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Old 17th Nov 2014, 10:54 pm   #41
lesmw0sec
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Default Re: "Temporary" fixes.

Quote:
Originally Posted by SiriusHardware View Post
So in the end, what we did was to solder a 1M resistor and low value capacitor (20pf? 50pf?) in parallel, from the offending pin down to ground - effectively a 'scope probe simulator'. The last I heard, it was still working.
A similar, but more modern fudge. My rig (Alinco DX77) started not selecting the appropriate filter after the PA. Found that this was due to a poor logic level coming from a shift register. Managed to make it work OK with a pull-up resistor. The alternative would have been to change an extremely small SMD part.

This has been working well for at least six years now!

Les.
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Old 18th Nov 2014, 10:43 am   #42
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Default Re: "Temporary" fixes.

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Probably a floating input.
It was a long time ago (~1980), but I think it was a bus signal line - our theory at the time was that there must be some high frequency noise or very short spikes which the capacitance was flattening. Unfortunately we couldn't verify that because the very act of trying to observe it made it go away! The scope we had at the time probably wouldn't have been able to see it anyway.
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Old 18th Nov 2014, 12:52 pm   #43
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Default Re: "Temporary" fixes.

Even longer ago in the '50s temporary fixes were the order of the day as there was very little money about.

We had a Phillips 663a TV I believe it was, in for repair. These were a very advanced set for their time as although they had mains EHT they also had electronic picture shift controls. The picture was shifted almost off the screen horizontally due to the fact that one of the mains transfromer windings had gone open circuit, this supplied about 60v to the shift circuit, applied to the scan coils. Our senior engineer wired a 66v HT battery in circuit, one with press studs for those who remember them, worked fine but we had to go and change it once or twice a year.

Another common failure of those days was the EHT winding on the mains transformer, a new transformer was about £5 or a weeks wages so many people couldn't afford it, we devised a mod consiting of a paxolin panel mounted on which were a three TCC Visconal capacitors and two STC K3/45 stick selenium recifiers configured in a voltage doubling circuit, the input was connected to the top cap of the line output valve, they gave somewhat less voltage than the transformer but at least they gave a picture, even if you did have to pull the curtains to see it. We did that mod for about £2.50 and most customers were delighted.

You of course had to remove the old EHT winding as it had generally gone short circuit, that was done with the judicious use of a hammer and cold chisel.

Peter
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Old 18th Nov 2014, 1:44 pm   #44
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Default Re: "Temporary" fixes.

Back in the early 80's, our computer timesharing service once had memory bus problems. The problem never occurred while a scope has hanging on the clock line, so we ended up running all day with a scope probe loading the bus so it worked!
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Old 18th Nov 2014, 3:11 pm   #45
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Default Re: "Temporary" fixes.

In the early 1970's we were designing a PLL data link for a surface-to-air missile that was powered by a thermal battery. While the lab prototype worked faultlessly, some of the first pre-production batch went into a false lock condition as the power rails were rising from which they could not escape when the full voltage was present. We had visions of having to redesign the loop for better stability, but the senior engineer suggested connecting a diode between the loop capacitor and one of the power rails that, in the steady state, would have a voltage greater than the false lock capacitor voltage, but lower than the capacitor voltage when operating normally. This did the trick, the reverse-biassed diode had no effect on the operation of a properly-locked loop once the supply rails had stabilized, and the diode modification got upgraded from "temporary fix" to "design feature".

Last edited by emeritus; 18th Nov 2014 at 3:23 pm.
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Old 18th Nov 2014, 7:55 pm   #46
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Default Re: "Temporary" fixes.

A client has just told me he asked his technician to repair the switch on his microphone as it wouldn't stay in the 'on' position. The technician effected a repair by rubbing the sliding contacts with a partially-sucked boiled sweet.
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Old 3rd Jun 2015, 3:20 pm   #47
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Default Re: "Temporary" fixes.

Re reading this thread calls to mind a "bodge" I made when I was working as a trainee Electronics technician for the University of Bristol. One day they gave me a mains/battery capacitor tester to look at-that had been through all the other guys in the dept, with a very strange fault. It worked fine on mains, but on batteries smoke would pour out of it. Even more strangely it worked perfectly with a bench PSU connected to the battery terminals. The supply current was normal when running from the PSu, but absolutely mad when on batteries.
The solution? Break the PCB track from the battery holder and insert 10 ohm resistor. Worked perfectly after that, even on batteries.
Weird or what! Worked though!
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Old 9th Jul 2015, 9:49 am   #48
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Default Re: "Temporary" fixes.

Thought I would upload this here, although it's not really temporary as I have absolutely no intention of replacing it!

The electronic thermostat comprising of 2x PCB's communicating over I2C (1 with the controls and the other with the relays/SCR's) failed and the freezer started to defrost.

I initially bodged a temporary solution with an RS digital thermostat, but the freezer has a heater for the defrost function and a fan for the circulation. You simply can't run it without a defrost function for any length of time without it clogging the condenser with ice so I had to make one which mimic's the original function of the controller.

This is the one I made, comprises of a PIC 18F2520 Micro controller, LCD display, pot for temperature control, bank of 4x relays and a linear mains transformer (and a Bluetooth module added later).

It monitors the condenser temperature and the cabinet temperature, applies a 2 degree hysteresis, start-stop-interval timers and defrost counter (accelerated by delta-T between the cabinet and condenser temps). Has been in-situ for 8 months or so now and is working ok.
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Old 9th Jul 2015, 12:27 pm   #49
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Default Re: "Temporary" fixes.

Two of the worst bodges I saw was on a Philips K70. I was called out to one in the early 1980's for no sound. When I removed the back there was no audio output valve or base on the pcb.
Opening the chassis I found a valve holder on very long wires loose on the floor of the cabinet complete with valve.
I also noticed a large wirewound resistor on the back of the chassis had been replaced with a short section of electric fire element!
I replaced the valve without a lot of hope and was surprised by a complete cure to the lack of sound.
I advised the owner about the state of the set and made a hasty exit. making a mental note to refuse any future requests for repair.
I never saw the set again!
I still can't believe it worked in a state like that! How the amplifier didn't burst into oscillation or at least have loads of pickup hum I still have no idea over 30years later!

Rich.
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Old 9th Jul 2015, 8:42 pm   #50
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Default Re: "Temporary" fixes.

One post deleted. Gas is strictly off topic for this Forum.
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Old 10th Jul 2015, 11:39 am   #51
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Default Re: "Temporary" fixes.

The drum on my stand alone servis spin dryer is mounted on 3 small rubber 'tubes' with a threaded portion sticking out either end. One of these blocks had ripped in 2 and despite trawling the web and appeals here I have failed to find a replacement. As a temporary bodge I replaced the mounting bush with a single cable tie more to hold the drum upright rather than a repair but the wife having confidence in my repair ability went ahead and used it while I wasn't there and still uses it 2 years or so on. I have the feeling it's about to give up any day but I am amazed it worked at all.
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Old 10th Jul 2015, 1:09 pm   #52
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Default Re: "Temporary" fixes.

Try a car exhaust repairer. They use rubber mountings with threaded studs out of each end.
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Old 10th Jul 2015, 1:23 pm   #53
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Default Re: "Temporary" fixes.

Hi Terry

Have you tried:

http://www.ransomspares.co.uk/

Like probably most of the folk on here, I repair my own white goods as well those of my girlfriend etc. and have found Ransomes very helpful. They seem to be able to supply most bits for fridges, washing machines, tumble and spin dryers that I've been involved in fixing.

Usual disclaimer: No connection, just satisfied customer.

HTH

TimR
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Old 18th Jul 2015, 6:49 am   #54
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Try a car exhaust repairer. They use rubber mountings with threaded studs out of each end.
I did try a couple and found nothing suitable. Thanks for the suggestion and I've messaged ransomspares so thanks for that too flyingtech55

Last edited by terrybull; 18th Jul 2015 at 6:57 am.
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Old 18th Jul 2015, 12:36 pm   #55
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Default Re: "Temporary" fixes.

hi Terry, something like this perhaps?

Last edited by ITAM805; 18th Jul 2015 at 12:54 pm.
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Old 20th Jul 2015, 6:40 am   #56
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Default Re: "Temporary" fixes.

Quote:
Originally Posted by Peter.N. View Post
Another common failure of those days was the EHT winding on the mains transformer, a new transformer was about £5 or a weeks wages so many people couldn't afford it, we devised a mod consiting of a paxolin panel mounted on which were a three TCC Visconal capacitors and two STC K3/45 stick selenium recifiers configured in a voltage doubling circuit, the input was connected to the top cap of the line output valve, they gave somewhat less voltage than the transformer but at least they gave a picture, even if you did have to pull the curtains to see it.
Back in the late '70's I was Service Manager/Senior Tech running a TV workshop and we used a similar ploy to get old mono sets back in action for elderly customers.

We removed the EHT overwind, installed a CTV tripler, took the pulse feed off the line output anode, then adjusted the tuning cap value to reduce the EHT and produce full scan. The odd set fell a little short on width when the EHT was optimised (usually 17kV), so a small change in the S correction cap value and a tweak on the horizontal linearity would fill the screen nicely.

The picture was invariably brighter and sharper with this mod, and the customers loved it, so it was a win-win all round.

Cheers

Billy
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Old 20th Jul 2015, 9:23 am   #57
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Default Re: "Temporary" fixes.

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The drum on my stand alone servis spin dryer is mounted on 3 small rubber 'tubes' with a threaded portion sticking out either end. One of these blocks had ripped in 2 and despite trawling the web and appeals here I have failed to find a replacement.
Look up Wurlitzer speaker rubber bushes on eBay and if they look to be suitable I can provide you with some F O C in a week or two. I'm not able to provide a picture myself at this time hence my reference above.

Jim
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Old 21st Jul 2015, 6:08 am   #58
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Default Re: "Temporary" fixes.

They certainly look similar Jim but don't seem 'heavy' enough. Could you send me the dimensions particularly thread length and rubber size.
Thanks
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Old 21st Jul 2015, 6:11 am   #59
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hi Terry, something like this perhaps?
That's looking very close. I'll do some research. Thanks for this.
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Old 21st Jul 2015, 8:57 am   #60
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Default Re: "Temporary" fixes.

I can't get round to measuring them just yet but can remember that the threads are 1\4" UNC which may help you to estimate their size from that picture.

Four of the Wurlitzer jukebox ones are meant to hold an 18" speaker which even on full bass isn't going to violently shake about.

The 'mini' ones look more substantial I must agree.

Jim
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