Bush TR 82C repair advice wanted

[Old Sparky]

Can't help with the other questions, but I've often replaced germanium point-contact detector diodes with either OA90/91 or AA119. These work well as replacements for OA80/81, so should do for the OA70.

[Yorkie]

The bush has a OA70 detector diode, will the OA90 as mentioned in Yorkie's post on this matter do the job if I can source?

The OA70 was originally intended for use as as a video detector diode, but also used for audio.  Not only will the OA90 - or indeed just about any germanium diode (1N34 etc) suffice as a replacement - if you look at the datasheet at the link below, you'll see that back in 1968 when the OA70 datasheet was written, it states at the bottom: 'For new designs  the successor type OA90 is recommended'.

http://www.datasheet4u.com/datasheet-pdf...?id=835815

Hope that helps.

Good luck with the restoration!

[Yorkie]

Has anyone got a service manual for this? Sovereign II RP25. I've had a look for a serial number but he only number I can see is stamped on the underside of the top of the chassis 05138. It does have AF117s and a Goodmans speaker and at least 1 Daly cap. I think I should start a new post on this.

Cheers

I'm not a Hacker enthusiast but they do have quite a fan base and user group, as do Roberts. There are two manuals for the Sovereign II RP25 - one is for the RP25B according to the index. The RP25 manual runs to 34 pages and the RP25B runs to 24 pages, so they seem to be very comprehensive. Hence, either or both are well worth the £1.99 instant download fee from the UKVRF here:

  http://www.service-data.com/search.php?xSearch=Hacker+Sovereign&search=Search

Hope that helps.

[Mark Hennessy]

You can find the Hacker service manual at the Yahoo Hacker Radio group: http://groups.yahoo.com/group/hackerradiogroup/

Registration is free, and there is a wealth of information buried within. Sadly, it's not as easy to navigate as it once was, because Yahoo radically altered their Groups platform, but don't let that put you off.

[ducatiguzzi]

Success with the Bush! :-)

I exchanged the audio amp transistors starting the TR4 as advised but no difference, I then replaced the TR4 then swapped out TR5 with an AC128 and the hissing is now hardly discernible. I'm not going to pursue it any further given the low level hiss on minimum volume. I see the MKII service manual states a modification from the OC71 to a OC81D for this transistor

I have my K7000 injector/tracer kit along with bits and pieces to finish it but havent built it yet but I'm sure it will come in useful, maybe even for fault finding the Hacker, I'm sue it wont be as pretty as Yorkie's but should do the job. I was thinking or incorporating the buffer caps, resistors and diode for the probes within the board and use standard Fluke probes (I have a spare set)

I've joined the Hacker group on Yahoo and got a service manual, thanks for the tip off Mark

Obviously I couldn't have got the Bush there without all your help, you all certainly got me on the learning curve, many thanks!!

Next challenge, get the Hacker working

[AlanBeckett]

I was in the Garage this afternoon and wanted to listen to TMS so I fished my old and neglected TR82 off the Shelf an fired it up. It worked fine

Alan

[boater sam]

I was listening to TMS as well, on my Bush VHF61. On LW of course, until the alabaster plaster caster next door turned his fluorescent  lights on, then the interference was severe. ( they cast garden ornaments in concrete )

[ducatiguzzi]

Just had a look at OC81D's price, jeeso!! must be a cheaper equivalent out there?

[Mark Hennessy]

Just about any PNP germanium transistor will do the job. The AC128 that you have, for example, would be fine

[ducatiguzzi]

Thanks Mark, I'll fit it tonight and order another for fault finding. Cheers