poynton said:
I have used them lots of times without incident. (That includes three VAM1202s). Always arrived within 24 hours via 1st-class post. Not quite sure how they manage that trick! Mind you Wembley to Paddington isn't exactly far.
I just don't understand where they get some of these chips from. There are fake TDA1541A chips out there too, though I think that was just standard ones being printed with single/double crowns. One has to be careful that's all.
Thomo said:
No, these are supplied from 1x12v extra tx. The regs are perfect, I have tried them on another circuit and they are good. Everything worked fabulously until the coax mod!
When you say i'm getting dc both sides of the cap, do you mean c505? If so then I think I got it wrong. I'm getting 4.2v on one side and 0v on decoder side.
Lee
I don't get how the DC levels can be wrong both sides of the cap that's all. Decoder HF in should float at 2.5v - I would concentrate on this for now. Is the decoder supply also supplying the RF PCB and HF amp? You may be drawing excessive current here for some reason owing to your coax mod going wrong.
Glenn2 said:
I believe I found my answer in a previous post by Elso Kwak. Here is the accompanying schematic.
Regards,
Dan
dantwomey said:
I believe I found my answer in a previous post by Elso Kwak. Here is the accompanying schematic.
Regards,
Dan
Don't forget in this machine if you disconnect the SM5872BS DAC you disconnect the clock! No sound!
ever so slightly off topic: that "rarity", the Phillips double crown chip, can you give me the exact ref. on it? and is it a drop in replacement for whatever is on my 67'? I ask this because I had a 63se years ago and I seem to remember at the time I got a hold of one and put it in. I sold this player to a friend who couldn't care less and I could probably talk him into swapping chips (if it's that easy)Is this something worth doing?
It' s the TDA1541S2 - quite literally has two crowns silk-screened on the top as well as the serial number and production date. Good luck finding one these days though - last one on eBay went over $120, and there are fakes out there. It's only a quality-selected part from the standard TDA1541 production though - tested for the best linearity in the lowest bit (a very close second is the single-crown, 'S1' variant)
Very definitely NOT. It accepts I2S input (amongst others) but needs a 1/2speed bitclock (5.66Mhz), +/-5 and -15v regulated supplies, and outputs single-ended current, not voltage, so you'd need a completely different output stage design.
Get that far and it will stomp a modded CD63 though
What experience have any of you regarding burn-in time for opamps? My LM4562 have about 24 hours now and seem to be changing constantly. I know this is a contraversial subject. If you don't believe, spare me, I do! The "knackered" 627 started to sound much more musical after about 50hrs, even though they obviously had a problem (very timid bass).
dantwomey said:
In the stock player the clock oscillator is on the NPC DAC and is buffered internally and fed on to the decoder etc. Hence the CKO clock output on the DAC chip (384fs=44.1kHz*384=16.9344Mhz)
You would have to feed your Kwak Clock into the decoder (where the clock signal CKO from the DAC currently goes into it - CRIN).
Then take SCLK, WCLK & DATA from the decoder
I can see no obvious reason why this would not work.
If this worked this player would probably give you a low-jitter, non-oversampled, I2S signal. Digital nirvana for some.
martin clark said:It' s the TDA1541S2 - quite literally has two crowns silk-screened on the top as well as the serial number and production date. Good luck finding one these days though - last one on eBay went over $120, and there are fakes out there. It's only a quality-selected part from the standard TDA1541 production though - tested for the best linearity in the lowest bit (a very close second is the single-crown, 'S1' variant)
Very definitely NOT. It accepts I2S input (amongst others) but needs a 1/2speed bitclock (5.66Mhz), +/-5 and -15v regulated supplies, and outputs single-ended current, not voltage, so you'd need a completely different output stage design.
Get that far and it will stomp a modded CD63 though
Martin - is this interesting? See note 1. We can't set the registers but we can SELPLL. Is this the 1/2speed bitclock one would need for a TDA1541A (if one could get one)?
Attachments
Just checked the CD67 schematic.
If you disconnected the NPC dac, clocked the Servo/decoder at 16.9Mhz, you'd get I2S out and 5.65Mhz from CL11 by default as SELPLL is held low. CL11 is just sitting there unconnected.
If I'm right then this would drive a TDA1541A (with suitable supplies) of course.
If you disconnected the NPC dac, clocked the Servo/decoder at 16.9Mhz, you'd get I2S out and 5.65Mhz from CL11 by default as SELPLL is held low. CL11 is just sitting there unconnected.
If I'm right then this would drive a TDA1541A (with suitable supplies) of course.