radman
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Finished! Now knowing where to look (and finally examining the schematic) I found that the solder point at the base of TR31 was elevated (see dental pick in image “pre”) with the corresponding trace to R109 obviously broken. I placed a short bridge between the two points (Image “post”) and the brake function magically returned.
The turntable is now ready to be placed back in the case. Thanks to everyone who have generously offered comments and suggestions.
John M
Thank you. I’ll have another look at it for the brake.
Concerning the change in arm speed it sounds like I need to ignore that one. The first 8002 I restored slows down for the search but you are correct, it doesn’t need to do that.
JM
I forgot to mention that I reflowed at least 40 solder points on the PCB2 board and a few points under the platter but didn’t notice any changes.
JM
The second of two Beogram 8002s is one the bench. I do have a few pics to share later but these would be better if I could actually say something useful. Right now, I have restored it from no standby light to about 90+% functionality but I am at another impasse.
The unit needed a new IR emitter at the wormdrive encoder (I replaced the two sensors also but had no actual data to suggest that was necessary). LDR voltages are set at about 630 mV. I could not achieve satisfactory voltage at R72 on PCB1 so I tried replacing R64 with 10K and 20K trimpots. This did not help. Eventually, I tried replacing C19 with a 47mF/16V cap instead of the 1mF/63V cap originally on the board. Initially, I thought this had helped as it did achieve higher voltage at R72 but was unstable and the tonearm still occasionally set down on the platter without a record. I tested TR14, TR15 and TR16 but these were fine. Finally, I completely removed R70 and went back to the original trimpot at R64 (4.7K variable) and the original 1mF/63V cap at C19. This combination seems to work best as the tonearm now sets down properly with a 45 or 33prm record and does not set down without a record. However, there are still two remaining issues:
- When not finding a record at the platter edge, the tonearm does not slow down but continues to scan across at initial speed. However, if a 45 rpm size record is in place it DOES set down properly and plays through. I am not sure this is a big deal but I believe it is designed to slow down. The first of the two 8002s does this correctly.
- At the end of a record the tonearm returns properly and the turntable motor shuts off but the platter is not induced to stop and continues to spin freely. Again, not a terrible problem but I cannot figure out why it won’t.
So… if anyone has some ideas, I would love to hear them. I am way past my knowledge base on this and probably made some mistakes in the above discussion. Again, Sonavor has been very helpful, obviously having been through possibly every issue this turntable can toss out.
John M
Success! A new IR emitter at the wormdrive encoder set it right. Now all functions seem to be working and it sounds great with just a used MMC3 cartridge. Hope to upgrade that soon.
Sonavar’s advise was extremely valuable. I doubt if I could have fixed this without his excellent posts. For anyone attempting to repair one of these 8002’s (and particularly starting as a novice such as myself) check out his incredible online instructions… concise and with great pictures showing exactly where to place probes for testing. I do have to add that after all the work with components open on the bench I thought I was never going to get everything crammed back into the cabinet! JM
Just a quick update on the 8002 progress. Your information was quite valuable. To make a long story short, I have seemingly appropriate voltage at all the checkpoints (R64 trimmer now maxed out) but still lack of complete function. It appears to me (and that is a big “appears” that the problem is related to at least one (at the worm drive) and maybe a second (at the arm) photosensor. Now waiting for parts.
Thank you for your help!
JM
Obvious typo above: PCB2 not PCB23.
Finally able to set close to 620 mV for <>. Beyond that, live to fight another day.
With your help I have made some progress. I had power to the main capacitors but intermittent 5V to the PCB23 cap. Someone had already done a recap but this capacitor was loose, After replacement the unit fired up!…
However, functions are not normal. It does not recognize a record edge and thus travels all the way to the end and gets stuck. Manually backing the tonearm with the worm drive will release it and allows for <>, play and stop functions but I cannot get a voltage at pin 4 or 6 of P5 at all.
Seems encouraging at least.
Probably stupid question… the short shielded black cable extending from PCB2 to a pin next R12 on PCB1 was broken. The shield and internal wire derive separately from PCB2 but where would the shield go? I attached only the internal wire… just don’t know.
Thank you for your help!
John M
Fantastic help!! I’ll also see about removing the keyboard and checking the traces.
I haven’t tried to remove the keyboard for fear of breaking something.
