Scandoubler problem - hardware fault?

[Amiwin]

Yes, it clips onto Lisa, but has no hole. It is a PCB with a chip socket underneath, with a cable that goes outside the amiga case to another PCB which has a VGA connector and a connector that goes into the Amiga RGB port.

"My external SD/FliFi crawls because of warming up, needing trim pot use if I want a good picture as cold as well as warm, too. "

What do you mean by the above?

Thanks.

[PiR]

Hi

I experianced and am still facing some mysterious problem and have only one explanation wich might be helpfull for you:
The POWER.

Yes, the power consumption seems to change together with the temeratue. Loosing the synchronization for me is obvious - the signal is too weak to be properly interpreted by the monitor.

I don't know what to advise - I didn't solve my problem yet. :-( But: I do have 250W PSU, so its not THIS problem. I guess that voltage is dropping down on the way through these paths on the MoBo.

I'd be really glad to hear that you've solved your problem and especially: HOW? :-)

[Amiwin]

IT'S FIXED!!! IT'S WORKING FINE!!!!!!!

I want to worship Zipper.

How I fixed it? 4 pieces of blu-tack, and a nice large brand new CPU fan.

I've tacked the fan onto the scandoubler and it's been running for at least an hour and a half with NO PROBLEMS!!!!

It's a miracle... I am SOOOO chuffed.

A little active cooling goes a long way...

Still, i wonder why its overheating in the first place. Maybe my power supply? I have just finished my towered amiga so it's using the PC power supply.

I don't know. Anyway its working great now and I'm over the moon.

Many thanks for all your help - everyone. :-)

I love this site.

[zipper]

During the tube times many electronic devices tended to drift away from precise tuning point - I still remember our table radio, which needed some re-tuning at some intervals. They had to develop AFC ciruits to keep things spot-on. And then came the transistors, which should be insensitive to heat...Btw, my analog transistor tuner still has an AFC. The digital devices should be better, but even the quartz oscillators drift because of heat - the better wrist watches do have a temperature compensation circuit. Some A1200s are more susceptible to heat than others, developing GFX glitches. And external scandoublers are housed in very tiny packages, developing drift when warming up - hence many of them have trim pots.

[Amiwin]

Thx v. much zipper, that explains a lot of things now :-)

That was some very informative info and I'm just so pleased that its all working again.

The fan is quite big... it seems to be cooling some of the other custom chips down :-) That can't hurt!

I'm now tidying up my lovely new tower A1200! Now complete with scandoubler :-D

I'll post some pics if you want! :-)

[Stedy]

@Amiwin:

If you have the DCE built scan-doubler, I know why it overheats.

I have the external model and it uses 3 by 12-5V regulators to power the electronics. When you drop from 12-5V using a linear power regulator, the unwanted volts get lost as heat. On the DCE boards, the regulators use the PCB as the heatsink. The Whole PCB would just be enough for the regulator that powers the fiels and line buffers but there are 2 more converters!

As a result, the PCB heats up, components around and in the case heat up. I measured an ambient temperature of 55C on my scandoubler before I added a fan. Once done, my screen bleeding problems disappeared. These scandoublers also dump a large amount of 15 KHz noise on the 5V power bus due to inadequate decoupling!

Bye,

Ian

[Amiwin]

So, should this present any long-term effects... will the noise on the power line affect anything?

Is the overheating a design fault or my use of a PC power supply?

Sorry, I'm no electronics expert and I'm afraid the first part of your post; I couldn't understand it.

Thanks :-)

[Stedy]

Hiya,

I should have switched geek mode off before replying!

The power line noise was just an observation, it should not affect the Amiga.

The overheating is a design fault.

On a related note, I am designing my own scan-doubler, what interest is there in such a unit?

[Amiwin]

I'm certainly interested! :-)

Keep me informed on this project :-D