BUSH TR82DAB

[Robert Darwent]

Yes, I asked for help on the TR82DAB on another forum and someone confirmed poor electrolytics and a 3.3v ldo voltage regulator as the most likely cause of problems with this model.

The specific part number for the regulator turns up a blank when searched for on the internet, but there are many other types available. I believe any of the alternatives having the same case style and a sufficient power rating would substitute without issue.

Regards

[Old Sparky]

Finding any SOT223 (surface mount) 3.3v regulator I.C. seems to be difficult, Robert. None of the usual suppliers stock the SE8117T33, or any similar component. Maybe it's available as a spare part for some device (Not the TR82DAB, for which no spares are available from Argos)

[Robert Darwent]

Yes that does seem to be the case. Apparently the regulator is specified at 1A current, replacement with a standard device instead of surface mount may be necessary. It may also be advantageous to do that anyhow as a regulator mounted away from the PCB would dissipate heat better - probably why the regulator fails in the first place.

Regards

[Keithstv]

The IC is a 3.3v LDO (Low DropOut) regulator and virtually any similar regulator from the major semiconductor manufacturers should work. E.g. the LD1117AS33TR from ST

They are available from the likes of Farnell and CPC. Do a search for fixed output 3.3v LDO SOT223 regulators on the Farnell or CPC websites and you should find a large number of suitable regulators.

Buying from CPC or Farnell may be a little expensive though for a one off small part but you should be able to find suitable part numbers then try other suppliers.

Keith

[AlanBeckett]

It's best to get 2 then when one pings off your Tweezers and disappears down a crack in the bench you'll still have one to try again

Alan

[Robert Darwent]

Yes the LM1117 (AMS1117) in the SOT-223 package is a substitute and available on eBay from several sellers for less than £3 for 10. The LD1117 is the TO-220 packaged version, available again on eBay for a little over £1 each - I am inclined to use this type instead fitted to a small heatsink mounted off of the PCB and connected via short leads.

Apparently, from what others have said, the main reason the DAB module on the TR82DAB stops working is due to overheating in this area - cooking the regulator and drying out the electrolytics. There is plenty of spare room around the module inside the case to mount a TO-220 version replacement regulator so ensuring that it runs cool and doesn't overheat again in the future.

Regards

[Old Sparky]

I've ordered some AMS1117s from eBay, but (and why didn't I think of that!) in view of what Robert has said, I may well fit a TO-220 regulator instead.

[Old Sparky]

Further to my earlier posts, I have now replaced a number of electrolytics with bulging tops, plus the 3.3v SMD regulator. This has restored normal operation on all bands, though a better regulator IC might, as others have noted, be a good idea.

[AlanBeckett]

That's a splendid result.
You're a better man than I am Gunga Din.
I think I'll stick to valves where at least I can see what I'm doing.

Alan

[Old Sparky]

That's a splendid result.
You're a better man than I am Gunga Din.
I think I'll stick to valves where at least I can see what I'm doing.

Alan

I still have to re-string the two drive cords it was necessary to remove to gain access to the PCB, though!