Variable resistors - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

Station X · 28th Jun 2017, 2:20 pm

We all seem to agree that the pre-sets are 500R, but we seem to have no idea what the component/s wired in parallel with them are.

All this discussion seems to have arisen because the presets are turned in different directions to achieve minimum current. Wouldn't it be easier just to sign write them MIN and MAX?

Herald1360 · 28th Jun 2017, 6:15 pm

Ah, but would that be remembered as Min/Max current or Min/Max resistance.

I'd go for MinI and MaxI (or Imin and Imax)

Nukeybrown · 28th Jun 2017, 8:06 pm

You would struggle to put min & max as theyre turned from the underside of the circuit board. The top side of the pot cannot be easily seen due to board position.

dave cox · 30th Jun 2017, 11:22 am

By the sounds of things, you need an adjustment close to 100R so a 100R pot is no good. A 220R would be too high at max setting, risking overheating. Al's suggestion of 20R in series with 100R preset seems the best option.

Are you sure the original is 50K ?
At max setting this would surely blow the output stage !

dc

Station X · 30th Jun 2017, 11:37 am

We've established that these are in fact 500R presets.

Ed_Dinning · 30th Jun 2017, 8:55 pm

Hi Nukey, if you are not sorted yet give me a PM as I may have something suitable.

Ed

28th Jun 2017, 2:20 pm	#41
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Variable resistors We all seem to agree that the pre-sets are 500R, but we seem to have no idea what the component/s wired in parallel with them are. All this discussion seems to have arisen because the presets are turned in different directions to achieve minimum current. Wouldn't it be easier just to sign write them MIN and MAX? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

28th Jun 2017, 6:15 pm	#42
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: Variable resistors Ah, but would that be remembered as Min/Max current or Min/Max resistance. I'd go for MinI and MaxI (or Imin and Imax) __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

28th Jun 2017, 8:06 pm	#43
Nukeybrown Heptode Join Date: Jan 2016 Location: Gateshead, Tyne and Wear, UK. Posts: 504	Re: Variable resistors You would struggle to put min & max as theyre turned from the underside of the circuit board. The top side of the pot cannot be easily seen due to board position.

30th Jun 2017, 11:22 am	#44
dave cox Nonode Join Date: Jan 2009 Location: Bristol, UK. Posts: 2,062	Re: Variable resistors By the sounds of things, you need an adjustment close to 100R so a 100R pot is no good. A 220R would be too high at max setting, risking overheating. Al's suggestion of 20R in series with 100R preset seems the best option. Are you sure the original is 50K ? At max setting this would surely blow the output stage ! dc

30th Jun 2017, 11:37 am	#45
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Variable resistors We've established that these are in fact 500R presets. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

30th Jun 2017, 8:55 pm	#46
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: Variable resistors Hi Nukey, if you are not sorted yet give me a PM as I may have something suitable. Ed