Bush TV22 No EHT.

[Ed_Dinning]

Hi Chaos, PM received.
Ref the LOPT, one of the biggest problem areas with this is the primary windings developing shorted turns or going down between windings. The overwinds are normally good unless they are operated when damp.
The primaries are not, unfortunately, a simple winding. the positioning of turns etc is quite critical to the self/ interwinding capacitance and correct operation.

Ed

[Chaos]

   
Managed to repair Horizontal Form transformer ! all back together again and i have a raster. Still need to sort reciever section, but before i do that i need to get going on my Hedgehog converter !

[ppppenguin]

Well done. You now know that the critical components are working OK.

Have you bought the bits for the Hedghog yet? You also have the option of getting an Aurora which is a simple "plug and play" solution.

[Chaos]

I have the PCBs (5off) and i have ordered some of the components modulators from china (just been reading about duff Chinese components) I also ordered a book of 1% 0805 resistors. After i ordered the PCBs i noticed there was a hedgehog II but i didn't fancy soldering the FPGA as i don't have the correct equipment or eyesight to do that kind of thing anymore. I can just about manage the resistors and as they are in a book will know the values. I used to be able to read the numbers on 0805 resistors with no glasses (many years ago). Worked in avionics and used to have a plastic cup of them on my bench that i would pour out and sift through with a cocktail stick for the required values. I thought about Aurora but due to the cost i will build the Hedgehog, but looking at it now i don't think there will be much in it cost wise. But a couple of quid here and there is easier to hide from Mrs Chaos than the Aurora in one go! The Aurora dos'nt seem to come up for sale second hand very often, i suppose it is a niche market. Might have to go the Aurora route though, once all my duff IC's arrive from china. I am going to Keep 2 of the PCB's. The other 3 are up for grabs if any one want's them.

[ppppenguin]

Probably a bit late now, but Stephen Evans in Falmouth will sell you a fully assembled and tested Hedghog for less than the cost of an Aurora. ISTR about £150.

Incidentally, if you do want an Aurora I'd not delay too long. They are available "off the shelf" at themoment but there's no assurance that it will remain in production for much longer.

[`FRANK.C]

Hi Chaos
With your experience of SMD's you should not have any trouble building Hedghog but if you do there is plenty of help on here.
I wouldn't be overly concerned about about duff modulator chips. There are some around but the vast majority that I have received are OK.
There is not a large difference between Hedghog and Hedghog II. The biggest is that Hedghog II can be used as a System A modulator.
The main reason for Hedghog II was that some that built Hedghog received poor or faulty EP2C5T144 development boards. It appears that the quality of the development boards available can vary a lot. The main trouble with them is poorly soldered components.
At least the board is pluggable so easily changed. As far as I know the boards that do work keep working and haven't gave trouble.

Frank

[Freya]

Hi Chris,

I'm happy to fit the 5150 to your HH board, that's the hardest part to get right.

Stephen

[Chaos]

That is very kind offer, and i may take you up on it. I haven't done anything that intricate for quite a few years, and back then my eyesight was much better. I also don't have all the correct equipment, not even hot air gun at moment. One way i used to do these was by tacking a couple of legs to get it held in position, then use a wide spade bit in a metcal iron and completely "Flood" one side at a time with solder, then comb all the access solder away. Some times if they wasn't lined up exactly, i would use the hot air gun to reflow them, tapping the board gently, and they sort of float into the correct position! Looking back i don't know how they survived all the heat ! Maybe i was just lucky.....Where do i send it ?
Chris

[Freya]

will send a PM