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Hitachi CSP 680 - ex crustytv  

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EmleyMoor
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As lockdown relaxes, I've been able to get some kit moved around including the former crustytv Hitachi CSP 680.

An initial test has been carried out, with the following findings:

I could not find a signal with the channel knob in "1" - maybe it just needs more effort.

I was able to find my Sky+ box on channel 45, with the channel knob in 2. I could also tune to the output from a video recorder, which was modulating the HDMI from my AV amp, but was unable to get locked colour. My Panasonic flat screen tuned to it OK, so maybe the Hitachi doesn't like the signal from the video. (The Panasonic would not tune to the video's test signal, but was fine with the blue screen of "no input signal".)

I noticed also that the picture had reduced height, though I expected that from the blog.

Some electrical noise - a sort of sizzle - from inside the set was followed by some smoke rising - I switched off at once and it abated. It came from approximately centre right. There was no apparent change in the condition of the picture.

I did say I wouldn't be surprised if it perfomed well, but I'd be pleased if it needed attention.

I will take a look, probably on Thursday if not tonight, to see what is failing - I think it could be a capacitor on the filter PCB, or a component on the power PCB - but of course it's "at rest" for now. I have the service manual, so will likely be able to get it sorted without too much bother.

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 19/07/2020 7:22 pm
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EmleyMoor
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No smoke or noise yet on a further test. Maybe it only happens after it's warmed up.

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 19/07/2020 7:40 pm
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EmleyMoor
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OK, plan of action on the Hitachi is to give the right hand side of the chassis a thorough clean, and check for anything that shows visible signs of overheating. I also need to source some other kit to act as a modulator as it clearly disapproves of the signal from a JVC HR-S6700EK, at least on channel 41, and that means I can't get the test card on either.

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 19/07/2020 8:49 pm
EmleyMoor
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Sadly no success as yet - dust cleared from power side of chassis, and readily accesible areas on other parts, but now no results. Flowchart in service manual followed, still nothing. Full check through to transformer passed, and at least the degauss voltage (nominally 100V, actual reading closer to 120) is present. I really need to get new multimeter leads but my next plan is to check voltages. I have to say it's not easy to get at some of the parts and connectors, but then again it was rarely necessary with these sets.

I note that the locking compound on the +B ADJ (R911) is broken, though the position doesn't appear to have been disturbed. It is highly probable that my handling has done something to a component on the power side of the chassis, but it will probably be fixable as most if not all of the parts have a modern replacement. Working out how to release the power audio board completely, for testing, may be the next task. It probably won't be too diffficult, unlike access to the transformer.

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 23/07/2020 2:18 pm
EmleyMoor
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OK, found a definite problem - although it seemed to test OK on Thursday, F903 has failed - it tested dead today (after I removed the board) and one endcap came off when I took it out. It's not clear if there is an actual cause, and TR41 passes testing (as, on a non-conclusive test, do 42 and 43), so I guess the next thing to do is get a suitable replacement for this 1A fuse. (what's the best type for the job?) ]

I have also tried to test the connections to C905 (successfully) and R902 - couldn't actually get a reading on that and will have to dig deeper to test that, if it is needed.

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 25/07/2020 5:39 pm
Nuvistor
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Usually marked on the fuse caps what type of fuse, T = antisurge/time delay, otherwise standard.

Question. Did the quick blow fuses have a letter F marking?

Frank

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Posted : 25/07/2020 5:54 pm
EmleyMoor
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I will take a look at the caps but they are not always easy to read.

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 25/07/2020 6:53 pm
EmleyMoor
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It says 250V/1A on one cap, circled S SOC on the other. I'm guessing RS 668-5966 would be suitable.

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 25/07/2020 7:14 pm
Nuvistor
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SOC is the SOC Corporation of Japan, originally developed fast acting fuses But they would have made all types.

Cant find any information on the letter S, could be slow blow but could mean anything. If it’s in the HT line I would think Fast acting, in the mains input T delay or anti-surge. If you have the circuit, by checking other fuses on the circuit if it’s marked with a T is time delay otherwise Fast acting.

 

 

Frank

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Posted : 25/07/2020 10:47 pm
EmleyMoor
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@nuvistor No fuses whatsoever are marked T, and there are two present that are not in the diagram as well. (this one is in)

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 25/07/2020 11:52 pm
EmleyMoor
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Just placed an order with Farnell for fuses, a resistor for capacitor discharging and a set of alligator clip leads for shorting things out (e.g. to disable a colour killer) or making testing easier.

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 30/07/2020 1:35 am
EmleyMoor
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Just been spending some time with this set again. First job, check which of the two wires labelled "JE" was which, knowing one of them to really be "JG" - a resistance check from JA6 clearly showed much more resistance to the blue one, making this "JG" as I had guessed. New F903 fitted, set tried and it now gives a picture again. Sound is there too, but quite weak - this may be as designed, though. However, colour has gone. Connected an alligator clip lead between the brown wire at HB4 and the bare pin P30, this gave unlocked colour.

Managed to get the Sky box tuned to channels 2, 6 and 8, and the JVC video to 1, but discovered that the tuner seems to be hitting its "top" at or just below channel 44 on 8, and Sky can easily be lost from it. Tuning of 1 gets disturbed a little if I try to correct it. Some of the other channel positions may also be affected, and sometimes the knob is hard to turn one way. I think something may be amiss with the tuner, and it is something I'd like to keep as original as possible - it was one of the points of interest about these sets. Looking for a spare HU-548UK, ideally, but may well see if it's something simple that is affecting this one mechanically. (incidentally I haven't seen the tuning pointer)

Fortunately there's no smoke appearing, so I was probably right to blame the dust bunnies for that issue.

I adjusted my DVD/video machine to give 4:3 output, but I get a narrow picture. I am wondering if either the HDMI adaptor or the AV amp could be interfering - may try it out with the Mitsubishi soon, just to see what happens now, though I am not expecting colour from the JVC on this at present due to its gain fault.

As far as the Hitachi goes, if I am able to get a 4:3 test card from the DVD player into it somehow, I will work on its geometry - I also think the horizontal hold may have shifted slightly in the work on the power side of the chassis. The colour problem probably needs L1005 adjusted, but to go much further needs an oscilloscope - I don't currently have one, but to get it right in black and white may be possible until I can acquire one.

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 06/08/2020 1:17 pm
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EmleyMoor
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I think the "ring" part of the tuning knob needs to be replaced as the back of it seems to be partially missing - but it may be hard to find one unless off another PAL-1 chassis set (15 or 17").

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 06/08/2020 1:30 pm
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EmleyMoor
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Have found the right setting on the DVD player - so I will be getting the Hitachi set up to display a good black and white picture next (probably tomorrow, at least to make a start).

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 06/08/2020 5:07 pm
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EmleyMoor
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Hmmm... it looks like the raster is slightly off centre as the black edge I'm seeing on the right is the apparent limit of the scan - this may need a full reconverge. I have managed to centre what can be seen a little better, but it's still clearly (but not far) amiss. Adjusting the height clearly showed linearity to be out, and it seems R626 (SUB V.LIN) may actually need some adjustment, but this is hard to access. I will investigate the 120V line on the deflection PCB as well, as that can cause some twisting in the picture (and there is a little).

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 07/08/2020 12:46 pm
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EmleyMoor
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Before I go much further I will do some voltage checks around the power audio and power PCBs, maybe also the deflection PCB, while I obtain some tools for adjusting some of the coils on the PAL PCB. I am thinking a few components may be a bit adrift.

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 08/08/2020 10:16 pm
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EmleyMoor
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One odd point - on the circuit diagram there seem to be a number of "points of interest", but nothing explaining them - such as the voltage or waveform that should be detectable there. I take it the voltages near the transistor terminals are what should be between there and chassis, though, and that's where I intend to start on Thursday.

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 09/08/2020 10:03 am
EmleyMoor
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There are waveforms shown for similar points on the PAL-2 chassis in its service manual but fewer of them - if necessary I will have to match up the points between the diagrams.

"Yes, a bit of wet string may get you a good TV signal here on four channels, but you'll have to dry it out to get Channel 5!"

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Posted : 10/08/2020 9:49 am
1100man
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@emleymoor

I was given a slightly earlier version of one of these when I was a lad. The internal layout looks very much how I remember mine. I was amazed at the time, as I was used to the British sets that came my way. The likes of the Thorn, Rank, old valve black & white and hybrid colour sets.

The Hitachi was a complete change from all that. No great wire wound resistors, no charred PCB's, mains transformer (which I'd never seen in a TV before) - all the components were small & neat.

The Hitachi just seemed to function with no drama- it didn't seem to be straining at the seems and about to blow up like the British sets! Not even any heat or smoke! No leaks from the tiny no-stress LOPT either!

Just looked up Crusty's original pictures of this set and I must say it's a very good looking beast- very stylish!

Cheers

Nick

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Posted : 10/08/2020 4:20 pm
Nuvistor
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@1100man

They just worked as well, I never did but they could have be taken in the box to the customer home and work with virtually no setting up. Not something that could said of many UK sets.

 

Frank

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Posted : 10/08/2020 9:37 pm
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