Anita Calculators - UK Vintage Radio Repair and Restoration Discussion Forum

ALANS ANITAS · 25th Aug 2010, 12:17 pm

I have received a PM from forum member Woodchips who has a DIY Anita Mark 8 calculator. Are you able to post some photos of the boards you have?
Do you have a keyboard and a case and a motherboard? As to your missing power supply, I am not certain if I have a circuit diagram as the few I was allowed to retain are packed away. I do have a complete machine, but I doubt it will work.

Spare parts will be difficult to obtain, particularly dekatrons, trigger tubes,and 19(or18)Meg resistors. 1N4148 diodes could replace the selenium twin pack logic diodes.

The power supplies used an Advance constant voltage transformer,to provide
+495v,+20v, and minus 125 volts.

PM me your phone numberand we can perhaps take this further.

Regards

ALAN

woodchips · 28th Aug 2010, 6:30 pm

Alan, I have sent another PM, did you receive it? Bob.

gingpeakin · 2nd Nov 2010, 12:11 pm

I have just inherited an Anita Mk8. All the numbers light up and the ring counter goes around but that's all. It's been in a loft for I guess at least 30 years so I'm not surprised.
Does anyone have any circuits - I'd love to get it going again.
I remember buying the counter boards, both the cold cathode and the transistor versions, from the junk shop that used to be in Deptford in the late 1970s.

Ging

ALANS ANITAS · 2nd Nov 2010, 9:23 pm

Hi

I'm afraid I dont have any circuits for the Anita Mark 8, but spent 10 happy years repairing various models of Anita, but this was more than 30 years ago.

You say you purchased boards in the 1970's. Do you still have them? They could be vital to getting the machine working because of the lack of spares.

First thing to check is that the keep alive electrodes, "night-lights" are all illuminated in every trigger tube. These are fed from the -125volt line through 19Megohm resistors, and go high resistance. Ones in excess of 25Meg must be replaced. The machine contains about 180 trigger tubes!!

Other problems include high forward resistance of the selenium logic diodes, the trigger tubes themselves, and dirty contacts and rotors on the keylines.
Critical voltages are +495, +20, and-125. The keyboard is earthed, but the power supply is fed by an Advance constant voltage autotransformer, and therefore not isolated.

I am intending to write a quick repair guide to the Mark 8, but it will take a little time to compile. If you wish to contact me please PM me your phone number, for a chat.

Regards

ALAN

armshead · 15th Nov 2010, 11:21 pm

I have several Mk 8s, a 9, a 10 an 11 and a 12 in various states + lots of service info and diagrams . A 1011 , a rusty `1011P in bits. etc etc. It'll all go in a skip when I'm gone, no doubt.
I can remember how an 8 works but a bit rusty on 9 up. Too old to bother now.

donutty · 16th Nov 2010, 1:18 pm

I wouldn't mind a Mk. 8 if there are any left over from Alan mobbing you

If you want I could send a courier round to pick them up and catalogue and dole them out here to other interested members.

Thanks for posting by the way - you must have been searching 'Anita' ??

woodchips · 16th Nov 2010, 4:55 pm

Hello, would be interested in one, or more, of the various models, try and get my Mk8? running. Yes, interesting post, thanks, Bob.

gingpeakin · 16th Nov 2010, 6:24 pm

I'l be interested in any info you have on the Mk8 and the 1011, of which I have a working example. Sadly I painted in with gold spray paint when it was 'fashionable' to do so. about 1977 I think.

Ging

ALANS ANITAS · 16th Nov 2010, 6:51 pm

A much bigger collection than I have. If you are selling, the Mark 10 would be of great interest, as it can convert into £,s,d. from decimal. I would also be interested in any documentation you have. As you will not have access to the private message system, can you contact my by the forum email system.

The 1011P was always problematic and the chance of saving it is poor, but maybe possible. The ones with trigger tubes will only be repaired by canibalisation. What model is the 1011? Can you quote the serial number?
I would certainly like to see your collection if possible.Whilst you are a fair way from me it is straight up the M6.

Regards

ALAN

25th Aug 2010, 12:17 pm	#1
ALANS ANITAS Rest in Peace Join Date: Jun 2006 Location: North West Northamptonshire, UK. Posts: 346	Anita Calculators I have received a PM from forum member Woodchips who has a DIY Anita Mark 8 calculator. Are you able to post some photos of the boards you have? Do you have a keyboard and a case and a motherboard? As to your missing power supply, I am not certain if I have a circuit diagram as the few I was allowed to retain are packed away. I do have a complete machine, but I doubt it will work. Spare parts will be difficult to obtain, particularly dekatrons, trigger tubes,and 19(or18)Meg resistors. 1N4148 diodes could replace the selenium twin pack logic diodes. The power supplies used an Advance constant voltage transformer,to provide +495v,+20v, and minus 125 volts. PM me your phone numberand we can perhaps take this further. Regards ALAN

28th Aug 2010, 6:30 pm	#2
woodchips Octode Join Date: May 2010 Location: Grantham, Lincolnshire, UK. Posts: 1,174	Re: Anita Calculators Alan, I have sent another PM, did you receive it? Bob.

2nd Nov 2010, 12:11 pm	#3
gingpeakin Hexode Join Date: Mar 2009 Location: Worthing, Sussex, UK. Posts: 276	Re: Anita Calculators I have just inherited an Anita Mk8. All the numbers light up and the ring counter goes around but that's all. It's been in a loft for I guess at least 30 years so I'm not surprised. Does anyone have any circuits - I'd love to get it going again. I remember buying the counter boards, both the cold cathode and the transistor versions, from the junk shop that used to be in Deptford in the late 1970s. Ging

2nd Nov 2010, 9:23 pm	#4
ALANS ANITAS Rest in Peace Join Date: Jun 2006 Location: North West Northamptonshire, UK. Posts: 346	Re: Anita Calculators Hi I'm afraid I dont have any circuits for the Anita Mark 8, but spent 10 happy years repairing various models of Anita, but this was more than 30 years ago. You say you purchased boards in the 1970's. Do you still have them? They could be vital to getting the machine working because of the lack of spares. First thing to check is that the keep alive electrodes, "night-lights" are all illuminated in every trigger tube. These are fed from the -125volt line through 19Megohm resistors, and go high resistance. Ones in excess of 25Meg must be replaced. The machine contains about 180 trigger tubes!! Other problems include high forward resistance of the selenium logic diodes, the trigger tubes themselves, and dirty contacts and rotors on the keylines. Critical voltages are +495, +20, and-125. The keyboard is earthed, but the power supply is fed by an Advance constant voltage autotransformer, and therefore not isolated. I am intending to write a quick repair guide to the Mark 8, but it will take a little time to compile. If you wish to contact me please PM me your phone number, for a chat. Regards ALAN

15th Nov 2010, 11:21 pm	#5
armshead Banned Join Date: Nov 2010 Location: GB Posts: 2	Re: Anita Calculators I have several Mk 8s, a 9, a 10 an 11 and a 12 in various states + lots of service info and diagrams . A 1011 , a rusty `1011P in bits. etc etc. It'll all go in a skip when I'm gone, no doubt. I can remember how an 8 works but a bit rusty on 9 up. Too old to bother now.

16th Nov 2010, 1:18 pm	#6
donutty Pentode Join Date: Aug 2010 Location: Sheffield, South Yorkshire, UK. Posts: 163	Re: Anita Calculators I wouldn't mind a Mk. 8 if there are any left over from Alan mobbing you If you want I could send a courier round to pick them up and catalogue and dole them out here to other interested members. Thanks for posting by the way - you must have been searching 'Anita' ??

16th Nov 2010, 4:55 pm	#7
woodchips Octode Join Date: May 2010 Location: Grantham, Lincolnshire, UK. Posts: 1,174	Re: Anita Calculators Hello, would be interested in one, or more, of the various models, try and get my Mk8? running. Yes, interesting post, thanks, Bob.

16th Nov 2010, 6:24 pm	#8
gingpeakin Hexode Join Date: Mar 2009 Location: Worthing, Sussex, UK. Posts: 276	Re: Anita Calculators I'l be interested in any info you have on the Mk8 and the 1011, of which I have a working example. Sadly I painted in with gold spray paint when it was 'fashionable' to do so. about 1977 I think. Ging

16th Nov 2010, 6:51 pm	#9
ALANS ANITAS Rest in Peace Join Date: Jun 2006 Location: North West Northamptonshire, UK. Posts: 346	Re: Anita Calculators A much bigger collection than I have. If you are selling, the Mark 10 would be of great interest, as it can convert into £,s,d. from decimal. I would also be interested in any documentation you have. As you will not have access to the private message system, can you contact my by the forum email system. The 1011P was always problematic and the chance of saving it is poor, but maybe possible. The ones with trigger tubes will only be repaired by canibalisation. What model is the 1011? Can you quote the serial number? I would certainly like to see your collection if possible.Whilst you are a fair way from me it is straight up the M6. Regards ALAN