Dansette Regina Help needed

[skamanuk]

Hi Guys. I have a problem with my Dansette Regina Transistor Amp Record player.

After around 10 minutes of play the sound deteriorates to nothing, A rapid twist of the Volume knob brings the sound back but only for a few minutes then disappears again.

I had the Volume pot changed thinking that was the culprit but alas it's still doing it. My now thought is it's a component on the circuit board failing when warmed up but not sure which it may be. Any Ideas

I will be downloading the Amp schematics from the site (if available for the Regina)

Gary

[AC/HL]

Service data here: http://www.service-data.com/section.php/1523/1/regina

[skamanuk]

Thanks, just need to know what members think is the culprit now

[Station X]

Does this player have red, yellow and black Plessey electrolytic capacitors?

I'm not one for changing caps just for the sake of it, but these caps are unreliable.

[skamanuk]

Yes it does

[skamanuk]

Does anybody know Which of the BC 108 Transistors is the correct replacement 108A , 108B or , 108C

[AC/HL]

It doesn't specify, if it was critical it probably would so could be any gain group. Did changing the capacitors help at all?

[skamanuk]

No unfortunately not. It's a real annoying problem.. It plays for a while then cuts out.. A slight tap on the outer case and the sound comes back but just for a while, Even thought it may be a dry joint so checked and re soldered all the joints on the circuit board but didn't make any difference

[AC/HL]

It does sound like a intermittent joint somewhere, although probably not on the board. Not a lot left, have you tried an external speaker or headphones?

[Nuvistor]

When its faulty what tests have you done to try and rule out, cartridge/wiring, amp and speaker circuit.
Appreciate you have replaced the VC and checked for dry joints.

[Station X]

The symptoms certainly suggest a mechanical problem with a component or connection.

All I can suggest is a gentle probing/proding/tapping of individual components when the fault is present.

Some people swear by freezer spray, but I've not tried it.

[Techman]

Funnily enough I've just been working on a similar small portable record player with a transistorised amplifier which needed cartridge replacement and mechanical work to the deck and while on test last Thursday, the amplifier suddenly failed half way through a record. Initially there had been some low level background crackling which had qickly cleared up by itself and had successfully played quite a few records over a few days. On switching it off and making a few checks to cartridge connections etc. (I had noted that there had still been a very slight hum from the speaker indicating that the main part of the amplifier was still working), I switched it back on and found it was working, but soon cut out again after a short time. Further investigation found that the first amplifier stage transistor immediately after the volume control had developed a dodgy base emitter junction (abnormal voltages and higher than normal forward resistance when removed and tested). This was one of the infamous BC148 'lockfit' types and and having opened a fresh a pack of RS Components BC108 transistors from my ancient stock and fitted one of these, all was back to normal operation.

So it sounds like it could well be the same amplifier stage in your amplifier that's causing the fault and a BC108 will work just fine.

[skamanuk]

Originally Posted by AC/HL

It does sound like a intermittent joint somewhere, although probably not on the board. Not a lot left, have you tried an external speaker or headphones?

yes checked those

Originally Posted by Nuvistor

When its faulty what tests have you done to try and rule out, cartridge/wiring, amp and speaker circuit.
Appreciate you have replaced the VC and checked for dry joints.

first thing i did was check the pickup wires and change the cartridge (twice in fact). Speaker connections were also checked early on in the investigations

Originally Posted by Techman

... So it sounds like it could well be the same amplifier stage in your amplifier that's causing the fault and a BC108 will work just fine.

Thank you for that.. I actually ordered all new transistors so will be fitting those in coming days will report back on progress

[skamanuk]

Originally Posted by Techman

So it sounds like it could well be the same amplifier stage in your amplifier that's causing the fault and a BC108 will work just fine.

Thanks for the information, It was indeed the BC108. Changed and finally working as it should.

[nigelr2000]

I had a similar fault on a bush discassette a while back and did a video to show the customer. It's here and shows use of soldering iron and freezer to prove the fault
https://youtu.be/XHGpUaR_kpA

[skamanuk]

Hi Update time...

well I have now changed EVERY component on the circuit board Resistors Capacitors and Transistors. I have checked every connection to the External outputs Checked AND Replaced the tonearm and pickup wires and tried with TWO different cartridges.. Unbelievably The Fault remains. I remember their was a HUM Problem in a 60s Ferguson (from memory) traced to a batch of cracked circuit boards, Is it possible the Dansette problem could be the same kind of Hard to see crack or similar.

[Stylo N M]

I'm not familiar with this model, and you say you have replaced every component, but unless I'm wrong, I haven't seen in any of the posts, anything refering to the inspection of the rectifier, or the transformer supplying the power to the circuit board.

Have you checked this, for perhaps heat expansion, where there may be a fine break in the transformer coil when it warms up?

I don't know if this model uses an output sound transformer, but if it does, that may have a similar fault on the windings on temperature change, or green spot in the windings.

Paul.

[Station X]

Wholesale changing of components is not a good repair technique and won't teach you anything about the way the circuit works.

You need to do some fault finding. I'd start by monitoring the voltage across the 4800uF ?? smoothing capacitor from the time the player is switched on until it cuts out. Whether this cap has been replaced or not is immaterial.

Once you ruled out a PSU failure you can start measuring voltages on the transistors.

[John10b]

Hi skamanuk, in your post #14, you say you changed bc108, and “..working as it should”. How long before fault reappeared, or have I misunderstood!
Cheers
John