Manufacturing Errors

[Station X]

My favourite in a Racal SG VFO. Amazingly it worked for years, with this unsoldered joint, including in my ownership.

That one was obvious, but it's sometimes difficult to know what is a manufacturing error. Circuit details and component values get changed over the manufacturing period and changes aren't always documented.

I recollect a brand new Yaesu VHF Transceiver which had an incorrect value resistor fitted, preventing the receiver from working. It can't have been tested during production.

[G6ONEDave]

I had a batch of iec cables with moulded on plugs at both ends. Whilst doing an appliance test of the cables, every one failed the polarity test. I cut one of the 13a plugs off and fitted a screw on type and did the test again. The cable failed again on the polarity test. They must all have been wrongly connected at the iec end but as the owner did not pay much for them and did not want to return them, the cables were consigned to the recycle skip.

Dave

[The Philpott]

An early Avometer Model 7 stood out as being shoddily put together. A couple of missing screws (with no witness marks to indicate they had ever been there) incorrect bakelite moulding, and other faults. I believe it to have been put together in a shadow factory.

One Avominor had a totally wrong value shunt installed, and a lump missing out of the front of the bakelite facia. I believe this one may have failed QC then been deliberately whacked onto the corner of the workbench in the factory, before being consigned to the bin. Someone presumably retrieved it and installed a new movement, but never bothered to change the wrongly wound shunt. 80 odd years later i changed the shunt and it lives in the garage as a scruffy backup meter.

Dave

[duncanlowe]

First one I remember is a Fidelity CTV. Bought from Woolies by my parents, using the discount vouchers I got through working there. Not long after we had it, it started changing channel all on it's own. Could have been the remote itself but even with the batteries out it did it, and was getting worse (I ended up sitting under the telly to switch it back to the channel we wanted to watch). Repairman came out to fix it under warranty and said it was the remote control receiver the SL490 (?) but they were out of stock. Followed it up a couple of times and it was still not available. I found it was in stock at Farnell (I'd just got an account). My Dad contacted the repairers and asked if it was OK if we got the part and they said yes. But before ordering I felt I wanted to check it was actually the part we needed. My hunch was right, the TV used a different chip than the SL490, but while checking, the unsoldered pin was obvious. 5 seconds with a soldering iron fixed it.

The other not long after was a digital tuner. Fisher. Richer Sounds had it as a sold as seen, cheap. It had come back to them. Tuner worked fine, but the VF display was completely blank. That was fine by me, I only listened to one station. But when I got it home I thought I'd have a look anyway, nothing to lose. One pin on the VF had no solder. Again seconds of work to fix, and that one is probably still in the loft 40 years later.

[emeritus]

At Plessey in the mid- 1970's we had designed a PLL receiver for a military project and had a batch of 10 prototypes constructed in the prototype shop from the drawings. All the parts were obtained from our usual reputable suppliers. We had paid a premium to have them screened for compliance with specification as the assembly had to be encapsulated in potting Araldite prior to testing because the dielectric constant of the potting compound affected the inductance of a critical printed circuit inductor. None of the 10 worked properly on test. After laborously carefully removing the Araldite and checking the components, the fault turned out to be a batch of zener diodes, incorrectly labelled with the wrong voltage that the supposedly MIL SPEC screening hadn't picked up. I believe they reverted to in-house component screening for that product as a consequence.

[AndiiT]

Hi, I have had at least two (possibly more) Fidelity Playmaster tape recorders where the edge type combined tone on/off control had no operating spigot for the mains switch, the spigot being present on the volume/record level control instead.
From memory, I have only seen this on Four-track models with the edge type controls, the latter manufactured models being fitted with rotary ones, although I have encountered a two-track machine with edge controls however its tone control did operate the mains switch in the correct fashion.

Has anyone else seen this on Playmaster models?

Andrew

[Beardyman]

A while back I had an HMV 1115 which, after replacing the obviously duff parts, worked very well on the bench. Put it in its case, LW went almost completely. Took it back out, LW back loud & proud. Eventually I found an un-soldered wire on a coil in the LW circuit which, although it looked soldered, never had been. It was just sheer luck (or the occasional cabinet thump) that it ever worked. Had me scratching my head for a while!