Vectrex is dead - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

SiriusHardware · 26th Jan 2025, 5:17 pm

Could you attach the original versions of those images in a .zip? I saved and zoomed in on the second one and it looks to me as though the audio input signal to the offboard amp is being picked up from the point shown in the 'mod' articles.

There are also a couple of messy flying leads (red and black) picking up power from way across the other side of the PCB

TonyDuell · 26th Jan 2025, 5:25 pm

This looks like the same modification :

https://int03.co.uk/blog/2016/02/06/vectrex-buzz-fix-enjoy-the-silence/

SiriusHardware · 26th Jan 2025, 5:32 pm

And at the same time, on the same site I found the service manual on, I found another which uses a slightly different principle - instead of replacing the onboard audio power amp, it takes the audio signal offboard, filters it using an op-amp, and then sends it back to the input of the onboard amplifier.

Both approaches are attempting to cure the same problem, but in slightly different ways.

https://wiki.console5.com/wiki/Vectrex_PreAmp_Buzz_Reduction

TonyDuell · 26th Jan 2025, 5:42 pm

Yes, I found that one too, but it doesn't look like Centrespot's board.

Since the replacement power amplfier module just connects to the speaker in place of the original wiring and picks up +5V, Ground, and audio from the logic board it's hard to see how it would stop the whole machine from working unless the dodgy soldering has somehow interrupted the 5V rail or something like that.

SiriusHardware · 26th Jan 2025, 5:46 pm

Intermittent short between +5V and 0V, either on the wiring / plug or on the amp PCB? The amp PCB isn't in an enclosure and doesn't look to be shrouded or sleeved in any way, if it was shoved out of sight under the mainboard it could have been touching anything. I think if it's going to stay it needs to be heavily heatshrinked or mounted properly so it can't go interacting with things it shouldn't.

TonyDuell · 26th Jan 2025, 5:53 pm

I thought Centrespot said in message#12 that the 3 power lines to the logic board were present and correct during the 20 second delay. A short from the +5V line to ground would shut down the associated 7805.

On the other hand it might have been touching a logic signal and forcing it high or low. But quite why it then cures itself after 20 seconds is a mystery.

centrespot · 26th Jan 2025, 6:02 pm

Quote:

Originally Posted by SiriusHardware

Could you attach the original versions of those images in a .zip? I saved and zoomed in on the second one and it looks to me as though the audio input signal to the offboard amp is being picked up from the point shown in the 'mod' articles.

There are also a couple of messy flying leads (red and black) picking up power from way across the other side of the PCB

Zipped photo of buzz-off

centrespot · 26th Jan 2025, 7:43 pm

The Vectrex is working as it should along with the buzz-off, there was a marked difference without the buzz-off fitted and was too annoying to leave it out.

The 20 second issue disappeared after the reset was sorted and before the buzz-off was discovered, the bad buzz-off connections seemed to only affect the lack of sound.

Anyways it's all working again, thank you both for your help and advice and I will try not to come up with anymore of these unusual issues; I can't promise though because I've hundreds more computers in my collection that need sorting

SiriusHardware · 26th Jan 2025, 7:54 pm

Can you say for definite what the reset problem actually was, or did it just go away after you manipulated the switch a few times?

Quote:

I will try not to come up with anymore of these unusual issues

Oh, bring them on, we are always interested as long as it's reasonably retro (and in this section, at least partly digital or something directly related to computers like monitors or cassette drives, etc).

The unexpected issues are often the most interesting ones to work through.

centrespot · 26th Jan 2025, 8:12 pm

Quote:

Originally Posted by SiriusHardware

Can you say for definite what the reset problem actually was, or did it just go away after you manipulated the switch a few times?

I would say that the repeated on/off of the reset button brought the Vectrex back to life.

As per thread #10 the crackle from the speaker made me wobble some of the cable/wires and that probably stopped the buzz-off board from shorting to earth. At that point I had video but no sound, I traced the speaker wires and noticed the red LED on the buzz-off board so I dragged it out from it's hiding place and after sorting bad connections I got sound.

centrespot · 30th Jan 2025, 9:47 am

I think I need some more advice on this Vectrex, it's working but not as it should.

Everyday since my last post, I have switched it on from cold and I get the following, after

5 seconds speaker crackle & CRT glows
10 seconds sound
40 seconds video
I then switch off at the volume switch and wait 10 seconds, after

5 seconds sound
10 seconds video

When I plug a cartridge in and switch on from cold (left at least an hour) it starts as it should.

SiriusHardware · 2nd Feb 2025, 8:01 pm

Sorry I missed the revival of this thread. Operation of the unit sounds normal / as expected when you have a cartridge plugged in. In real terms, would the user ever be likely to power the system on without a game cartridge plugged in?

If you do power the unit up and you wait for long enough for it to make sounds, what sounds does it make and what does it show on the CRT, when there is no cartridge inserted?

TonyDuell · 3rd Feb 2025, 3:23 am

There is a game in the internal ROM of the Vectrex so it's quite reasonable to power it up without a cartridge. I am assuming the sound and graphics you get after waiting are the ones for that game.

However due to recent events on this forum I am not prepared to spend much time thinking about or researching solutions to any problems posed here. (PM me for an explanation)

26th Jan 2025, 5:17 pm	#21
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 13,777	Re: Vectrex is dead Could you attach the original versions of those images in a .zip? I saved and zoomed in on the second one and it looks to me as though the audio input signal to the offboard amp is being picked up from the point shown in the 'mod' articles. There are also a couple of messy flying leads (red and black) picking up power from way across the other side of the PCB Last edited by SiriusHardware; 26th Jan 2025 at 5:33 pm.

26th Jan 2025, 5:25 pm	#22
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 6,062	Re: Vectrex is dead This looks like the same modification : https://int03.co.uk/blog/2016/02/06/vectrex-buzz-fix-enjoy-the-silence/

26th Jan 2025, 5:32 pm	#23
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 13,777	Re: Vectrex is dead And at the same time, on the same site I found the service manual on, I found another which uses a slightly different principle - instead of replacing the onboard audio power amp, it takes the audio signal offboard, filters it using an op-amp, and then sends it back to the input of the onboard amplifier. Both approaches are attempting to cure the same problem, but in slightly different ways. https://wiki.console5.com/wiki/Vectrex_PreAmp_Buzz_Reduction

26th Jan 2025, 5:42 pm	#24
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 6,062	Re: Vectrex is dead Yes, I found that one too, but it doesn't look like Centrespot's board. Since the replacement power amplfier module just connects to the speaker in place of the original wiring and picks up +5V, Ground, and audio from the logic board it's hard to see how it would stop the whole machine from working unless the dodgy soldering has somehow interrupted the 5V rail or something like that.

26th Jan 2025, 5:46 pm	#25
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 13,777	Re: Vectrex is dead Intermittent short between +5V and 0V, either on the wiring / plug or on the amp PCB? The amp PCB isn't in an enclosure and doesn't look to be shrouded or sleeved in any way, if it was shoved out of sight under the mainboard it could have been touching anything. I think if it's going to stay it needs to be heavily heatshrinked or mounted properly so it can't go interacting with things it shouldn't.

26th Jan 2025, 5:53 pm	#26
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 6,062	Re: Vectrex is dead I thought Centrespot said in message#12 that the 3 power lines to the logic board were present and correct during the 20 second delay. A short from the +5V line to ground would shut down the associated 7805. On the other hand it might have been touching a logic signal and forcing it high or low. But quite why it then cures itself after 20 seconds is a mystery.

26th Jan 2025, 7:43 pm	#28
centrespot Hexode Join Date: Jan 2021 Location: Eardisley, Herefordshire, UK Posts: 314	Re: Vectrex is dead The Vectrex is working as it should along with the buzz-off, there was a marked difference without the buzz-off fitted and was too annoying to leave it out. The 20 second issue disappeared after the reset was sorted and before the buzz-off was discovered, the bad buzz-off connections seemed to only affect the lack of sound. Anyways it's all working again, thank you both for your help and advice and I will try not to come up with anymore of these unusual issues; I can't promise though because I've hundreds more computers in my collection that need sorting

30th Jan 2025, 9:47 am	#31
centrespot Hexode Join Date: Jan 2021 Location: Eardisley, Herefordshire, UK Posts: 314	Re: Vectrex is dead I think I need some more advice on this Vectrex, it's working but not as it should. Everyday since my last post, I have switched it on from cold and I get the following, after 5 seconds speaker crackle & CRT glows 10 seconds sound 40 seconds video I then switch off at the volume switch and wait 10 seconds, after 5 seconds sound 10 seconds video When I plug a cartridge in and switch on from cold (left at least an hour) it starts as it should.

2nd Feb 2025, 8:01 pm	#32
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 13,777	Re: Vectrex is dead Sorry I missed the revival of this thread. Operation of the unit sounds normal / as expected when you have a cartridge plugged in. In real terms, would the user ever be likely to power the system on without a game cartridge plugged in? If you do power the unit up and you wait for long enough for it to make sounds, what sounds does it make and what does it show on the CRT, when there is no cartridge inserted?

3rd Feb 2025, 3:23 am	#33
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 6,062	Re: Vectrex is dead There is a game in the internal ROM of the Vectrex so it's quite reasonable to power it up without a cartridge. I am assuming the sound and graphics you get after waiting are the ones for that game. However due to recent events on this forum I am not prepared to spend much time thinking about or researching solutions to any problems posed here. (PM me for an explanation)