if the erase head is O.K. I would check:
- the shielded cable to erase head for open or short or solder joint
- the tank circuit for broken wire or solder joint problem with secondary coil or with cap .022
- or this cap itself
- cable shield usually is a mesh made from thin wire, inspect with a magnifying glass for tiny whiskers or single strands on both ends of cable which could cause a partial short ...
happened to me more than once ...
- the shielded cable to erase head for open or short or solder joint
- the tank circuit for broken wire or solder joint problem with secondary coil or with cap .022
- or this cap itself
- cable shield usually is a mesh made from thin wire, inspect with a magnifying glass for tiny whiskers or single strands on both ends of cable which could cause a partial short ...
happened to me more than once ...
I have now changed the shielded cables , still no luck, do you think the 220 and 150 caps are UF or PF? I've probably put the wrong ones in , I've also disconnected the screen wire from resistor 68k and that's made no difference as well as changing the valve,, I did notice however that as the voltage surged on initial switch on the ptp went right up then back down again
The valve isn't the problem, as it oscillates at the correct frequency.
120 and 150 are pF, pico-F, they form an AC voltage divider for the 100v pre-magnetising bias for the recording head.
Caps with a dot .xxx value are uF, micro-F, so you have
.0022uF=2.2nF, nano-F.
.022uF=22nF
.0047uF=4.7nF
120 and 150 are pF, pico-F, they form an AC voltage divider for the 100v pre-magnetising bias for the recording head.
Caps with a dot .xxx value are uF, micro-F, so you have
.0022uF=2.2nF, nano-F.
.022uF=22nF
.0047uF=4.7nF
I'm now getting 54khz 80v ptp on the 00.22 00.22 section but it doesn't get past the 220 150 section , I'm also getting 30vptp on the erase, thankyou for your help
It's now just over 100v ptp on the recording head and 30v on the erase , the recording is very faint
Could you replace the erase head with equivalent L. Just cause its resistance is correct does not mean it does not have a shorted turn.
I only say this cause I had the same problem and had to replace it (not on your unit though). I think if the coil was faulty it would not oscillate at all.
It sounds strange but I think the oscillator is pulling current away from the first ecc83 valve as the guitar sounds really awful ( just through the machine without the echo ) like the valve isn't getting enough juice, tomorrow I'm going to take the el84 out to see if the sound improves
If the record bias is too low you will get something like crossover distortion which will sound bad.
The transformer has given up, the ez81 was roasting , now I need a new transformer, what would you recommend 200ma?
Thanks for your help
Thanks for your help