DIY Doctor UK DIY Forums

Hi Guys & Happy New Year

I'm a Brit expat living in Bulgaria and have a really annoying problem affecting my VOIP telephone - a conversation stopping buzz which appears to be triggered by at least some appliances and I would really appreciate some help please if anyone can see an answer.

When the problem first started I stripped my computer system down, tried different phones but could not pinpoint the problem. Recently, with the weather cooling down, I put an oil filled radiator in the same room and noticed as soon as it kicked in the buzz would start ... switch it off and the buzz instantly stopped. I then checked this with the cooker (because the problem appeared to be worse in the evenings), it too had the say affect and to a lesser degree the kettle. However, sometimes even when none of these are on, the buzz can still happen; more in the evening when power demand increases - I'm wondering?

Bulgarian power supply leaves a lot to be desired, especially in a small village and recently; the power went off several times and when checking to see if my computer was still running I smelt burning. What had actually happened was, when the power came back on it was at a greatly reduced voltage; lights were dim and the burning I smelt was something in the 450w PSU of my computer burning out ... through low voltage?

If anyone can see a cause/effect pattern above and any possible solution, it will be good to hear from you.

Many thanks - Scott.

hi Scott, it would appear the noise is mains bourne rather than RF so would suggest a UPS which should act as a buffer/filter & have additional benefit of maintaining correct voltage to the PC's power supply.
Clearly they don't worry too much about limiting interferance from devices as we do in UK!
People worry about over voltage surges but in fact low voltage 'brown-outs' cause much more damage.
As the power supplies in my area are so unreliable we run individual UPS's on each PC plus a small seperate one for our router plus a multiway outlet with filters built in to feed the UPS's.
regards Sparx

Hi Sparx, many thanks for your thoughts; although presently I am not winning this battle.

When this problem started I was already using an UPS, but took it out whilst trying to trace the problem. Originally I got an UPS because the power supply would just go off and then instantly back on rebooting the system, or go off for 6 minutes and as I maintain my website mostly from home the UPS was to keep me connected for at least the 6 minutes. However, sometimes it would work and other times it would hang up the computer or I would find it asking me to setup the motherboard again. Plus, when the power went off it was not just local to me it was the whole village ... so I lost the internet anyway.

Today, firstly as the UPS was to hand, I connected just the telephone via the UPS ... that made no difference; so then I used the UPS between the wall socket and the computer system ... computer, monitor, cable modem and router with phone connected to router ... this too made no difference.

Most times when I turn the oil filled rad on I get an instant buzz, off and it goes ... but sometimes it does not affect it ... but more often it does. Now, in the evening, the buzz can occur without these items switched on and with the system still through the UPS.

9 times out of 10 the rad will cause the buzz, so what is different on the odd times it does not (more in the day)?

Should I use the UPS on one specific item and if so which one, where/how does the dail tone pick up the buzz?

My UPS is probably not the best money can buy, an MGE - Nova 1100 AVR ... but don't want to buy another unless sure it would solve problem. However, after my experience with the PSU an UPS does look like an essential here even if it does not cure the buzz!

Any further thoughts much appreciated.

Cheers - Scott.

This could be wrong track but I had problems with one house when lights were on but not all the time.
After a lot of work we found it was because the stairs two way lighting was wired between switches with twin rather than 3 core cable and it took a live from the other switch in a pair.
This mean the line and neutral wires did not follow same route.
In UK with most wiring done with twin and earth or in conduit unlikely anything wired where line and neutral does not follow same route.
However things may be different there. What type of cable is used? and is the neutral and line run together?

hi Scott,
i have 2 MGE 850's running one PC each plus 1 Belkin 250 running router as discovered to my cost that whilst short power failures would not affect PC's due to having MGE UPS's running still lost wibbly,wobbly, web. hence very cheap £25 Belkin added!
Have supplied many MGE ups's for customers inc. MOD and find great for around 5 years when batteries start to lose capacity, but are easy and reasonable price to change.
Does the stat on the heater interfere with a nearby portable radio?
Try it to see if mains bourne or RF direct.
Eric & I are both radio 'hams' and will have spent many hours tracking down such sources of interferance.
In my 'shack' I have tried several types of heater and lights to avoid such problems and in fact the worst interferance to my radio's is the PC attached to use for data transmissions!!!
Have to use ferrite rings on mains leads, computor connecting cables etc.
If you have or can borrow a portable battery/mains radio seeif it picks up interfeance on batts, or mains which point you in right direction, if tuned away from a station the background noise may help trace causes if interferance,
happy hunting, Sparx