure but the question is when will be the next tour??
One place I always visit and a must in Beijing in called Zhong fa.... the photo gives an idea of what to expect... floors of tiny cubicles of Vendors selling every possible component!

Talking of obsolete parts I came across this website yesterday.... would it be of interest to you?

http://markhindes.easywebstore.co.uk/

Cheers

jascha · 23rd May 2020, 7:52 pm

Now we can be sure that all 3 ICs on both boards of the Studer A807 are identical Proms as I removed the label with some difficulty but worth doing.
Here is the image just to confirm. Next step is sourcing some blanks and then one day borrowing a set of programmed PROMs from another machine and then have them programmed please.

SiriusHardware · 23rd May 2020, 8:07 pm

Happy to do that when you are ready.

jascha · 23rd May 2020, 8:28 pm

Thank you so much. It might take some months till I get my hands on the A807s that are sitting in a room overseas and borrow the PROMs just for sending to you.

All the best

SiriusHardware · 23rd May 2020, 8:57 pm

No problem, did you see the moderation-delayed post from jsantoro? #30. I gather you must have been talking to him about this issue already. When I do eventually get sight of some programmed devices I'll not only save copies offline and email copies to you, I will attach copies of the PROM contents in a .zip to a post here as well (at 32 bytes each, the files will be tiny). That way, anyone who comes looking will find them.

As said earlier, I have an Arduino sketch / program for reading PROMs which could be altered very easily to read and display the content of 32-byte PROMs, I'll be happy to put that up for anyone who wants to try reading out their PROMs that way.

jsantoro, welcome to the forum.

23rd May 2020, 1:43 pm	#23
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! oops the message came out twice thinking it was not uploaded. Apologies

23rd May 2020, 1:50 pm	#25
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! Thanks again, I will attempt to get into the machine and lift off the stickers covering the ICs so we can get to the bottom of this issue and curiosity It would be an absolute shame if one such device would fail on us making such a machine useless. They sound amazing. Best regards

23rd May 2020, 1:55 pm	#26
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! jascha, thanks for the service manual upload, always interesting to read. Unfortunately the parts list only refers to the PROMs by their proprietary part numbers which is not unreasonable, as only that type of chip programmed with that specific code will do. You can either carefully lift the labels to read the chip numbers, or we can make assumptions about compatible types based on the pin connections on the circuit diagram. We appear to have narrowed it down to several types which could be used as replacements even if we never read the numbers under the labels on your devices.

23rd May 2020, 4:01 pm	#27
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! I opened one of my machines and luckily the label must have come off from the IC on the Capstan motor board. I attach a photo of the IC. I would imagine that they used the same type of ICs on the other board? I managed to peel off part of the label and it looks like it’s the same chip. We are getting somewhere it seems Thanks again Attached Thumbnails

23rd May 2020, 4:23 pm	#28
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! One is certainly a Phillps / Signetics 82S123N, the other might be, it would be good if you could be absolutely sure. I'll just fire up my programmer software and make sure it definitely does do that device or one of the others which are pin compatible. Back shortly. Make sure those labels don't get separated from their chips, fix them back on afterwards by whatever means necessary.

23rd May 2020, 5:20 pm	#29
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! After looking around in the programmer's software, these are the pin-compatible, read-compatible devices which I can do, starting with the type which is already fitted in your machine. Philips / Signetics 82S123 82S123A AMD 27S19 27S19A National Semiconductor DM74S288 Harris 7603 While my programmer does support some MMI PROMS it does not support the 6331. If the chip has 'N' on the end of the number as yours do, that usually just means that the chip is in a DIP package. The 'A' suffix on two of the devices above signifies a version which has a faster access time but is otherwise no different to the plain non-'A' version. For your purpose either will do but the 'A' version may be more expensive. Also note that there are quite a few 'Tesla' branded clones of the National Semiconductor 74S... series PROMs with an 'MH' prefix instead of 'DM' as per National Semiconductor. If you go looking for '74S288' you may well be offered Tesla MH74S288s, if so, avoid. Despite the similarity in the part numbers the Tesla devices, while read compatible with the Nat Semi versions, are hardly supported by any current or historic programmers. My programmer can't programme the Tesla devices either.

23rd May 2020, 6:04 pm	#30
jsantoro Diode Join Date: May 2020 Location: Fort Mill, South Carolina, USA. Posts: 9	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! Hi Folks, Pardon me for jumping in, I new here and usually hang out on the tapeheads forum. I work primarily on Studer/Revix machines.(and any tube gear). Jascha and I were speaking about this offline for a bit The Proms in question provide the sequencing for the drive transistors for the motor phase switching for the spooling and capstan motors. Bipolar proms were the one that could provide really fast access times back then, 50ns access I believe. I've never seen one go bad but they are getting old.. I'm working on an A807 right now with a 2802 calibration EEPROM failing before my eyes, so anything is possible. I will probably try to make a copy of them in the coming weeks from my personal 807 so between SiriusHardware and I we should be covered on both sides of the pond. Jim

23rd May 2020, 6:21 pm	#31
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! Thanks again sir. Do you think that the partially uncovered chip might be different to the one that lost its label? To me they seem to look identical but as you say it would be worth removing the label for your reference and peace of mind. When it comes to purchasing blanks I will only purchase exact replacements unless I am told otherwise if there are equivalents I can use. I feel very positive that there is light at the end of this tunnel and a sigh of relief as these ICs have been on my mind causing some concern if they failed and am stuck without them. I shall try and remove the label and come back to you. Thanks

23rd May 2020, 6:33 pm	#32
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! @ricard: I found the adapter on eBay you mentioned earlier so they do exist: https://www.ebay.co.uk/itm/164101688490 Cheers

23rd May 2020, 6:42 pm	#33
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! I would not like to assume they were the same - the fact that every visible part of the number including the '8749' highly suggests that they are the same type of chip from the same batch but it is up to you. Now that think we know what type of chip the original ones are I can assure you that any of the alternative types I say I can programme in #29 will work equally well, but by all means obtain the original 82S123 type if you can. Looking around, none of them are especially cheap apart from the MMI 6331, the one I can't program of course. Do you have some kind of label making machine, maybe you can print new labels for both chips with the correct numbers on?

23rd May 2020, 6:51 pm	#34
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! I think printing the label is the least of my worries and I am sure I can find a way to print a nice label with similar fonts like the original. I will search everywhere for them and will purchase 6 blanks so I can have reserved for both my machines. I will check a few stores also in my home town in Malta and when I go back on tour (as I’m a musician) I will search for them in local electronic shops. You would be amazed what you would find in multi storey electronic centres in China... I have been there a few times and brought back every possible component I needed at the time. I bet they would even have these in stock in boxes of thousands and costing next to nothing! . I will pull out the label and be 100% sure and will come back to you. I did search on eBay and found the 6331 which was the cheapest option but I’m pleased and thankful of your warning that your programmer doesn’t do the 6331 version! I shall stick to the originals and play safe Thanks again

23rd May 2020, 7:02 pm	#35
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! If you do go to China and find boxes of PROMs for a few cents each be sure to bring us back a few National Semiconductor DM74S571s, as they are often needed, in pairs, for a different type of unit (not a tape recorder). Good luck!

23rd May 2020, 7:16 pm	#36
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! I shall keep that in mind for sure but the question is when will be the next tour?? One place I always visit and a must in Beijing in called Zhong fa.... the photo gives an idea of what to expect... floors of tiny cubicles of Vendors selling every possible component! Talking of obsolete parts I came across this website yesterday.... would it be of interest to you? http://markhindes.easywebstore.co.uk/ Cheers Attached Thumbnails

23rd May 2020, 7:52 pm	#37
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! Now we can be sure that all 3 ICs on both boards of the Studer A807 are identical Proms as I removed the label with some difficulty but worth doing. Here is the image just to confirm. Next step is sourcing some blanks and then one day borrowing a set of programmed PROMs from another machine and then have them programmed please. Attached Thumbnails

23rd May 2020, 8:07 pm	#38
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! Happy to do that when you are ready.

23rd May 2020, 8:28 pm	#39
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! Thank you so much. It might take some months till I get my hands on the A807s that are sitting in a room overseas and borrow the PROMs just for sending to you. All the best

23rd May 2020, 8:57 pm	#40
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Studer / Revox etc BiPolar PROMS! Question and concerns! No problem, did you see the moderation-delayed post from jsantoro? #30. I gather you must have been talking to him about this issue already. When I do eventually get sight of some programmed devices I'll not only save copies offline and email copies to you, I will attach copies of the PROM contents in a .zip to a post here as well (at 32 bytes each, the files will be tiny). That way, anyone who comes looking will find them. As said earlier, I have an Arduino sketch / program for reading PROMs which could be altered very easily to read and display the content of 32-byte PROMs, I'll be happy to put that up for anyone who wants to try reading out their PROMs that way. jsantoro, welcome to the forum.