Silvertone RP - modified? - UK Vintage Radio Repair and Restoration Discussion Forum

RojDW48 · 28th Apr 2017, 7:14 pm

'While you're here...' said the nice young man, whose purchase of an old RP I had just dropped off.... And it was this Silvertone RP. I hadn't come across a Silvertone before but a quick look at the interweb proved they were quite prolific. Does anyone recognize this model? I think it is fair to assume that the original knobs were round. The 2 rather crude holes have RCA phono sockets behind them and I haven't identified what lies behind the slot yet. The amp has 2 ECL86s and, presumably, a metal rectifier lurking somewhere. Does it ring any bells before I explore further? The only Silvertone circuit I could find in the service data was for a transistor radio

teetoon · 28th Apr 2017, 7:31 pm

Hi Roj. There was a matching amp on ebay earlier this month. Here's one of the pics. You can still see all pics in completed listings. Search for silvertone revelation amp.
Hope this helps.

David.

ms660 · 28th Apr 2017, 7:43 pm

According to radiomuseum the AP15 and the AP18 used a pair of ECL86's:

http://www.radiomuseum.org/dsp_herst...mpany_id=11222

Lawrence.

'LIVEWIRE?' · 28th Apr 2017, 7:55 pm

I have exactly the same model as yours, bought at a Car Boot Sale maybe 15 years ago for the princely sum of £3.00! Those knobs aren't original, but otherwise it's the same player. The amplifier is a good quality push-oull type featuring a 'Concertina' phase splitter, producing about 6 watts o/p. On mine there is a very small amount of hum, even though I replaced the reservoir & smoothing capacitors some years ago. The circuit is available for £1.99 from the VRSD link at the top RH side of the page, although I 'reverse engineered' mine not long after I bought the RP. It is listed as 'Revelation'. The service sheet covers all their record players, plus the 'add-on' stereo amplifier. IMHO the only improvement the designers could have made would have been to use a bridge rectifier instead of the half-wave single diode fitted. Maybe that's the cause of the small amount of hum. One of the two RCA sockets is an output to a (mono) tape recorder, the other is the connection to the add-on amplifier. The word 'stereo' should appear at the LH side of the left socket, and 'Tape' to the RH side of the right socket. These sockets were designed to take the longer pinned RCA Plugh available back in the 60s. but I was able to connect a modern plug by slightly enlarging the hole in the front panel.

RojDW48 · 28th Apr 2017, 11:36 pm

What a great forum this is! Many thanks folks. Now I know what it is. I know it hasn't been interfered with - just lost its control panel (and knobs). I also know what the phono sockets are for. And all that without dismantling further.

Livewire - any tips about extracting the amp? Lots of battens and bits of hardboard in there.

The owner reports a loss of volume and clarity together with a (not too bad) volume dependent hum. Cartridge is an X5H, fairly recent, so, with a 6-ish W push/pull amp it ought to have plenty of go!

'LIVEWIRE?' · 29th Apr 2017, 9:04 am

Remove the panel behind the speaker (4 screws), takeout the autochanger on it's wooden baseboard (3 woodscrews) Note that internal connections from the tagstrip to the amp., and the motor leads need to be unsoldered to remove the record deck completely. To gain access to the underside of the amplifier, turn the cabinet over, and remove the bottom panel at the front of the cabinet (4 screws). For most servicing purposes, removing the bottom panel will be sufficient as it gives access to all the under-chassis components. The valves are unlikely to give trouble, and in any case they are accessible with the pnael behind the speaker removed as in your photo#2.. I've never extracted the amplifier, working on it inside the cabinet. I don't recall any waxed paper capacitors in this model, but, if they are present they should be replaced with modern equivalents, such as LCR or similar polypropylene (the yellow axial caps. stocked by Cricklewood Electronics and others) types. Should you need to remove the amplifier it is secured to the batten by two screws at it's rear, though you will have to remove the knobs (those 'chicken head' knobs on yours are held with grubscrews, btw), and may have to unscrew the potentiometer fixing nuts. In addition the wires to the speaker, motor, and pickup tagstrip will need to be unsoldered as previously mentioned. Originally there was a plastic trim strip along the front (behind the knobs) with the name 'Revelation' printed to the right of the two sockets. Incidentally that X5H carrtidge may be the original one fitted over 50 years ago, though they don't often fail. It may be worth substituting a known good cartridge as a dirst check. A SC11m or similar should be suitable, since the player has a 2-stage amplifier.

Edward Huggins · 29th Apr 2017, 10:07 am

The X5H (high-output) is worth a small fortune in its own right, but these are not normally used with 2 stage amplfiers such as in your player. They can cause an overload which might manifest itself in distortion. As suggested the SC11M would be a far better match. Silvertone were famous for their cases which of course they made, but I suspect the innards of these were sub-contracted out for assembly.

'LIVEWIRE?' · 29th Apr 2017, 1:04 pm

The rectifier in these, or at least in the one I have is a'Top Hat' diode (silicon) mounted on the tagstrip at the rear of the amp. chassis. Itis a metal cased type similar to the BY100. Be aware that the outer part (body) of this device is at HT+ve potential when the player is switched on.

'LIVEWIRE?' · 29th Apr 2017, 1:30 pm

These two pictures may be of assistance, especially pictre #1, which shows the underside of the amplifier chassis. The rectifier is to the left of he reservoir & smoothing capacitors near the bottom of the photo.

RojDW48 · 29th Apr 2017, 11:58 pm

Quote:

Originally Posted by 'LIVEWIRE?'

Remove the panel behind the speaker.....

That is really helpful - thanks a lot. I should be able to take a crack at it tomorrow or Monday and I have a spare SC11M. Will report back!

'LIVEWIRE?' · 30th Apr 2017, 12:22 pm

A couple of notes regarding pickup cartridges. My AP15 (the model number doesn't appear anywhere on the RP, btw.) is fitted with a BSR X5M. According to the service sheet available from 'up top', these players were originally fitted with the BSR TC8M turnover cystal PU. Edward is right - the X5H has too high an output for two-stage amplifiers such as the AP15. Fitting your SC11M may well solve the problems, Roj. In a 'sticky' thread at the head of this section, there is a list of Cartidges with data, including their o/p's in mV., but I've never measured the sensitivity of the AP15, or, if I did, I've not noted anything other than it's max. o/p is 6watts ino 3.5 ohms. When fitting the SC11m be sure to connect both channels, using the wo 'spare' leads inside the pickup arm. If you will not be adding a stereo amplifier, parallel the two channels at the tagstrip under the deck chassis by soldering a short length of wire between the two outer tags. The negative leads should also be paralleled. If not join these together also. The notes about pickup connections apply to any record player originally fitted with a mono pickup). The SC1m/12M cartridges only have an o/p of 100mV, compared to 400mV for the X5M, so a SX5M, if available, might be a better choice.

RojDW48 · 1st May 2017, 4:40 pm

What a sensible arrangement for servicing! I would have been rooting about for ages without the guidance - thanks again. VRSD is only admitting to having the service data for a transistor radio - is it all hidden in there somewhere?

As you can see in the photo - there is only one smoothing/reservoir cap - 47uF, 350V - is that right? I was expecting something like an 8 and a 16

Edward Huggins · 1st May 2017, 4:51 pm

There will be 2 large value capacitors for the HT supply. One is the reservior and the other the smoother. Typical values are between 32-50uF @ 350/450V.

RojDW48 · 1st May 2017, 4:59 pm

Got it now! I went on the net and found an old post on the forum telling me to look for 'Revelation' rather than Silvertone. And I wasn't wrong - I should be seeing 8 and 16uF caps. Has this been bodged or is this acceptable?

Cobaltblue · 1st May 2017, 4:59 pm

Search under Revelation (the maker) rather than Silvertone which is the model

Haha

Crossed.

Cheers

Mike T

RojDW48 · 1st May 2017, 5:46 pm

Thanks Mike!

I take it all back - now I'm looking at the RIGHT schematic for the AP15 - I can see it does use a 47uF cap, C12 (or '48' to be exact - you always got a bit more for your money in the 60s!) and another, C8, which I guess is the other one in the pic. Are C6, C9 and C10 (0.01 uF) grid couplers? Are they likely to be suspect in this circuit?

Cobaltblue · 1st May 2017, 5:58 pm

Hi Roj

Looking at the picture you posted earlier of the underneath of the chassis I can see Mullard "mustard" and tubular ceramic capacitors neither of which are very likely to be faulty.

Cheers

Mike T

'LIVEWIRE?' · 1st May 2017, 6:40 pm

Roj, the original Reservoir & Smoothing Capacitor (C12 & C8) was a dual 48uf 350v wire-ende type. I replaced mine with two 47uf 350 or 400v axial electrolytics about 8 years ago. Looking at your (clearer than mine) amplifier photo, the original dual unit has been replaced with two seperate 47uf axial electroltyics in that amplifier. The rectifier in your amp. is a plastic type, mounted at the RH end of the tagstrip close to the 47uf Electrolytic. As long as the voltages are within spec (i.e. similar to those on the circuit diagram, bearing in mind, that they would have been taken with an AVO 8 with an impedance of 20k/volt, so if you measure the voltages with a DMM, they will be higher than those on the circuit diagram. As a silicon rectifier is used, higher value Reservoir & Smoothing capacitors could be fitted, but I wouldn't reduce them.

RojDW48 · 1st May 2017, 7:33 pm

I haven't made any measurements yet but I have substituted a cartridge - an X5M. Interestingly the gain dropped dramatically. I know it's a lower output cartridge but, as discussed earlier, it should have more than enough output for this amp (the result was nothing like enough). Should that loss of gain tell me something useful? The owner remarked that he noticed a significant loss of volume (with the X5H)

Edward Huggins · 1st May 2017, 7:51 pm

Your amplifier has a sensitivity of 250mV and a BSR X5M should fully load this to give an "on-spec" output. If it needs a BSR X5H to drive this, then there must be some lack of stage-gain in the amplifier or possibly low HT.

This might be well be why a BSR X5H was fitted as a crude "quick fix" earlier in its life.

28th Apr 2017, 7:43 pm	#3
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Silvertone RP - modified? According to radiomuseum the AP15 and the AP18 used a pair of ECL86's: http://www.radiomuseum.org/dsp_herst...mpany_id=11222 Lawrence.

28th Apr 2017, 7:55 pm	#4
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Silvertone RP - modified? I have exactly the same model as yours, bought at a Car Boot Sale maybe 15 years ago for the princely sum of £3.00! Those knobs aren't original, but otherwise it's the same player. The amplifier is a good quality push-oull type featuring a 'Concertina' phase splitter, producing about 6 watts o/p. On mine there is a very small amount of hum, even though I replaced the reservoir & smoothing capacitors some years ago. The circuit is available for £1.99 from the VRSD link at the top RH side of the page, although I 'reverse engineered' mine not long after I bought the RP. It is listed as 'Revelation'. The service sheet covers all their record players, plus the 'add-on' stereo amplifier. IMHO the only improvement the designers could have made would have been to use a bridge rectifier instead of the half-wave single diode fitted. Maybe that's the cause of the small amount of hum. One of the two RCA sockets is an output to a (mono) tape recorder, the other is the connection to the add-on amplifier. The word 'stereo' should appear at the LH side of the left socket, and 'Tape' to the RH side of the right socket. These sockets were designed to take the longer pinned RCA Plugh available back in the 60s. but I was able to connect a modern plug by slightly enlarging the hole in the front panel. Last edited by 'LIVEWIRE?'; 28th Apr 2017 at 8:05 pm.

28th Apr 2017, 11:36 pm	#5
RojDW48 Nonode Join Date: Jun 2014 Location: Bristol, UK. Posts: 2,074	Re: Silvertone RP - modified? What a great forum this is! Many thanks folks. Now I know what it is. I know it hasn't been interfered with - just lost its control panel (and knobs). I also know what the phono sockets are for. And all that without dismantling further. Livewire - any tips about extracting the amp? Lots of battens and bits of hardboard in there. The owner reports a loss of volume and clarity together with a (not too bad) volume dependent hum. Cartridge is an X5H, fairly recent, so, with a 6-ish W push/pull amp it ought to have plenty of go! __________________ '....don't go mistaking Paradise for that home across the road!' (Bob Dylan)

29th Apr 2017, 9:04 am	#6
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Silvertone RP - modified? Remove the panel behind the speaker (4 screws), takeout the autochanger on it's wooden baseboard (3 woodscrews) Note that internal connections from the tagstrip to the amp., and the motor leads need to be unsoldered to remove the record deck completely. To gain access to the underside of the amplifier, turn the cabinet over, and remove the bottom panel at the front of the cabinet (4 screws). For most servicing purposes, removing the bottom panel will be sufficient as it gives access to all the under-chassis components. The valves are unlikely to give trouble, and in any case they are accessible with the pnael behind the speaker removed as in your photo#2.. I've never extracted the amplifier, working on it inside the cabinet. I don't recall any waxed paper capacitors in this model, but, if they are present they should be replaced with modern equivalents, such as LCR or similar polypropylene (the yellow axial caps. stocked by Cricklewood Electronics and others) types. Should you need to remove the amplifier it is secured to the batten by two screws at it's rear, though you will have to remove the knobs (those 'chicken head' knobs on yours are held with grubscrews, btw), and may have to unscrew the potentiometer fixing nuts. In addition the wires to the speaker, motor, and pickup tagstrip will need to be unsoldered as previously mentioned. Originally there was a plastic trim strip along the front (behind the knobs) with the name 'Revelation' printed to the right of the two sockets. Incidentally that X5H carrtidge may be the original one fitted over 50 years ago, though they don't often fail. It may be worth substituting a known good cartridge as a dirst check. A SC11m or similar should be suitable, since the player has a 2-stage amplifier. Last edited by 'LIVEWIRE?'; 29th Apr 2017 at 9:19 am.

29th Apr 2017, 10:07 am	#7
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,327	Re: Silvertone RP - modified? The X5H (high-output) is worth a small fortune in its own right, but these are not normally used with 2 stage amplfiers such as in your player. They can cause an overload which might manifest itself in distortion. As suggested the SC11M would be a far better match. Silvertone were famous for their cases which of course they made, but I suspect the innards of these were sub-contracted out for assembly. __________________ Edward.

28th Apr 2017, 7:14 pm	#1
RojDW48 Nonode Join Date: Jun 2014 Location: Bristol, UK. Posts: 2,074	Silvertone RP - modified? 'While you're here...' said the nice young man, whose purchase of an old RP I had just dropped off.... And it was this Silvertone RP. I hadn't come across a Silvertone before but a quick look at the interweb proved they were quite prolific. Does anyone recognize this model? I think it is fair to assume that the original knobs were round. The 2 rather crude holes have RCA phono sockets behind them and I haven't identified what lies behind the slot yet. The amp has 2 ECL86s and, presumably, a metal rectifier lurking somewhere. Does it ring any bells before I explore further? The only Silvertone circuit I could find in the service data was for a transistor radio Attached Thumbnails __________________ '....don't go mistaking Paradise for that home across the road!' (Bob Dylan)

28th Apr 2017, 7:31 pm	#2
teetoon Heptode Join Date: Dec 2010 Location: Barnstaple, N.Devon, UK. Posts: 557	Re: Silvertone RP - modified? Hi Roj. There was a matching amp on ebay earlier this month. Here's one of the pics. You can still see all pics in completed listings. Search for silvertone revelation amp. Hope this helps. David. Attached Thumbnails

29th Apr 2017, 1:04 pm	#8
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Silvertone RP - modified? The rectifier in these, or at least in the one I have is a'Top Hat' diode (silicon) mounted on the tagstrip at the rear of the amp. chassis. Itis a metal cased type similar to the BY100. Be aware that the outer part (body) of this device is at HT+ve potential when the player is switched on.

29th Apr 2017, 1:30 pm	#9
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Silvertone RP - modified? These two pictures may be of assistance, especially pictre #1, which shows the underside of the amplifier chassis. The rectifier is to the left of he reservoir & smoothing capacitors near the bottom of the photo. Attached Thumbnails

30th Apr 2017, 12:22 pm	#11
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Silvertone RP - modified? A couple of notes regarding pickup cartridges. My AP15 (the model number doesn't appear anywhere on the RP, btw.) is fitted with a BSR X5M. According to the service sheet available from 'up top', these players were originally fitted with the BSR TC8M turnover cystal PU. Edward is right - the X5H has too high an output for two-stage amplifiers such as the AP15. Fitting your SC11M may well solve the problems, Roj. In a 'sticky' thread at the head of this section, there is a list of Cartidges with data, including their o/p's in mV., but I've never measured the sensitivity of the AP15, or, if I did, I've not noted anything other than it's max. o/p is 6watts ino 3.5 ohms. When fitting the SC11m be sure to connect both channels, using the wo 'spare' leads inside the pickup arm. If you will not be adding a stereo amplifier, parallel the two channels at the tagstrip under the deck chassis by soldering a short length of wire between the two outer tags. The negative leads should also be paralleled. If not join these together also. The notes about pickup connections apply to any record player originally fitted with a mono pickup). The SC1m/12M cartridges only have an o/p of 100mV, compared to 400mV for the X5M, so a SX5M, if available, might be a better choice. Last edited by 'LIVEWIRE?'; 30th Apr 2017 at 12:42 pm.

1st May 2017, 4:40 pm	#12
RojDW48 Nonode Join Date: Jun 2014 Location: Bristol, UK. Posts: 2,074	Re: Silvertone RP - modified? What a sensible arrangement for servicing! I would have been rooting about for ages without the guidance - thanks again. VRSD is only admitting to having the service data for a transistor radio - is it all hidden in there somewhere? As you can see in the photo - there is only one smoothing/reservoir cap - 47uF, 350V - is that right? I was expecting something like an 8 and a 16 Attached Thumbnails __________________ '....don't go mistaking Paradise for that home across the road!' (Bob Dylan)

1st May 2017, 4:51 pm	#13
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,327	Re: Silvertone RP - modified? There will be 2 large value capacitors for the HT supply. One is the reservior and the other the smoother. Typical values are between 32-50uF @ 350/450V. __________________ Edward.

1st May 2017, 4:59 pm	#14
RojDW48 Nonode Join Date: Jun 2014 Location: Bristol, UK. Posts: 2,074	Re: Silvertone RP - modified? Got it now! I went on the net and found an old post on the forum telling me to look for 'Revelation' rather than Silvertone. And I wasn't wrong - I should be seeing 8 and 16uF caps. Has this been bodged or is this acceptable? __________________ '....don't go mistaking Paradise for that home across the road!' (Bob Dylan)

1st May 2017, 4:59 pm	#15
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,864	Re: Silvertone RP - modified? Search under Revelation (the maker) rather than Silvertone which is the model Haha Crossed. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk Last edited by Cobaltblue; 1st May 2017 at 5:00 pm. Reason: Crossed with OP

1st May 2017, 5:46 pm	#16
RojDW48 Nonode Join Date: Jun 2014 Location: Bristol, UK. Posts: 2,074	Re: Silvertone RP - modified? Thanks Mike! I take it all back - now I'm looking at the RIGHT schematic for the AP15 - I can see it does use a 47uF cap, C12 (or '48' to be exact - you always got a bit more for your money in the 60s!) and another, C8, which I guess is the other one in the pic. Are C6, C9 and C10 (0.01 uF) grid couplers? Are they likely to be suspect in this circuit? __________________ '....don't go mistaking Paradise for that home across the road!' (Bob Dylan) Last edited by RojDW48; 1st May 2017 at 5:48 pm. Reason: more detail

1st May 2017, 5:58 pm	#17
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,864	Re: Silvertone RP - modified? Hi Roj Looking at the picture you posted earlier of the underneath of the chassis I can see Mullard "mustard" and tubular ceramic capacitors neither of which are very likely to be faulty. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

1st May 2017, 6:40 pm	#18
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Silvertone RP - modified? Roj, the original Reservoir & Smoothing Capacitor (C12 & C8) was a dual 48uf 350v wire-ende type. I replaced mine with two 47uf 350 or 400v axial electrolytics about 8 years ago. Looking at your (clearer than mine) amplifier photo, the original dual unit has been replaced with two seperate 47uf axial electroltyics in that amplifier. The rectifier in your amp. is a plastic type, mounted at the RH end of the tagstrip close to the 47uf Electrolytic. As long as the voltages are within spec (i.e. similar to those on the circuit diagram, bearing in mind, that they would have been taken with an AVO 8 with an impedance of 20k/volt, so if you measure the voltages with a DMM, they will be higher than those on the circuit diagram. As a silicon rectifier is used, higher value Reservoir & Smoothing capacitors could be fitted, but I wouldn't reduce them.

1st May 2017, 7:33 pm	#19
RojDW48 Nonode Join Date: Jun 2014 Location: Bristol, UK. Posts: 2,074	Re: Silvertone RP - modified? I haven't made any measurements yet but I have substituted a cartridge - an X5M. Interestingly the gain dropped dramatically. I know it's a lower output cartridge but, as discussed earlier, it should have more than enough output for this amp (the result was nothing like enough). Should that loss of gain tell me something useful? The owner remarked that he noticed a significant loss of volume (with the X5H) __________________ '....don't go mistaking Paradise for that home across the road!' (Bob Dylan)

1st May 2017, 7:51 pm	#20
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,327	Re: Silvertone RP - modified? Your amplifier has a sensitivity of 250mV and a BSR X5M should fully load this to give an "on-spec" output. If it needs a BSR X5H to drive this, then there must be some lack of stage-gain in the amplifier or possibly low HT. This might be well be why a BSR X5H was fitted as a crude "quick fix" earlier in its life. __________________ Edward.