1967 19" HMV Colourmaster 2701: BRC 2000 Chasssis

Very Nice!

Its good to see that these first gen colour-sets are still turning up--Gives me hope to find a 22" G6 one day!

I'll bet with a little TLC that 2000 will give quite excellent results.....

I have the same model set in my garage. Mine is a lot worse for wear.

I know Malc perched on the end of your Princess bonnet. 

Forty odd years in your garage, won't have been kind, much longer and it will be a basket case if its not already from what I saw. Remember the state of the Thorn 8500 and 9000 I recently repaired, if they are anything to go by you can certainly expect those sort of issues. I think if they had been stored another few years they would have certainly been right off's.

I must try and drag it out together with the 25 inch dual standard Ekco CTV which still lurks at the back.

Very nice indeed Chris A VERY worthy addition to the CrustyTV stable!

When I picked this set up as I mentioned earlier the faults were described as bad EHT tracking in three places placing the tripler as suspect and a decoder fault.

Decided not to fit my working triplers but spent the early part of the evening addressing the 2701 tripler and its EHT tracking.

I hoped it was not failing but just suffering the same issue as my other one which I fixed. In an attempt to cure this I used the same method as I applied to the 3700 tripler.

The entire unit was cleaned up using IPA, all lead-outs had the securing tape removed and were again cleaned. They were then secure with cable ties to the lead-out tags, encased in hot melt then finally sealed with self amalgamating tape.

The final anode output was cleaned in the same manner and also sealed with hot melt where it meets the Tripler body. The anode cap, CT8 claw were again thoroughly cleaned along with the anode and surrounding area of the CRT. I also discovered a nick in the main EHT lead this was sealed and also wound with amalgamating tape.

Powered on and absolutely no tracking at all EHT rustled up nicely and a full raster was presented. Fed in Test Card F, selected BBC1 and tuned to locate. Found the signal and I do have colour of sorts, bit difficult to photo as the set was in the conservatory as the workshop needs bench space clearing as I have the G6 and Fergy 3700 in there, but I wanted to see quickly what was what with this one.

It needs a bit of centring, height reduced, linearity and very much needs grey-scaling and convergence. But colour is there and likely just needs a scope on it to check set it up, all of which will be done in due course.

Moved the set from the conservatory to the ideal place now, the workshop, after last nights tripler repair the EHT remains stable and no tracking thus far, fingers crossed that's resolved.

The CRT tests good on all guns, looking at the colour issue and feeding in colour bars, the scenario seems to be wrong colours accompanied by hanover blinds. Certainly lots of things to check, clamp circuits, bistable 7.8 Ident and phase errors for the blinds. But first to read up on the grey scale procedure on the 2K, although its looking fairly good in that area, still no harm to run through it to be sure its at optimum and it may resolve.

Another incredible find Chris, how do you do it? Definitely looks lack of red to me also, check the A1 and cathode voltages .

Out of curiosity what type of CRT is fitted? Your A49-15X should be a drop in replacement, Is it too much to hope that the original has been replaced with a push through type during its life. Do see where I'm coming from?

John.

It is indeed and I'm ahead of you on that one John 

The colour fault would appear to be related to the grey-scale tracking not being set up, its not the whole problem but I need to address this procedure first.

Attempting the grey-scale tracking first resulted in me finding the set white switch was inoperative on the convergence panel, this was resolved.

Starting again setting tint to mid range, the three A1 pots to minimum, green & blue video bias to mid point with red ¼ turn from the full anti clockwise position. With the set white switch set to collapse the frame, I adjusted the video reference pre-set for 9.5V by monitoring via TP1.

Next is where it goes wrong, monitoring the voltage via TP2 I need set the red,green and blue video bias for 90V ( my video board is the Type 135) starting with red I cannot get the Video bias set to 90V, there seems to be a dead spot leaving either side well over, or well under. I believe the pre-set is flaky. For the time being I returned the bias to mid points and will see if I have any 25K pre-sets in the morning.

Just me and the tumble weed in the wee hours.. Ooops burning the midnight oil again 

Well that's already an improvement and shows its a drive fault rather than a real decoder fault. You'll soon have that resolved!

Progress update

The handy thing having two 2000 stacked on top of each other is a diagnostic aid. The Fergy 3700 is producing good colours so I used that as my test rig for the 2701 fault finding.

Putting the 2701 video board in the 3700 revealed all the drive errors, I did a quick rough and dirty set-up of the 2701 video board. This led me to discover R79 the 25k blue bias preset to be faulty. This was replaced, that allowed me to get the board producing good colours on test card F, Carols dress was red, the puppets green and the blue background, all good so far.

Putting the Video board back in the HMV 2701 the colours were all gone with just a heavily biased blued screen presented, then the raster would suddenly go blank. This was traced to the convergence board S2 & R35 of the Blue A1, replaced then and this resolved that fault. Now I was left with a grey test card with virtually no colour but wrong colours could be seen running through.

So knowing the 2701 video board was OK in the 3700, I removed the decoder from the 2701 and fitted the working decoder from the 3700. Happy days locked colour, so now I've isolated the fault to the 2701 decoder.

The picture below shows the 2701 working with its own video board but using the 3700 decoder. Next steps will be to start fault finding on the 2701 decoder.

That 2701 is gorgeous chris , I`m very envious .
Reading threw this thread reminds me why I like early colour sets so much , board swapping.
Life can be made so much easier if you can try another board to help find where the fault is .
I bet the rental company`s loved these type of sets with removable boards , you can imagine how quick service calls were.
Keep up the good work.

Robin

As I mentioned in the first post the TV is an early one the serial number of the set is 18xx so it would put being released in late 67. Here is the faulty decoder/chroma board, the DL1 glass delay line is dated March 1967. Now its time for the scope and get down to component level.

Progress update

The handy thing having two 2000 stacked on top of each other is a diagnostic aid. The Fergy 3700 is producing good colours so I used that as my test rig for the 2701 fault finding.

That rapidly became the normal way of isolating faults. It removed a lot of guesswork!

You can fix my faulty chroma board 

I thought from reading the thread on UKVRRR, Glyn sent you a couple of spare boards this time last year, were they faulty as well?

Surely you must be able to make one good one with what you already had and all of those. Failing that the decoder king himself, Mike Bennett ( Mikey405) offered to fix it for you if you sent it to him.

The spare boards are only good for spares due to damage. I dont fancy posting my only servicable chroma board anywhere, it could get lost. It is not easy working on the chroma board in these huge 25 inch sets. Not a problem, I will just use my 19 inch 2000 set for a source of spares.

It is not easy working on the chroma board in these huge 25 inch sets.

I disagree I think the 25" is relatively easy to work on, simple to hook the scope up and adjust coils and presets. You want to try and service the 19" its a total nightmare to access with the chroma board covered by the PSU regulator.