XL500 sample timing

[ahmet19]

Errata in design of pro-TR (posting #190):
1. The resistance of R7 should be lower ohm for fast charging and discharging input capacitance of Q1.
2. Tere is no point connecting R41 to R39 & R40.

ok..
1.R7= 100R~470R
2.you're right, I was doing a drawing error

[selim]

xl-500 analog

http://www.geotech1.com/forums/showthread.php?t=12840

[mikebg]

Errata in design of pro-TR (posting #190):
1. The resistance of R7 should be lower ohm for fast charging and discharging input capacitance of Q1.
2. Tere is no point connecting R41 to R39 & R40.

[ahmet19]

xl500 digital

xl-500 full digital

[mmlove2007]

please uplodae full cicuit

thank you

[pebe]

Micheal,
You may be interested in this free software that makes your PC into a oscilloscope, using the sound card in your PC.

http://www.zeitnitz.de/Christian/scope_en

The 'scope has a limited frequency response, and is intended mainly for audio circuits. But will probably give you a fair idea of what's going on in most MD circuit.

It also has a frequency analyser for frequencies up to 20kHz, which you can use to measure the frequency of an oscillator. There is also an audio oscillator.

As I said, it is limited in its use, but -heh - it'd FREE. So why not dowload it and try it? Take note of the need to use a resistive attenuator if the circuit you are measuring exceeds 5V.

[mmlove2007]

i can old pcb in pdf file

is not pcb xl500

[homefire]

Hello to all Dear

If someone has a circuit xl500 Please complete this section to upload files together with Pcb

Go back through the pages of this thread and you will find it all.

[mmlove2007]

Hello to all Dear

If someone has a circuit xl500 Please complete this section to upload files together with Pcb

[Micheal]

Sorry I dont have the correct schematic for this model ,and I cant find it anywhere on the internet.It will make things a lot more easier if anybody has it.

[Qiaozhi]

There are similarities but it is not the same one,(i am currently considering throwing the whole thing in the rubbish bin,but sledge hammering it first)

Do you have the correct schematic?
If so, please can you post it here?

[Micheal]

There are similarities but it is not the same one,(i am currently considering throwing the whole thing in the rubbish bin,but sledge hammering it first)

[Qiaozhi]

the schematics you have drawn the parts on is different to my xl500 if you have a look at my photo.The 3055 in mine is a RFP8N18L and on mine there is no MPSU60(I couldnt find anywhere on the net a schematic for this version of the xl500 )

Here's the schematic I have in my data archive. Is it incorrect?

[Micheal]

the schematics you have drawn the parts on is different to my xl500 if you have a look at my photo.The 3055 in mine is a RFP8N18L and on mine there is no MPSU60(I couldnt find anywhere on the net a schematic for this version of the xl500 )

[Qiaozhi]

Thanks for your help guys...please bare with me ,I dont have a scope and I dont know how to use one .Thats why I try to use this elimination method to fix things and a lot of the times it works ,Which ones are the output transistors are they the 3906 little buggers becuase I have replaced all of them I think there was 5 and the 79L05 and all the 2 black and all the blue capacitors in the picture I have tried a new lm555 I am trying hard to trace it down but i just cant find it ...I have attached a picture of the board which one is it in the picture

The TX transistors are shown in the attached schematic, and the component layout. I would try replacing these first. Please also check that you have the transistors in the right way round. This may seem obvious, but the pinout depends on the country of manufacture, even for the same part number.