TM-TWIN-OE front panel (only) failed

[m1maj]

The front panel on my TM-TWIN-OE seems to have suddenly failed. I left it on standby overnight and in the morning there was no display.

Even after a full power cycle:

- There is no front panel display other than a flashing red light
- None of the buttons work
- The remote control does not work

However the receiver does boot. I can control it over the web interface. I can watch programmes, and can make and watch recordings, to the extent that the OpenWebif interface lets me. So the power supply and main board must be OK.

I presume the problem lies with the front panel board or a power regulator feed it or some such.

Has anybody seen this symptom before? Any ideas on where the problem might lie?

 

[abu baniaz]

Looks like the PSU has failed.

 

[m1maj]

Looks like the PSU has failed.

It can't be the whole PSU because the receiver does boot up and work. I'm watching the news on it now....

 

[telemanic]

hello, I've just repaired one of these with the exact same fault, turned out to be the power supply panel . It has two transformers on the circuit board one for multi voltages and one for the standby/display 5 volts.Mine was due to the 5 volt transformer not getting a drive voltage. the switching IC was blown to pieces.

 

[telemanic]

take the lid off and have a look be careful 340volts on main smoothing capacitor ouch the chip that had blown on mine sat just behind the smaller transformer

 

[m1maj]

hello, I've just repaired one of these with the exact same fault, turned out to be the power supply panel . It has two transformers on the circuit board one for multi voltages and one for the standby/display 5 volts.Mine was due to the 5 volt transformer not getting a drive voltage. the switching IC was blown to pieces.

I assume you're referring to the VIPER22A IC U3. Mine is physically intact, but it is obvious that it has been getting very hot. The 5V standby rail is definitely missing so it seems a likely culprit.

Can you confirm that replacing U3 fixes the problem, or is the root cause somewhere else? It looks easy and cheap to do.

 

[telemanic]

replacing that chip (viper22) on mine cured the fault but as I said it was blown to pieces as in the top was missing.

 

[m1maj]

replacing that chip (viper22) on mine cured the fault but as I said it was blown to pieces as in the top was missing.

Thanks for that. Unfortunately replacing it hasn't fixed it for me, so the fault must lie somewhere else. I've put a scope on it and I can see that the primary side is oscillating. There is _some_ voltage on the output but it's very low (about 2V). I have limited experience with this kind of power supply and it's a bit awkward to probe any further without even a cicuit diagram. I suppose I'll be looking for a replacement PSU board.

Meanwhile I have lashed up an auxiliary 5V supply using an old wall wart, so I now have the display and remote control working again.

 

[abu baniaz]

Ring TM, see if they can help.

020 8884 0259.

 

[TK4|2|1]

Are there any capacitors around this regulator? If yes change them. They may not show visible sign of being bad, but worth a shot.


Sent by pressing the screen on 1 of my Apple devices, cuz that's how I roll.

 

[m1maj]

Are there any capacitors around this regulator? If yes change them. They may not show visible sign of being bad, but worth a shot.

Yes there's an electrolytic nearby. I was about to change it on spec, and then realised I didn't have a replacement with a high enough voltage rating in stock. I should probably get one and give it a go.

I was slightly suspicious of the diode on the secondary side but it turned out to be OK.

 

[pz8l8t]

I have a similar problem on my twin. The front panel display is not working nor is the remote. However the buttons on the front panel do work. Any ideas if this is related to the viper22a chip?? I have tested the voltages to the main board and all appear OK. Only one I don't know about is the on/off rail which I believe is outputting about 3v when on.