chiily
PFM Special Builder
I fancied trying one of these old tuners. I heard a friend's Troughline way back when and wasn't wholly impressed, to be perfectly honest I had a Prinzsound FM tuner, little wooden clad thing, through a 32.5/160/Epos 14s, that sounded better than my mate's Troughline.
Anyway, the Stereofetics are quite cheap on ebay, I paid about £30 for the first one, badged as "perfect working order", apart from the tuning spindle being all bent making the top PCB go up and down as the tuning wheel went round. So, I bought another, non-working one for 99p; these things are cheap. They just don't have the mystic (read cost) that surrounds the Troughlines.
I swapped the bent spindle for the non-bent spindle, managing to keep all the tuning string in the right place - it was easier than I thought it would be. Much less concentric to tune now.
PXL_20220425_103119841 by Garf Arf, on Flickr
I do like the way it looks. And yes I know it is missing a silver piece for the on/off, I shall remove one from the donor tuner. The lamp does still work, just can't see it in daylight. Interestingly the lamp is on the transformer side of the bridge diode and pulls the voltage down that the rectifier sees. If the bulb fails then the smoothing cap after the rectifier can see more than it's rated voltage of 12V. So, when recapping the PSU it is wise to replace both smoothing caps with higher voltage ones - caps are much smaller these days and higher voltage spec ones fit very easily.
There's a fair bit on the internet about these tuners, mainly about the PSU section and a small cap in the front end that often needs replacing. Re-capping the PSU was again straight forward, the board unclips and swing upwards making access to the underneath relatively easy.
Old board (poor pic)
PXL_20220424_183435883 by Garf Arf, on Flickr
As you can see the trimmer pots look shot with dirt, so I replaced them too. I measured the resistances of each one as I took them out and set their replacements to the same value.
Recapped and re-trimmed
PXL_20220424_193416480 by Garf Arf, on Flickr
All caps and trimmers replaced. The caps on the -5VDC side were replaced with 3.3uf ones, upped from the original 1.6uf - gleamed from the internet to reduce the ripple on the -5VDC line as the tuner is susceptible to PSU ripple/hum. Powered the tuner up and trimmed the voltages to +9VDC and -5VDC.
The only other cap that needs attention is C98 in the front end stage. I'm not technical in the art of FM radios and I gleamed replacing C98 with a same value tant cap from a thread on the UK Vintage Radio Repair and Restoration forum, Stereofetic hum
I need to fashion a reasonable aerial for it, but even with a bit of wire stuffed in to the aerial connector it picks up plenty of stations, not quire enough signal for stereo, but does a fabulous job with the mono button pushed in.
Has anyone a spare wooden sleeve for this Leak? Happy to pay. PM me.
Anyway, the Stereofetics are quite cheap on ebay, I paid about £30 for the first one, badged as "perfect working order", apart from the tuning spindle being all bent making the top PCB go up and down as the tuning wheel went round. So, I bought another, non-working one for 99p; these things are cheap. They just don't have the mystic (read cost) that surrounds the Troughlines.
I swapped the bent spindle for the non-bent spindle, managing to keep all the tuning string in the right place - it was easier than I thought it would be. Much less concentric to tune now.
PXL_20220425_103119841 by Garf Arf, on FlickrI do like the way it looks. And yes I know it is missing a silver piece for the on/off, I shall remove one from the donor tuner. The lamp does still work, just can't see it in daylight. Interestingly the lamp is on the transformer side of the bridge diode and pulls the voltage down that the rectifier sees. If the bulb fails then the smoothing cap after the rectifier can see more than it's rated voltage of 12V. So, when recapping the PSU it is wise to replace both smoothing caps with higher voltage ones - caps are much smaller these days and higher voltage spec ones fit very easily.
There's a fair bit on the internet about these tuners, mainly about the PSU section and a small cap in the front end that often needs replacing. Re-capping the PSU was again straight forward, the board unclips and swing upwards making access to the underneath relatively easy.
Old board (poor pic)
PXL_20220424_183435883 by Garf Arf, on FlickrAs you can see the trimmer pots look shot with dirt, so I replaced them too. I measured the resistances of each one as I took them out and set their replacements to the same value.
Recapped and re-trimmed
PXL_20220424_193416480 by Garf Arf, on FlickrAll caps and trimmers replaced. The caps on the -5VDC side were replaced with 3.3uf ones, upped from the original 1.6uf - gleamed from the internet to reduce the ripple on the -5VDC line as the tuner is susceptible to PSU ripple/hum. Powered the tuner up and trimmed the voltages to +9VDC and -5VDC.
The only other cap that needs attention is C98 in the front end stage. I'm not technical in the art of FM radios and I gleamed replacing C98 with a same value tant cap from a thread on the UK Vintage Radio Repair and Restoration forum, Stereofetic hum
I need to fashion a reasonable aerial for it, but even with a bit of wire stuffed in to the aerial connector it picks up plenty of stations, not quire enough signal for stereo, but does a fabulous job with the mono button pushed in.
Has anyone a spare wooden sleeve for this Leak? Happy to pay. PM me.
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