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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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26th Jun 2020, 12:48 pm | #1 |
Triode
Join Date: Jan 2013
Location: Lutterworth, Leicestershire, UK.
Posts: 18
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HMV Radiogram 2346 Repair
Hi all
Hope you can set me on the right course. I have recently purchased a 1970/1 HMV Radiogram 2346. The reason for this is because my parents had one when I was a child and I have been after the same model since they disposed of theirs in the local landfill I have finally got one in very good condition cosmetically so well chuffed. The BSR Gram works great and plays records well. The main problem is the radio as it does not work, lots of crackle but I cannot get any reception on any band, they all sound the same. I believe this is a common problem because of its age so can anyone advise on the route i should take, I am very handy with a soldering iron if parts need replacing. I have had the back off and it looks like the insides have never been touched, even a little component drawing stapled to the bottom of the cabinet. Look forward to your help Cheers ciaolflyer |
26th Jun 2020, 1:19 pm | #2 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,823
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Re: HMV Radiogram 2346 Repair
Your set may have the dreaded AF116's tin wisker problem transistors, it seems they used AF11* or AF12* the later not suffering tin whiskers.
It's also got a big bank of switches that will need cleaning. I think that's where I would start. Check for the AF11*'s if they are all AF12* then clean the switches. Cheers Mike T
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Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |
26th Jun 2020, 1:22 pm | #3 |
Triode
Join Date: Jan 2013
Location: Lutterworth, Leicestershire, UK.
Posts: 18
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Re: HMV Radiogram 2346 Repair
Great, which transistors can I replace them with?
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26th Jun 2020, 1:23 pm | #4 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
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Re: HMV Radiogram 2346 Repair
First of all I would spray the push button waveband selectors with Servisol 10 and actuate them to clean the contacts. Also is the tuning moving freely from side to side?
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Edward. |
26th Jun 2020, 1:41 pm | #5 |
Triode
Join Date: Jan 2013
Location: Lutterworth, Leicestershire, UK.
Posts: 18
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Re: HMV Radiogram 2346 Repair
Thanks, I have sprayed with Servisol and actuated them but this makes no difference at all, may have a second go at it. Tuning work smoothly.
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26th Jun 2020, 1:53 pm | #6 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,823
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Re: HMV Radiogram 2346 Repair
__________________
Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |
26th Jun 2020, 2:00 pm | #7 |
Triode
Join Date: Jan 2013
Location: Lutterworth, Leicestershire, UK.
Posts: 18
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Re: HMV Radiogram 2346 Repair
This is all great stuff, thanks for your replies! I have now read on this site that you can dismantle the transistor and remove the whiskers! Gonna have a go and see what happens! Cheers all! Will keep you updated with progress!
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26th Jun 2020, 3:12 pm | #8 |
Triode
Join Date: Jan 2013
Location: Lutterworth, Leicestershire, UK.
Posts: 18
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Re: HMV Radiogram 2346 Repair
I assume it is the 4 circled in red which are the offending items, is this correct?
They are labeled: 3 x AF116 1 x AF115 I assume I have to remove the board in order to solder them, is this a difficult task? Could I snip them out and then re solder them back? |
26th Jun 2020, 5:11 pm | #9 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,823
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Re: HMV Radiogram 2346 Repair
They are the offenders, if not faulty now likely will be in the not too distant future. If you cut them out will the leads be long enough to refit?
Cheers Mike T
__________________
Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |
26th Jun 2020, 6:47 pm | #10 |
Dekatron
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 4,985
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Re: HMV Radiogram 2346 Repair
It's unlikely you'll need to replace any of those AF*** transistors.
Normal transistors have three leads, the AF*** types have four leads. This extra lead is a silly screen lead which causes problems due to the dreaded tin whisker problem. Download the data sheet for the transistors and identify the "screen" lead and just snip it off on each one and your radio will work - make sure you hit the right lead otherwise you'll have problems. If you want to be less of a butcher then you can carefully un-solder the lead from the board on each one and bend it up out of the way, but it doesn't really matter which method you use. I've never had a recurring problem doing this, so worth a try before going to all the trouble of actually finding replacements and changing them. |
26th Jun 2020, 9:26 pm | #11 |
Heptode
Join Date: Mar 2014
Location: Leeds, West Yorkshire, UK.
Posts: 899
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Re: HMV Radiogram 2346 Repair
I read somewhere on here that putting a hot soldering iron on the case for a few seconds melts the whiskers and the transistor starts working. Worth a try before you start undoing things
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27th Jun 2020, 6:14 pm | #12 |
Triode
Join Date: Jan 2013
Location: Lutterworth, Leicestershire, UK.
Posts: 18
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Re: HMV Radiogram 2346 Repair
Update: It is deff the transistors so thanks to all! I have tried heating with soldering iron but it did nothing. So then I tapped them and one of them made a loud cracking sound, nothing from the others. After tapping a bit more LW sprang into life on Radio 4! However, after switching off it did not work again, so may need to dismantle!
I did fine a parts guarantee inside, do you think they will still honor it? |
27th Jun 2020, 7:16 pm | #13 |
Triode
Join Date: Jan 2013
Location: Lutterworth, Leicestershire, UK.
Posts: 18
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Re: HMV Radiogram 2346 Repair
Another strange note that when the radio is working, if I tap the tuning knob, it gets louder.
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27th Jun 2020, 7:31 pm | #14 |
Hexode
Join Date: Aug 2014
Location: Wigston, Leicester, UK.
Posts: 348
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Re: HMV Radiogram 2346 Repair
Tommy Cooper would probably have said "well don't tap it then"
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28th Jun 2020, 8:35 am | #15 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
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Re: HMV Radiogram 2346 Repair
I usually replace all four with AC125’s. Double check the pin outs but they will be a straight fit onto the board.
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28th Jun 2020, 11:16 am | #16 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,786
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Re: HMV Radiogram 2346 Repair
Do you mean AF125s Michael?
AF11x transistors are usually straightforward to replace and lots of substitute types will work. Even silicon types will often work despite the different bias requirement. There are many threads on AF11x replacement if you search the forum. |
29th Jun 2020, 11:29 pm | #17 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
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Re: HMV Radiogram 2346 Repair
Sorry Paul yes AF125's
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1st Jul 2020, 3:09 pm | #18 |
Triode
Join Date: Jan 2013
Location: Lutterworth, Leicestershire, UK.
Posts: 18
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Re: HMV Radiogram 2346 Repair
would these be ok to replace with:
https://www.cricklewoodelectronics.c...QaAkWgEALw_wcB Please remove if this post is not allowed - Thanks |
1st Jul 2020, 3:17 pm | #19 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
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Re: HMV Radiogram 2346 Repair
No, you cant fit a silicon transistor in place of a germanium without modifying the bias conditions. In any case a BC transistor is for low frequencies like audio.
You can use these |
1st Jul 2020, 3:22 pm | #20 |
Dekatron
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 4,985
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Re: HMV Radiogram 2346 Repair
Just do as I said and isolate the screens on all the AFs and the job's done. You can look into possible replacements should you have problems further down the line and need to actually replace them. I find that clipping or lifting the screen to each transistor cures the fault, although in theory a 'whisker' could actually short across the junction rather than just junction to screen, but this is very rare.
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