Brenell Mk.5 TR. - UK Vintage Radio Repair and Restoration Discussion Forum

Geoff 555 · 25th Apr 2012, 12:09 am

Hello everybody I just thought I would run this past you to see what you thought and ask for any advice. Brief history is that my father bought this in 1959 and it was in use until 1978. I inherited it in 1980. The Reslo (?) mike and transformer were missing. Having found some tapes of Dads thought I would listen to them But It has died so it seems.
It is a Mk5 with a level meter.
The amp works, with a mike.Plenty of volume with just a trace of distortion when turned right up.
Turned to record the level meter works .
Turned to play back there is nothing recorded , if the volume is turned up above half way then there is a lot of hum and if turned up more then what sounds like motor boating and is too bad to keep it there too long.
The erase and P/R heads measure OK and are clean.
I know Dad had it repaired in about 1970 but I dont know what was done. I can't see anything burnt or nasty the only thing I have done is replace the smoothing block, 50 + 50 at 500 volts as it didn't want to reform.
It hasn't been used for something like 25 years approx.
Sorry for the long post I do tend to ramble on.
Cheers and thank you.
Geoff.

Refugee · 25th Apr 2012, 12:32 am

I would check that the record switch is moving fully into place and give it a shot of switch cleaner.
Then have another go.

Geoff 555 · 25th Apr 2012, 5:25 pm

Thank you for that.The switches have been cleaned and a couple of things found, more of which later when a valve and a pot have arrived. One thing that I do not fully understand is that there is a 'humdinger' pot ( not the one I have ordered.) that has to be fully turned to one end and that does cut the hum down 90%. It measures correctly but the adjustment is very critical. (150 ohm.)
Cheers.
Geoff.

Refugee · 25th Apr 2012, 9:50 pm

There might be a heater to cathode short if if the hum pot is near the end of its range. Not tricky to sort if you have a valve tester.

Geoff 555 · 25th Apr 2012, 10:23 pm

Hello again refugee thank you.I did test all the valves apart from 1 and that one has no discernible markings, the EL84 was borderline. On order.
The unmarked valve looked like a ECC83 but may well not be, there does seem to be variations in circuits/models and I have yet to find anything that matches. I did not want to damage the unknown valve.
Cheers.
Geoff.

Refugee · 25th Apr 2012, 11:36 pm

I had a quick look at the radio museum website and it says there is an ECC83 in it.
I would be tempted to have a look at the valve museum and check the connections and voltages against there data sheet.

Geoff 555 · 26th Apr 2012, 12:52 pm

Thanks. Quick one because I am late not supposed to be here. There is a ECC83 and a ECC81 And XXXXX one with no marking. I will try your suggestion and get some voltages.Later.
Cheers.
Geoff

Geoff 555 · 29th Apr 2012, 11:56 am

Hi sorry for the delay, despite items being listed as available I have just had mail stating no stock so there will be a delay. I will be back shortly.
Cheers.
Geoff.

25th Apr 2012, 12:09 am	#1
Geoff 555 Heptode Join Date: Jan 2008 Location: Bristol, UK. Posts: 981	Brenell Mk.5 TR. Hello everybody I just thought I would run this past you to see what you thought and ask for any advice. Brief history is that my father bought this in 1959 and it was in use until 1978. I inherited it in 1980. The Reslo (?) mike and transformer were missing. Having found some tapes of Dads thought I would listen to them But It has died so it seems. It is a Mk5 with a level meter. The amp works, with a mike.Plenty of volume with just a trace of distortion when turned right up. Turned to record the level meter works . Turned to play back there is nothing recorded , if the volume is turned up above half way then there is a lot of hum and if turned up more then what sounds like motor boating and is too bad to keep it there too long. The erase and P/R heads measure OK and are clean. I know Dad had it repaired in about 1970 but I dont know what was done. I can't see anything burnt or nasty the only thing I have done is replace the smoothing block, 50 + 50 at 500 volts as it didn't want to reform. It hasn't been used for something like 25 years approx. Sorry for the long post I do tend to ramble on. Cheers and thank you. Geoff.

25th Apr 2012, 12:32 am	#2
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Brenell Mk.5 TR. I would check that the record switch is moving fully into place and give it a shot of switch cleaner. Then have another go.

25th Apr 2012, 5:25 pm	#3
Geoff 555 Heptode Join Date: Jan 2008 Location: Bristol, UK. Posts: 981	Re: Brenell Mk.5 TR. Thank you for that.The switches have been cleaned and a couple of things found, more of which later when a valve and a pot have arrived. One thing that I do not fully understand is that there is a 'humdinger' pot ( not the one I have ordered.) that has to be fully turned to one end and that does cut the hum down 90%. It measures correctly but the adjustment is very critical. (150 ohm.) Cheers. Geoff.

25th Apr 2012, 9:50 pm	#4
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Brenell Mk.5 TR. There might be a heater to cathode short if if the hum pot is near the end of its range. Not tricky to sort if you have a valve tester.

25th Apr 2012, 10:23 pm	#5
Geoff 555 Heptode Join Date: Jan 2008 Location: Bristol, UK. Posts: 981	Re: Brenell Mk.5 TR. Hello again refugee thank you.I did test all the valves apart from 1 and that one has no discernible markings, the EL84 was borderline. On order. The unmarked valve looked like a ECC83 but may well not be, there does seem to be variations in circuits/models and I have yet to find anything that matches. I did not want to damage the unknown valve. Cheers. Geoff. Attached Thumbnails Last edited by Geoff 555; 25th Apr 2012 at 10:26 pm. Reason: Signature went missing.

25th Apr 2012, 11:36 pm	#6
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Brenell Mk.5 TR. I had a quick look at the radio museum website and it says there is an ECC83 in it. I would be tempted to have a look at the valve museum and check the connections and voltages against there data sheet.

26th Apr 2012, 12:52 pm	#7
Geoff 555 Heptode Join Date: Jan 2008 Location: Bristol, UK. Posts: 981	Re: Brenell Mk.5 TR. Thanks. Quick one because I am late not supposed to be here. There is a ECC83 and a ECC81 And XXXXX one with no marking. I will try your suggestion and get some voltages.Later. Cheers. Geoff

29th Apr 2012, 11:56 am	#8
Geoff 555 Heptode Join Date: Jan 2008 Location: Bristol, UK. Posts: 981	Re: Brenell Mk.5 TR. Hi sorry for the delay, despite items being listed as available I have just had mail stating no stock so there will be a delay. I will be back shortly. Cheers. Geoff.