Could someone sanity check my LM317/LM337 reg boards please?
I've tested them quickly today, but I'm getting some strange output results around 4.5v to 6v where I'm expecting 12v, so I've obviously done something wrong somewhere....
Here's what they look like
Here's Ray's 12v LM317/337 regulator schematic
and here's how I transposed it to make my boards
Output pins for my 317 boards go 3 2 1 and for the 337, 1 2 3, I was just going to flip the 317 board around when I fit it.
Can anyone spot a mistake? 😕
I've tested them quickly today, but I'm getting some strange output results around 4.5v to 6v where I'm expecting 12v, so I've obviously done something wrong somewhere....
Here's what they look like
Here's Ray's 12v LM317/337 regulator schematic
An externally hosted image should be here but it was not working when we last tested it.
and here's how I transposed it to make my boards
Output pins for my 317 boards go 3 2 1 and for the 337, 1 2 3, I was just going to flip the 317 board around when I fit it.
Can anyone spot a mistake? 😕
If you are testing them 'naked' on the workbench, you may have to add an extra output cap for the regs to work properly. Your schematic looks ok, so I'd expect the missing cap is the problem.
Ray
Ray
Thanks, that makes sense. Yes, this was a naked test, so to speak. I've gone over the schematic a few times now and I couldn't see why it should work any different.
I'll test them with a large cap across the output instead 🙂
Stupid question I'm sure, but have you checked the input voltage, it's going to need at least 14v input to get 12 v output.
Pete
Pete
With my 67 I just soldered a 75ohm inside an old rca plug and plugged it in the socket. Can't say I noticed any difference but it costs nothing and doesn't do any harm, and doesn't prevent further use of the digi.
From memory, most of the positive comments I've seen for this have tended to be related to older players then the 67 (and I think 63) though.
Pete
cheers Pete,
I'm feeding them off the supply to the original 7812 and 7912, so they're getting around +-28v
I'm trying to get my player working again after a few weeks of downtime. The output suddenly went dead. I opened it up and found the output section diodes were fried. I replaced them and found my -12v reg is putting out -24v! I guess it's just failed too :-/
I'll pop a replacement in tomorrow and see what I get.
I'll pop a replacement in tomorrow and see what I get.
I'm not sure why the voltage is so high. I have a 15VAC tx driving them. That should give me +/- 19VDC, right? Even that seems high for 7x12s - I think they're rated for +/- 15. I always thought they ran hot. What voltage output transformer and output regs are people running? I'm wondering if I should replace with 7x15s.
Ah no, it looks like LM7912s are rated for -19v, so if I'm right then I should be feeding them bang on their max voltage. I'm seeing -25v input though, so something must be wrong somewhere. Does anyone have any opinion on changing output regs to +/- 15v?
A 15VAC winding can give you over 20VDC after rectification and buffer cap. Also, most transformers put out a significantly higher voltage at no load.
See here: Rectifier - Wikipedia, the free encyclopedia
78xx/79xx series regulators can handle between 35 and 40V input voltage.
See here: Rectifier - Wikipedia, the free encyclopedia
78xx/79xx series regulators can handle between 35 and 40V input voltage.
Thanks Ray. So maybe I'll just replace the reg and see what happens. I wonder if it was dead for a while and that was why I had a slight mains hum.
I'm getting +-26v on the inputs of my 7812 and 7912 regs. Only thing I've changed is to swap out the rectifier diodes for Schottkey 11dq10.
Still waiting for my LM49720HA op-amp.
My fingers were itching to do some more mods. On this thread I had read about how C505 can make a big difference. So I bought 2n2 Polystyrene cap for replacement. I guessed that the yellow end is the outermost foil, so that end went at the output of the HF amp.
First impression sound wise: higher frequencies seems to be clearer, more attack and precision in the bass area.
Attachments
I got a CD63 today. that's my 3rd player.
Got it cheap, seller told me it always write DISC, even when one is inserted.
Of course, that's what happened when I put a disc. I tried again without disc, and with the player opened. Lens did not move. So I swapped the lens for one I have from my first player, working one, but that skip sometimes. Powered it up without disc : lens went up and down 😀
So I put a disc : immediately recognized.
I push play : works.
Next track : works.
Tried to compare with that disc, once in my CD57, once in this one.
Wanted to try another disc : detected.
Play : nothing.
Try again : same thing.
Try another disc : not found, shows DISC.
Another disc : shows DISC...
without disc, I still see the lens going up & down, but obviously something else is wrong.
What should I check ?
Got it cheap, seller told me it always write DISC, even when one is inserted.
Of course, that's what happened when I put a disc. I tried again without disc, and with the player opened. Lens did not move. So I swapped the lens for one I have from my first player, working one, but that skip sometimes. Powered it up without disc : lens went up and down 😀
So I put a disc : immediately recognized.
I push play : works.
Next track : works.
Tried to compare with that disc, once in my CD57, once in this one.
Wanted to try another disc : detected.
Play : nothing.
Try again : same thing.
Try another disc : not found, shows DISC.
Another disc : shows DISC...
without disc, I still see the lens going up & down, but obviously something else is wrong.
What should I check ?
It lives!
It's sounding good. I wonder how long my output stage B- was unregulated -24v :-/
I added a new PSU with separate windings for the decoder and servo control/CPU, bringing total PSUs in my player up to 7.
I also changed my grounding scheme for my regs from multiple local ground wires to a single wire running from my PSU PCBs to the star point. Far less mess.
It's sounding good. I wonder how long my output stage B- was unregulated -24v :-/
I added a new PSU with separate windings for the decoder and servo control/CPU, bringing total PSUs in my player up to 7.
I also changed my grounding scheme for my regs from multiple local ground wires to a single wire running from my PSU PCBs to the star point. Far less mess.
Luke2Fr: it sounds to me like the laser is on its last legs and you need to get a new one. I've had my CD63KI since 1999 and I'm on my 3rd laser. It's common for some discs to stop working before others when this happens. If you also hear skipping on a disc that works, that would most likely be it.
Hi,
Im doing the 50va servo tx @ the moment is regulating the chips with + and - 12v too
much ?. most do 8v or 9v im doing it in a similar manner to dwjames only problem is fuse holder 11 is pos and neg is 12 am i right .
thanks alan
Im doing the 50va servo tx @ the moment is regulating the chips with + and - 12v too
much ?. most do 8v or 9v im doing it in a similar manner to dwjames only problem is fuse holder 11 is pos and neg is 12 am i right .
thanks alan
Alan, I'm certain that 12v +- regs for the servos are fine. I think that's what Brent has in his recommended list iirc.
Not sure what you mean about problem with the Fuse holders, but I'll have mine apart this evening to fit Ray's DOS board, so just shout if you want any pictures or measurements 🙂
Not sure what you mean about problem with the Fuse holders, but I'll have mine apart this evening to fit Ray's DOS board, so just shout if you want any pictures or measurements 🙂