[hcraig244]

Fortunately Beolover posted a blog detailing how to get to it which was a great help, lots of dismantling going on

 

• This reply was modified 2 weeks, 3 days ago by hcraig244.
• This reply was modified 2 weeks, 3 days ago by hcraig244.

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[hcraig244]

Ok

Parts have arrived from Martin and the exercise can go on removal of the carriage travel lamp isn’t easy

 

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[hcraig244]

Great news….particularly around the archive posts….so much knowledge and pictures contained therin

Craig

[hcraig244]

Ok….received 2 cartridges in the post, fitted one and balanced the tone arm to neutral then set it to 1.0 gram. With the platter drive connections unplugged I hit play….tone arm moved to the correct position and dropped…however the carriage refused to move forward when nudged inward…hit stop and the tone arm moved back to rest.

My view is that the tracking sensor lamp (like the << and >> manual operators) and possibly the LDR too has passed its/their best, tried again and this time measured the voltage to the lamp 14.68vdc…so good, concentrated on the adjustment screw and had some success….after several adjustments managed to get the unit to play over halfway through an album at which point it decided to stop and return to rest…did this a couple of times despite a number of attempts at adjusting the shutter….looks like everything else is functioning correctly however the lamp and as it will be exposed the LDR too will need replacing….the carriage isn’t moving forward every 2 or 3 rotations of the platter but will move forward after around 9 0r 10 rotations…clearly not good.

• This reply was modified 1 month ago by hcraig244.

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[hcraig244]

Mark

Thanks for the detailed explanation above, your bang on with the LDR / Aperture Sensor Drift in the Control Panel being responsible for the issue….and following replacement of the lamp and both LDR’s (changed them out as I was in there anyway) as detailed above, the set appears to be working fine. I still need to set the carriage travel sensitivity, as I have disturbed the original setting during the work carried out, will need a cartridge fitting to complete this…..watch this space ;¬)

Craig

[hcraig244]

Belt replaced with new one and re-assembly commenced, had to think about this as its a while since I took it apart ;¬)

 

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[hcraig244]

Replaced the lamp box cover and connected the control box up…powered up and with a disc on the platted hit start, everything operated correctly, the platter spun, tone arm moved the drop position, and it dropped onto the disc, with no cartridge so I hit pause and the tonearm lifted and waited for the next instruction..,,I adjusted the LDR adjusting screws and managed to get them both to around 560mv (should be around 600 to 700) so we’ll see…..it may be due to slightly different LDR’s fitted? however when I operated >> and << everything worked fine….so I’m calling this a win!

Just need to replace the carriage drive belt on this, replace the double sided tape on the wayward panels, set the carriage travel sensitivity once we have a cartridge fitted and this is done (famous last words I know)

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[hcraig244]

Separated the control panel PCB from the pushbuttons and de-soldered the two LDR’s and the lamp, soldered in the new components…the new LDR’s are smaller than the originals however I’m confident they will function correctly.

 

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[hcraig244]

New components have arrived….decided to replace the lamp and both LDR’s

 

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[hcraig244]

Lampbox cover back off…..the voltages at P5 pins 4 and 6  840mv  and 630mv respectively….and the pickup moved nicely across the platter and returned to rest….looking good.

New lamp and photo cells is my conclusion…unless anyone has anything to add? maybe replace the lamp alone would be enough?

Craig

[hcraig244]

Lamp box cover back on, adjustment screws would all the way out and could not get the voltages at P5 pins 4 and 6 below 1,5v and 960mv respectively…and the pick up moved its usual 2cm and actually did wander very slowly further in…

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[hcraig244]

However I was astonished to see the platter spinning and the pick up marching happily across the deck and back!

I have a very bright flourescent lamp above the workbench along with the desk top magnifier lamp, when I turned off the magnifier lamp the unit still functioned as above, when turning off the flourescent tube the pickup arm moved to the drop area and held up there….I will try later with the lampbox cover in place to see if it can be adjusted but having seen the above I’m thinking a new lamp with more lumens will be required, and in doing so i feel the photo resistors should be replaced at the same time….any advice Mark/Dillen?

 

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[hcraig244]

Connected the control panel back up with the cover still off the lampbox to view the operation of the lamp itself…I know these old incandescent lamps go off in time, and when I powered up sure enough the glow was a little subdued

 

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[hcraig244]

And again with the desk lamp switched off, again not very close but I’m encouraged by the change in resistance from lamp on to lamp off.

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[hcraig244]

Removed the cover from the lightbox and with a meter checked continuity across the lamp….all good, checked the resistance of the LDR’s with the light from my desk lamp on and got the following readings…not the same but they should be ok?

 

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[hcraig244]

Happy with the encoder signals from the drive carriage im looking at the forward/Reverse Scanning Sensors (Control Panel LDRs)..

not the best image i know, existing wisdom tells that if the voltage goes high at either P5 pins 4 or 6 a high signal will be fed to I1C pin 31 thus disabling the pick up arm after approx 2cm travel…..just what I’m getting

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[hcraig244]

And if I’m not mistaken someone has carried out a full recap too…

 

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[hcraig244]

Ok…..gone to full service position now!

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[hcraig244]

is there a problem with the site today? can’t seem to post pictures?

• This reply was modified 1 month, 3 weeks ago by hcraig244.

[hcraig244]

Right……measured the voltage signals above at R10 & R11 on the Beogram that is functioning normally, drive belt removed to enable the encoder wheel to be turned by hand, and the voltages measured are the same…0-2.9vdc so its looking very like the encoder circuit is working fine?

Craig

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