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Old 25th Nov 2020, 4:55 pm   #141
Rich400
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Default Re: Adding a selectable line input to valve radiogram

Hi all some great posts there.
I’ll just reaffirm that the mods I have discussed and implemented here are working well, and I have no intention of breaking into the internal circuitry of the amp. All inputs will be channeled through the original 3 pin input socket. The signal conditioning through this from each source has been done externally and is effective.
I would like to thank the forum posters that have helped with this, my experience in electronics is not audio based. I have learned a significant amount of how these systems work with yesterday’s technology and have used this applied with what I know to achieve my goal!
The most important element of this has to be how to remove the live chassis element and I now have all the necessary components to fit now the ext and phono signals have been successfully completed. It’s nice to know there are in the main helpful people out there, and hopefully the ‘jobsworths’ have not been too put out when their suggestions are not appropriate.
If it is still of interest I will update the site with photos of the completed mods when the final parts are assembled.
It has been an absolute pleasure doing this project and although I know electronics I am no enthusiast, but I have enjoyed this and the kind support in the main offered here.
Regards
Richard
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Old 11th Jan 2021, 9:09 pm   #142
Rich400
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Default Re: Adding a selectable line input to valve radiogram

Hi all
I thought I’d post a photo of the completed fascia for the SRG600 including the additional input selector and additional bass, treble and ‘fade’ controls. (The fade control was included to reduce the input signal where required but is largely unused).

I wonder if there are any genuine Garrard 121 mk2 experts available for assistance?
I am interested in any tips to minimise friction on the auto return mechanism and also what is an achievable tracking weight for this deck. It will track nicely at 2.5-3 grams before the auto return resistance but I am having to put it up to about 6.5g to prevent this skipping. I am playing 78’s and using an Audio Technica AT3600 cartridge with a 0.3mm 78 specific stylus.
I have tried cleaning the auto return slide and catch plate and tried it dry and also oiled with synthetic oil. I have also tried WD40 without much improvement.
Does anyone have any figures/advice what is achievable here?
Thanks in advance
Richard
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Old 17th Jan 2021, 12:18 pm   #143
Rich400
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Default Re: Adding a selectable line input to valve radiogram

Hi
Thanks for the series of PM’s helping with this, and a public thankyou for these expert replies and assistance.
For the benefit of anyone else viewing this forum I thought it right to publish the result.
The Garrard RC121 Mk 2 was originally fitted with the GC8 cartridge which has a designed tracking weight of 7-10g and was originally fitted to my DECCA SRG600.
I think it’s reasonable to assume a mid point figure is attainable on this deck with improvements possible using a few tips.
I personally now have this tracking on 78’s safely at 6.5g and with the microgroove stereo records (33/45) tracking on an alternative head-shell fitted with a Ortofon OM pro-s AT 4.5g which is nicely Within it’s spec.
The main issue causing the tracking weight to be increased was the auto return mechanism. This was stripped out, cleaned in alcohol and polished. It was then given a very light wipe with a PTFE dry lubricant and reassembled. The tone arm pivots and shafts were given the same treatment.
This end result works well and I do not intend to try to reduce these figures any more as I am certainly satisfied with this result.
Thanks again those who helped out, and I hope this post may be of some help to others in the same position.
Richard
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Last edited by Rich400; 17th Jan 2021 at 12:31 pm. Reason: Spelling
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Old 17th Jan 2021, 12:59 pm   #144
Edward Huggins
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Default Re: Adding a selectable line input to valve radiogram

Thanks for this update. As to the original cartridge being a GC8 (Mono), it's unlikey that Decca would ever have fitted this into their then proudly announced new Stereo Radiograms, so it may have been substituted at some time.
As to using the interchangeable heads at different tracking weights, I guess you will need to to make the manual tone arm weight adjustment each time?
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Old 17th Jan 2021, 3:21 pm   #145
vidjoman
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Default Re: Adding a selectable line input to valve radiogram

The Decca SRG300, 1st of the stereograms, was supplied with 2 head-shells of which one had a GC8 mono and the other with a GCS10 stereo cartridge. I think they changed that to a Ronette BF40 at a later date. There was no need to change the playing weight as that was balanced out within the supplied headshells .
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Old 17th Jan 2021, 4:06 pm   #146
Rich400
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Default Re: Adding a selectable line input to valve radiogram

Edward you are more than welcome
Indeed the previous post is as I have found, this unit coming from the original purchasers family complete with documentation and boxed interchangeable headshells. One with a flip GC8 (78/45) and Ronette BF40 in the other for stereo. ( this one being DECCA branded).
I have retained these as original items and have purchased others as I have upgraded the system to mm cartridges and a pre-amp. The mm stereo unit being wired through the cartridge in series with pleasing results. This being part of the upgrade to WiFi and an additional EXT (2) input.
Richard
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Old 19th Jan 2021, 1:29 pm   #147
Rich400
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Question Re: Adding a selectable line input to valve radiogram

Could someone recommend a replacement capacitor for my turntable motor switch please?
I have attached a photo of the old wax one currently fitted.
Thanks in advance
Richard
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Old 5th Feb 2021, 12:45 pm   #148
Rich400
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Default Re: Adding a selectable line input to valve radiogram

Hi
An update of progress hopefully this will be of some interest, as I am nearing completion of my project.
The mods being completed, I decided to not tackle the servicing of the chassis, as I felt this is one area where an experienced hand would perform a better job. After some consideration it was shipped off to the excellent Rob Howard at the Vintage TV and Wireless Company at Norwich who not only changed out the elderly components (capacitors/resistors etc) stripped and cleaned the potentiometers amongst many other works. In discussion we arrived at a solution to update the safety to include a 160 VA isolation transformer, and earth the chassis. This fed via the RCBO mentioned earlier. The chassis was retuned with a wiring loom for the new TX and required no further work to install. I am very happy I took this to him and am very pleased with what I received for a very fair price.
I have attached a few photos but am limited to only a few per post and the resolution is not brilliant.
The final mods to complete are to add a sub plate amp at the rear to enable the two new 8" speakers I added to perform bass duty. I have tested this prior to a permanent installation and am extremely satisfied with the final sound from this gram. The server providing hi res music via wifi through this valve amp sounded very sweet through the original elliptical Celestion speakers, albeit with low frequencies tailing off at 160 Hz. The new 8" speakers set via the sub plate amp crossover to fill the missing low end nicely supplying frequencies down to 40 Hz. (tested using a frequency analyser).
I will post photos of this when I have mounted it permanently on the rear.
Richard
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Old 7th Feb 2021, 6:16 pm   #149
dave walsh
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Default Re: Adding a selectable line input to valve radiogram

Well that really is impressive Richard. Almost a work of Art! I think we were all a bit diverted by the unusual AC/DC circuitry which was certainly a bit different. I'd seen that sort of Auto-Transformer arrangement elsewhere but not really in a Radiogram! Overall it looks to be in mint condition ["cracking" as Wallace from the famous cartoon series might say!]. I think you should leave an account for your grandchildren to show them the work that has gone into it and also your determination to keep it absolutely safe for them.

Dave W
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Old 7th Feb 2021, 11:37 pm   #150
Richardgr
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Default Re: Adding a selectable line input to valve radiogram

Looks to me that you have very successfully given that unit a new lease of life, finding the sweet spot between originality, and sympathetic improvements for safety and sound.

And it looks good, too!
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Old 8th May 2021, 10:18 am   #151
Rich400
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Default Re: Adding a selectable line input to valve radiogram

Quote:
Originally Posted by dave walsh View Post
Well that really is impressive Richard. Almost a work of Art! I think we were all a bit diverted by the unusual AC/DC circuitry which was certainly a bit different. I'd seen that sort of Auto-Transformer arrangement elsewhere but not really in a Radiogram! Overall it looks to be in mint condition ["cracking" as Wallace from the famous cartoon series might say!]. I think you should leave an account for your grandchildren to show them the work that has gone into it and also your determination to keep it absolutely safe for them.

Dave W
Thanks everyone for their very kind words it is very much appreciated.
I am looking for a bit of help from someone who has experience with the 4HF type headshell (please see attached photo) I wish to remove the old original stereo cartridge (bought as a spare) and fit an audio Technica VM95SP with a AT XP3 high output cartridge. But I don’t want to damage the old headshell getting this cartridge out. I am pretty sure there are two small BA screws under the garrard logo that I need to access from the underside like all the others I have but not sure how to remove this old cart!
Has anyone done this before?
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Old 9th May 2021, 7:15 am   #152
Rich400
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Default Re: Adding a selectable line input to valve radiogram

All sorted out now.
The cartridge was held in bizarrely by screws hidden under the garrard foil logo.
Unusually this covered the screw heads which sat in the hexagonal holes where the 6 BA nuts usually sit. (Nut and screw positions reversed to normal)
I managed to remove this by pressing the screws upward from inside after “dismantling “ the cartridge. This enabled the foil logo to press out in damaged.
I hope this info is useful to someone with the same problem.
Richard
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Old 9th May 2021, 4:08 pm   #153
AD360 Rob
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Default Re: Adding a selectable line input to valve radiogram

Quote:
Originally Posted by Rich400 View Post
Hi
Thanks for the series of PM’s helping with this, and a public thankyou for these expert replies and assistance.
For the benefit of anyone else viewing this forum I thought it right to publish the result.
The Garrard RC121 Mk 2 was originally fitted with the GC8 cartridge which has a designed tracking weight of 7-10g and was originally fitted to my DECCA SRG600.
I think it’s reasonable to assume a mid point figure is attainable on this deck with improvements possible using a few tips.
I personally now have this tracking on 78’s safely at 6.5g and with the microgroove stereo records (33/45) tracking on an alternative head-shell fitted with a Ortofon OM pro-s AT 4.5g which is nicely Within it’s spec.
The main issue causing the tracking weight to be increased was the auto return mechanism. This was stripped out, cleaned in alcohol and polished. It was then given a very light wipe with a PTFE dry lubricant and reassembled. The tone arm pivots and shafts were given the same treatment.
This end result works well and I do not intend to try to reduce these figures any more as I am certainly satisfied with this result.
Thanks again those who helped out, and I hope this post may be of some help to others in the same position.
Richard
Hi Richard, I've followed your thread with interest, especially the part about arm friction in the RC121 record deck. (I have a number of these decks that all stick when the arm starts moving the auto trip lever) What PTFE dry lube did you use? I have seen WD40 branded stuff but tend to keep any WD40 strictly for automotive use.

Thanks
Rob
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Old 10th May 2021, 11:20 am   #154
Rich400
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Default Re: Adding a selectable line input to valve radiogram

Quote:
Originally Posted by AD360 Rob View Post
Quote:
Originally Posted by Rich400 View Post
Hi
Thanks for the series of PM’s helping with this, and a public thankyou for these expert replies and assistance.
For the benefit of anyone else viewing this forum I thought it right to publish the result.
The Garrard RC121 Mk 2 was originally fitted with the GC8 cartridge which has a designed tracking weight of 7-10g and was originally fitted to my DECCA SRG600.
I think it’s reasonable to assume a mid point figure is attainable on this deck with improvements possible using a few tips.
I personally now have this tracking on 78’s safely at 6.5g and with the microgroove stereo records (33/45) tracking on an alternative head-shell fitted with a Ortofon OM pro-s AT 4.5g which is nicely Within it’s spec.
The main issue causing the tracking weight to be increased was the auto return mechanism. This was stripped out, cleaned in alcohol and polished. It was then given a very light wipe with a PTFE dry lubricant and reassembled. The tone arm pivots and shafts were given the same treatment.
This end result works well and I do not intend to try to reduce these figures any more as I am certainly satisfied with this result.
Thanks again those who helped out, and I hope this post may be of some help to others in the same position.
Richard
Hi Richard, I've followed your thread with interest, especially the part about arm friction in the RC121 record deck. (I have a number of these decks that all stick when the arm starts moving the auto trip lever) What PTFE dry lube did you use? I have seen WD40 branded stuff but tend to keep any WD40 strictly for automotive use.

Thanks
Rob

Hi Rob
I am glad my posts have been of some interest to you.
First off I will answer your question, the PTFE spray is indeed by the WD40 manufacturer but NOT the common type we all have known for years.

The type I have used with great success is from their specialist range, and can be found by searching WD40 specialist dry PTFE lubricant. The easiest place to find it for me was my local Screwfix, but of course it is available elsewhere.

I can clarify what I did to my RC121 MK2 decks (I have now repeated this process with a second standby deck with the same results) I am not sure if this will be accepted by the more experienced element on here but this method was developed by trial and error and using my engineering experience, it works but its up to you. I would say that after reading it through if its seems like its a bit fiddly let someone else do it for you, its just what worked for me and I would hate to be responsible for anything happening to your decks.

Procedure

1. Fully service the deck and clean all old mineral oils/grease from pivot points gears etc using alcohol and cotton buds. I won't complicate things here with describing further.

2. Lubricate above with a good quality oil (with the exception of the auto return slide). No need to buy the ridiculously over priced oil from so called specialist suppliers, i used a high grade semi synthetic 10w 40 oil but fully synthetic is fine if you have some spare on the shelf. I would stay away from mineral oils if you can, to extend the service life (we are probably talking many many years with semi and synthetic oils in this application). Importantly purchase a fine dropper with extended fine metal tip and provide minimal tiny amounts of oil exactly to the point of interest. Ensure no oil goes anywhere other than where needed. I also used a graphite grease sparingly for the tone arm lifter slide and speed control cam selector. Make sure all the tone arm pivots are cleaned with alcohol and sparingly lubricated with oil.

3. Auto return slide - Access the auto return slide by the removal of the platter etc.
Remove the tiny 'C' clip holding the small copper coloured spring/bush/washer retaining the auto return slide. (be careful here to ensure none of these are lost) and lay out in order to reassemble in the correct order.
Lift out the two sections of the slide return mechanism and de grease with alcohol the top of the main drive gear they sit on, and both sections of the slide, and the shaft.
When these are clean from grease use steel wool (super fine - 0000 grade) and mirror polish the small raised sections of the slide mechanism that slide against each other. Do the same for the top of the main gear and shaft where the movement occurs. Then remove any tiny fragments of steel wool with alcohol and tissue.

When dry (use inspection gloves) take a clean piece of kitchen tissue and spray the PTFE dry lubricant onto the tissue (this will end up soaking in it) then carefully rub into the surface of the slides and top of the main gear until these are fully coated. They will dry quickly and when so, take a dry piece of tissue and polish again lightly.

Re-assemble the components dry with the exception of the tiniest amount of of oil on the shaft before fitting the slides back. There should be no oil at all anywhere here except a slight moistening of this pivot shaft, and the PTFE should be completely dry.

Repeat the procedure for the small arm that acts on the slide by removing its 'C' clip and application of dry PTFE as before on the sliding surfaces with a small amount of oil on the pivot.

Make sure the connecting levers and slides from the tone arm mechanism are suitably cleaned and oiled and its job done.

I use 3 different headshells each with a different cartridge/stylus combination for the job and there is no suggestion of skipping during auto return in any fitment.
they are:-

1. Stereo for 33/45 - Ortofon OM Pro-S wired in parallel mounted to provide a tracking weight of 4.2 g (which is just below its minimum tracking weight of 4.5-5.5g)

2. Mono 33/45 - Audio Technica 3600L wired in series for mono (using each stereo coil shunted) and tracking at 4.2g. (This is strictly above its spec of up to 3.5g but easily handles much more with good results) Wired in series also helps to match the higher output of the Ortofon and the XP3 cartridge and maintain a common output with the other headshells.

3. Mono Shellac 78 - Audio Technica VMN95SP stylus mounted on Audio Technica XP3 cartridge. As above this is wired in series for mono. This is mounted with a higher tracking (downforce) weight of just over 5g to prevent skipping on 78's. The XP3 cartridge gives a higher output than the standard VM95SP for output matching to the other headshells.

I hope this is of some help, i searched online and no one was giving away a good method to minimise the friction from this particular device, so if it works for you please feel free to share it.

Regards

Richard
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Old 10th May 2021, 9:06 pm   #155
AD360 Rob
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Default Re: Adding a selectable line input to valve radiogram

Richard, Thank you so much for your detailed procedure, as you say, no one else was giving up their secrets, I will follow your instructions to the letter and fingers crossed all will be well. All of my RC series decks are from suitcase players (Bush SRP31 qty 2 and Pilot Cavalier) so will be using a stereo ceramic, probably one of those chinese ones with the flip under stylus so I'm hoping that the decks will track those cartridges once your procedure has been followed (I've already serviced them to the extent of cleaning all the old grease off and re-lubricating with a good oil sparingly applied so they all cycle well and run at the correct speed )
I hope to get to it in the next week or so so will update you on progress.

Cheers
Rob
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Old 12th May 2021, 6:36 pm   #156
Rich400
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Default Re: Adding a selectable line input to valve radiogram

You are more than welcome Rob.

Let me know if you need any further clarification, I'm sure your cartridge will track securely during auto return once the friction has been reduced on this mechanism. I am not sure what weight the newer ceramic cartridges track at but the older GC8's that came with my gram were set to about 8g and my new MM cartridges now work with anything above 4g. (I dare not try less). So you should be well in i'd say!

Good luck!
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