ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Greetings all 4002 experts,
the arm-lowering/rising automatic does not work.
I refurbished the main-board by changing all trimmers and electrolyte caps -almost successfully:-)
After 'start' the Platter spins, carriage moves accross but does not stop at 30cm record.
It will stop when < or > is press, I can use the lift-function and plays fine until the arm reaches the run-out groove......again the arm remains on the record and does not automatically rise and carriage returns to its resting postion.
I noticed that I am unable to adjust the R88 trimmer,so 5V is achieved at 4IC1 collector as per SM request. !!?. The lowest voltage I can adjust to is about 9.55V
Pin7 of P5 shows 1.1V.
I have almost given up on any further fault-finding as I seem to turn in circles ?
Would be very happy if someone out there could feed me some new leads or ideas.
Looking forward to read your replies
Cheers ALF
Was this problem also present before you "repaired" the deck ?Are you sure, you fitted correct trimmers ? - Their values vary from version to version and are sometimes also differentfrom what's stated in the service manual.
Martin
Hi martin,
all trimmers for the 33-45 speed and carriage slow forward-revers were correct and achieved the required values - the R88 trimmer measures 25Kohm before installing it onboard ?!
I double and tripple-checked !
The automatic lowering worked before the refurbishment :-)
That is one of the points that puzzles me ! Has the foto-transistor accidentially died ?
wish I would have a clue or two.....
ALF
If the record is not sensed, the deck will not lower the tonearm, neither automatically nor manually.
Don't get me wrong, but if the deck was working, what made you want to "repair" it?Did you do other things or replace other parts besides the trimmers and caps?
Thanks for asking - in short: the table had serious speed problems.
After menahem refurbished one table for me I decided to purchase
The necessary parts from him to do the overhaul myself - all seemed straight forward !
Now I am facing multiple questions:
Why can't I adjust the 5V at the 4IC1 collector via R88 trimmer ?
Is 4IC1 damaged by receiving 9.6V plus at its collector and if it has been damaged,
Where can I get a replacement ?
Would that make sense in the absence of 5V ??
The automatic arm lowering was definitely working before,despite
Sorry, part2:
..... despite those speed problems !
The problem must surely be able to be isolated as it is either a matter of not detecting a record, or/and perhaps a fault on board4 with the foto transistor ??
Whatever it may be, I guess it would not make sense to replace 4IC1 in the absence of the required 5V ?!
There is also the question where I would find a replacement ??
Anyhow, would be most grateful to receive helpful clues, if not solutions, as I am absolutely stuck right now :-((
Love to read your replies - cheers
Good point about the sensing of a record!
I can confirm the arm can be lowered by stopping the carriage presssing < or > and then pressing the armlift, meaning in my case the detector arm must be sensing the record and it plays fine.
The only thing is the missing automatic arm-lowering function and arm-rising at the run-out groove.
Cheers - ALF
Hi everyone,
Thanks to all who were willing to help but could not find an answer :-):-)
I wish ii could tell you the reason behind that wheird problem but the table now works as it should.
After checking out the foto-transistor andand the LED on board 4 all seemed fine, putting everything back together
Installing the main board again!! , plugging everything back in and the P3 being the last one I heard a surprise click
From one of the relais, the carriage moved across an the arm lowered at the 30cm-record position ?????
Don't ask why ? I simply don't know !
The strange remaining issue is however that the 5V at the collector of 4IC1 can not be achieved via R88 trimmer !!
Beats me !!
cheers, ALF
Correction: 5V at 4IC1 are now present !!
Table fully working - case closed.
Enjoy you BO treasures!