TM-7102 - buzzing from PSU board?

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#1
Hi all

Moved house 8 weeks ago and finally got around to reconnecting my TM 7102 to the TV (for terrestrial HD viewing and replay of HDD recordings, while researching a motorised dish installation).

There's quite a buzzy noise coming from what I think is the PSU/transformer board. When first turned on, there was a screaming noise from the fan. A replug and switch off/on at the back seemed to deal with that.

I thought all was working fine - we had to re-tune all channels to get the full Freeview set. Watching BBC 1 HD a little later, though, signal kept dropping out momentarily. We have an amplified distributed TV connection from our loft, with a loft aerial directly facing and close to the Wrekin transmitter. Our TV has perfect vision off the same aerial feed, so I'm not sure it's a signal issue and possibly a sign of imminent failure.

As I'm about to invest in a top quality dish and motor to take in as much as I can get, I'm also considering running cables to a 2nd room, so, if the receiver is about to die, acquiring a new one isn't really a problem.

On the other hand, if it's a quick and easy fix, that saves my open/patched channels without having immediately to get to learn a newer technology receiver!

Any hints/tips - I have put in a message direct to TM too.
 
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#2
The first thing I would check is for faulty Caps in the PSU. Sometimes you can see them. They will have the tops raised.
 
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#3
The first thing I would check is for faulty Caps in the PSU. Sometimes you can see them. They will have the tops raised.
Hi, thanks. Yes, that's what I noticed, so that's probably what it is. Don't know whether the whole board is replaceable - maybe TM will offer a solution or I can look for a 2nd user box (did this with a HDD/DVD recorder last year). I'm not up to acquiring and resoldering components...!
 

trevortron

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#4
Hi, thanks. Yes, that's what I noticed, so that's probably what it is. Don't know whether the whole board is replaceable - maybe TM will offer a solution or I can look for a 2nd user box (did this with a HDD/DVD recorder last year). I'm not up to acquiring and resoldering components...!
A friend had a problem with a 7102 & took it back to TM (out of warranty - just) and although they tried to fix it they couldn't and just offered him a generous discount on a new 5402. The 7102 has been obsolete for a few years.
A local TV repair shop (if there's any left) should be able to help you. Just stipulate that you want low ESR, 105° capacitors. You'd be as well to have the fan changed while it's apart, those boxes get hot even with the fan, it would cook itself to death if the fan seized up.
 
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#5
Trevor, thanks for this.

Having moved from a couples of mile from Technomate's workshops to deep country near Wales (!), that's an irony.

I guess if I was replacing the 7102 (it was the triple tuner capability I bought it for at the time), it would make more sense to move to a Linux box (these do give me open access to normally locked channels, right?). How does a TM TM-Twin compare to, say, a Mutant HD51?
 

trevortron

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#6
Moved eh? That'll teach you!
I thought the 7102 was a great piece of kit but it seems they weren't that reliable; of the 3 I know, two have given problems.
I cannot comment on Linux or other open-source boxes as I don't have any experience with them. Perhaps someone else could take over here....
But it would be a shame to forsake the Technomate for the sake of a couple sick capacitors....
 
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Moved eh? That'll teach you!
I thought the 7102 was a great piece of kit but it seems they weren't that reliable; of the 3 I know, two have given problems.
I cannot comment on Linux or other open-source boxes as I don't have any experience with them. Perhaps someone else could take over here....
But it would be a shame to forsake the Technomate for the sake of a couple sick capacitors....
Haha - yes, but on the other hand, I have views from every room out over fields to the Welsh mountains on the horizon, no traffic noise, night time silence (apart from the - beautifully tuned - church bells every quarter hour!) and dark skies!

Agree with you about a duff capacitor (I think it is just the one - large black one with a domed top) but I'm not up to replacing it myself. I have photographed the capacitor and board. The PSU board is easily removable, 1 plug-in connector each end and 4 screws. I've checked eBay for a 2nd user 7102, without success.

If there's anyone here up to the repair job, I'd be happy to post you the board. I guess if you have access to the relevant part (G-LUXON 450v 100 uF), it's the work for a pound or two and 10-15 minutes. Or if anyone knows an engineer near Shrewsbury who does this kind of thing... :)
 

trevortron

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Haha - yes, but on the other hand, I have views from every room out over fields to the Welsh mountains on the horizon, no traffic noise, night time silence (apart from the - beautifully tuned - church bells every quarter hour!) and dark skies!
Sounds like bliss. Apart from the Welsh weather perhaps....
 

spud1966

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#10
fleebay


182607361509

not that hard to replace m8

if you not good with unsoldering just wiggle it off ( check first if you have the space to fit underneath ) and just solder onto the bottom PCB long as you make sure about the + and - legs ect
 
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#12
fleebay


182607361509

not that hard to replace m8

if you not good with unsoldering just wiggle it off ( check first if you have the space to fit underneath ) and just solder onto the bottom PCB long as you make sure about the + and - legs ect
Cool - thanks. I'm OK wiggling out the old one but worried that I might melt something or short a track of the circuit board trying to get the new one on! But having seen this part if £1.88 it's almost worth a go... even if I moved to a Linux box later...
 
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#13
Just cos the other caps aren't domed doesn't mean they're ok. I always check surrounding caps with my esr meter and replace as necessary.
Ah. An ESR meter's a special thing isn't it? I can't test using my multimeter? As they seem cheap, maybe order the smaller ones too... trickier soldering tho!
 

chookey

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Ah. An ESR meter's a special thing isn't it? I can't test using my multimeter? As they seem cheap, maybe order the smaller ones too... trickier soldering tho!
A multimeter can't truly check a capacitor but it's good practice to replace the caps anyway. When I esr them it is only for confirmation that they are indeed at fault. I replace them even if they pass the test as I've already removed them.
 
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#17
OK, well I bought a replacement cap and soldered it in tonight. No difference - box came on, stalled, switched on, box restarted. Buzzing. Then after couple of seconds went off. I switched off and on, same again - turned itself off after couple of seconds.

So either my soldering is defective (it was pretty straightforward I thought, and the pins were well away from anything else) or that component was not at fault or other components are also defective.

Unless there's some enthusiast here who could help - or point me to someone who might (the PCB is easily removable to send for repair), it looks like a new Linux box is required.

Thank goodness all 3 years' recordings on the HDD can be accessed directly from the disc!
 

spud1966

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#18
Can you take a pic of the power board and post it on hear

Plus check the board for a parts number and see if you can get a secondhand one on fleebay ?
 
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Spectre

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#19
Can you take a pic of the power board and post it on hear

Plus check the board for a parts number and see if you can get a secondhand one on fleebay ?
I'd like to see it too, I couldn't find a picture of one.

Asked our SMPS expert at work ages ago what was actually making the sound from one and it's usually the ferrite core of the transformer changing shape rather then the windings, which I first thought. Sometimes caused by the converter working at a lower than designed frequency. Just a bit PSU trivia :).
 
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#20
Can you take a pic of the power board and post it on hear

Plus check the board for a parts number and see if you can get a secondhand one on fleebay ?
Hi - here's the pics. I have search fleabay for a box or spares without success...
 

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