Vectrex - Another one that has a missing -13v at cold start..

[kbj]

Hi All,

 

I'm repairing a Vectrex atm - and it has a weird fault same as the one in this post - thought that I'd create a new post rather than hijacking an old one..

 

 

If I leave the Vextrex off for a couple of hours, then plug it in and switch it on, I get audio but no picture.  If I leave it switched on, remove and reinsert the power connector J204, the Vectrex works, picture is back.. 

 

Work done:

• Recapped the whole Vectrex (power board, logic board and integrator caps)
• Replaced faulty 6522
• Taken the power switch apart, cleaned and put back in
• Replaced the 2 diodes and the 1 zener in the -13v power section.
• Checked all caps to make sure that they have continuity top and bottom on the board.
• Replaced the +5v and -5v regs (as part of the recap as I broke a leg on both removing them)

 

From the very start after a recap and replacing the faulty 6522, there's always been around 10.5VAC on each of the AC taps from the switch.  One thing I did note is that when measuring the 2 AC taps when there's no picture, both measure around 10VAC, when I remove J204 and reinsert it to get the picture to start up, those 2 taps then measure around 10.6VAC. (Probably not relevant)

 

I've also socketed and replaced the DAC, 4052 and LF chips and tried swapping them with new chips - no difference.  The machine works absolutely fine if I power it up and remove/reinsert J204.  Maddening.

 

Anyone any ideas as I'm just about out..

 

Cheers,

 

KbJ

 

[kbj]

Well, an update on this..

 

Looks like one side of the power switch is faulty.  Measuring the power switch with a meter, both poles read 2.2R (dead short) when the switch is turned on but it looks like when power is applied to the system, one of the poles passes the ~10VAC until there is a load, when it will sometimes just stop working.

 

Wiring across the switch on that pole and the machine starts every time.  I don't think I've seen a switch fail like that..

 

Oh well.. I'm going to have to try and find a switch that will work I guess..

[minwah]

I have one that has a similar problem - I think it's quite common. I cleaned the switch as I don't think a suitable replacement is easy to find.

[Carey85]

On 6/30/2023 at 5:33 AM, kbj said:

Well, an update on this..

 

Looks like one side of the power switch is faulty.  Measuring the power switch with a meter, both poles read 2.2R (dead short) when the switch is turned on but it looks like when power is applied to the system, one of the poles passes the ~10VAC until there is a load, when it will sometimes just stop working.

 

Wiring across the switch on that pole and the machine starts every time.  I don't think I've seen a switch fail like that..

 

Oh well.. I'm going to have to try and find a switch that will work I guess..

TE 23ESA103MMF50AF is your only viable option for a new power switch. It is the only DPST switch/10K pot that I could find after a LOT of searching. It requires some modifications to work, mainly cutting and filing of the shaft. I have a couple as spares. If you want one, PM me.

[kbj]

On 9/13/2023 at 8:19 AM, Carey85 said:

TE 23ESA103MMF50AF is your only viable option for a new power switch. It is the only DPST switch/10K pot that I could find after a LOT of searching. It requires some modifications to work, mainly cutting and filing of the shaft. I have a couple as spares. If you want one, PM me.

Hey Carey,

 

Thanks for the information - and thanks for the very kind offer, but since you're in the US, I would suspect that I'd be better getting this switch from RS in the UK (£10.30 +shipping)?

 

Looking at the switch, it looks like I'd have to cut down the shaft and reshape the 3 terminals that solder into the Vectrex PCB?  Is that enough to get it to fit?

 

Many thanks,

 

Mark.

[Carey85]

I don't think you would be able to reshape the solder lugs on the switch in such a way as to make them fit in the holes on the PCB. You would be much better off by just running jumpers from the lugs to the PCB which shouldn't be a big deal as the switch will be mounted to the chassis of the machine.

[kbj]

On 9/26/2023 at 1:41 PM, Carey85 said:

I don't think you would be able to reshape the solder lugs on the switch in such a way as to make them fit in the holes on the PCB. You would be much better off by just running jumpers from the lugs to the PCB which shouldn't be a big deal as the switch will be mounted to the chassis of the machine.

Think I might just get one of these and see how I can best make it fit.  Sounds like jumpers to the PCB would be the best bet right enough

 

@Carey85 Did you actually fit one of these in a Vectrex then?

 

Many thanks,

Mark.

[Carey85]

I did not. I thought I needed one after a lug popped off of my OEM switch when I was determinating wires from it to replace a transformer so I ended up buying a small lot of them for a few dollars more than the supplier charges for 1 and ended up not needing them. The one I filed down is up on ebay right now for essentially cost from a supplier. I have no reason to believe that it wouldn't fit, though. I'd bet you a Coke.

[kbj]

On 9/29/2023 at 7:10 PM, Carey85 said:

I did not. I thought I needed one after a lug popped off of my OEM switch when I was determinating wires from it to replace a transformer so I ended up buying a small lot of them for a few dollars more than the supplier charges for 1 and ended up not needing them. The one I filed down is up on ebay right now for essentially cost from a supplier. I have no reason to believe that it wouldn't fit, though. I'd bet you a Coke.

I've managed to order a couple of these from CPC Farnell in the UK - and when fitting either of them to the Vectrex, I get a bit of weirdness..

 

This is the item I ordered using your part number:

 

 

I connected it: INP side are the 2 RED wires (AC) from the mains transformer secondary inside the Vectrex.  The 2 OUTP wires go to the power board inside the Vectrex.  The white wire (centre) on the secondary of the mains transformer just goes straight onto the Vectrex power board.  After testing the switch, the 2 poles (P1/P2) of the switch are as noted on the picture below.  Testing this out of circuit shows the switch will switch these poles fine (DP-ST).  When in the Vectrex, when the switch is in the off position and I measure beween the OUTP side (any of the 2) and the centre from the transformer, I get 11.2VAC!  When I switch it to the ON position, I get 10.7VAC across the 2 OUTP poles... WTF?  Am I having a bad day??

 

 

Any idea what the heck is happening here?

 

I should say that I bought a couple of these switches and both do the same.

 

If I take either one of the INP connections off and leave the other on, the switch appears to work properly.. i.e. If i take the top one off, then the 10.5VAC will only appear on the corresponding opposite OUTP connection.!?

 

Think I'm going slightly mad here..

 

Mark

[Carey85]

That is a peculiar issue. I just got one of my switches out and wired a 9V battery across the two line poles on the switch and then ran some continuity and voltage checks and everything worked out OK. I'm a little puzzled that you are having that end result but I wholeheartedly believe you. Is the Vectrex powering on at any point during this ordeal or no?

[kbj]

On 10/14/2023 at 7:58 PM, Carey85 said:

That is a peculiar issue. I just got one of my switches out and wired a 9V battery across the two line poles on the switch and then ran some continuity and voltage checks and everything worked out OK. I'm a little puzzled that you are having that end result but I wholeheartedly believe you. Is the Vectrex powering on at any point during this ordeal or no?

I haven't actually tried to power up the Vectrex with this switch yet.  I'm assuming that it will just always be on regardless of the position of the switch.  The weird thing is that if I remove any 1 of the 2 input wires from the switch, it then starts to behave normally.. that's really weird.  I guess I could power up the machine and see what happens...  The other thing I find weird is the 11.2vAC across the switch in the OFF position which drops to 10.5vAC (or 10.7 sometimes) when the switch is turned on with no load..

 

I'm really not sure what the heck is going on - unless these switches behave differently with an AC voltage applied?! I can't see how though - a switch is just a switch at the end of the day..

 

Not sure where to go with this..

 

Cheers,

 

Mark.

[Carey85]

Yeah, I'm with you. I get the little bit of voltage drop just given that there may be a natural degree of resistance between the switch contacts. As for the actual behavior of the switch, I am quite puzzled. Especially considering that they are rated for a fair amount of voltage. Either way, it's a massive bummer and I sincerely apologize that you have looked for a pig in a poke. The genuinely crap thing is that said switch is the only thing even remotely close to what the Vectrex is looking for. Is there any possibility of you doing an RMA and being able to return the switches as defective?

[kbj]

On 10/16/2023 at 7:20 PM, Carey85 said:

Yeah, I'm with you. I get the little bit of voltage drop just given that there may be a natural degree of resistance between the switch contacts. As for the actual behavior of the switch, I am quite puzzled. Especially considering that they are rated for a fair amount of voltage. Either way, it's a massive bummer and I sincerely apologize that you have looked for a pig in a poke. The genuinely crap thing is that said switch is the only thing even remotely close to what the Vectrex is looking for. Is there any possibility of you doing an RMA and being able to return the switches as defective?

Right Carey... the weirdness just got weirder..

 

I put the new switch in the Vectrex and powered the Vectrex up for the first time and everything works beautifully.. and the voltage across the poles is no longer there in the off position!?! 😵‍💫 No idea what the heck is going on.. 

So, I took the second switch, tested that again and it showed the same issues as the first (wired up outside the Vectrex).  I then pulled another Vectrex out of the repair pile with a similar dead switch issue, wired in the new switch and it works fine!  I've no way to explain it.  When wired in circuit, inside the Vectrex, it works as it should.  Wire it up outside the Vectrex to test it (using AC) and it goes all wierd.

 

Anyhow, the take home from this is that these switches work beautifully once wired into the Vectrex - I've just placed an order for more of them to repair more Vectrex here in my workshop.

 

Thanks for all of the help Carey - the switch is a good find!

 

Mark.

[Carey85]

I love it when a plan comes together. Like I said, I spend a solid 2-3 hours digging through Digikey, Mouser, Newark, TME, etc catalogs just to find a switch that was remotely close and that was the only hit that I ended up getting. Good to know that there is a viable replacement out there for people that would be otherwise hosed.

[kbj]

Hey all,

 

An update to this thread...

 

The Vectrex that I'd replaced the power switch in has now reverted back to having no -13v on J204 when left off for a few hours.  If I then take the back off, power up the machine I get sound with no picture.  I pull J204 off and plug it back into the board.. voila! picture is back.. As long as I don't switch it off for more than a couple of hours it will switch back on again without having to remove J204.

 

I've recapped it (and checked that all caps have continuity top and bottom) - and replaced the integrator caps as part of the recap

I've replaced the +5v and -5v regulators as part of the recap (replaced the +5v reg with a 2A version)

I've replaced the power switch with a brand new one (see above in this thread)

I've replaced all the components in the voltage doubler circuit that produces the -13v

 

Run out of ideas.. it's almost like the action of unplugging and plugging in J204 'kickstarts' (for want of a better term) the -13v production (although I can't see how that could be)

 

I've also changed the socket that the DAC chip is in for a new socket in case it was an oxidised socket..

 

Anyone any ideas?

 

Many thanks,

 

Mark.

[miata505]

Hi kbj. I now found this phenomenon on 2 different Vectrex‘s and like you I was really clueless. All the voltages were good across the board. Just the -13V missing after a cold start. Found only -0,7V or so there. 
 

At the end of the day it seemed to be only related to a bunch of capacitors (C120,121,122) and a few diodes. The capacitors were already replaced, so I changed out the diodes D106, D107 and DZ102. 

 

That fixed the issue on both units. I cannot tell which diode was the culprit but I would put my money on a marginal working zener diode….

[kbj]

On 12/13/2023 at 7:25 PM, miata505 said:

Hi kbj. I now found this phenomenon on 2 different Vectrex‘s and like you I was really clueless. All the voltages were good across the board. Just the -13V missing after a cold start. Found only -0,7V or so there. 
 

At the end of the day it seemed to be only related to a bunch of capacitors (C120,121,122) and a few diodes. The capacitors were already replaced, so I changed out the diodes D106, D107 and DZ102. 

 

That fixed the issue on both units. I cannot tell which diode was the culprit but I would put my money on a marginal working zener diode….

Hey Miata,

 

Thanks for the info.  I've replaced all the components on one of them (C120,121,122) and D106,107 and the Zener and even the power switch for a brand new switch.  Still it shows the same problem.  I've even replaced J204 and the wiring up from that to the power board.  Pulling my hair out as if I pull J204 off with the Vectrex switch on, and then plug J204 back in, it powers up just fine - and will stay like that as long as I don't switch it off for more than an hour or so.

 

What diode did you use to replace the zener?  I just used a 13v 500mW - maybe that's not good enough and I needed a higher wattage diode?

 

Really no idea where to go with this one.  

Edited December 15, 2023 by kbj

[miata505]

That’s a good zener diode. The manual says 400 mW and that’s what I installed. 
One important thing I have learned when working on the Vectrex - replacing parts and de- and resoldering wires on the board may cause the vias not giving good contact anymore on the component side of the board although it looks good on the solder side (as we typically solder there). I believe it’s just due to the bad quality of these vintage boards.
Some traces are connected to the vias at component side. For example the trace between EP106 (where one wire comes from the switch) and C120. It happened to me that there was no good contact at EP106 (anymore) which caused an unstable system. Also found this issue on some capacitors I have replaced. So, you may want to double check your work and check on continuity between the parts especially on that -13V circuit. Maybe you have to solder the capacitor legs from both sides.

 

good luck and don’t give up 😁 My last Vectrex restoration took me 6 months and a lot of head scratches but at the end there were just missing contact issues (plus a faulty  IC401 and likely a diode).

Edited December 15, 2023 by miata505