Upgrading a Beogram TX-2 to Beogram 7000 specification

[TK]

I’ve been enamored with B&O Datalink-enabled systems from the 80s and 90s for the better part of a year now, but I’ve struggled with the cost of acquiring a Beogram 6500 or 7000 due to the <ahem> lofty retail price premiums they command these days. So while I wait for the right system to come along, I’ve been bottom-feeding off of eBay, buying a few early non-working tangential Beograms to get a feel for the technology.  I’ve made the discovery which is probably known to most who have been doing this for a while: apart from a very few things like an RIAA board and a different audio cable, there is almost zero difference between a TX-2, 5005, 7000, and up to the 9500.  Inside, they are essentially the exact same model. This is both great and depressing news – great, because it means that you’re not getting much extra for your money with a more costly purchase of a higher-number model.  But also sad, because it means that B&O basically stopped innovating the Beogram in 1985, leaving it to die a slow death.

I’ve found many posts over the years where folks have discussed what can be done to improve the TX-2 (which is generally the cheapest of the bunch), but no real hands-on guide.  So when an inexpensive TX-2 popped up on eBay, I decided that I’d make a bid for it, with the plan of putting one together.

It arrived today, so I set off by giving it a spit-shine, and testing basic function.  It’s a suitable candidate for a refreshtoration, so off I go.  I’ve got 3 main objectives: 1) Refresh the board, and add the Datalink transistor; 2) Replace the output wire with a Din-7 plug; 3) Create an inexpensive RIAA board, and upload the design to PCB Way to produce (Perhaps there is a forum member who would be willing to share their existing files).

Attachments:

You must be logged in to view attached files.

[TK]

First things first – does the TX-2, in fact, ship with Datalink enabled?

Early answer: yes, it appears so. But more testing is required to verify the entire instruction set.

I’ve been postulating on this for the past month, trying to find a definitive “it does” or “yes, but there’s a catch…” post, but I figured I’d have to do my own testing anyways.  So before changing out the RCA output cable, I thought I’d run a quickee test of the Datalink channel on the main board, to see what signals were being sent, if any.  I attached a signal analyzer to the board output (going from CPU pin 19 through some circuitry to pin 1 of the white connector) and measured the results.  Presto: Datalink. I received both a “No Media” signal and a “Status Playing” signal, depending on whether I held the record sensor down. With this experiment done, I’m quite confident I’ll be able to attach a Din-7 cable to the output board, and use the Datalink features on a Beomaster 5500, at least.  For the later units, I’ll still need to find or create an RIAA card.

Attachments:

You must be logged in to view attached files.

[adyan]

Hello again,

as already answered here I have done this with my TX2. I have PCB´s of my RIAA left, if you like to get one send a private message.

Details:

https://forum.beoworld.org/forums/topic/beograd-59xx-riaa/

[Author]

Posts