Dynatron HFC100A. Speaker output problems! Help! - UK Vintage Radio Repair and Restoration Discussion Forum

indykid20 · 18th Dec 2016, 5:44 pm

Hi, I'm looking for some help and troubleshooting on a Dynatron HFC100A. Just bought it and its immaculate, apart from the right sided speaker ports aren't working. The left ones are fine and speakers work perfectly. But when I plug a speaker into the right side of the amp, no sound! I've taken off the turntable and had a quick peruse of the electronics, and all the soldering and components seem fine and the fuses are intact. Thats as far as I have got as I'm a novice and don't want to break anything. Any assistance and help anyone can give me would be greatly appreciated!

'LIVEWIRE?' · 18th Dec 2016, 6:22 pm

Are you sure, sorry if I'm stating the obvious, that the balance control is set to the mid position, and not wound all the way to the left. If the control is set midway between L & R, approximately equal volume should be heard from left and right speakers. If this is still not the case, or if turning the balance control to the left mutes the RH speaker(s) without producing sound from the LH one(s), this indicates a fault somewhere in the LH Channel. Is the HFC100A purely a record player, or does it have a radio tuner? If so, is the LH channel silent on both radio and record player? No sound from the record player can indicate a faulty pickup cartridge.

indykid20 · 19th Dec 2016, 12:57 am

I've definitely got the balance set midway and I have tried turning it on to LH channel only and it plays through that then vice versa, no sound when you turn it onto the RH channel.

The HFC100A is a record player only. There are actually 4 speaker outputs and the RH channels are not working on both

Station X · 19th Dec 2016, 10:12 am

I assume you've tried both speakers on the RH channel to prove that it's not a speaker fault?

Your only hope of a quick fix is that the problem is a faulty cartridge. Lift up the arm and you'll see four pins or tags on the rear of the cartridge. With the volume turned up touch the metallic part of each of these tags in turn with a small screwdriver. If the cartridge is OK, touching two of these tags should result in a hum or buzz from each of the speakers.

jamesperrett · 20th Dec 2016, 1:01 pm

I'm assuming that the HFC100 is the record player only equivalent to the HFC101 as a search doesn't bring up anything apart from this thread. Do you hear any noise or hiss from the RH channel? If you do then it means that the power amp section is working. It may also be worth plugging in a pair of headphones just to check that that the speaker switches aren't faulty.

You have a number of switches on the front panel that can cause problems. I'd first check the tape monitor switch as this will interrupt the signal if it is faulty - do you hear any clicks or noises on the RH channel when you push it in? If you hear some noise then it may be worth feeding a signal into the tape input (though this will be a DIN connector so you'll probably need an adaptor to whatever you want to connect it to).

Edward Huggins · 20th Dec 2016, 2:03 pm

These units are notorious for the failure of one of the amplifier channels, there was poor QC in Dynatron at that time. If all the above good advice does not solve the problem, the amplifier will need troubleshooting and repairing. By the use of you word speaker "ports", I suspect you may not be all that experienced with vintage electronics?

18th Dec 2016, 5:44 pm	#1
indykid20 Retired Dormant Member Join Date: Dec 2016 Location: Glasgow, Scotland, UK. Posts: 2	Dynatron HFC100A. Speaker output problems! Help! Hi, I'm looking for some help and troubleshooting on a Dynatron HFC100A. Just bought it and its immaculate, apart from the right sided speaker ports aren't working. The left ones are fine and speakers work perfectly. But when I plug a speaker into the right side of the amp, no sound! I've taken off the turntable and had a quick peruse of the electronics, and all the soldering and components seem fine and the fuses are intact. Thats as far as I have got as I'm a novice and don't want to break anything. Any assistance and help anyone can give me would be greatly appreciated!

18th Dec 2016, 6:22 pm	#2
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,305	Re: Dynatron HFC100A. Speaker output problems! Help! Are you sure, sorry if I'm stating the obvious, that the balance control is set to the mid position, and not wound all the way to the left. If the control is set midway between L & R, approximately equal volume should be heard from left and right speakers. If this is still not the case, or if turning the balance control to the left mutes the RH speaker(s) without producing sound from the LH one(s), this indicates a fault somewhere in the LH Channel. Is the HFC100A purely a record player, or does it have a radio tuner? If so, is the LH channel silent on both radio and record player? No sound from the record player can indicate a faulty pickup cartridge.

19th Dec 2016, 12:57 am	#3
indykid20 Retired Dormant Member Join Date: Dec 2016 Location: Glasgow, Scotland, UK. Posts: 2	Re: Dynatron HFC100A. Speaker output problems! Help! I've definitely got the balance set midway and I have tried turning it on to LH channel only and it plays through that then vice versa, no sound when you turn it onto the RH channel. The HFC100A is a record player only. There are actually 4 speaker outputs and the RH channels are not working on both

19th Dec 2016, 10:12 am	#4
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 22,834	Re: Dynatron HFC100A. Speaker output problems! Help! I assume you've tried both speakers on the RH channel to prove that it's not a speaker fault? Your only hope of a quick fix is that the problem is a faulty cartridge. Lift up the arm and you'll see four pins or tags on the rear of the cartridge. With the volume turned up touch the metallic part of each of these tags in turn with a small screwdriver. If the cartridge is OK, touching two of these tags should result in a hum or buzz from each of the speakers. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

20th Dec 2016, 1:01 pm	#5
jamesperrett Nonode Join Date: May 2007 Location: Liss, Hampshire, UK. Posts: 2,019	Re: Dynatron HFC100A. Speaker output problems! Help! I'm assuming that the HFC100 is the record player only equivalent to the HFC101 as a search doesn't bring up anything apart from this thread. Do you hear any noise or hiss from the RH channel? If you do then it means that the power amp section is working. It may also be worth plugging in a pair of headphones just to check that that the speaker switches aren't faulty. You have a number of switches on the front panel that can cause problems. I'd first check the tape monitor switch as this will interrupt the signal if it is faulty - do you hear any clicks or noises on the RH channel when you push it in? If you hear some noise then it may be worth feeding a signal into the tape input (though this will be a DIN connector so you'll probably need an adaptor to whatever you want to connect it to).

20th Dec 2016, 2:03 pm	#6
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 9,161	Re: Dynatron HFC100A. Speaker output problems! Help! These units are notorious for the failure of one of the amplifier channels, there was poor QC in Dynatron at that time. If all the above good advice does not solve the problem, the amplifier will need troubleshooting and repairing. By the use of you word speaker "ports", I suspect you may not be all that experienced with vintage electronics? __________________ Edward.