PR99 counter in a B77 - UK Vintage Radio Repair and Restoration Discussion Forum

NorfolkDaveUK · 28th Oct 2018, 5:34 pm

I have a customer thats buying a B77 mk2 I have coming and he wants me to make it the ultimate B77. He wants me to fit a PR99 counter into it , now i know i can fit the counter thats no problem , but how does the detection work on them . I have yet to get the manual for the pr99 that will be a good place to look i guess but thought i would ask you experts too .. thanks ...

NorfolkDaveUK · 28th Oct 2018, 6:01 pm

I THINK the sensing is done via the move sensor . Can someone confirm or quash that ?

Ted Kendall · 28th Oct 2018, 7:09 pm

Not ideally simple. The count comes from a rotary RH guide on the headblock which needs the RH swing arm as found on thr PR99 to ensure low slippage, This is apart from any modifications to the control logic.

Restoration73 · 28th Oct 2018, 7:09 pm

No, the time/counter data is derived by the tacho controller, which replaces the right
hand tape roller guide in B77.

The PR99 Mk3 IS the ultimate B77 development !

(Crossed with Ted)

Michael Maurice · 28th Oct 2018, 7:35 pm

You will also need to cut out the top cover for the RH swing arm to go through. The PR99, audio boards are somewhat different from the B77.

Personally, I'd just buy a PR99, the fact that the tape and audio sections are at the same height will make it easier to use in the future.

NorfolkDaveUK · 28th Oct 2018, 7:47 pm

Thanks guys I`ll pass this info on to the customer and see what he wants to do . He seems dead set on having this done , I must admit it does look real nice in the pic I posted and I can do it if I can get the parts , so I`ll see where this goes . Like I say its for a customer and you know what they say .......

TIMTAPE · 29th Oct 2018, 9:52 am

I generally only make custom modifications to my own equipment where I bear all the costs and the risks and if the first incarnation doesn't work out as well as I'd hoped I can always make further improvements with experience as I go. With paid jobs it's more tricky as it's unlikely all my costs will realistically be reimbursed from that one job. It can also be tricky to quote an estimated cost. When someone enquires about custom mods I tell them this. Often they havent considered the implications from the serviceman's point of view.

ricard · 29th Oct 2018, 10:03 am

Wise words Timtape. When doing custom mods one is essentially taking on the role of designer but without peer review, QA control, etc.

Michael Maurice · 29th Oct 2018, 10:47 am

There is another implication and that is if you modify equipment for someone else, it has to comply with all modern legislation and safety regulations, If you have public liability insurance you may find it doesn't cover such modifications which would not be approved by the manufacturer.

NorfolkDaveUK · 29th Oct 2018, 12:19 pm

I managed to talk him out of it so all good. It looks great in there but, me personally, I don't think it's worth the hassle.

28th Oct 2018, 5:34 pm	#1
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	PR99 counter in a B77 I have a customer thats buying a B77 mk2 I have coming and he wants me to make it the ultimate B77. He wants me to fit a PR99 counter into it , now i know i can fit the counter thats no problem , but how does the detection work on them . I have yet to get the manual for the pr99 that will be a good place to look i guess but thought i would ask you experts too .. thanks ... Attached Thumbnails

28th Oct 2018, 6:01 pm	#2
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: pr99 counter in a b77 I THINK the sensing is done via the move sensor . Can someone confirm or quash that ?

28th Oct 2018, 7:09 pm	#3
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,670	Re: pr99 counter in a b77 Not ideally simple. The count comes from a rotary RH guide on the headblock which needs the RH swing arm as found on thr PR99 to ensure low slippage, This is apart from any modifications to the control logic. Last edited by Ted Kendall; 28th Oct 2018 at 7:16 pm.

28th Oct 2018, 7:09 pm	#4
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: pr99 counter in a b77 No, the time/counter data is derived by the tacho controller, which replaces the right hand tape roller guide in B77. The PR99 Mk3 IS the ultimate B77 development ! (Crossed with Ted)

28th Oct 2018, 7:35 pm	#5
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,224	Re: pr99 counter in a b77 You will also need to cut out the top cover for the RH swing arm to go through. The PR99, audio boards are somewhat different from the B77. Personally, I'd just buy a PR99, the fact that the tape and audio sections are at the same height will make it easier to use in the future. __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/

28th Oct 2018, 7:47 pm	#6
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: pr99 counter in a b77 Thanks guys I`ll pass this info on to the customer and see what he wants to do . He seems dead set on having this done , I must admit it does look real nice in the pic I posted and I can do it if I can get the parts , so I`ll see where this goes . Like I say its for a customer and you know what they say .......

29th Oct 2018, 9:52 am	#7
TIMTAPE Octode Join Date: Jul 2006 Location: Perth, Western Australia Posts: 1,969	Re: PR99 counter in a B77 I generally only make custom modifications to my own equipment where I bear all the costs and the risks and if the first incarnation doesn't work out as well as I'd hoped I can always make further improvements with experience as I go. With paid jobs it's more tricky as it's unlikely all my costs will realistically be reimbursed from that one job. It can also be tricky to quote an estimated cost. When someone enquires about custom mods I tell them this. Often they havent considered the implications from the serviceman's point of view.

29th Oct 2018, 10:03 am	#8
ricard Octode Join Date: Mar 2006 Location: Lund, Sweden Posts: 1,632	Re: PR99 counter in a B77 Wise words Timtape. When doing custom mods one is essentially taking on the role of designer but without peer review, QA control, etc.

29th Oct 2018, 10:47 am	#9
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,224	Re: PR99 counter in a B77 There is another implication and that is if you modify equipment for someone else, it has to comply with all modern legislation and safety regulations, If you have public liability insurance you may find it doesn't cover such modifications which would not be approved by the manufacturer. __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/

29th Oct 2018, 12:19 pm	#10
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: PR99 counter in a B77 I managed to talk him out of it so all good. It looks great in there but, me personally, I don't think it's worth the hassle.