Paramount PMX repairs? in Oz?

[graham.hobart]

My PMX has stopped working. Does anyone in Oz look at them/ repair them? I think it's the motor board as the omni board light comes on but nothing happens after that. I know it will be expensive to ship from tas but its an expensive item.
Graham

[gregbradley]

You can probably get a replacement board from SB and do it yourself. It probably just plugs in and a bunch of screws.

Greg.

[graham.hobart]

they are out of stock at SB apparently

[PRejto]

I doubt anyone can repair the main board unless it happens to be a USB socket issue which is the weak link in these boards. Have you thoroughly looked at the USB socket?

If the board is toast, it is certainly user replaceable. You had best get in line at Software Bisque. You do not need or want to ship your mount over this kind of issue!

Good luck!

Peter

[Dennis]

If you do go down the board replacement path, check to see if you can fit the new beaut MKS6000 kit as an upgrade.

Probably expensive.

Dennis

[graham.hobart]

cheers Dennis, the MKS 5000 board is out and they have no date for shipping the new 6000 board that can replace it.

[Hans Tucker]

Have you tried to contact Peter Ward at ATS?

http://www.atscope.com.au/

[Peter Ward]

I have indeed serviced and repaired a number of Paramounts.

That said, if SB have no replacement PCB's (while I haven't checked recently, there have been legacy supply problems) that will be problematic.

If it was me, I'd not ship the mount and simply upgrade to the MKS6000 (kit available).

While I appreciate this will not be cheap, due the pathetic $A, it will avoid
shipping, assessment and repair costs.

[tempestwizz]

My PMX died after a couple of years of being idle.
Considering the potential shipping problems, I bit the bullet, and disassembled the unit. After removal of the main board, while there was nothing obvious, I made a very close inspection of the components under a bright light.
I noted slight discolouring on one of the components. With a multimeter it measured to be a short circuit across it. With assistance from SB they advise it to be a capacitor, 16v 10uF in value. I removed the discoloured component which was the cause of the short. Not having access to a suitable shop, replaced it with an equivalent tantalum discreet version I had with me.
After assembly, I powered up the unit, and was welcomed by the familiar ‘bing’. Quite smug with myself, I started moving the controls, but a minute or so later, there was a loud ‘pop’ followed by deafening silence!
Again I removed the main board, and again, after close inspection discovered another discoloured capacitor that presented a short to the multimeter.
Accordingly, I replaced that faulty capacitor (which SB advised was across the 12 volt power rail on the board) and tried again.
Again it powered up normally. This time, I’m happy to say, the unit has been working for several days without issue.
It wound appear those 16volt 10uF surface mount capacitors may be a bit dodgy with time.
I have attached a couple of pics from the first capacitor failure. The second failure hadn’t occurred in the pics, but when it did, the same discolouration was apparent.
Hope this helps. Brian

[wasyoungonce]

Brian

Check your power supply isn’t putting out too high a voltage and or noise/ripple. Let’s say if it’s a 5 Amp power supply (12v) use a load of around 10% to test it. Which means resistor of around 12-15 ohms (5-10 watts it’ll get hot) or a car light bulb around 1watt or qty in parallel. Again it’ll get hot quickly so don’t run test too long.

Measure voltage across the load (even a $20 Jaycar multimeter is useful) that it’s 12v and try it on AC to ensure PSU ripple Isn’t an issue or high.

The caps that blew were tantalum’s that are prone to over-voltage or reverse polarity and or high voltage ripple issues. The mfgr has spec’d the Tant capacitors fitted, voltage rating, very close to the input voltage level.

I’d prefer you use a 20-35Vdc tant capacitor(of same dimensions or SMD code size) as I think they spec’d them too low wrt to variances users power supplies may run at.

AnywY fwiw this is what I’d do. Tant’s (and electros) are a bit of an issue you are better to over spec the voltage rating required and buy long life high temp versions.

Anyway power supply’s can degrade in their output filter electro capacitors (as they dry out and their internal impedance rises (they start to heat) and they cannot filter as well) and this may/will/could be causing the issue you had so do check this power supply.

Electros used in PSUs by the industry are a real issue a bane of repairers as designers: lower specs, cheaper parts. Always use long life (2000-5000hr electros, 105 degree low impedance (unless audio stuff)) electros in PSUs even linear PSUs.

FWIW 10c or wisdom! Electros have been casing issues especially in switch mode PSUs since 1985~ around the time they started to appear.

Bren

[tempestwizz]

Thanks for the advice. The supply powering my PMX is the one that came with the mount and I had been using for around ten years.
My problem was with failing surface mount electrolytics. Possibly as they had been sitting idle for a while, or maybe a bad batch from when SB had their Mk5 boards manufactured in the first place. (Unfortunately, the seeing at my place in Laos is terrible, and the utilisation of my PMX for purely visual is way overkill. It sits idle mostly)
I questioned SB regarding other motherboards failing with bad capacitors, but there has been no response on that topic.
I just twigged that if indeed there were substandard electrolytics used on my board, then other users may have experienced a similar failure.
If identified as the cause then replacement of failed capacitors is a relatively simple and inexpensive exercise for an average electronics technician. Obviating the absolute need to rerun equipment to SB.

[wasyoungonce]

Brian those caps that burned were tantalum’s. Which are quite different to electrolytics but sometimes interchangeable.

But burning indicates heat or over voltage or capacitor has degraded. I have read moisture degrades Tant’s! Somewhere???. Here (AVX site) they are describing tantalum selection that the operating voltage is 1/3 or rated selected tant voltage ! Also leakage and ESR degradation of a tant can be depend on too low a voltage rating.

I suggest your Tant’s are too low in operating voltage selection and they do degrade with age. I’d suggest using 25v (or more) Tant’s low esr and low leakage for 12v (of course same form factor)!

From EEVBLOG:
[‘Things to watch out for with dry Tantalum caps:
over voltage = bang. Reverse polarity = bang, high age = eventual short circuit. ‘]

Your Tant’s looked like getting hot which is age, too high ripple, which lowers due to poor voltage selection. Use higher voltage rated versions.

But do check your PSU electros as well.

A bit of ordering wisely selecting and replacing with higher voltage ratings (than fitted ) low esr and as said check your power suppply as electros do age esr snd ripple output goes high. Which tantalum’s hate!

Buy from digikey or mouser (ensure search is or “in stock “. You can get free delivery orders over $60 Aud Same with E14 but they do anghh “fib” about their stock levels of their location. A few dollars spent can save you from headaches and indeed I do agree they did fit Tant’s that are failing early but probably due to reasons stated (or your 12 supply ripple is high from bad electros) Maybe even replace these “on spec as well”!

Easy enough to replace use 2 irons. Reflow each end joins with flux and fresh solder, reheat with twin irons lift out toss. Clean up pads with soder wick dipped in flux solder away. Take time try not to over heat them

Cheap irons will suffice or one good one cheap. Clean with flux solvent spray after fix with “fitch” (non conductive brush) brush or with Kim wipes .

Oh take pics before you start! You may be able to help others on this! Good luck if you need further advice, I’m not sure your level of experience but you sound confident and capable, …ask away.

Cheers FWIW, you have done well!

Bren